Transcript
Page 1: Impronte specie aliene inglese

ALIENS IN THEIR OWN LANDNon - native species:

responsibilities and solutions

Massimo Vitturi and Barbara Bacci

Page 2: Impronte specie aliene inglese

THE AUTHORS

Barbara BacciTranslator and wildlife enthusiast. Her work as volunteer and her studies in wildlife management brought her to collaborate withLAV on this report.

Massimo VitturiResponsible for the Hunting and Wildlife sector within LAV, he's been a member of the National Board of Directors since 2009.Vitturi often holds conferences on humane methods of wildlife control. He works with Italian and foreign veterinarians andbiologists to perfect new methods for the management of wildlife respecting the well-being of the animals and the interests ofthe stakeholders involved.

Editor Peter Oswald

LAV thanks the Cariplo Foundation for the propagation of this Dossier

Page 3: Impronte specie aliene inglese

Contents

1 - The Invaders 4

2 - The Invasion Process 5

3 - Resident Aliens 7

4 - Eradication and Control 9

5 - Towards a More Humane Management of Allochthonous Species 12

6 - Italy 16

7 - Social and Financial Implications 23

© COPYRIGHT LAVVIALE REGINA MARGHERITA 177 - 00198 ROMA

RIPRODUZIONE CONSENTITA CITANDO, ANCHE PER LE SINGOLE PARTI, LA FONTE: LAV 2013

Page 4: Impronte specie aliene inglese

1. THE INVADERS

“We are seeing one of the greatestconvolutions of the world’s floraand fauna.”

Charles Elton, 1958

When we talk about invasive alien species (IAS) we usually referto animals or plants introduced intentionally or unintentionallyinto a natural environment. The Convention on Biological Diver-sity (CBD), in its Conference of the Parties (COP) VI/23, defines“alien species” as a species, subspecies, or lower taxon, both ani-mal and plant, introduced outside its natural past or present di-stribution. According to Richardson et al. (2010), alien species are“those whose presence in a region is attributable to human ac-tions that enabled them to overcome fundamental biogeogra-phical barriers.” Other researchers have a different view. NedHettinger (2001), philosophy professor at the College of Charle-ston in South Carolina, proposes a more flexible and comprehen-sive meaning for the term, defining nonnative as “any speciessignificantly foreign to an ecological assemblage, whether or notthe species causes damage, is human introduced, or arrives fromsome other geographical location.”It is generally understood that when IAS start spreading theymight become a threat to local species and damage whole eco-systems, destroying their biodiversity and causing the extinctionof local species. Alien species can be harmful to autochthonousspecies in different ways: by competing over resources, such aslight, food, water, and space, by predating on them, displacingthem, parasitising them or by introducing new pathogens andparasites to which indigenous species are not adapted; and final-ly, by hybridising with local species, causing global homogenisa-tion (McKinney and Lockwood, 1999). Alien species haveimportant socioeconomic consequences for society. To estimatein probabilistic terms the percentage of an alien species beco-ming an invasive the tens rule is applied. According to this rule10% of imported species become casual, 10% of these becomenaturalised and 10% of naturalised species have a negative im-pact (Williamson & Fitter, 1996). Thus, in reality only a very smallnumber of introduced species eventually becomes establishedand has a negative impact on its new environment.All invasive alien species share characteristics which facilitatetheir colonisation of new habitats, such as rapid reproductionand high growth rate, high dispersal ability, phenotypic plastici-ty—that is, the ability to adapt physiologically to new condi-tions—as well as the ability to survive on a varied diet and indifferent of environmental conditions. These characteristics,matched with the vulnerability of some ecosystems, speed up theprocess of invasion.

At present, there is a global consensus that IAS represent a dan-ger. A new Strategic Plan was adopted by the COP 10 of theConvention for Biological Diversity held in Nagoya, Japan, in Oc-tober 2010. Other international bodies, such as The InternationalPlant Protection Convention (IPPC), the World Organization forAnimal Health (OIE), and the International Maritime Organiza-tion (IMO), deal with the question of exotic species.In Europe, however, there is no comprehensive European Unionlegislative instrument addressing the question of IAS, and Mem-ber States vary in the way they address the issue. Different legi-slative instruments addressing the question of IAS exist: the EUlegislation (e.g., Council Regulation 338/97 (Wildlife Trade Regu-lation), Directive 2000/29/EC (Plant Health Directive), VeterinaryLegislation, Council Regulation 708/2007 (concerning use ofalien and locally absent species in aquaculture), Nature Directi-ves (Directives 92/43EEC and 79/409/EEC, Habitats and Bird Di-rectives), Water Framework Directive (2000/60/EC) and theMarine Strategy Framework Directive (2008/56/EC).The Council of the European Union, in its meeting on Dec 19,2011, covered the issue of IAS in its conclusions on the imple-mentation of the EU 2020 Biodiversity Strategy. In the documentthe European Parliament called for the preparation of a dedica-ted legislative instrument by 2012, and for the inclusion of que-stions relating to the impact of IAS on biodiversity within the EUPlant and Animal Health Regimes. Furthermore, Member Statesshould ratify the Ballast Water Convention to minimise the spre-ad of IAS from maritime and inland water transport. The dedica-ted legislative instrument should cover all aspects relative to IAS,including their identification and prioritisation, control and era-dication, management and implementation of their pathwaysfollowing a risk-based approach and in a proportionate andcost-effective manner.Risk assessments (RA) are employed by the different MemberStates to establish whether an organism is an IAS, and whatcourse of action should be taken: prevention, control, or eradica-tion. There is no EU risk assessment procedure, and each MemberState defines its own based on two criteria: the obligation toconduct risk assessments for IAS in defined circumstances, andthe existence of a standardised methodology for conductingsuch assessments.The existing research projects on alien species are DeliveringAlien Invasive Species Inventories for Europe (DAISIE), AssessingLarge-scale Risks for biodiversity with tested Methods (ALARM),Increasing Sustainability of European Forests Modeling for secu-rity against invasive pests and pathogens under climate change(ISEFOR) and Vectors of Change in Oceans and Seas Marine Life,Impact on Economic Sectors (VECTORS).Prevention, early detection, and a rapid response are the bestway to minimise the impact of alien species. Prevention can be

4

Page 5: Impronte specie aliene inglese

implemented through stricter import regulations, by adoptingmore biosecurity measures, such as quarantines, for specieswhich have been introduced.

KEY TERMS

Alien species (synonyms allochthonous, foreign, exotic, introdu-ced, nonindigenous, nonnative): Refers to a species, subspecies,or lower taxon, introduced outside its normal past or present di-stribution and outside of their natural dispersal potential; inclu-des any part, gametes, seeds, eggs, or propagules of such speciesthat might survive and subsequently reproduce.

Autochthonous species (synonyms indigenous, native): Refersto a species, subspecies, or lower taxon living within its naturalrange (past or present), including the area that it can reach andoccupy using its own legs, wings, wind/waterborne or other di-spersal systems, and therefore without human intervention, evenif it seldom found there.

Biological invasions (synonyms bioinvasions, biotic invasions):Refers to events and processes by which a species, introduced byhuman agency through various introduction pathways into anew range, adapts and starts spreading into a region. It includesall aspects of adaptation: how species become established, re-produce, disperse, spread, proliferate, interact with resident bio-ta, and have an impact over their new ecosystem.

Casual alien species (synonyms acclimatised, not established,adventive): These are alien species that occasionally reproduce ina new environment, but which eventually die out because theydo not form self-replacing populations, and rely on repeated in-troductions. (CBD, 2000).

Eradication: This is the extirpation of all the individuals in a po-pulation or propagules of an invasive species.

Introduction: Refers to movement of a species, subspecies, orlower taxon (including any part, gamete, or propagule thatmight survive and subsequently reproduce) outside its past orpresent natural range. This movement may be intentional or ac-cidental, by human agency, within a country or between coun-tries.

Invasive Alien Species (IAS): Refers to an allochthonous specieswhich has spread in its new environment and represents a threatto its biodiversity and/or for human activities, agriculture, has anegative impact on human health and has important socioeco-nomic consequences. Invasives often reproduce in large numbersand can spread over large areas quickly, thus expanding rapidlytheir new range.

Naturalised species (synonym established refers to plants, whileanimals are said to be naturalised): These are allochthonous spe-cies that form free-living, self-sustaining, and durable popula-tions in the wild unsupported and independent of humans(IUCN, 2000, 2002; Richardson et al., 2000: Occhipinti-Ambrogiand Galil, 2004; Pyšek et al., 2004).

Para-autochthonous species: In Italy, this term refers to a spe-cies of plant or animal, nonnative to a certain environment,which was introduced and naturalised before 1500 (Genovesi,2007). According to the Decree of the President of the ItalianRepublic, no. 120/03, these species may be considered auto-chthonous.

Pest species: According to Pyšek (2009) This is a cultural termapplied to animals (not necessarily alien) occupying environ-ments where they are not wanted and which have a detectableenvironmental and/or economical impact.

Residence time: Refers to the time since the introduction of a

species to a region; as it is not usually known exactly when aspecies was introduced, Rejmánek (2000) introduced the term“minimum residence time” (MRT).

2. THE INVASION PROCESS

“It is ironic to me to hear people ofEuropean ancestry accuse otherorganisms of being invasive exo-tics, displacing native species.”J. L. Hudson, 1997, American seedsman

Alien species are at the core of both our food production andthe very way we live. We inhabit all areas of the world, and wetake different species with us wherever we go; for food purpo-ses—like rice, maize, chickens, cows, sheep, etc.—to use in fore-stry and landscaping, or as biological control, for sport, or aspets. We can travel anywhere by plane in twenty-four hours car-rying with us plants and animals, pathogens and parasites, whichcan in this way easily overcome natural barriers limiting their di-spersal. As Charles Elton pointed out in his pioneering work onbiological invasions in 1958, the most successful invasive speciesare the ones crossing major barriers thanks to their relationshipwith man. Not only we are the cause of the phenomenon of in-vasive alien species, though. The number of alien species will in-crease in line with the increase in shipping, air transport, andtrade in different products (Bright 1998, Mack et al., 2000), aswell as the progressive trend towards the elimination of protec-tive measures in favour of free trade. At the same time, thegrowth in human population and development will continue tobe the primary cause of biodiversity loss, due to habitat loss andfragmentation (Wilson, 1992) which, in turn, will continue fa-vouring biological invasions (Hobbs and Huenneke 1992). Out ofall the different plant and animal species introduced into a newarea, an estimated 10% get established to the point of spreadingand becoming a “pest.” (Williamson and Fitter, 1996). Eventhough only a very small percentage of organisms introduced in-to a new environment becomes invasive, some authors considerIAS to be one of the major causes of biodiversity loss, second on-ly to habitat destruction (Wilcove et al., 1998; Wilson, 1992). Di-sturbed habitats are more vulnerable to biological invasions, butat the same time invasive species alter disturbance regimes innatural systems, exacerbating the effects of fragmentation anddisturbance (Mack and D’Antonio, 1998). Other factors favouringinvaders are lack of predators, great abundance of spatial andfood resources (Orians 1986, Shigesada and Kawasaki 1997), andthe presence of established pathways. This type of synergism re-sults in a cycle of invasion, habitat loss and therefore more inva-sion.Other factors can play a role in either amplifying or inducing thephenomenon of alien species. Climate change facilitates thespread of alien species, enabling them to survive in previously in-hospitable areas. The global decline in amphibians has been bla-med in part on chytridiomycosis, an infectious disease ofamphibians, caused by the chytrid fungus, Batrachochytriumdendrobatidis. The emergence of the disease is due both to hu-man transportation of infected frogs and to the spread of thefungus, which is favoured by global warming (Pounds et a.l,2006).In the past, species spread their ranges and colonised new habi-tats, sometimes as a result of natural events. On November 14,1963 an eruption started southwest of Heimaey, in Iceland. By1967, the islands of Surtsey and Jólnir were formed. Soon afterthe formation of Surtsey, plants and animals started colonisingit: seeds reached the island through the sea, or through disper-

5

Page 6: Impronte specie aliene inglese

sion by the wind or by birds. A few weeks after the eruptionsceased the sea rocket, Cakile edentula, was already blooming.During the first few years of the island’s life, scientists counted170 different insect species. Since 1967, over ninety bird specieshave been observed in or around the island, and at least six ofthem breed on the island. Grey seals, Halichoerus grypus, havebeen breeding on the island since 1983. Marine life is varied andthriving. Vermeij (1991) points out that the breaking down ofnatural barriers – as a result of physical events, such as movingland masses or volcanic activity, changing environmental condi-tions, biological ones, or because of ecosystems separating– allallow species to move freely and invade new areas. While in thepast these occurrences were limited, human agency is removingthese natural barriers at unprecedented rates. The constructionof the Suez Canal, for instance, has caused hundreds of marinespecies to cross over to the Mediterranean Sea from the Red Sea.Non indigenous species can colonise all habitats, but they areespecially problematic when they become established on islands.Due to their endemic and unique species, and given their geo-graphic isolation, the lack of strong competitors and predators,as well as the availability of uncolonised niches, islands are morevulnerable to biological invasions.And yet, exotics were once considered very differently from now.In 1854, the first acclimatisation society was created in Paris. LaSociété Zoologique d’Acclimatation had as objective to promotethe acclimatisation, domestication, and reproduction of exoticspecies considered useful or ornamental. More societies were so-on founded—the American Acclimatization Society was openedin New York in 1871 with the aim to import European flora andfauna into North America. Acclimatisation societies spread toEuropean countries, Australia and New Zealand. The introductionand spread of desirable nonnatives was actively encouraged.Many species introduced for hunting purposes have become aserious threat to their new environments. In Europe, differentspecies of deer such as the fallow deer, Dama dama, native ofthe Near East and introduced into the Mediterranean region inRoman times, are now considered invasive species to be eradica-ted.In the XVII and most of the XIX century, in Italy, the boar was notwidely distributed throughout the territory (Massei and Toso,1993), even after a massive reintroduction. From the 1950s on-wards populations of eastern wild boar coming from Hungary,Poland, and Chzechoslovakia were introduced for hunting pur-poses (Pedrotti et al., Banca dati ungulati, http://digilander.libe-ro.it/urcalomb/Banca%20dati%20ungulati.htm). Compared tothe endemic boar, the Eastern subspecies is bigger, capable of re-producing up to three times a year and bearing more pigletsthan the original subspecies. Although wild boars now cause se-rious damage to local crops and natural reserves, eradicating orotherwise controlling their population is not always taken intoconsideration because they are defended by the hunting lobbies.(http://www.giornale.sm/pesaro-i-cinghiali-sono-sempre-piu-un-problema-per-lagricoltura-ma-la-caccia-spietata-e-lunico-rime-dio-possibile-71691/)European rabbits, Oryctolagus cuniculus, were introduced by Bri-tish colonists into Australia in 1788 and later into New Zealand.They reproduced successfully, have had a devastating effect onthe local ecology, destroying vegetation to the point of causingerosion, and they also feed on crops, causing damages in themillions of dollars. Various methods of eradication have beenused, with little success. Heedless of this lesson, when native po-pulations of rabbits in the south of Europe were decimated bythe Myxomatosis virus, hunters introduced the eastern cotton-tail, Sylvilagus floridanus. The eastern cottontail is a lagomorphintroduced in the area of Pinerolo, in the Italian Piedmont, in1966. Since then, the species has colonised plains and hilly areas,where it occupies ecological niches belonging to the European

hare, Lepus europaeus, which is experiencing a serious decline.Not only the eastern cottontail displaces this native species, italso damages local crops, and is a carrier of dermatophyte fungi(M. canis, M. mentagrophytes and M. gypseum), which are tran-smissible to men. Thus, it is a possible source of infection for ga-mekeepers, hunters, and veterinarians (Gallo et al., 2005)The repeated introduction of new fish by anglers and the intro-duction of new invasive alien species and parasites in many fi-shing sites have caused hybridisation, decline in local species,and habitat destruction. In the 1970s, the Welsh catfish, Silurusglanis, native to central and eastern Europe, was introduced intoseveral lakes for fishing purposes but has since colonised allaquatic ecosystems in Northern Italy. This fish is a formidablepredator and it is drastically reducing the biodiversity of the wa-ters it inhabits. A population census carried out in 1996 in theTiber River shows the presence of nineteen exotic species, repre-senting 57.6% of the total of species found in the river.Many species have been introduced as ornamental animals orplants, as is the case of the American grey squirrel, Sciurus caro-linensis, in Italy, or the ruddy duck, Oxyura jamaicensis. The rud-dy duck was introduced into England in 1949 by Sir Peter Scott,a British ornithologist. Since then, the ruddy duck has spread tomost of the Western Palearctic, further endangering the alreadyvulnerable white-headed duck, Oxyura leucocephala, with whomit often hybridises. As a result, the Council of Europe has enactedan eradication plan for the whole region.A very high number of invertebrate species have been introdu-ced worldwide for biological control. However, according to re-search carried out by Roques, of the Institut National de laRecherche Agronomique (INRA), these species represent only10% of the total number of alien species present in Europe. Theother 90% has arrived as contaminants aboard airplanes or othertransport, or with imported plants. The tiger mosquito, Aedes al-bopictus, native to Southeast Asia, is the most well-knownexample. The mosquito reached Europe through trade in used ti-res, and is a vector for many diseases, amongst them dengue fe-ver, chikungunya disease, and Nile virus.(Source:http://cordis.europa.eu/fetch?CALLER=NEWSLINK_IT_C&RCN=29063&ACTION=D)Exotic pets are constantly being released, whether voluntarily orinvoluntarily. Anthropophilic species are those which live in asso-ciation with humans, such as the animals we raise for food or aspets, or species which depend on our style of life for survival;commensal rodents and their host-specific pests and parasitesbelong to this category. When some of these species escape andbecome feral they have higher chances of survival in their newenvironment and may act as invasives. Two kinds of parakeets,the ring-necked parakeet, Psittacula krameri, and the monk pa-rakeet, Myiopsitta monachus, have established breeding coloniesin urban areas of North America, Europe, Africa and Asia (Lever,1987) and have now become a common site in many major citiesthroughout the world. The red-eared slider, Trachemys scriptaelegans, one of hundreds of the world’s worst invaders (ISSG,2006), is an exotic pet that has been repeatedly released in Euro-pean waters. It now competes for resources with the native pondterrapin, Emys orbicularis, classified as Near Threatened on theInternational Union for Conservation of Nature (IUCN) Red List.Other species, like the tiger mosquito discussed earlier, are notintroduced intentionally but travel as unwanted passengers withcargo, as hull fouling, in ballast water, or inside transportedplant materials, soil or related equipment. They are small orga-nisms, usually insects, some of which can now be found globally(Nentwig, W. 2007) like the giant Asian huntsman spider, Hetero-poda venatoria (Platnick 2006).Fur farms are another important pathway of introduction of al-lochthonous species. Animals regularly escape these farms, or arereleased, and form feral populations. The best known example is

6

Page 7: Impronte specie aliene inglese

the South American nutria, Myocastor coypus, present in Europeand the Americas, or the East Asian raccoon dog, Nyctereutesprocyonoides, spreading in the whole of Europe. Many Europeanraccoons are infected with the roundworm Baylisascaris procyo-nis, which causes encephalitis in a variety of birds and mammals,including man. The South American nutria was both intentional-ly released and escaped from fur farms in North America, Europe,and Asia. It is presently distributed worldwide and causes seriousharm by destroying river banks, dikes, and irrigation facilitiesthrough burrowing, besides damaging vegetation in the wet are-as it inhabits. Considered one of the world’s one hundred worstinvasive species it is often fought with a variety of methods.Finally, zoological gardens, aquaria and oceanaria represent yetanother pathway of introduction for alien species. Animals canescape enclosures, because of damage to boundaries or throughwaterways, or because of damage to the zoological structuresdue to floods, storms, or fires; and they can be accidentally re-leased, or bought and then released (Hulme et al., 2008; Padillaand Williams, 2004, Fàbregas et al., 2010). Out of 140 alien birdspecies present in Europe, 27 have escaped from zoological gar-dens (Kark et al., 2009), and, more broadly, escapes represent to6% of known causes of introductions (Genovesi et al., 2009). Ofthe many documented cases, Fitter (1959) points out that thepresence in Derbyshire of the grey squirrel Sciurus carolinensis,and the red-necked wallaby, Macropus rufogriseus, is the resultof a voluntary release from a zoo. Native species too can become invasive, due to changes in theenvironment (Howard and Chege, 2007) such as habitat loss.New pathways of biological invasions also come from our neces-sity for biofuel crops. Plants chosen as biofuel stock species, suchas oilseed rape, Brassica napus, share many traits with highly in-vasive species: they are habitat generalists, are adaptable, have ahigh relative growth rate (RGR) and produce propagule early intheir development, vegetative reproduction. To minimise impactbiofuel crops are planted in disturbed habitats and marginallands (Rajagopal 2008, Gopalakrishnan et al., 2008), but the riskof these plants becoming invasives remains great. African oilpalm, Elaeis guineensis, is the second most traded oil crop in theworld after soy. Oil palm plantations are one of the major causesof tropical rainforest clearance, and also have adverse impactson food production and poor net carbon benefits; and the spe-cies has already become invasive in the Atlantic forest in Brazil(Howard and Ziller, 2008).It stands out that the phenomenon of exotic invasive species isindissolubly tied to the way we live, to our agriculture, trade,travel. For every species we try to eradicate, many more arebeing introduced. The answer, often, lies in prevention.

3. RESIDENT ALIENS

“History shows that it is not onlysenseless and cruel, but alsodifficult to state who is aforeigner.”

Claudio Magris, Danubio

Nobody would argue that exotics sometimes cause great damageto their new environments, but is the idea of alien species a bia-sed concept?In the United States the controversy between mute swans, Cy-gnus olor, and trumpeter swans, Cygnus buccinatur, rages on. In-troduced as an ornamental species to North America fromEurope in the mid-1800s, the mute swan is considered a pest. Al-though they were first brought to America to live in city parksand estates, they are now thought to be a threat to humans, ofwhom they have little fear and whom they apparently someti-

mes attack. They are also considered to threaten other wildlife,displace native trumpeter swans, and destroy the wetlands theyinhabit. Once common in North America, the trumpeter swan al-most went extinct because of the trade in its meat and feathers.Reintroduced into the wild in the 1900s, it is now thriving in re-stored wetlands. The two swans share the same habitats, feed onplant materials and small invertebrates, and are almost identicalto the degree that a common concern is that trumpeters getshot by those same hunters who should keep the mute swan po-pulation in check. Mute swans can be shot and their eggs shakenor even covered in oil. In April 2012, the state of Michigan deci-ded to eliminate 13,500 mute swans to reduce their population,estimated to be 15,500 birds. A lot of money goes into nativetrumpeter reintroduction programmes, and a lot of money isbeing spent on destroying mute swans.In the 1990’s, the birth of a new discipline, “invasion biology,”brought about a terminology derived partly from common lawand partly from military jargon. The new discipline somehowcompared introduced nonindigenous species to a natural enemy.Natives were associated with pure and natural, while aliens weredamaging, aggressive, and quick to reproduce and displace themore desirable indigenous species. The stage had been set. In1998, the European Environment Agency defined alien species asone of the main threats to Europe’s biodiversity. Since then, thedichotomy of native versus alien has been accepted by the publicas well as the scientific and political world, with all the biases itcarries. While native seems to evoke feelings of protection andnationalism and equals desirable, alien is perceived as the outsi-der, polluter, undesirable. The portrayal of invasive species by thepress, or by biologists, is always meant to trigger repulsion, di-stancing people from the fate of those creatures. They are de-scribed as a “threat,” tolerant of poor and squalid conditions,aggressive, displacing native species or being the cause of habi-tat degradation, as highly fecund, and so on. This negative viewof allochthonous species as harmful and to be removed pervadesthe society and the scientific world alike. Yet not all introducedspecies have a negative impact: certain populations have rea-ched an equilibrium with indigenous communities (Chanin &Linn, 1980; Smal, 1988) or may be keeping another alien speciesunder control (Nogales & Medina, 1996). Some species are evol-ving and becoming naturalised. A species may be classified asharmful due to its origins alone, rather than because it damagesits present environment (Hone, 1994).Some species such as the wild goat and the mouflon were consi-dered autochthounous, but recently it was shown that they wereintroduced by man in the Neolithic. Masseti (2009) suggests thatthese species of ancient anthropochorous origin be consideredcultural heritage. For this reason, they should not be eradicatedbut protected and studied as historic documents that can tell usa lot about how they survived and adapted to the environment,and about the history of man, who have used these animals forits process of colonisation.Other species have a bad reputation. Rats, although consideredthe most harmful invasive mammals in Europe, were found to beless damaging than previously thought. The presence and abun-dance of seabirds on Mediterranean islands, most of which havebeen invaded by rats, are affected more by the islands’ physicalcharacteristics than by rats. Some seabirds, shearwaters for in-stance, tend to choose sites inaccessible to rats for reproduction,such as deep limestone caves. Rats seem to influence directly on-ly the presence of storm petrels (Hydrobatidae), which are themost susceptible to rat predation amongst the Procellariiformes(Ruffino et al., 2009).Tamarisk shrubs, Tamarix spp., were introduced from Eurasia andAfrica into the United States in the nineteenth century as orna-mental species. In the 1930s, during a water shortage in easternArizona, central Mexico and western Texas, it was thought the

7

Page 8: Impronte specie aliene inglese

shrubs were using the precious resources of water left. Duringthe Second World War they were defined “alien invaders” andthe US declared war on them. For seventy years they tried eradi-cating them using herbicides and bulldozers. The shrubs were noteradicated and now they are the nesting place of choice of theendangered southwestern willow flycatcher, Empidonaz trailliiextimus. Given their capacity to survive drought, high salinity,and erosion, these plants are beneficial in maintaining river bankenvironments modified by human use and presence (Davis, 2011).When species move of their own volition we describe their mo-vements as natural colonisations rather than biological invasions,and thus they are not perceived as threatening. Until recently,cattle egrets, Bubulcus ibis, were found only in Africa, southernSpain, and Portugal. Towards the end of the nineteenth centurythey had expanded their range to South Africa. In 1880 they we-re spotted on the Corantyne River, in West Suriname. By the1930s they were present in Guyana and Suriname. In 1953 theywere breeding in Florida. Soon they arrived in Argentina and inCanada. Now, they are present as far as New Zealand and in Eu-rope as far north as England and Ireland. They are a commonsight in cow pastures all over the world, from Texas to Italy. Dueto their high rate of expansion and success in adapting to newenvironments, they are listed as an invasive species in the GlobalInvasive Species Database. Under “General Impacts” it is notedthat, given their capacity to thrive in areas densely populated byother bird species they could, potentially, compete over nestingsites. It is stated as well that a number of articles indicate thatcattle egrets do not appear to have an impact on native birdspecies. Furthermore, cattle egrets spend their days in the pastu-res where they feed on beetles and grasshoppers and occasional-ly pluck ticks and flies off the cows. They return to the nestingsites at night, sites they share with other herons who feed onfish and aquatic invertebrates.

Through which evolutionary process do alien species becomenaturalised?According to Peretti (1998), “It is unclear how long a species ne-eds to be established in a location before it is considered native.Is a species ‘naturalised’ in 100 years, 1,000 years, or 10,000 ye-ars? The distinctions are arbitrary and unscientific.” And fourteenyears later, there is still no agreement in the scientific world.The idea of minimum residence time was first suggested by Rej-mánek (2000), but it refers mostly to plants, with little agree-ment when it comes to animal species. Genovesi (2007) suggestsfive hundred years must pass for a species to become naturali-sed. In Italy, the term para-autochthonous species is used in thiscontext, referring to taxa introduced and naturalised before1500. However, as we have seen earlier, rats are not considerednaturalised although they were introduced in Mediterranean is-lands as early as two thousand years ago, and in other islands,such as the New Zealand islands, about seventeen hundred yearsago, traveling with the first navigators to reach those lands. Car-they and Banks (2012) argue that it is the ecosystem which si-gnals that enough time has passed. They studied whetherbandicoots, Perameles nasuta, were aware of the danger repre-sented by dogs and thus avoided them. Dogs are closely relatedto the dingo, Canis lupus dingo, introduced around four thou-sand years ago in Australia. Dingoes are considered either pro-tected species or pest species, depending on the area in whichthey are found. According to evolutionary theory, prey must le-arn to recognise and adapt to threats in order to survive. In Au-stralia, bandicoots have been exposed to dingoes for thousandsof years, while domestic cats, Felis catus, were introduced onlyabout 150 years ago, and it is unlikely they realise the threatthey represent. Therefore, bandicoots should recognize and avoiddogs, but not cats or other pets. The study established that ban-dicoots avoid gardens where dogs can be found, even when tho-

se dogs are inside the house, showing they do recognize them aspotential predators, which makes the idea of system adaptationplausible. Although there is no general agreement as to how many yearsare necessary for naturalisation to take place, the capacity to re-produce and spread are often an indicator. A small population ofashy-throated parrotbills, Paradoxornis alphonsianus, was spot-ted for the first time in Italy in April 1995, at the Brabbia SwampNature Reserve, near Varese. The presence of the small passerine,native to southwestern China and northern Vietnam, was attri-buted to accidental escapes from a local animal and bird trader.In 1999 (Boto et al.) the parrotbills were considered naturalised,given their capacity to reproduce and self-sustain, to grow innumbers, and to spread outside the reserve. At present, a secondallochthonous species closely related to the first, the vinous-throated parrotbill, Paradoxornis webbianus, is present and natu-ralised in the reserve and even hybridises with the first(Galimberti et al., 2009). The vinous-throated parrotbill also co-mes from the same areas as the ashy-throated and is again a re-sult of accidental escape from the same trader.Adaptation is an ongoing process, and it increases over time.Establishing how much the immigrant organism has to haveadapted to its new abiota is no linear matter. Ecosystems varyconsiderably and so does the amount of adaptation needed tosurvive in them. A suburban, human-degraded area might con-sist mostly of exotics because disturbed ecosystems are eithermore vulnerable or favourable—depending on the side we wantto stay on—to biological invasions. This, of course, does not meanexotics cause deterioration, but merely that disturbance favourscolonisation.

Can ecosystems be restored to the “equilibrium” they enjoyedbefore a biological invasion?

Herodotus’s (484-425 BC) observations on prey and predatorsand on the position of an animal in the food chain gave originto the idea of balance in nature, the view that nature is harmo-nious, which is at the basis of a natural theology. This view persi-sted until Darwin caused havoc with his insight on evolution, butfor a long time scientists went on to believe in balance, purity ofspecies, and the idea that species live in integrated communities.Ecologists have abandoned the idea that ecosystems are homeo-static and that nature is a stable-equilibrium system. On thecontrary, they agree that ecosystems are dynamic and in con-stant evolution, occupied both by native species, the long-termresidents, and by new introductions, the resident aliens. There re-ally is no balance exotic species can upset. New, “novel” ecosy-stems, whose characteristics are mostly unknown, emerge all thetime. Restoring an ecosystem to conditions present at some hi-storical time, when the balance of nature is considered to havebeen right, is not feasible. What we must do is avoid further da-mage. Ecosystems, together with all their components, have al-ways undergone changes, and different species have always goneextinct, but the rate at which these phenomena are taking placeat present is alarming. In 1993, Wilson estimated that the cur-rent rate of species extinction due to habitat destruction was inthe range of thirty thousand species per year. The increased mo-vement of plants, animals, and diseases between continents,ozone thinning, global warming, toxification, fallout of radionu-clides caused by bomb testing, removal of top carnivores, andthe general degradation of nature due to a variety of anthropo-genic factors—all are perilously increasing the rate of change ofecosystems. Cities, dams, and water withdrawals alter hydrology,sometimes beyond recovery. Our planet is being altered in unpre-cedented ways. Roughly half of the earth’s surface is significan-tly disturbed by humans, and half of that is dominated byhumans (Hannah et al., 1993).How to define which is the pristine natural state to be restored?

8

Page 9: Impronte specie aliene inglese

Undoubtedly, invasives and other disturbances degrade and pol-lute ecosystems, but how to restore them, or how to re-create asystem resembling pre-disturbance? Restoring vegetation is pro-ving a difficult task. Restored wetlands have less plant-speciesdiversity than natural ones, with lower colonisation rates (Sea-bloom, van der Valk, 2003). Will these poorer habitats supportthe same animal species that lived there in the past, or aid intheir recovery? In the Americas, where traditionally colonial Eu-ropeans are blamed for the degradation of local ecology, it isthought that Native Americans lived in harmony with nature.Hence, some wildlife managers believe ecosystems should be re-created as the first Europeans found them.This view is in contrast with how anthropologists and archaeolo-gists alike believe that Native Americans caused the extinctionof most of the Pleistocene megafauna (Chase, 1987). Indeed, hu-mans have had a disruptive impact on the earth since they ap-peared and have caused species to become extinct wherever theyhave migrated to. J. Diamond (1989) points out that one-quarterof all bird species present in the New World went extinct just be-fore or after European contact. Large mammals and flightlessbirds went extinct at the time humans arrived in North America,Madagascar, New Zealand, and Australia. Humans have been mo-ving species on five continents for thousands of years. Heywood(1989) states that even in the Amazon rain forest it is possible toobserve the impact of man. Lions, camels, elephants, and specta-cled bears are only some of fifty-seven species of large mammalsthat went extinct in North America a few thousand years ago.Many of the plants they fed on are still there and they couldprobably re-adapt to current conditions (Soulé, 1990). Yet, theywould certainly be considered exotics.The fragile ecosystems of the Mediterranean have been modifiedby human intervention for over ten thousand years. Archeologi-cal findings indicate that the first nonindigenous mammals werebrought onto Cyprus as early as the eighth millennium BC. Atthat time, seafarers brought on board their vessels both domesti-cated and wild species. This is how predator mammals, insectivo-res, micromammals and ungulates (Masseti, 2009) reached manyMediterranean islands.All these considerations call for a more moderate view on exo-tics, opposed to the policy of plain extermination. Wildlife thatcauses considerable damage, such as feral pigs, or rats, shouldmostly certainly be controlled and their populations kept in lownumbers. This need not be done by means of cruel methods oferadication but using more humane techniques. In 1990, theconservation biologist Michael Soulé envisaged the birth of anew discipline, recombinant ecology or mixecology, which wouldstudy “the interactions within these new, biogeographically com-plex assemblages.” Recombinant ecology does not consider alienspecies as bad per se. On the contrary, it examines why somespecies mix better than others.The Channel Islands of California provide an interesting exampleof the dynamicity of ecosystems and of subtle interactions bet-ween populations, as well as of the difficulties in choosing whichequilibrium to re-establish. On these islands, the introduction offeral pigs, Sus scrofa, in the 1850s facilitated the colonisation ofgolden eagles, Aquila chrysaetos. Golden eagles prey both on pi-glets as well as on endemic fox species like Urocyon littoralis,with the result that three endemic subspecies are now threate-ned by hyperpredation by golden eagles. The decline in foxes hascaused the increase of its natural competitor, an endemic skunk,Spilogale gracilis amphiala (Roemer et al., 2002). Foxes, whichhave inhabited the islands for the last twenty thousand years,are endangered by golden eagles, which before the introductionof feral pigs were only transients on the islands but now can su-stain a large breeding population. The question of conservation,however, is further complicated by the fact that golden eagles,threatened in other places, are too to be protected.

4. ERADICATION AND CONTROL

Eradication and control

The key points in the strategy to fight the threat of invasive spe-cies are

• prevention;

• early detection and constant monitoring; and

• mitigation, eradication, and control.

Prevention relies on the implementation of effective preventati-ve measures to minimise the risk of invasions. These measuresrange from stricter control on trade and monitoring of invasionpathways, to restoring habitats to make them less vulnerable toinvasions.Detecting a new invasive species and being able to assess whe-ther it represents a threat allows the best possible method tomanage such population to be chosen. If the aim is eradication,this is possible only when an invasive is detected early.Mitigation consists in reducing a population or creating a newhabitat for a species endangered by an alien species. Eradicationis more drastic and can be carried out by killing or removing theunwanted animals. J.H. Myers (2000) defines it as “the completeremoval of all the individuals of the population, down to the lastpotentially reproducing individual, or the reduction of their po-pulation density below sustainable levels.” As seen earlier, thistechnique can be used only in the early stages of the process ofinvasion, or on small and accessible islands. Moreover, it is costly,both logistically and financially. Once an invasive becomes esta-blished, control is the only option left.Undesirable species may be eradicated and controlled through avariety of methods, sometimes employing one or more of themtogether.

Barriers deny access to unwanted animals. Fencing works forlarger animals, such as ungulates, but also excludes smaller onessuch as foxes, cats, possums, rabbits, stoats, rats, and mice. Asuccessful example of fencing is found on Amsterdam Island inthe Indian Ocean, where feral cows have been thus excludedfrom areas populated by breeding birds like the Amsterdam alba-tross, Diomedea amsterdamensis (Micol & Jouventin, 1995). Net-ting is used for smaller animals such as birds or crabs, but thereare some for coypus and rabbits, and screening is adequate forinsect control.

Biological control makes use of parasitism, immunocontracep-tion, predation, or competition to decrease the survival rate ofunwanted species. The introduction of predators to reduce thepopulation density of exotic species has usually ended in failure.Predators turn into invasives themselves, ignore the target preyand hunt local species, or have unexpected impacts on the envi-ronment. When Indian mongooses, Herpestes auropunctatus,were introduced in the West Indies to control rats, the rats beco-me arboreal to escape the new terrestrial mongoose predator. Asa result, rats preyed more on tree-nesting birds, while mongoosesbegan to prey on ground birds (Seaman, 1952).The presence of alternative prey is now a well-known factor inthe failure of some eradication projects. Let’s examine the caseof Macquarie Island, where the introduction of rabbits, whichtook place when cats where already present, had a negative im-pact on the bird population. The number of birds present couldin fact support only a small cat population, but the arrival ofrabbits provided an alternative prey they could feed on duringthe winter, allowing the cat population to expand. Ten years af-ter the introduction of rabbits, cat hyperpredation of birds cau-sed the extinction of three different bird species (Taylor, 1979a).Introduced species often spread beyond control, which is what

9

Page 10: Impronte specie aliene inglese

happened with the Indian Myna, Acridotheres tristis, introducedin Hawaii for the control of Fall armyworms, Spodoptera frugi-perda, or in Melbourne where they were meant to control insectpests in market gardens. To consider how easily predator intro-ductions can backfire, we can look at what happened in Jamaica.In an attempt to control rats damaging their sugarcane crops,farmers introduced ants, Formica omnivora. Rat numbers werenot reduced and the ants spread out of control, so they introdu-ced marine toads, Bufo marinus, to control the rats. Again, toadsturned into a problem themselves, and Indian mongooses wereintroduced to control both toads and rats. But they preyed inste-ad on native birds, endangering them.Competition is achieved by introducing a superior competitor toreduce the undesired population. Arctic foxes, Alopex lagopus,were introduced in the Aleutian islands in the early 1800s for furfarming. Due to the Arctic foxes’ devastating impact on seabirds,it was decided to eradicate them by introducing sterilised red fo-xes, Vulpes vulpes. A few sterilised red foxes were released ontwo of the smaller islands when there were no breeding seabirdcolonies present—larger islands would have required too manyindividuals to make the technique possible. Arctic foxes disap-peared from the islands, but the red foxes also preyed on localbirds (Bailey, 1993).A different kind of biological control is achieved through patho-gens (viruses and bacteria) used as lethal agents to control po-pulations. A few examples of such agents are Salmonella spp.used for the control of rodents; myxomatosis and rabbit hae-morrhagic disease (RHD) against rabbits; and feline panleukope-nia (FLP) against cats. It is understood that neither predators norpathogens (Bell, 1995) will completely eradicate a species, ma-king the use of further measures necessary. Microbial insecticidesare another method of biological control.Finally, immunocontraception uses a vaccine to cause the immu-ne system to attack its own reproductive cells, making the indivi-dual sterile. Considered the most ethical of all methods, it will be explored more in depth in the next chapter.

Biocides include insecticides, herbicides, rodenticides, and poi-sons. Rodenticide anticoagulants, used extensively to control,amongst others, rats, cats, and rabbits, work by altering the nor-mal blood-clotting process. Anticoagulants have been usedagainst rats worldwide, and resistance to these substances wasfirst noticed in Europe in the 1960s and in the Unites States inthe 1970s (Meehan, 1984; Jackson, Ashton et al., 1985). A newseries of anticoagulants called second generation and third ge-neration have been developed since. Second generation poisonsare far more toxic than the first, are usually lethal after only oneingestion, have a longer elimination half-life, and are effectiveagainst warfarin-resistant rodents. Difenacoum, brodifacoum,and bromadiolone are in this group. Anticoagulants are harmfulto a large number of animals: they accumulate in the stomachsand livers of wild carnivores, killing them. Polecats, barn owls,and red kites (Newton et al., 1990; Shore et al., 1996; Gillies &Pierce, 1999; Carter & Burn, 2000; Carter & Grice, 2000) areamongst the recorded nontarget fatalities. Fatal secondary anti-coagulant poisoning has caused the death of red foxes, owls,buzzards, kites, and corvids (Newton et al., 1990; Proctor, 1994;Berny et al., 1997; Shore et al., 1999; Stephenson et al., 1999), aswell as domestic dogs and cats. The risk to nontarget species canbe lessened by capturing the animals to be protected and relea-sing them once the eradication programme is over. This is, howe-ver, possible only in a few situations, it is a very costly solution,and it requires manpower.At present, other rodenticides such as diphacinone, which has ashorter tissue residue half-life, are being researched as alternati-ves in island eradications to reduce the risk of secondary poiso-ning.

Non-anticoagulants include compounds such as alpha-chloralo-se, a tranquillizer which acts by retarding metabolic processes. Itcan be used to kill mice and small rodents, causing death by hy-pothermia. Calciferol may be used on rats by overdosing, causingdeath by kidney failure within three to six days of ingestion(Meehan, 1984). Carbon dioxide, used against burrowing animals,causes death by asphyxiation. The length of the list speaks for it-self: Alpha-naphthylthiourea (ANTU), arsenate, bromethalin, car-bon disulfide, crimidine, fluoroacetamide (1081), formaldehyde,gophacide, hydrocyanic acid, lindane, methyl bromide, norbormi-de, phosphine, pyrethrins, pyriminyl, reserpine, scilliroside, so-dium monofluoroacetate, strychnine, tetrachloroethane, thalliumsulphate, zinc phosphide. Habitat management modifies the environment to make condi-tions less favourable for invaders. In agricultural ecosystems, ad-ding diversity can provide alternative food, nectar, or shelter inthe form of noncrop plants grown together with crops. Anotherpossibility are artificial structures. Supplying nesting and roo-sting boxes for birds—both songbirds and owls—and bats increa-ses their numbers and provides natural insect and rodent control,and at the same time reduces the use of pesticides.

Trapping. It is used for rodents, cats, mustelids, mongooses, rab-bits, hares, possums, and other animals. It is more effective withcarnivores. There are many kinds of traps in existence, compri-sing both harmful and harmless versions. In spite of new designs,leg-hold traps and snares—both widely used—result in high non-target captures. Animals caught in these traps often die a slowdeath, and some animals chew their own limbs off in an attemptto escape. To reduce nontarget captures, less-damaging trappingmethods can be used to allow for the release of the trapped ani-mal: foot-hold snares, stops in neck snares and foot-hold trapswith padded jaws. In reality these traps, although approved bythe Agreement on International Humane Trapping Standard, canstill cause severe injuries. And the suffering caused by the stressof being trapped, maybe for days, is still very high. Cage trapsare equipped with a system permitting the animal to enter, butnot to exit. Birds can be captured with mist nets, which cause noharm if expertly employed.

Shooting. Considered a very efficient method to eradicate herdsof large ungulates, it has been used against various species ofbirds and mammals. It is often employed in conjunction withother methods, such as helicopters, dogs, or judas animals. Thislast technique is effective with large, highly social vertebrates Aferal animal, such as a goat, is fitted with a radio collar and usedto locate the herd. The animals are then destroyed by shootingfrom helicopters, or from the ground, or they can be trapped andtaken elsewhere.Other harmful methods employed to control wildlife are huntingwith bows or dogs, explosives, electrocution, drowning, burrowcollapse, injection of gases, and preventing lactation to kill milk-dependant young (Littin & Mellor, 2005).

Is eradication effective?

Removing a species from an ecosystem, whether it is an establi-shed alien or a native, will have consequences, some of whichare undesirable. Careful studies realised before the enactment ofthe project will help predict some of these consequences, buteach attempt at eradication is like a new experiment whichcould yield unexpected results not predictable by earlier pro-grammes, even successful ones. On planning eradications, ourability to successfully manipulate populations and complex sy-stems should not be overestimated (Jamieson, 1995). Ecosystemsare dynamic, and relationships between populations of differentspecies change over time. Plus, it should be noted that animalpopulations are subject to periodic fluctuations, and the impact

10

Page 11: Impronte specie aliene inglese

of invasives may vary with seasonal or environmental conditionsor with population density. The interactions between native andnonnative species create complex links depending on the use ofavailable resources, competition, and predation. In many cases,the removal of invasive species has caused what is known as atrophic cascade effect rather than the recovery of the ecosystem(Zavaleta et al., 2001). Removal of a single species, herbivore orpredator, often results in the ecological release of a second spe-cies, plant or prey, previously controlled by the removed species(Zavaleta, 2002).Sometimes, the success of an eradication is defined solely interms of the absence of the target alien species, and does not ta-ke into consideration the response of the invaded ecosystem.Eradicating a species does not bring the whole system back topre-invasion equilibrium, nor does it eliminate the modificationsthe invader brought to the system. Towns (2008), studying theeradication of Pacific rats, Rattus exulans, from islands aroundNew Zealand, found that ecosystem recovery was scarce andslow, because it was limited by the reduced number of nativespecies remaining. In this case, reintroduction of seabirds is nee-ded to restore seabird trophic interactions. Secondary effects oferadication include trophic cascade, mesopredator release, andthe Sisyphus effect.Trophic cascades take place when changes in the distribution ofpredators affect the abundances of other species across lower le-vels in the food web. The dingo, considered an invasive species inAustralia, is an apex predator, albeit an alien one. Its removal hasallowed the increased activity of herbivores such as the kanga-roo, and of the red fox, Vulpes vulpes, itself an exotic mesopreda-tor, causing both the loss of grass cover and the higher predationof small native mammals (Letnic et al., 2009). Reintroducing andmaintaining a constant population of dingoes would benefit lo-cal mammal populations (Letnic et al., 2009), indicating that analien species can assume a functional role as a key predator.A related theory, the mesopredator release hypothesis, holds thatreduced abundance of top predators results in increased abun-dance or activity of smaller predators (mesopredators) with de-trimental impacts on the vegetation and on the prey of thesmaller predators (Crooks & Soulé, 1999). Eradication of catsfrom islands, for instance, should be done together with the re-moval of their introduced prey, whether herbivores, omnivores,or carnivores. This, however, is no guarantee of success: rat era-dication on Bird Island, in the Seychelles, caused the spread ofthe nonindigenous crazy ant, Anoplolepis longipes, which is nowa threat for breeding sooty terns, Onychoprion fuscatus, and thenative skink Mabuya sechellensis (Feare, 1999). Macquarie Islandis yet another example of how cat eradication was detrimentalto the local fauna. In 1878, rabbits were introduced to the island,but their numbers were kept at bay by cats, introduced sixty ye-ars earlier. Both species were detrimental to the island environ-ment, rabbits because of extensive grazing and cats because ofhyperpredation, resulting in the extinction of two local flightlessbird species. In an attempt to eradicate rabbits, the myxoma vi-rus was introduced yearly. When the rabbit population decrea-sed, it soon became clear that cats were switching their prey ofchoice and targeting seabirds. In 1985, a cat eradication pro-gramme was started, and the last cat was shot in 2000. The rab-bit population exploded, and complex vegetation communitieswere transformed into short, grazed lawns or even bare ground(Bergstrom et al, 2009).Sisyphus, a figure of Greek mythology, was condemned by thegods to the futile task of forever pushing a boulder up a moun-tain, only to see it roll down again. In ecology, the Sisyphus ef-fect occurs when the removal of an alien species results in theunexpected spread of another alien species. The eradication ofgoats and pigs from Sarigan Island, one of the Mariana Islands,caused the spread of the exotic vine Operculina ventricosa,

which, within a few years, was suffocating the recovering vege-tation.Finally, the risk of reinvasion is becoming more real as more timehas elapsed since eradications that were previously consideredsuccessful. Upon examining eradications of rats conducted onNew Zealand islands or in the Seychelles, Clout (2007) foundthat after about ten years the possibility of reinvasion by rats isvery high (HISTOGRAM). Furthermore, concerning inshore is-lands, he surmises that reinvasion is inevitable (Clout, 2008), asthe animals can reach them by swimming.Nevertheless, where possible, eradication remains the method ofchoice in ecology and is preferred to containment, which is ai-med at limiting further spread of the unwanted species, or con-trol, whose objective is reducing the presence of invasives.Although a number of attempts at eradication in small areas ha-ve been successful and have benefited native biota, most eradi-cation programmes, especially when aimed at well-establishedspecies, have a high failure-to-success ratio. Moreover, theseprogrammes are costly, require much manpower and resources,and can be dangerous to the environment and to nontarget spe-cies.

Is eradication humane?

Most of the eradication techniques employed are extremely crueland cause suffering to both target animals as well as to otheranimals that accidentally fall victim to them. Often, one methodis not sufficient to ensure the complete removal of the targetalien species, and therefore a combination of techniques is em-ployed at once, for long periods of time.Cage traps cause fear and stress. When the trap closes on theanimal’s leg, it can cause wounds, cut tendons and ligaments, aswell as break bones. Often, the animals caught in the traps chewoff their own limbs to escape, and even when they do not, strug-gling will result in further injury. Death occurs days later by de-hydration, blood loss, hypothermia, or predation by otheranimals, the victims conscious, in fear, pain, and distress. Accor-ding to Iossa (2007), most killing traps in use today fall belowthe standards of animal welfare. Both killing and restrainingtraps used for mammals are effective when tested in compounds,but not in the field. Moreover, tested animals are anaesthetisedand therefore show different responses compared to the animalscaught in the wild.In their study on the humaneness of rodent control, Mason andLittin consider a method humane when it causes the least num-ber of symptoms before inducing unconsciousness and death,and which has no lasting ill effects on surviving animals. Inhu-mane methods cause severe and/or prolonged pain or distress,and leave surviving animals ill or disabled. Not surprisingly, theirfindings indicate that most methods of rodent control are inhu-mane and they are applied with little consideration for the wel-fare of the animal. More humane methods, such as snaptrapping, electrocution, cyanide gassing, and alpha-chlorase, aswell as exclusion and elimination of food supplies and a place tohide and nest, should be adopted instead. Anticoagulants such asbrodifacoum, one of the most widely used rodenticides, causes aslow and agonising death. Death can occur within a day (Gill etal., 1994; PSD, 1997; Littin et al., 2000) but it can take as long asfour to eight days. Furthermore, it leaves sublethally poisonedindividuals ill for long periods of time.The definition offered by Fraser (1996) of humane shooting re-quires that the animal be shot in the head at close vicinity. Mostanimals are not shot in such a clean way and do not die a quickdeath. Wounded animals can suffer acute and chronic damagefrom infected wounds, and dissociative and/or anxiety disorders.Moreover, wounded animals cannot keep up with their group,nor feed, drink, or escape undesired situations.

11

Page 12: Impronte specie aliene inglese

Even when eradication could yield positive results, its costs interms of suffering for the animals, and the growing hostility ofthe public towards these techniques makes research for new,ethical methods a priority. The complete eradication of feral catsfrom Marion Island, in the Southern Indian Ocean, is consideredby some a success, by others an abhorrently cruel programme. Tocompletely remove all cats from an island measuring 115 squaremiles (290 square metres), inhabited by no more than 2,300 cats(van Aarde, 1980), it took biologists nineteen years and multipleeradication methods. The project, started in 1974 and concludedin 1993, was divided into seven different stages. After a prelimi-nary study, the ad hoc Task Group on the Extermination of Catsand Mice on Marion Island chose to use biological control bymeans of the feline panleukopenia virus. Cats were live trappedand then held in cages on the island to serve as future carriersfor the disease. In 1977 the disease, meant to be only a primarycontrol measure, was released through aerial spraying. After aninitial decrease in numbers, the population rebounded and in1981 a three-year hunting programme was enacted. Hunting byshooting and using dogs was combined with trapping with gintraps, considered to be one of the most cruel and harmful traps.Many nontarget species were caught in gin traps, amongst themSalvin’s prions, Pachyptila salvini; subantarctic skuas, Catharactaantarctica; lesser sheathbills, Chionis minor; rockhopper pen-guins, Eudyptes chrysocome; and many more. Finally, a poisoningprogramme using sodium monofluoroacetate, compound 1080—which had previously been rejected due to its impact on birds—finished off the feral cat population. The last individuals weretrapped in July 1991.Such unwarranted cruelty is not necessary, not even to succes-sfully eradicate an animal many biologists consider to be one ofthe most detrimental introduced species, especially on islands.Cats were removed from San Nicolas Island, California, withoutunnecessary suffering and with the collaboration of the HumaneSociety of the United States. The study, initiated in June 2009and concluded in February 2010, tried to make use of nonlethalmethods: altered padded leghold live traps and feline-detectiondogs. To capture as many cats as possible alive, spotlight huntingwas used only in areas where trapping did not work. Fifty-sevenferal cats were captured and transferred to a sanctuary in Cali-fornia

INSERT

Interview with Pedro Luís GeraldesPedro Luís Geraldes is working on a LIFE (Safe Island for Seabirds)project organized by the RSPB. It is financed by the EuropeanCommunity, and its partners are the local city hall, the Por-tuguese BirdLife Partner SPEA. The aim is to eradicate rats andkeep under control cats present on the island of Corvo, in theAzores, as well as recover natural vegetation by reintroducingendemic plants. Corvo Island is the smallest Island of the volcanic Azores archi-pelago. It measures 17.13 square kilometres (7 sq miles), and ishome to about 500 people. Agricultures occupies about 17.5%of the island surface. It’s served by planes (Corvo airport), andferries. The Corvo Nature Park covers the Protected Area ofCaldera of Corvo and the Protected Resource Area of the Coastof Corvo. Like many other islands, Corvo has its share of human-intro-duced invasive species: a variety of plant species, rodents, cats,dogs, sheep, and goats. The breeding population of seabirds pres-ent on the island has decreased, possibly as a result of predationby cats and rats.At the moment, the team is carrying out a preliminary research.In 6 months from now it will present a report saying whethereradication is feasible, what is the status of seabirds and what

are the solutions to the problem of predation of seabirds by rats,mice, and cats. All the inhabitants live in Vila do Corvo, and the rest of the is-land is destined to cattle and agriculture. Many seabirds repro-duce on the island: Cory shearwaters, little shearwaters, andother procellarids, amongst which is the storm petrel. Seabirdcolonies are located on vertical cliffs up to 500 m. tall, and aretherefore inaccessible, so recording devices, motion detectionsensors, etc. are employed to study bird behavior. Most of thesebirds breed in places cats and rats cannot reach, but some do notand are exposed to predation.The team is working on public awareness, teaching the impor-tance of seabird colonies, of managing waste –promoting recy-cling -, of neutering cats and keeping them under control. Theteam carried out a spay and neuter project which lasted about3-4 months, and was able to neuter and chip 90% of the catspresent on the island. Local authorities have been asked to takeover from there, as there are still an estimated two hundredstrays.In the past excluder fences like the ones used in New Zealandwere employed to control rodents. The fences allowed to create asmall reserve free of predators around the breeding colonies. Formany months no rats or mice entered the area, but they eventu-ally got it through a hole. The team is studying rodent density,peaks in the population, habitat interactions, the impacts onbirds, the percentage of birds killed per year, how breeding suc-cess is affected by the presence of rats and cats. The project was started in 2009. Results obtained that same yearshowed that rats represented an alternative prey to birds forcats. In the absence of rats, cats prey more on shearwater chicks.The team is open to non traditional control methods, such asfertility control. But, we need to compare cost and manpowerfor each method. And, if it’s possible, consider how it should bedone, and compare it with other solutions.

SUMMARY

• Methods of eradication are highly controversial.

• They are mostly inhumane and cause unnecessary suffering,both to animals and to people concerned about their well-being.

• They are often counterproductive (secondary effects, negati-ve impacts on the environment.

• They can be just as costly as or even more so than the expen-ses caused by the species they want to remove.

• They are seldom as effective or as final as they initially pro-mise.

5. TOWARDS A MORE HUMANE MANAGEMENT OFALLOCHTHONOUS SPECIES

“Man’s highest duty is to protectanimals from cruelty.”

Emile Zola

“Man is the measure of all things.”Pythagoras

Ethical implications

Although a large amount of research has been carried out onhow to fight alien species, the question of their welfare—and thesuffering inflicted by methods of eradication and control—hasbeen mostly overlooked. This is the reflection of a more general

12

Page 13: Impronte specie aliene inglese

trend. In Europe the Bern Convention, in its recommendations onalien terrestrial vertebrate, states that methods of eradicationshould be selective, ethical, without cruelty, and consistent withthe aim of permanently eliminating the invasive species. At thesame time, it allows exceptions for conservation or managementreasons. The truth is that wildlife species, once labeled as pests,do not have any legal protection and no regard is given to theirwelfare.In more recent years, some of the cruelest methods of killingwildlife have been under public scrutiny. In Europe, this has ledto the banning of leghold traps and inhumane poisons such asarsenic and strychnine (Litton & Mellor, 2005). In some cases, pu-blic outcry has been beneficial to both the targeted species andto research. In New Zealand, possums, Trichosurus vulpecula, in-troduced in 1837 to establish a fur industry, have become one ofthe major threats to native forests and birds and contribute tospreading bovine tuberculosis. In 1940, New Zealand started era-dicating possums using a variety of poisons, including sodiummonofluoroacetate, called 1080, and leghold traps. Concern overthe humaneness of these methods led to research on new andmore humane methods. As a result, international standards fortrap efficacy and humaneness have been developed, and pestcontrol managers now employ different kinds of traps whichcause less injury. Not only New Zealand now has different stan-dards, which consider the welfare of possums, but the Interna-tional Union for Conservation of Nature has suggested thecreation of a single international standard for traps. Mammal and bird eradication programmes are attracting moreattention worldwide, due to employed methods having a pro-found effect on the targeted species’ welfare (Thiriet, 2007;McEwen 2008; Warburton and Norton 2009). Animals, be theyconsidered pests or pets, experience pain in equal measure; pu-blic concern for “pests” as sentient animals is growing worldwi-de. This phenomenon is paralleled by an increased interest andinvolvement by NGOs and animal welfare organisations (Littin &Mellor, 2005; Schmidt, R.H. 1989; de Boo, J., Knight, A., 2005).The public should be fully informed about eradication program-mes, and its costs, whether ethical or not, should be clearly defi-ned in order to justify undertaking the programme. The methodschosen should cause the least harm. Targeted animals should notbe unduly portrayed in a negative light to gain support. Avoidingthe suffering of target and nontarget species should be a priori-ty. According to Peter Singer’s (1990) utilitarian philosophical pointof view, the benefits of eradication must outweigh the ethicalcosts. The ethical costs represented by the unpredictability of theresults of these programmes, their secondary effects, and non-

target animals falling victims to them do not justify the suffe-ring inflicted. Failed eradications are common enough to be a re-al concern. In all these cases, costs have been huge both in termsof finances and in suffering of the animals killed, but there havebeen no benefits. Looking at various studies carried out in NewZealand, we learn that in rat eradication there, there have been159 successful programmes, with an 8% failure rate, which is 15cases; for mice the figures are 30 successes with 19% failures(seven cases); for goats, 120 successes with 8% failures (ten ca-ses); for feral cats 79 successes with 18% failures (two cases);and for rabbits the number of successful eradications are 17with 11% failures (two cases) (Nogales, 2004; Campbell and Don-lan 2005; Clout and Russell, 2006; Howald et al., 2007). In all ofthis, however, we do not know what the post-eradication condi-tions of the islands are and whether the term success refers onlyto the complete removal of the animals or to the recovery of theecosystem.The ethical decisions we make depend on our own set of values,which are a product of our culture, religion, beliefs, intuitions,upbringing experiences, and education. Science is not free ofprejudice; both the public and scientists alike are imbued withtheir own culture and beliefs. While the welfare of animals be-longs to the scientific realm, the way each one of us interpretshumaneness and justifies the treatment of animals is more per-sonal and philosophical.The question of animal welfare is an important point in the ma-nagement of so-called pest species. Although the reaction of thegeneral public may vary considerably depending on the speciestargeted, the trend towards a stronger protection of animals’rights is not a reversible process and cuts vertically through so-ciety. Scientists and animal rights supporters need to find com-mon grounds to discuss the issue and find a solution acceptableto both parties.Although conservation biologists and animal rights supportersboth share a concern for animals, the first view them as assets,while the second perceive them to be sentient beings. Conserva-tion biologists want to protect, preserve, and restore species andwhole ecosystems through scientific means, regardless of thepain and distress these methods inflict on the targeted animals.They often accuse animal welfare activists of being cynical aboutnative species while worrying only about pests, or of becomingsentimental about feral cats, squirrels, foxes, and other animalsconsidered cuddly and cute. However, eradication programmesdo not harm target species alone, but also nontarget animals(Cowan, 1992). These projects can last for years, during whichhundreds or thousands of animals are exterminated with greatsuffering.

13

Table 1. Largest islands where eradication was deemed successful. Feral cows were eradicated only on part of the island, while the rest of the population was managed by exclusion.

Mammal species Island and country Size (km2) Method Estimated Operation durationnumber (years) eradicated

Arctic fox Attu, Alaska, USA 905,8 shooting and trapping 373 ?Black rat St Paul, F 8 poison 8-12000 3Brushtail possum Rangitoto-Motutapu, New Zealand38.5 poison, trapping, dogs 21000 8Brush-tailed rock wallaby Rangitoto-Motutapu, New Zealand38.5 poison, trapping, dogs 12500 8Cat Marion, Sub Antarctic 190 biocontrol, trapping, 2790+ 1124 19

shooting, poisoningCows Amsterdam, Indian Ocean 55 shooting 1059 2Goat San Clemente, California 148 Shooting, trapping 30000 19Mouse Enderby, New Zealand 7.1 poison ? 3Norway rat Langara, Canada 32.5 poison 3000 <1Pig Santiago, Galapagos 584.6 shooting, dogs 19210 27Pacific rat Kapiti, New Zealand 19.7 poison ? <1Rabbit Enderby, NZ 7.1 poison ? 3Red fox Dolphin, Australia 32.8 poison 30 10Sheep Campbell, New Zealand 112.2 shooting ? 21

Page 14: Impronte specie aliene inglese

Adapted from Courchamp et al. (2003) Mammals invaders onislands

To animal rights advocates, cruelty is not an option, and the me-thods used by biologists are considered both unethical and in-creasingly illegal. Animal rights supporters share the viewbrought forward in the eighteenth century by Jeremy Bentham,where the question is not: “Can they reason?” nor, “Can theytalk?” but, “Can they suffer?” Animal rights supporters want toreduce animal suffering in general. While biologists are concer-ned about quantitative results, animal welfare activists worryabout the individual fate of the animals.

What is a humane method of wildlife control?

Present models for vertebrate eradication consider safety, costs,feasibility, efficacy, availability, timing, weather, biology, and la-bour requirements. We ask that animal welfare be incorporatedinto the decision model, as it should be already (Schmidt, 1989).The humaneness of a method of eradication depends on the suf-fering and distress it causes, how long the pain lasts, and howmany animals are affected (Gregory et al., 1996). Along with Lit-ton (2004), we should minimise the harm we cause animals, andresearch more humane methods. Besides, resorting to euthanasiashould be taken into consideration more often.Fisher (1998) lists a few common sense views that should alwaysbe taken into consideration:

• “Animals are sentient beings, therefore it matters to themhow they are treated;

• We are responsible for animals within our care;

• Animals should never be hurt, unless it is absolutely necessa-ry;

• If there are less painful ways of treating animals then theyshould be used;

• Some harms should be prohibited, regardless of their bene-fits.”

The increasing importance of animal welfare is driving scientificresearch towards more humane methods of control, but there isan urgent need for a specific animal welfare policy on wildlife. Existing laws aim to protect people and biodiversity from the im-pact of invasive species, but what are the legislative obligations,in Italy and in the EU, that aim to reduce and avoid inhumanemethods of control of wildlife, minimising their suffering?

Humane alternatives for the control of feral animalsNonlethal methods of control of alien species exist and can beemployed with success. Devices such as fencing, electric fences,or wires to prevent access to vertebrates, or chemical repellentsagainst birds, rodents, insectivores, and ungulates are less har-mful and avoid agricultural damage. Live capture traps, fertilityand breeding controls should be employed whenever possible. Allof the above methods can be used together with other measures.In 2005, a project of eradication of feral cats on Pianosa, part ofthe Tuscan Archipelago, was carried out without the use of cruelmethods. The cats were trapped with the help of volunteers andtaken from Elba, where they were neutered and released near lo-cal cat colonies. In 2000, at the Melbourne Royal Botanical Gar-dens, animal rights activists blocked an attempt to cull a colonyof grey-headed flying foxes, Pteropus poliocephalus. In 2002 anew programme was enacted, which resulted in the attempt torelocate the flying fox colony with the aid of acoustic deterrentsand a number of individuals being moved to the relocation site.The colony relocated not to the designated site, but to differentones, and finally settled in Yarra Bend Park, in the Melbourne su-burb of Kew, where they are now allowed to stay.

Perhaps the real problem lies in the fact that to conservationbiologists, economic considerations are more important thanethical and social ones. An eradication plan based on shooting isless expensive than the same plan based on live trapping and re-location, and is thus more probable that it will be approved bypoliticians. At the same time, not taking into consideration thewelfare of the animals targeted will trigger public opposition,endangering the public image of the politicians supporting suchplans. The failure of the project of eradication of the grey squir-rel, Sciurus carolinensis, started in April 1997 in Piedmont, wascaused by the opposition of the general public and of animalrights organisations. Only through cooperation between conser-vation biologists and animal rights advocates can a solution beachieved. A plan based on noncruel methods will enjoy more pu-blic support and will have more chances of being successful inthe long run. It will, in fact, result in less financial expenses.

Fertility control

Fertility control is perhaps the most humane and effective me-thod for the management of wildlife populations. This techniqueoffers many advantages over more traditional methods of remo-val. It is effective because it results in the constant decrease ofthe population. Since it is designed to cause no suffering, it isethically acceptable. Not making use of poisons has less impacton the environment. Being species specific, it does not affectother species. Virus-vectored immunocontraception is self-disse-minating and can be used to manage large areas at very lowcost. Fertility control can be achieved by mechanical and surgical te-chniques, endocrine disruption, and immunocontraception. Sur-gical techniques require capturing the animals, which makes themethod too costly and impossible to apply to most wildlife spe-cies. Endocrine disruption requires implanting steroidal and non-steroidal hormones to disrupt hormonal regulatory functions.Immunocontraceptive vaccines trigger the response of the im-mune system and immunise the animal against proteins such asegg coat proteins or sperm proteins, or a hormone such as gona-dotropin-releasing hormone (GnRH), which is needed for re-production. Some of these vaccines can be administered by remote delivery.This technology uses a compressed-air powered rifle that deliversa bio-absorbable bullet or dart carrying the vaccine. Viral, bacte-rial, and microbial vectors have been studied to deliver vaccinesto different wildlife species. The theory is that porcine zona pel-lucida (PZP) or GnRH, which causes the inhibition of fertility,could be engineered in a nonpathogenic virus that could then bedelivered to target species (Kirkpatrick, 2011). The vaccine PZP isderived from pig eggs. Once administered, it stimulates the ani-mal’s immune system to produce antibodies. These bind to spermreceptors on the zona pellucida of the animal’s eggs, blockingfertilization (Paterson & Aitken, 1990).When an individual is infected by virus-vectored immunocontra-ception (VVIC), its immune system attacks its own reproductivecells, making the animal sterile. Individuals are infected througha gamete protein triggering the immune response: the antibo-dies produced bind to these proteins and block fertilisation (Bra-dley, Hinds & Bird, 1997). VVIC uses a species-specific virus tospread this vaccine through a population by placing the geneencoding the reproductive protein into the genome of the virus(Tyndale-Biscoe, 1994). Such techniques have been used with va-rying degrees of success on ground squirrels, Spermophilus bee-cheyi (Nash at al., 2004); feral dogs and cats; wild horses, Equuscaballus; and African elephants, Loxodonta africana, amongstother species. Kirkpatrick (2011) indicates that seventy-six capti-ve exotic species and six free-ranging wildlife species are curren-tly managed through the use of PZP immunocontraception. VVIC

14

Page 15: Impronte specie aliene inglese

has been considered appropriate where species are found overlarge and inaccessible areas. Recombinant-microorganism vec-tors to deliver reproductive antigens could be spread by sexualtransmission, contagion, orally or via an arthropod carrier (Tyn-dale-Biscoe, 1994). Fertility control by means of vaccination isnow a reality.In Australia, in spite of intensive eradication efforts, the possumis still considered one of the biggest menaces to local crops. Po-pulations of possums kept low using 1080 baits recover throughrecolonisation and enhanced breeding, making further manage-ment very expensive. Furthermore, possums develop poison-shy-ness—that is they learn to avoid poisoned baits. Scientists havebeen able to genetically engineer carrots, a food of choice forpossums, to express the zona pellucida protein. When injected,the protein can reduce fertility in possums by up to 75% (Wei-hong Ji, 2009). Courchamp and Cornell (2000) propose the use of immunocon-traception as an alternative to anticoagulants, feline panleuko-penia virus, hunting, trapping, and shooting to control feral cats.In their mathematical simulation, they analyse VVIC. Miller et al.(2004) report that the GnRH vaccine has had promising results inmale cats. More recently, Levy (2011) published her study on thelong-term fertility in female cats, which indicates that GnRH im-munocontraception works in domestic cats. Most rodents are r-selected species: they have an early sexualmaturity onset, produce many litters over a year’s time, have ashort gestation period, disperse well their young, and have ashort life expectancy. House mice, Mus domesticus, have a lifeexpectancy in the field of four to six months; females can pro-duce a litter every twenty-one days, and a pair of mice could gi-ve birth to hundreds of offspring during their lifetime. Thesespecies are best controlled by curbing their reproductive poten-tial rather than by increasing mortality, which is what poisoncontrol does. In 1997, Miller et al. compared the efficacy of twoimmunocontraceptive vaccines on Norway rats, Rattus norvegi-cus, the mouse zona pellucida peptide (MZPP) and GnRH. Theyfound that GnRH induced 100% infertility in both males and fe-males and could be used as a control agent for rats in the wild.Avian contraceptives are also being researched. Diazacon is acholesterol mimic, first developed to reduce cholesterol levels inhumans. It inhibits the conversion of desmosterol to cholesterol,thus indirectly blocking the formation of hormones dependingon cholesterol and necessary for sperm and egg production. Itcan be delivered in baits and has been tested on a number ofdifferent species (Yoder et al. 2005). Nicarbazin is commonlyused on broiler chickens to prevent coccidiosis. Because it dis-rupts the yolk membrane preventing the formation of the em-bryo and can be delivered in baits, it has been used to controlfertility in different avian species (pigeons, waterfowl).

INSERT

An interview with Jay KirkpatrickJay Kirkpatrick is the director of the Science and ConservationCenter, in Montana, United States. The center, created in 1998, isan independent non-profit organization dedicated to the hu-mane control of wildlife by means of fertility control. Probablythe best world expert on immunocontraception, Jay Kirkpatrickhas carried out contraceptive research for over 40 years, devel-oping non-lethal and humane methods of controlling wildlifepopulations, and on non-capture methods for studying repro-duction in free-ranging wildlife species.

Q: How did you first start working on immunocontraception?JK: In 1971, Congress passed the Wild Free-Roaming Horses andBurros Act, granting total and complete protection for feralhorses. At that time, herd numbers were controlled by culling –

the horses were rounded up and sent to slaughter, there were nopatrol systems, nothing - but this crude system caused and ex-plosion in the population. The Bureau of Land Management andU.S. Forest Service were charged with managing the number ofwild horses on public land. I was just starting my carrier then,and the Bureau of Land Management contacted us asking forhelp in sterilizing wild horses. Since then, we at the Science and Conservation Center in Mon-tana have been working successfully with 5 different groups ofanimals: horses, and equids in general. Urban deer, where hunt-ing is not legal or safe; zoo animals in places as far as Australiaand Tel Aviv, Israel. We have worked with 85 different specieskept in zoos. We have been working with African elephants in 14or 15 different parks in Africa. More recently, with bison, onSanta Cathalina island. We’ve also embarked on smaller projects,such as wapiti, water buffalo. Immunocontraception has beentried with success not only on ungulates, and hoofed animals,but also on elephants, pinnipeds, bears and even bats.

Q: You have been working in the field of immunocontracep-tion for around 40 years, what are the biggest obstaclesyou’ve encountered when “bringing” the technique onto thefield – technical problems in applying the vaccine, unexpectedundesirable consequences, opposition by hunter lobbies, orsomething other?JK: There are many problems, a few are scientific, but the realobstacles that stand in the way of widespread application of im-munocontraception are social, political, cultural, and economicissues. And biological issues. GnRH analogues are probably goingto be the answer for cats and dogs, but when it comes to highlysocial animals like horses, you can’t interfere with behaviour. Youcan’t interfere with the complexity of wild horse behaviour, orthat of elephants.

Q: Can you briefly summarize the benefits and/or differencesof PZP contraceptives versus GnRH contraceptives?JK: PZP contraceptives have been shown to be safe, and havemany advantages over GnRH analogues: they are tissue specific,and lack cross-reactivity with other tissues and protein hor-mones. They block fertilization, but do not disrupt natural be-haviour, such as herd cohesion and social interactions. Whenused on a pregnant animal, they do not cause abortion, as wouldGnRH contraceptives in some species. What is more, treatedmares are in better physical condition, because they are beingspared the costs of pregnancy and lactation. Receptors for GnRHhave been found all over the body, the heart, in the cerebellum,in the spinal fluid. Whether or not this has a clinical significancein wildlife it is not fully understood yet. Lupron is a drug used totreat prostate cancer in men. Like other GnRH agonists it lowersmale hormones, and slows the growth of prostate cancer orshrinks tumours. Treated individuals were shown to have signifi-cant higher risk of cardiac failure. However, if you want to extinguish certain behaviours, as youmight wish to do with pet animals, certain tools like GnRH vac-cines and analogues will be better than PZP.

Q: I understand that there is a varying degree of reversibilityof infertility in different species. Are some species more likelyto become permanently infertile?JK: It depends on the species, as well as the duration of contra-ception. With horses, we have a larger body of information andwe know that you can treat a horse 5 consecutive years and thatit will reverse over the years. A horse treated for 3 consecutiveyears will sometimes reverse in 4 or more years. The mean is 4years, the range is 1 to 10. In horses treated for 7 consecutivethere is no possibility of reversibility.Each species has a different pattern as far as reversibility goes.

15

Page 16: Impronte specie aliene inglese

Elephants can be treated for several years and will reverse in 18months. There are positive effects, too: health gets better, mortality goesdown and longevity increases.

Q: What are the short and long term financial costs of im-munocontraception application versus traditional cullingmethods, such as shooting? JK: If you are a proponent of contraception, you can make thecost look low. You need to consider the cost of training. Peopleneed to be trained to deliver vaccines with dart guns, and dealwith the animals. We offer three day intensive workshop, andthe cost is travel expenses plus 200 dollars.Then, there’s the cost of delivery equipment. Dart guns rangefrom 900 to several thousand; there are many different deliverysystems. It depends on which one you choose.The real cost is the labour. The cost of vaccines is very low, 24dollars each. There is no money to be made in wildlife contracep-tion! The cost of labour can be as much as 50.000 dollars a year.The solution here is to train volunteers, or park employee. Theadvantage in getting the public involved and in the manage-ment of wildlife is that it reduces the conflict. The adversarial re-lationship between whomever manages the animals and publicopinion diminishes.

Q: Is remote delivery of vaccines safe? Are some species moreprone to developing granulomas on the site of injection? Howis each individual later identified?JK: First of all, you need to differentiate between an abscess anda granuloma. The first is a swelling which will eventually breakopen and drain. It is rare and is not life threatening. Granulomasare very common, but they are no more than a hard lump underthe skin, and pose no health problem. In some wildlife reserves there’s someone in charge who checkson the animals every day and recognizes each individual. Howev-er, in order to identify animals, you can use a key, just like aplant key. To identify wild horses you can use the differences incolour, facial markings, leg marking (stockings, socks, coronets, 4different legs, there are over a thousand permutations). There areother ways too. Sometimes you don’t need to identify each indi-vidual, but only the social group. With fallow deer you’ve gotspots, which are like fingerprints, they are different on each ani-mal. Finally, if you have no other option, you use what we call“saturation bombing”. This means you dart every single fallowdeer you see. Of course, some you won’t get the first year, butyou do the same next thing next year and over 3 to 5 years youwill have achieved your goal.

Q: What percentage of the population needs to be targeted inorder to obtain a substantial decrease in fertility? JK: The answer is site specific. It depends on the fertility rate,mortality rate, sex ratio… If we want to generalize, you want totreat 60 to 75% of the adult females. It depends on the goalyou’ve set for yourself, whether you want to decrease the herd,or simply reach zero growth.

Q: Although your field is that of large herbivores, do you seethe use of immunocontraception expanding to include smalleranimals and carnivores?JK: Yes, of course. There are teams in Australia working on kan-garoos, teams in England working on grey squirrels. Research isbeing carried out on feral dogs, on different bird species, on allkinds of different animals. Immunocontraception is the answerwhere traditional lethal controls are not longer legal, wise, safeor publicly acceptable.

6. ITALY

We need another and a wiser and perhaps a moremystical concept of animals. Remote from univer-sal nature and living by complicated artifice, manin civilization surveys the creature through theglass of his knowledge and sees thereby a feathermagnified and the whole image in distortion. Wepatronize them for their incompleteness, for theirtragic fate for having taken form so far belowourselves. And therein do we err. For the animalshall not be measured by man. In a world olderand more complete than ours, they move finishedand complete, gifted with the extension of thesenses we have lost or never attained, living byvoices we shall never hear. They are not brethren,they are not underlings: they are other nations,caught with ourselves in the net of life and time,fellow prisoners of the splendour and travail ofthe earth.

Henry Beston, The Outermost House, 1928

In Italy, alien species are estimated at 1,516 (Project DAISIE). Ofthese, 253 are found in Sicily and 302 in Sardinia. There are 119of them are in Mediterranean Sea waters, and they are havingserious ecological and economical impacts. (HISTOGRAMS)Of the forty amphibian species present in Italy, 40% (eighteenspecies) are endemic and 7% are established aliens. They all be-long to the order Anura: the American bullfrog, Lithobates cate-sbeinaus, which was first introduced from 1932-1937 and is nowwidely distributed in the centre and in the north of the peninsu-la; the Balkan frog, Pelophylax kurtmuelleri, introduced in 1941and now spreading quickly throughout the north of the country;the marsh frog, Pelophylax ridibundus, and the African clawedfrog, Xenopus laevis, the most recently introduced species, pre-sent only in Sicily (Lanza et al., 2007). The American bullfrog wasintentionally introduced in many countries to be harvested asfood and it is now considered a noxious species everywhere. Itcompetes and preys on native amphibian species, has a negativeimpact on water taxa, and is probably a vector for Batrachochy-trium dendrobatidis, a chytrid fungus causing an infection whichis decimating amphibian populations worldwide. In Italy, there are fifty-seven reptile species (Sindaco et al.,2006); of these, only four are endemic, which constitutes 7% ofthe total, while 10% are introduced species. The red-eared slider,Trachemys scripta elegans, an established species, is found throu-ghout the territory and resulted from the release of captive indi-viduals. Other alien species present in the country are turtlesbelonging to the genus Mauremys (M. leprosa, M. caspica, bothnot established); the Greek tortoise, Testudo graeca; the margi-nated tortoise, Testudo marginata; the common chameleon, Cha-maeleo chamaeleon; Kotschy’s gecko, established; and Agamaagama, a species of lizard not established. T. graeca and margi-nata were introduced by man in historic times and are establi-shed alien species, while the common chameleon has reachedSicily and Puglia—where it is occasionally observed—travelingaboard ships. The main threat comes from the red-eared slider,which competes over resources with the endemic European pondturtle, Emys orbicularis, itself an endangered species. The checklist for birds found in Italy comprises 529 species (Ho-ward & Moore, 3rd edition, corrigenda 8). Of these, sixteen areglobally threatened and six have been introduced.There are fifteen nonindigenous terrestrial mammal species inItaly, four of which were introduced in historic times, and theother eleven having been introduced somewhat more recently.These species represent a high portion on the seventy-three au-thocthonous terrestrial species (Spagnesi & Toso, 1999), or 117

16

Page 17: Impronte specie aliene inglese

17

Aliens by Country (Terrestrial Vertebrates) Species count

Page 18: Impronte specie aliene inglese

including species belonging to the Chiroptera, Pinnipeda and Ce-tacea (Amori et al., 1996).

ITALIAN VERTEBRATE SPECIES

Amphibia: 40 species, with 18 endemic and 4 introduced.Reptilia: 57 species, of which 4 are endemic.Aves: 529 species.Mammals: 117 speciesInsectivora: 16 species with 3 endemic species and 21 subspe-

cies.Chiroptera: 29 species, of which only Myotis blythii oxygna-

thus is considered endemic.Lagomorpha: 6 species, with 4 endemic species.Rodentia: 27 species, comprising 24 endemic subspecies.Carnivora: 17 species, many of which are endangered becau-

se they have been hunted as pests until recently.Cetacea: 13 species have been observed in Italian waters.Artiodactyla: 9 species, of which 5 are subendemic.

Nonindigenous mammal species in detail

Two subspecies of rabbit, O. cuniculus and O. c. huxleyi, establi-shed. Native to the Iberian Peninsula, these rabbits were introdu-ced into Italy in Roman times. Impact: overgrazing activity,especially on islands; it can act as a natural host for the Myxo-matosis virus.

Cape hare, Lepus capensis, established. Introduced in Paleolithictimes, it is thought it could compete over resources with the Ita-lian hare, Lepus corsicanus.

Eastern cottontail, Sylvilagus floridanus, established. Introducedinto Piedmont in the sixties for hunting purposes. Impact: it da-mages crops, but also orchards because of bark stripping; it is acarrier for Myxomatosis, rabbit haemorrhagic disease virus(RHDV), and dermatophyte fungi, these last transmissible to hu-mans.

American grey squirrel, Sciurus carolinensis, established. Introdu-ced in 1948 to Turin, Piedmont, it is now considered a threat tothe native red squirrel, Sciurus vulgaris.

Finlayson’s squirrel, Callosciurus finlaysoni, established. Native ofcentral Thailand. Impact: it damages trees through bark strippingand it competes with passerine species over nesting sites.

Pallas squirrel, Callosciurus erythraeus, not established. Alsoknown as the red-bellied tree squirrel, it comes from EasternAsia. Widely sold throughout the world, it has been released andbecome established in different areas, namely Argentina, Japan,and Hong Kong. It is thought it might compete over resourceswith the endemic red squirrel and damages trees by gnawingbark.

Siberian chipmunk, Tamias sibiricus, established. Native to nor-thern Russia, China, and Japan. Widely sold as a pet, it has esca-ped repeatedly from captivity and has established populations inmany European countries. In Italy, it is found mostly in thenorth. Impact: it destroys cereal crops and predates on eggs andchicks of Dusky warbler, Phylloscopus fuscatus.

Muskrat, Ondatra zibethicus, of unknown status. Native to NorthAmerica, it was introduced to Europe in the early twentieth cen-tury for fur farming; it escaped into the wild and it is now pre-sent in Europe, Asia, and South America. In Italy, it is found onlyin Friuli-Venezia-Giulia.

House mouse, Mus domesticus, established. It occurs in commen-sal and noncommensal habitats worldwide. Impact: it predates

on different species of invertebrates, damages crops, and preyson chicks and eggs of seabirds on islands.

Black rat, Rattus rattus, established. It was introduced to Italy inPaleolithic times; archeological findings show that five thousandyears ago it was already present in Sardinia (Spagnesi & Toso,1999). Impact: it preys on seabirds and terrestrial bird species,whether they nest on the ground or on trees on islands; it dama-ges crops and orchards. It acts as a reservoir host of diseasestransmissible to humans and domestic animals.

Brown rat, Rattus norvegicus, established. In Italy, it has beenobserved since the mid-eighteenth century and is now widelyspread throughout the territory. Impact: same as the black rat.

Coypu, Myocastor coypus, established. Native to South America,it has been farmed for its fur in different areas of the world. Itwas imported into Italy in 1928, and since the 1960s it has beenintentionally and unintentionally released into the wild. Impact:it can damage crops, aquatic vegetation through feeding, and ir-rigation structures and bank rivers because of its burrowing ha-bits.

Raccoon dog, Nyctereutes procyonoides, not established. Indige-nous to east Asia, it was introduced into the Soviet Union from1928 to 1958 for fur farming and it has since migrated to mostof Europe. Impact: it preys on birds, especially waterfowl.

Raccoon, Procyon lotor, not established. It comes from NorthAmerica. Impact: it preys on birds and amphibians.

American mink, Mustela vison, established. It was deliberately in-troduced into Europe to be harvested for fur. It rapidly expandedand in Italy is present in the northeast, but has also been obser-ved in the centre (Spagnesi & Toso, 1999). Impact: it could hybri-dise with the native European mink, Mustela lutreola, andcompete over resources with both the mink and the Europeanotter, Lutra lutra.

Common genet, Genetta genetta, not established. It is found inmany European countries. Impact: it acts as a vector for zoonosisand damages crops.

Fallow deer, Dama dama. According to Massetti (1996) it is notpossible to determine whether the Italian populations of fallowdeer are to be considered an allochthonous species. It was widelyintroduced for game hunting in historic times throughout Euro-pe. Certainly, the fallow deer was present in Castelporziano inthe eleventh century and in San Rossore in the fourteenth cen-tury. Impact: it competes with the European roe deer, Capreoluscapreolus, and with the red deer, Cervus elaphus, and acts as areservoir host for infectious diseases of farm animals.

Mouflon, Ovis aries musimon, established. Indigenous to westAsia, it was probably introduced in Sardinia and Corsica in Neoli-thic times. It is thought that it represents a threat for the alpinechamois, Rupicapra rupicapra, and the Apennine chamois, R. py-renaica ornata.

Barbary sheep, Ammotragus lervia. Not established. Indigenousto Saharan and arid Africa (Algeria, Chad, Libya, Mali, Niger, Su-dan), it is listed as vulnerable. It has been introduced into Spain,the United States, Mexico, and Italy. The population present inVarese, Italy, resulted from an accidental escape from captivity(Gagliardi et al., 2008).

Eurasian wild boar, Sus s. scrofa, established. It is one of the mostwidely distributed mammals in the world. It occurs from WesternEurope and the Mediterranean basin to eastern Asia as far as Ja-pan. It has been introduced into Australia, New Zealand, Northand South America, and reintroduced in England. It is bigger andstronger than the indigenous subspecies Sus scrofa majori, indi-

18

Page 19: Impronte specie aliene inglese

genous to the peninsula, and Sus scrofa meridionalis, which hasa different origin and is descended from ancient feral and re-cent domesticated pigs (Oliver W.L.R, 1995). The introduction ofthe Eurasian wild boar into Italy in the 1950s resulted in the al-most complete disappearance of the local subspecies.

Nonindigenous bird species in detail

Pink-backed pelican, Pelecanus rufescens, not established. Nativeto tropical Africa and southern Arabia, it moves by natural di-spersion. It has been sporadically observed in various regions inItaly.

Western-reef heron, Egretta gularis, not established. It occursnaturally along the coasts of western Africa, the Red Sea, and asfar as India. It has reached Italy by natural dispersion, where ithas been observed since the 1970s. It is now included in the Ita-lian bird checklist. It could hybridise with the local egret, Egrettagarzetta, resulting in a loss of genetic diversity.

African sacred ibis, Threskiornis aethiopicus, established. It occursin sub-Sahara Africa and Egypt. In Italy it is present because ofaccidental releases from zoological gardens. In recent years it hasstarted breeding within heron nesting sites.

Chilean flamingo, Phoenicopterus chilensis, not established. Itsnatural range goes from Peru as far as southern Brazil. It hassporadically been observed in Italy.

Mute swan, Cygnus olor, established. Native to the northern Pa-learctic region, it was intentionally released in Switzerland befo-re 1950 and has expanded to Italy, where it reproduces.Wintering subjects are migratory birds coming from Eastern andcentral Europe. Impact: damages aquatic vegetation, especiallythe Potamogeton species.

Black swan, Cygnus atratus, established. Native to Australia andTasmania. It has been observed in various Italian regions.

Bar-headed goose, Anser indicus, not established. A migratoryspecies often kept in captivity, it has been observed in NorthAmerica and in Europe.

Canada goose, Branta canadensis, not established. The Canadagoose is a migratory species, native to arctic and temperate re-gions of North America; it comprises about ten to twelve sub-species, of which it is the nominal to have been introduced intoEurope. In Italy, it has been observed mostly in the centre and inthe north. Impact: it damages crops and has been implicated indeadly aviation strikes.

Egyptian goose, Alopochen aegyptiacus, not established. Nativeto sub-Saharan Africa and the Nile Valley, the Egyptian goosewas introduced into various European countries and has beenobserved in Italy.

Mandarin duck, Aix galericulata, not established. It comes fromEast Asia but has been introduced into North America and Euro-pe. Although it is not naturalised, it has been included on theItalian bird checklist.

Ruddy duck, Oxyura jamaicensis, not established. It comes fromNorth America and the Andes Mountains. It has been involunta-rily introduced into Europe as a result of accidental escapes fromindividuals kept in captivity. In Italy, it has been observed sincethe 1980s. Impact: it hybridises with the local white-headedduck, O. leucocephala, a threatened species.

Bobwhite quail, or Northern bobwhite, Calliplepla virginianus,established. Native to North America, Mexico, and the Caribbean,it was introduced into India, New Zealand, Great Britain, France,and Germany. In Italy it is naturalised in Piedmont and in Lom-bardy, but it is present in other areas (Mozia Island, Sicily).

Chukar partridge, Alectoris chukar, established. A Eurasian spe-cies, it was introduced into many countries for hunting. In Italyit was released into the wild in the nineteenth century but didnot survive, and new releases took place in the 1950s. Impact: itcan hybridise with the red-legged partridge, Alectoris rufa; andthe rock partridge, Alectoris graeca; creating a loss of diversity.

Barbary partridge, Alectoris barbara, established. Native to NorthAfrica, it was introduced without success into many Europeancountries, New Zealand, Australia, and the US. In Italy, it is pre-sent in Sardinia, but it is not known whether the Sardinian andthe African partridges are separate species.

Erkel’s francolin, Francolinus erckelii (Pternis erckelii), establi-shed. An alpine species native to East Africa (Eritrea, Ethiopia,Sudan), it was released into various Italian regions around 1950.

Japanese quail, Coturnix japonica, established. Native to EastAsia, it was introduced into Hawaii, North America, and variousEuropean countries. After 1950 in Italy, it became the speciesmost frequently released into the wild. Impact: it hybridises withthe common quail, Coturnix coturnix.

Common pheasant, Phasianus colchicus, established. An Asianspecies widely introduced worldwide for hunting purposes. InItaly, it has been repeatedly introduced, and was released in thehighest numbers in the 1920s and 1940s.

Green pheasant, Phasianus versicolor, not established. Native tothe Japanese archipelago, it was introduced into North America,Europe, and the Hawaiian Islands.

African collared dove, Streptopelia roseogrisea, established. Itoccurs worldwide; in Italy, it is often raised in semi-freedom.

Rose-ringed parakeet, Psittacula krameri, established. It comesfrom tropical Africa but is found throughout Western Palearctic,the result of intentional and accidental releases. It is present inItaly and reproduces mostly in the centre and in the north. Im-pact: it competes over nesting sites with local bird species andcan damage crops.

Monk parakeet, Myiopsitta monachus, established. It comes fromSouth America and has been introduced into the western Palear-ctic, United States, the Caribbean, and Brazil. In Europe, it hasbeen released intentionally and unintentionally and has formedgroups in different cities. Impact: it competes over food resour-ces with local bird species and may damage crops.

Blue-fronted Amazon, Amazona aestiva, established. Native toSouth America. In Italy, it has been repeatedly observed; it isascertained that in Genoa a pair of blue-fronted Amazons hasreproduced.

Red-billed Leiothrix, Leiothrix lutea, established. A Sino-Hi-malayan species, it has been widely traded. Regularly observed inItaly. Impact: it can damage crops and orchards.

Ashy-throated parrotbill, Paradoxornis alphonsianus, established.Native to southwest China and northern Vietnam, its presence inItaly is attributed to accidental escapes from captivity. Impact: itcan compete over food resources with local bird species.

Vinous-throated parrotbill, Paradoxornis webbianus, established.Same as the vinous-throated parrotbill.

Black-rumped waxbill, Estrilda troglodytes, not established. Nati-ve to South Africa, its presence in Italy is due to accidental esca-pes from captivity.

Common waxbill, Estrilda astrild, not established. Native to sub-Saharan Africa, the species has become naturalised in many Eu-ropean areas.

19

Page 20: Impronte specie aliene inglese

Red munia, Amandava amandava, established. An Asian speciesthat has been traded for a long time, the red munia is naturali-sed in many areas in the world. In Italy, it reproduces in variousregions.

Common myna, Acridotheres tristis, not established. Native toAsia, the common myna has been introduced to control insectsdamaging crops in many areas of the world. Highly adaptable, itreproduced beyond expectation and has become naturalised. Itspresence in Italy is due to individuals that escaped from captivi-ty. Impact: it can compete with local bird species and damagecrops.

Yellow-crowned bishop, Euplectes afer, not established. Native tothe area south of the Sahara, it is widely traded and its presencein Italy is due to accidental releases.

Zanzibar red bishop, Euplectes nigroventris, not established. Itcomes from East Africa, it is widely traded and subject to acci-dental releases.

Southern red bishop, Euplectes orix, not established. Native toAfrica in regions south of the equator, it is widely traded andsubject to accidental releases.

Red-billed fire-finch, Lagonosticta senegala, not established. Na-tive to sub-Saharan Africa, it is widely traded and subject to ac-cidental releases.

Red-crested cardinal, Paroaria coronata, not established. It comesfrom eastern South America, is widely traded, and was acciden-tally released.

Village weaver, Ploceus cucullatus, established. Found in sub-Sa-haran Africa, it is widely traded and subject to accidental relea-ses.

Eastern golden weaver, Ploceus subaureus, not established.Found in southern Africa, it is widely traded and subject to acci-dental releases.

Red-whiskered bulbul, Pycnonotus jocosus, not established. Nati-ve to South Asia, it is widely traded and subject to accidental re-leases.

Rats

Rats, Rattus norvegicus, R. rattus, and R. exulans, have expandedby natural dispersion or have accompanied humans in the colo-nisation of islands worldwide. The black rat, R. rattus, for exam-ples, spread out of Asia by swimming. These rodents are nowpresent on more than 80% of the world’s major islands, wherethey can have negative impacts on the flora and the fauna,especially on seabirds. Seabirds, having always reproduced on is-lands where predators were not present, have not evolved a de-fence mechanism and are a vulnerable prey. Rats are found on most Mediterranean islands and are routinelycontrolled by poison baits containing the anticoagulant brodifa-coum. The project of eradication of the black rat, on the islandof Montecristo, Italy, used dispersal of poisoned pellets scatteredalmost exclusively by helicopter. Rats represent a threat to theyelkouan or Mediterranean shearwater, Puffinus yelkouan, bypreying on their eggs and chicks. The risks to predators and other animals from the use of brodifa-coum are well known, and they appear to be greatest with aerialbaiting techniques (Eason & Spurr, 1995). The capacity of theseanticoagulants to persist for months in tissues and organs suchas the kidney or the liver heightens the risk of their causing pri-mary and secondary poisoning in many nontarget species. Thenumber of worldwide reports of wildlife poisoned by anticoagu-lants is growing; mammalian carnivores and predatory and sca-

venging birds are certainly at risk, but herbivores have beenshown to have died after secondary exposure to brodifacoum(Stone et al., 1999). In the United States alone between 1981 and 2004, 244 poiso-ning incidents of birds and nontarget mammals associated withbrodifacoum exposure were reported (US EPA, 2004). In fact,bioaccumulation of brodifacoum—insoluble in water and brokendown slowly by microbial activity in baits (Dowding et al., 1999;Eason et al., 1999)—its persistence in carcasses and sub-lethallypoisoned animals, as well as the way in which it causes the deathof the animal are raising concerns everywhere in the world (Ma-son and Littin, 2003; Paparella, 2006; Meerburg et al., 2008). It ispredicted that on Montecristo the population of the barn owl,Tyto alba, will be wiped out by the use of the poison. Becausesnails, slugs, and carrion insects (cockroaches, ants) feed on bro-difacoum baits or the carcasses of poisoned rodents, they can inturn poison insectivore species, mostly birds, which prey uponthem (Webster, 2009). Many different species of migratory birdsstop on the island during migration, and some species, such asthe Dartford warbler, Sylvia undata, and the spotted flycatcher,Muscicapa striata, reproduce on it. Other animals at risk will begoats, Capra aegragus, rodents other than rats, rabbits, ravens,Corvus corax, bats (Rhinolophus euryale, P.ipistrellus nathusii),and possibly reptile and amphibian species. The rat eradicationprogramme carried out using aerial baiting on Rat Island, in theAleutians, successfully rid the island of rats but also killed forty-three bald eagles, Haliaeetus leucocephalus, 213 glaucous-win-ged gulls, Larus glaucescens, and birds of different species(Woods et al., 2009). Given that islands tend to be reinvaded byrats, the long-term use of poison appears to be more detrimentalthan beneficial. The cost in terms of nontarget animals, bioaccu-mulation of the substance, as well as the financial costs of re-peated operations would be better channeled into new researchon fertility control methods to provide a long-lasting solution,with a lesser impact on the environment.

Squirrel wars

On May 25, 2012, the Italian newspaper La Stampa published anarticle, one of many, on the same recurrent theme: “Squirrelwars: Italy vows to eliminate its American invaders.” Italy is “wa-ging a war” against “these strong American invaders” that stealfood, space, and resources from the smaller endemic red squir-rels, threatening their survival.The American grey squirrel, Sciurus carolinensis, has been intro-duced repeatedly in Italy: in Stupinigi, Piedmont, in 1948; inside apark in Genoa Nervi in 1966; in Trecate, Novara, in 1994. Milana& Rocchi (2010) indicate that the squirrels have formed four dif-ferent nuclei: in Turin and Cuneo, Piedmont; at Genoa Nervi,where they can be found in the urban parks of Nervi and Boglia-sco; in Novara; and in Perugia, Umbria. The squirrels have been si-ghted in Tuscany, too. They have an economic impact becausethey strip barks, damaging timber crops, and they tend to displa-ce the endemic red squirrel, S. vulgaris. The American grey squir-rel, which in autumn exhibits higher body weight compared tothe red squirrel, is stronger; moreover, it retrieves seeds stored byred squirrels, depriving them of their stored reserves of food forthe winter. Another possible threat comes from the hypothesisthat the grey squirrel acts as a reservoir host of parapoxvirus, le-thal for the endemic squirrel. Furthermore, the grey squirrel couldexpand and spread to other countries in Europe. The native redsquirrel, considered threatened in Europe, occurs throughout theItalian peninsula with its three subspecies. Its decline is attributedfirst to the fragmentation of woodland habitats (Celada et al.,1994; Wauters, 1997), and second to the presence of the Ameri-can grey squirrel. Therefore, designating more green areas to thisspecies should be the first protective measure to be implemented.

20

Page 21: Impronte specie aliene inglese

Various eradication techniques have been used to eliminate thegrey squirrel: anticoagulants such as Warfarin, nest destruction,trapping, euthanasia induced by prolonged use of anaesthetics,and surgical sterilisation. Chemical sterilisation is currently beingresearched. If it is not possible to completely eradicate the greysquirrel by killing more and more individuals, which might simplyresult in better breeding performance, why not finance researchon new, more humane ways of controlling its population? Whynot spend and support projects to expand and restore the frag-mented habitat of the red squirrel? Finally, only a complete banon trade could avoid the intentional and unintentional release ofexotic species in the environment. In January 2013, the Italiangovernment approves a ban on trade and possession of threedifferent squirrel species, introduced in 2012 in the Annex B ofthe Council Regulation No. 338/97, regulating the introductionof species dangerous to native flora or fauna. The ban, which isvalid in the whole European Union, forbids the import of livespecimens of grey squirrels, fox squirrels, Sciurus niger, and Pal-las squirrels, Callosciurus erythraeus. Although the ban coversgrey squirrels-without clear indications as to what is the fate ofthe individuals kept as pets or on the market-, the other twospecies are not the next most problematic ones and the markethas already responded by finding new, commerciable species.Other species of alien squirrels, the Siberian chipmunk, Tamias si-biricus, Finlayson’s squirrel, Callosciurus finlaysoni, and Pallassquirrel, Callosciurus erythraeus, are present within the Italianterritory. Free-ranging populations of Siberian chipmunks arefound in the north of Italy: in the towns of Verona and Belluno,in the north, where they were introduced in the 1970s, and inthe Roman park of Villa Ada, where they were released in the1980s. Finlayson’s squirrel was first introduced into Acqui Terme,Piedmont in 1981, and into Maratea, Basilicata, a few years later.

Both species cause extensive damage to the vegetation. Chip-munks destroy cereal crops and predate on eggs and chicks ofPhylloscopus fuscatus, while Finlayson’s squirrels damage fruitcrops, piping systems, and electric cables. Pallas squirrels are pre-sent near Varese and it is thought they might compete over re-sources with the endemic red squirrel.

Coypu

The coypu is a semiaquatic rodent that feeds on crops and aqua-tic vegetation, damaging both. Coypus can alter aquatic ecosy-stems and weaken irrigation structures, or river banks, throughtheir burrowing habits. Due to dispersal habits and the high re-productive rate of the species, complete eradication is impossi-ble.

INSERT

Interview with Samuele VenturiniBiologist Samuele Venturini has worked for years with coypusand is now responsible for a neutering project. Coypus are a non-problem, Venturini tells us. Of course, within acertain context, any animal can become problematic, dependingon various factors, such as population density. While a smallnumber of coypus doesn’t seem to cause any damage, high den-sity populations could be a problem for agriculture.We are working on a neutering project in Buccinasco, near Mi-lan, using an ecological method to contain the population. Ouraim is to solve the problem a given species may represent. In theUnited States, studies carried out on coyotes proved that fertilitycontrol works and that treated populations of coyotes exhibit alower rate of predation on sheep.

21

Page 22: Impronte specie aliene inglese

Culling can have a counterproductive effect on the populationtrend. In Italy, coypus have been culled for twenty years, yettheir numbers increase constantly. Studies showed that cullingprogrammes can increase reproduction capacity. Females getpregnant more often and have more offspring, because theytend to hide and move about less than males. The more activeadult males are killed in greater numbers, favouring youngermales which, like females, don’t move about very much. Whenan animal gets killed, a niche is made available and it gets filledright away, in this case by younger animals with higher repro-duction rates. Hunting pressure also selects for the early onset ofsexual maturity. In the wild, coypus start reproducing at 6 to 8months of age. Fur farming selected animals which could repro-duce earlier, at 3-4 months of age, favouring individuals rea-ching sexual maturity earlier. We neuter coypus by surgical intervention. Males and femalesare live-trapped and taken to a veterinary clinic, where they un-dergo a minor surgical procedure and some blood tests. Neuteredanimals are then marked in order to be later recognized. Afterthis procedure, the animals are returned to the same place wherethey were caught. Coypus are highly territorial and when an in-dividual occupies a niche, it means other coypus will stay awayand won’t have access to trophic resources and nesting sites, andtherefore won’t be able to reproduce. Over time, the populationtends to reach a balance. New arrivals are chased away, andwhen resources are lacking females can abort or terminate pre-gnancies through resorption, so that the number of individualsdiminishes. In the wild, coypus live 4 to 7 years; in captivity – inparks or natural reserves – they can reach 20 years of age.As I said, the final objective of the project is to reduce popula-tion density. Farmers want that the number of animals be keptunder control.At the moment, we’re still in an experimental phase of the pro-ject and we need more time to assess the various aspects and re-sults of this technique. Once the animals are neutered andreturned to their sites, a long period of observation starts. This isthe hardest part, requiring manpower and long hours of work.Coypu sterilization can be used only in circumscribed and easilymonitored areas, such as parks and karst springs. In the opencountryside, it is impossible to contain the expansion of the ani-mals through this method alone. However, sterilizing a small, cir-cumscribed population limits the expansion of the species,allowing for better control.A common problem in the countryside is the stability of riverbanks: it is feared that coypus make them fragile and friable bydigging burrows. Coypus prefer to dig their dens where emban-kments have a certain slope and there is no vegetation. They do-n’t always excavate burrows; in the wild, they build a den insidesmall rafts made of dry vegetation. Where this is not possible butthere are trees and bushes, coypus settle for a good hiding place.They only dig burrows when there is no vegetation. Tunnels mea-sure between 50 cm and 2.30 metres in length, and rarely reach5 m. These tunnels don’t make embankments unstable, but lackof vegetation-the result of anthropomorphic disturbance-does.Tunnels excavated by coypus can have a positive impact on theecosystem, offering shelter to other animals, such as winteringamphibians or water rails. Often, coypus use abandoned burrows,excavated by otters, once more common throughout Italy, or byother coypus. When tunnels are artificially refilled, coypus willdig more burrows and thus make banks more unstable; onceagain, this problem is exacerbated by human intervention. Coy-pus are highly social animals and sometimes share their dens.During hunting and culling campaigns, they sometimes react bydigging deeper and larger tunnels, up to 5 m. in depth, to housemore individuals.To solve the problem of so called “pest” species you need to ac-quire an in-depth knowledge of the biology of the target species

and its habitat. Many people talk about England as the countrywhere coypus have been eradicated completely, but it was not asimple process. First of all, in England they tackled the problemvery early on, before the population could expand. Besides, inthe English countryside there are no capillary systems for irriga-tion, but only small rivers and drainage basins. There weren’t ma-ny animals, and they were isolated. Limited but well aimedfunding was sufficient to capture most of the animals. And, afew very cold consecutive winters decimated the population,making possible a complete eradication where it could not havebeen so.It is possible to contain the damage done to banks using emban-kment barriers. In Mantua and in Rovigo, they used special net-tings which prevent coypus from digging, strengthenembankments and favour the process of recolonization by marshvegetation. Natural embankment vegetation gives extra stabili-zation, creates a favourable micro-environment, filters the waterand attracts insects and birds. These, in turn, protect crops byfeeding on certain noxious insects. Farming is made more secure,because embankments are less fragile and do not collapse whenfarmers drive over them with a tractor. In Argentina - the coy-pu’s original range – they use and simple and functional methodto contain the population. Unlike us, who sow crops up to thewater’s edge, they leave a strip of a few metres of unsown landbetween the field and the water, to allow for vegetation growth.In Italy, the structure of the soil is alluvial, and therefore morefriable. Five to 10 metres of unsown land would be sufficient forvegetation to colonize the embankments. Natural vegetation ke-eps coypus from damaging crops: in the wild, they prefer feedingon the aquatic vegetation they find on the river banks ratherthan corn or other crops. Besides, they don’t like straying fromthe water because by doing so they expose themselves to preda-tors. Coypus damage crops only when they are deprived of theirnatural habitats.

Wild boars

Located in coastal central Italy, the Maremma Regional Park cov-ers an area of about 10,000 ha. Wild boars are some of the ani-mals inhabiting the park. They are opportunistic feeders so whileplants make up most of their diet, they also feed on vertebratesand invertebrates, carrion, eggs, fruits and fungi. When food isscarce, they can seriously damage agricultural crops of any kind.Because they can reproduce at rates higher than most largemammals, resulting in high local densities, they have a strongnegative impact on human economy. Although traditionallyhunting has been used to control wild boars populations, theMaremma Regional Park is now looking into new technologies tomanage wildlife, namely fertility control. Andrea Sforzi, biologist,will work with Giovanna Massei, an Italian wildlife ecologistworking at the Food and Environment Research Agency in York,England. For over 25 years, Massei has been working on non-lethal approaches to mitigate human-wildlife conflict. The parkwill test a boar-operated-systems (BOS), a device used to deliverbait-delivered pharmaceuticals to wild boars and pigs. BOS is ametal pole onto which is fitted a cone, which boars can openand feed from. The study aims to test whether free living wildboars will feed from BOS devices. If so, in the second phase ofthe project, they will be fed baits treated with oral vaccines(Massei et al., 2008; Massei et al., 2011). At present, GnRH oralvaccines are still being perfected and have to be approved foruse by the Italian Health Authorities.

Cervids

The fallow deer, Dama dama, was introduced into Italy in the Ne-olithic. Since then, it became extinct and was reintroduced sev-

22

Page 23: Impronte specie aliene inglese

eral times. Although it can hardly be considered an alien species,it often behaves like an invasive one and can compete fiercelywith local ones, such as the endemic red deer, Cervus elaphus, inthe Mesola Park, or the roe deer, Capreolus capreolus, at theMaremma Regional Park. The Mesola Forest, situated near Ferrara in the north of Italy,covers an area of 1,058 ha. The population of fallow deer be-came extinct in 1945 and was reintroduced in the Fifties andSixties. It expanded rapidly and in recent years has seriously re-duced pastures by overgrazing. The presence and rapid expansionof the fallow deer represents a threat for the small population ofabout 120 individuals of red deer. Attempts to control the fallowdeer through by hunting started in 1982, but they only exacer-bated the problem. 3,180 animals were shot dead, and numberskeep rising, with the population rising from 602 individuals in2006 to 950-1,000 in 2011. Modena Local Veterinary Service(AUSL) proposes a project based on immunocontraception (Ferriet al., 2011). For a period of 7-15 years female deer are treatedwith GonaConTM vaccine and ear-tagged with the objective toreduce deer population to a small group considered of “historicalimportance”, comprising about 20 to 40 individuals. To the pres-ent time, the Italian Health Authorities have not yet approvedthe use of the vaccine, much to the detriment of the wholeMesola ecosystem. We badly need alternative solutions to cullingthrough hunting, which is both undesirable and opposed by thegeneral public.

Birds

Since 1997, the Modena Local Veterinary Service (AUSL) hasbeen working on fertility control of feral pigeons using an oralveterinary licensed drug, Ovistop®, ACME (Ferri et al., 2009). Theuse of the vaccine has been integrated with architectural barri-ers to limit pigeon access to scaffold holes, used for nesting,while still allowing other species (birds, mammals, reptiles) to ac-cess them. The project resulted in the decrease of urban pigeonsand the preservation of other species, such as common swifts,Apus apus, insectivore passerines, bats and geckos. While pigeonsare not an alien species, they certainly are an invasive one, andthe success of this effort could be applied to other situations. The active component in Ovistop is Nicarbazin, a compoundwhich decreases egg production and hatching rates by disruptingthe yolk membrane. It is non toxic, has anticoccidial propertiesand is considered ethical; plus, it has already been used on Cana-da geese, Branta canadiensis, and other waterfowl to control fer-tility.

7. SOCIAL AND FINANCIAL IMPLICATIONS “An ounce of prevention is worth apound of cure.”

Henry de Bracton, 1240, jurist

Biological invasions are mostly the intentional or unintentionalresult of economic activity. We have seen how certain ecosystem,such as islands, lakes, rivers, and near-shore marine systems, orsystems of low diversity with few predators, are more vulnerableto colonisation by alien species. But a country’s socioeconomicfactors and land use increase the introduction and spread of al-lochthonous species due to the increase in trade, transport, andhuman movement. Transport systems support high trade volu-mes, both national and international. Economically developedcountries possess good transport systems and their road net-works cover large areas, especially in densely populated regions.

Roads act as introduction pathways, people act as vectors, anddisturbed land – degraded habitats favour biological invasions(Marvier et al., 2004) - surrounding roads, maintenance works,and movement further promote the process of invasion. Finally,also the volume of disturbed and suburban areas, which also fa-vours the spread of invasive species, is high in developed coun-tries (Sharma et al., 2009).The control of wildlife and unwanted exotic species is a growingindustry. Biologists and other researchers tend to concentratetheir studies on projects for which they are more likely to obtainfunding. Invasive species which have a proven economic impactare of higher interest than casual, or naturalised species. A studycarried out by Pyšek (2008) highlights that the most-researchedinvasive animals are the ones with a serious impact. Online rese-arch using science search engines shows the existence of a largenumber of studies on zebra mussels, Dreissena polymorpha, rats,the house mouse, possums, coypus, wild boars, and foxes. Eradi-cation programmes of these pest species or papers on the sametopics offer an attractive and quick solution to a costly andcomplex problem. The bias does not affect taxa alone, but alsocountries: most research on exotic invasive species takes place inEurope and the United States (GRAPH from Pyšek, Geographicaland taxonomic biases in invasion ecology). Wealthy countrieswith a high gross domestic product and large trade volumes ha-ve more alien species, which partly justifies a higher concentra-tion of research in this area. At the same time, fundamentalaspects of the invasion process—habitat properties, the processof naturalisation, and each new case of biological invasion,amongst others—are understudied and need to be understood toaddress the problem and to effectively curb new invasions.In Europe, out of the ten thousand invasive alien species present,an estimated 10%-15% of them are expected to have a negativeimpact. A study carried out in 2009 estimated that IAS cost Eu-rope about €12 billion per year, but this is expected to keep ri-sing along with the rise in the number of new alien species. On alarger scale, according to Pimentel (2005), alien species cost theglobal economy $1.4 trillion per year, 5% of global production.However, the question of allochthonous species is open to eco-nomic solutions (Perrings at al., 2002). The regulatory frameworkof a country—e.g., quarantine, the list of exotic species whichcan be traded—could play an important role in limiting furtherintroductions or the spread of existing alien species.In a globally expanding economy where lobbies are likely tofight against stricter regulations aimed at limiting trade of exo-tic species, trading partners should be encouraged to includespecific insurances covering the costs of the damage these spe-cies could cause. These insurances would prevent higher ecologi-cal and economical costs resulting from the damage inflicted byinvasive species. Taxes on exotics could push stakeholders with aspecific interest in trading wildlife (sellers and buyers of exoticspecies, organisations related to hunting and fishing, farmers rai-sing new species) into learning more about the species they tra-de and their potential as invasives. All traders in exotic speciesshould know that the longer a species has been marketed, thegreater the probability that it could escape and get established(Enserink, 1999). Both traders, and buyers alike, should pay taxes.Intentional release of exotic species should be discouraged byhefty fines. Money coming from these taxes could be spent onprevention, control, and research.In Europe, the import of allochthonous species is covered by theWildlife Trade Regulation. Although the WTR could suspend theimport of potentially harmful species, its current rules only coverfour species but does not regulate trade and holding within theEuropean Community. The Habitats Directive and the Birds Direc-tive also have a general provision asking Members States toavoid or regulate the introduction of alien species in protectedareas.

23

Page 24: Impronte specie aliene inglese

REFERENCES

• Van Aarde, R.J. (1980) The diet and feeding behaviour of theferal cat, Felis catus, at Marion Island. South African Journalof Wildlife Research, 10, 123-128

• Amori, G., Angelici, F.M., Prigiont, C., Vigna Taglianti, A.,(1996), The mammal fauna of Italy, a review. Hystrix, (n.s.)8(1-2): 3-7

• Bailey, E.P. (1992). Red foxes, Vulpes vulpes, as biologicalcontrol agents for introduced Arctic foxes, Alopex Lagopus,on Alaskan Islands, Canadian Field-Naturalist 106, 200-205-

• Bell, B.D., (1995) The effects of goats and rabbits on breedingseabirds: methods of eradication and control. Bol. Mus. Mun.Funchal Sup. 4, 83-95

• Bergstrom, D.M., et al., Indirect effects of invasive species re-moval devastate World Heritage Island, Journal of AppliedEcology 2009, 46, 73-81

• Berny, P.J., Buronfosse, T., Buronfosse, F., Lamarque, F., Lorgue,G. (1997) Field evidence of secondary poisoning of foxes(Vulpes vulpes) and buzzards (Buteo buteo) by bromadiolone,a 4-year old survey. Chemosphere 35: 1817-1829

• Bertolino, S., Currado, I., Mazzoglio, P.J., Amori, G., 2000, Na-tive and alien squirrels in Italy, Hystrix, (n.s.) 11(2):65-74

• Bertolino, S., Genovesi, P. (2001), Spread and attempted era-dication of the grey squirrel (Sciurus carolinensis) in Italy,and consequences for the red squirrel (Sciurus vulgaris) inEurasia

• Bester, M.N., Bloomer, J.P., van Aarde, R.J., Erasmus, B.H., vanRensburg, P.J.J., Skinner, J.D., Howell, P.G., Naude, T.W. (2002).A review of the successful eradication of feral cats from sub-Antarctic Marion Island, Southern Indian Ocean. South Afri-can Journal of Wildlife Research 32(1): 65-73

• Boto, Alberto; Rubolini, Diego; Viganò, Andrea & Guenzani,Walter (1999): Paradoxornis alphonsianus: una nuova specienaturalizzata per l’Italia [“P. alphonsianus: a new naturalisedspecies in Italy”]. Quaderni di Birdwatching 1(1)

• Bradley, M.P., Hinds, L.A. & Bird, P.H. (1997) A bait deliveredimmunocontraceptive vaccine for the European red fox (Vul-pes vulpes) by the year 2002? Reproduction, Fertility and De-velopment, 9, 11-116.

• Bright, C. (1998) Life Out of Bounds. W.W.Norton, New York

• Campbell, K. and Donlan C.J. (2005). Feral goat eradicationson islands. Conservation Biology 19: 1362-1374

• Carter, I., Burn, A. (2000) Problems with rodenticides: thethreat to red kites and other wildlife. British Wildlife, Februa-ry 2000: 192-197

• Carter, I. and Grice, P. (2000) Studies of re-established red ki-tes in England, British Birds 93: 304-322

• Carthey AJR, Banks PB (2012) When Does an Alien Become aNative Species? A Vulnerable Native Mammal Recognizes andResponds to Its Long-Term Alien Predator. PLoS ONE 7(2):e31804. doi:10.1371/journal.pone.0031804

• CBD (2000): Global strategy on invasive alien species.- Con-vention on Biological Diversity, UNEP/CBD/SBSTTA/6/INF/9

• Celada, C., Bogliani, G., Gariboldi, A., Maracco, A., 1994. Oc-cupancy of isolated woodlots by the red squirrel Sciurus vul-garis L. in Italy. Biological Conservation, 69, 77-183

• Chase, A (1987) Playing God in Yellowstone. New York; Har-

court Brace and Company

• Clout, M.N. and Russell, J.C. (2006), The eradication of mam-mals from New Zealand islands. In: Koike, F.; Clout, M.N.; Ka-wamichi, M.; De Poorter, M and Iwatsuki, K. (eds) Assessmentand Control of Biological Invasion Risks, pp. 127-141. Kyoto,Japan and Gland, Switzerland, Shoukadoh Booksellers andIUCN.

• Clout, M.N. and Russell, J.C. (2007), The invasion ecology ofmammals: a global perspective. Wildlife Research, 35, 180-184

• Clout, M.N. and Russell, J.C. (2008), Review of rat invasionbiology. Implications for island biosecurity. Science for Con-servation 286. Published by Science & Technical Publishing,Department of Conservation, PO Box 10420, The Terrace,Wellington 6143, New Zealand

• Council of Europe. Eradication of the Ruddy Duck Oxyura Ja-maicensis in the Western Palaearctic: a review of progressand a revised action plan, 2011-2015. Final Version, January2011

• Courchamp, F., Chapuis, J., Pascal, M. (2003). Mammal inva-ders on islands: impact, control, and control impact, Biol. Rev78, 347-383

• Crooks K. R., Soulé M. E. 1999 Mesopredator release and avi-faunal extinctions in fragmented system. Nature 400, 563–566

• Davis, Mark A.; Chew, Mathew K.; Hobbs, Richard J.; Lugo,Ariel E.; Ewel, John J.; Vermeij, Geerat J.; Brown, James H.;Rosenzweig, Michael L.; Gardener, Mark R.; Carroll, Scott P.;Thompson, Ken; Pickett, Stewart T.A.; Stromberg, Juliet C.;Del Tredici, Peter; Suding, Katharine N.; Eherenfeld, Joan G.;Grime, J. Philip; Mascaro, Joseph; Briggs, John C. 2011. Don’tjudge species by their origins. Nature. 474: 153-154

• De Boo, J., Knight, A. “Concepts in Animal Welfare”: A Sylla-bus in Animal Welfare Science and Ethics for VeterinarySchools. World Society for the Protection of Animals, J VetMed Educ, 2005 Winter; 32(4):416-8

• Dowding, J.E., Murphy, E.C., Veicth, C.R. (1999). Brodifacoumresidues in target and nontarget species following an aerialpoisoning operation on Motuihe Island, Hauraki Gulf, NewZealand. New Zealand Journal of Ecology 23, 207-214

• Eason, C.T., Spurr, E.B. (1995), The Toxicity and Sub-lethal Ef-fects of Brodifacoum in Birds and Bats. Science for Conserva-tion: 6. Department of Conservation, New Zealand

• Eason, C.T., Wickstrom, M., Turk, P., Wright, G.R.G. (1999). Areview of recent regulatory and environmental toxicologystudies on 1080: results and implications. New Zealand Jour-nal of Ecology 23, 129-137

• Elton, C.S. 1958: The ecology of invasions by plants and ani-mals. London: Methuen

• Fàbregas, M. C., Guillén-Salazar, F. & Garcés-Narro, C. (2010).The risk of zoological Parks as potencial pathways for the in-troduction of non-indigenous species. Biol Invasions, DOI10.1007/s10530-010-9755-2

• Feare, C. (1999). Ants take over from rats on Bird Island, Sey-chelles. Bird Conservation International 9, 95-96

• Fernández Orueta, J., Aranda Ramos, Y (2001). Methods tocontrol and eradicate nonnative terrestrial vertebrate species,Nature and Environment, No.118, Council of Europe Publi-shing

24

Page 25: Impronte specie aliene inglese

• Fisher, M. (1998) Intersections between ethics and science inthe promotion of animal welfare. In Ethical Approaches toAnimal-based Science. Ed. D. Mellor, M. Fisher and G. Suther-land. ANZCCART, Wellington, pp.33-37

• Fisher, M., Mark Fisher’s Report on Animal Ethics - Issues inthe Application. Animal Ethics Issues Associated with the Useof 1080 To Manage Pests, accessible at.http://www.1080science.co.nz/ (accessed on 5/29/12]

• Fitter R.S.R, The Ark in our Midst, Collins 1959

• Fraser, D., (1999) Animal Ethics and animal welfare science:bridging the two cultures. Applied Animal Behaviour Science,Vol. 65, Issue 3, pp. 171-189

• Gagliardi, A., Martinoli, A., Tosi, G., (2008). Un berbero inLombardia: il caso dell’ammotrago, Ammotragus lervia, bovi-dae, artiodactyla, in provincia di Varese. In: Prigioni C., Me-riggi A., Merli E. (eds). VI Congr. It. Teriologia, Hystrix, It.J.Mamm., supp. (2008): 1-120, Atti del VI Congresso Italianodi Teriologia: Ricerca e conservazione dei mammiferi: un ap-proccio multidisciplinare, Cles (TN) 16-18 aprile 2008 Galim-berti, A., Crottini, A., Boto, A., Serra, L., Barbuto, M., Casiraghi,M. (2009). Il caso degli alloctoni Paradoxornis webbianus e P.alphonsianus: uno studio molecolare. Boll. Mus. Ist. Biol.Univ. Genova, 71

• Gallo, M.G., Tizzani, P., Peano, A., Rambozzi, L. and Meneguz,P.G. Eastern Cottontail (Sylvilagus Floridanus) as Carrier ofDermatophyte Fungi, Mycopathologia, Volume 160, Number2 (2005), 163-166

• Genovesi, P. (2007): Linee guida per la reintroduzione e il ri-popolamento di specie faunistiche di interesse comunitario.Quaderni di Conservazione Natura, 27: 1-51

• Genovesi, P., Bacher, S., Kobelt, M., Pascla, M., Scalera, R.,(2009). Handbook of Alien Species in Europe, Chapter 9:Mammals of Europe, DAISIE, Springer Science

• Ghetti, L., Carosi, A., Lorenzoni, M., Pedicillo, G., Dolciami, R.(2007) L’introduzione delle specie esotiche nelle acque dolci:il caso del carassio dorato nel lago Trasimeno. Litograph Edi-tor, Città di Castello

• Gillies, C.A., Pierce, R.J., (1999) Secondary poisoning of mam-malian predators during possum and rodent control opera-tions at Trounsen Kauri Park, Northland, New Zealand. NewZealand Journal of Ecology 23: 183-192

• Gopalakrishnan, G., Negru, M.C., Wang, M., Wu, M. and Sny-der, S. (2008). Use of marginal land and water to maximizebiofuel production. In: Zalesny, R.S., Mitchell R., Richardson,J. (eds). Biofuels, bioenergy, and bioproducts from sustainableagricultural and forest crops: proceedings of the short rota-tion crop international conference, 2008 August. U.S. Depar-tment of Agriculture, Forest Service, Northern ResearchStation, Bloomington, MN. p.15

• Gregory, G. (1996) Perception of pain associated with 1080poisoning. In Humaneness and Vertebrate Pest Control. Ed.P.M. Fisher & C.A. Marks. Department of Natural Resourcesand Environment, Frankston. Pp- 62-64.

• Hannah, Lee, Lohse, David, Hutchinson, Charles, Carr, John L.,and Lankerani, Ali (1993) “A Preliminary Inventory of HumanDisturbances of World Ecosystems”, Ambio 23: 246-50

• Hanson, C., Bonham, J.E., Campbell, K.J., Keitt, B.S. (2010). TheRemoval of Feral Cats from San Nicolas Island: Methodology.Proceedings 24th Vertebrate Pest Conference, Published atUniversity of California, Davis, 2010. Pp. 72-78

• Heywood, V.H. (1989) “Patterns, extents and modes of inva-sion by terrestrial plants”, in J.A. Drake et al. (eds.) BiologicalInvasions: A Global Perspective, pp. 31-35. New York; JohnWiley

• Hobbs, R. J. and L. F. Huenneke. 1992. Disturbance, diversity,and invasion: implications for conservation. Cons. Biol.6:324-337

• Hone, J. 1994. Analysis of vertebrate pest control. CambridgeUniversity Press.

• Howard, G.W. and Chege, F.W. (2007). Invasion by plants inthe inland waters and wetlands of Africa. In Gherardi, F. (ed).Biological Invaders in Inland Waters: Profiles, Distributionand Threats. Springer, New York. Pp.193-208

• Howard, G.W. and Ziller (2008). Alien alert – plants for bio-fuels may be invasive. Bioenergy Business Jully/August 2008:14-16

• Howald, G., Donlan, J.C., Galvan, J.P., Russel, J.C., Parkes, J.P:,Samaniego, A., Wang, Y., Veitch, D., Genovesi, P., Pascal, M.,Saunders, A. and Tershy, B. (2007) Invasive rodent eradica-tions on islands. Conservation Biology 21. 1-21

• Hulme, P.E., Bacher, S., Kenis, M., Klotz, S., Kuhn, I., Minchin,D., Nentwig, W., Olenin, S., Panov, V., Pergl, J., Pysek, P., Ro-ques, A., Sol, D., Solarz, W. & Vila, M. (2008) Grasping at theroutes of biological invasions: a framework for integratingpathways into policy. Journal of Applied Ecology, 45, 403–414.

• Hettinger, N. Exotic Species, Naturalisation, and BiologicalNativism. Environmental Values 10 (2001): 193-224

• Institute for Biological Invasions. 2010. “living document,”consisting largely of excerpts from Campbell (2000) and quo-tes found in Low (1999), was last updated by Todd Campbellon 04/19/2010. Available at: http://invasions.bio.utk.edu/over-view.htm [Accessed 23 May, 2012.]

• Iossa, G., Soulsbury, CD, Harris, S. (2007) Mammal trapping: areview of animal welfare standards of killing and restrainingtraps. Animal Welfare, 16: 335-352

• IUCN (2000) Guidelines for the prevention of biodiversity losscaused by alien-invasive species prepared by the Species Sur-vival Commission (SSC) invasive species specialist group. Ap-proved by the 51st Meeting of the IUCN Council, Gland,www.iucn.org/themes/ssc/publications/policy/invasivesEng.htm

• IUCN (2002) Policy recommendations papers for sixth mee-ting of the Conference of the Parties to the Convenvion onBiological Diversity (COP6). The Hague, The Netherlands, 7-19April 2002. www.iucn.org/themes/pbia/wl/docs/biodiversity/cop6/invasives.doc

• Jackson, W.D., Ashton, A.D., Frantz, S.C., Padula, C., (1985).Present status of rodent resistance to warfarin in the UnitesStates. Acta Zool. Fennica, 173: 163-165

• Jamieson, D., (1995) Wildlife conservation and individual ani-mal welfare. In: Norton, B.G.; Hutchisons, M., Stevens, E. andMaple, T.L. (eds) Ethics on the ark – zoos, welfare, and wildlifeconservation, pp. 69-73. Washington, Smithsonian Institu-tion Press

• Kirkpatrick, J. F., Lyda, R. O. and Frank, K. M. (2011), Contra-ceptive Vaccines for Wildlife: A Review. American Journal ofReproductive Immunology, 66: 40–50. doi: 10.1111/j.1600-0897.2011.01003.x

25

Page 26: Impronte specie aliene inglese

• Lanza B., Andreone F., Bologna M.A., Corti C., Razzetti E.(2007), Fauna d’Italia. Vol XLII.

• Amphibia. Edizioni Calderini, Il Sole 24 ORE, Editoria specia-lizzata S.r.l., Bologna

• Letnic, M., Koch, F., Gordon, C., Crowther, M.S., Dickman, C.(2009). Keystone effects of an alien top-predator stem extin-ctions of native mammals, Proceedings of the Royal Society,276, 3249-3256

• Lever, C. (1987) Naturalised birds of the world. Longman,London

• Levy, J.K., Friary, J.A., Miller, L.A., Tucker, S. J., Fagerstone, K.A.(2011) Long-term fertility control in female cats with Gona-ConTM, a GnRH immunocontraceptive, Theriogenology 761517-1525

• Littin, K.E., O’Connor, Eason, C.T., (2000) Comparative effectof brodifacoum on rats and possums. New Zealand Plant Pro-tection 53: 310-315

• Littin, K.E., Mellor, D.J., Warburton, B., Eason, C.T. (2004) Ani-mal welfare and ethical issues relevant to the humane con-trol of vertebrate pests. New Zealand Veterinary Journal 52,1-10-

• Mack, M. C. and C. M. D’Antonio. 1998. Impacts of biologicalinvasions on disturbance regimes. TREE 13:195-198

• Mack, R.N., Simberloff, D., Londsale, W.M., Evans, H., Clout,M. and Bazzaz, F.A. (2000). Biotic invasions: causes, epide-miology, global consequences and control. Ecological Appli-cations 10: 689-710

• Mason, G., and Littin, K.E. (2003). The humaneness of rodentpest control. Animal Welfare 12: 1-7

• Massetti, M., 1996 – The postglacial diffusion of the genusDama Frisch, 1775, in the Mediterranean region. In: FocardiS., B.M. Poli (eds.) Resources Utilization in Fallow Deer, Suppl.Ric. Biol. Selvaggina, XXV: 7-29

• Marvier M, Kareiva P, and Neubert MG. (2004). Habitat de-struction, fragmentation, and disturbance promote invasionby habitat generalists in a multispecies metapopulation. RiskAnal 24: 869–77.

• Massei, G, Cowan, DP, Coats, J, Gladwell, F, Lane, JE, Miller, LA(2008). Effects of the GnRH vaccine GonaCon on the fertility,physiology and behaviour of wild boar. Wildlife Research, 35,540-547

• Massei, G, Sugoto, R, Bunting, R. (2011). Too many hogs? Areview of methods to mitigate impact by wild board and fe-ral hogs. Human-Wildlife Interactions 5(1): 79-99

• Massei e Toso, 1993, Biologia e gestione del Cinghiale. Doc.Tecnici INFS

• Mauremootoo, J. (2009). Biofuels and Invasive Species, IUCN,Nairobi, Kenya

• McEwen, G. (2008). The challenge posed by feral animals. Re-form 91: 30-36

• McKinney, M. L. and J. L. Lockwood. 1999. Biotic homogeni-zation: a few winners replacing many losers in the next massextinction. TREE 14:450-453

• Meehan, A.P. (1984). Rats and Mice. Their biology and con-trol. Rentokil Ltd East Grinstead. 383 pp.

• Meerburg, B.G., Brom, F.W.A. and Kijlstra, A. (2008) The ethicsof rodent control. Pest Management Science 64: 1205-1211

• Micol, T. & Jouventin, P. (1995). Restoration of Amsterdam Is-

land, South Indian ocean, following control of feral cattle,Biological Conservation 73, 199-206

• Miller, L.A., Johns, B.E., Elias, D.J., Crane, K.A. (1997b). Compa-rative efficacy of two immunocontraceptive vaccines. Vacci-nes, Vol. 15, No 17/18, pp. 1258-1862

• Miller, L.A., Rhyan, J., Killian, G., GonaConTM, a Versatile GnRHContraceptive for a Large Variety of Pest Animal Problems,Proc. 21st Vertebrate Pest Conference. Published at Univ. ofCalifornia, Davis, 2004, Pp. 269-273

• Nentwig, W., 2007, Biologival Invasions, Ecological Studies,Vol.193.

• Newton, I,. Wylie, I., Freestone, P, (1990) Rodenticides in Bri-tish barn owls. Environmental Pollution 68: 101-117

• Nogales, M., Martin, A.; Tershy, B.R., Donlan, C.J., Veitch, D.,Puerta, N., Wood, B. and Alonso J. (2004). A review of feralcat eradication on islands. Conservation Biology 18: 310-319

• Padilla, D. K. & S. L. Williams, 2004. Beyond ballast water:aquarium and ornamental trades as sources of invasive spe-cies in aquatic ecosystems. Frontiers in the Ecology and Envi-ronment 2: 131–138

• Paparella, M. (2006). Rodenticides: an animal welfare para-dox? Altex 23: 51-51

• Paterson, M, Aitken, RJ, (1990). Development of vaccines tar-geting the zona pellucida. MRC Reproductive Biology Unit,Centre for Reproductive Biology, Edinburgh, UK. PMID:2701977 [PubMed - indexed for MEDLINE]

• Pauza, M., Driessen, M., (2008) Distribution and PotentialSpread of Amphibian Chytrid Fungus Batrachochytrium den-drobatidis in the Tasmanian Wilderness World Heritage Area

• Perry, D., (2004). “Environmental Wrongs and Animal Rights,”The Society for Conservation Biology web page: http://con-bio.org/SCB/Information/Mission/

• Pieracci, Al., 07/05/2012 Parte la guerra allo scoiattolo grigio,lastampa.it [accessed on August 12, 2012]

• Pimentel, D. Zuniga, R. and Morrison, D. (2005) Update onthe environmental and economic costs associate with alien-invasive species in the United States. Ecological Economics52: 273-288

• Platnick, NI (2006) The world spider catalogue http://rese-arch.amnh.org/entomology/spiders/catalog/

• Pounds, J.A., Bustamante, M.R., Coloma, L.A., Consuegra, J.A.and Fogden, M.P., et al. (2006) Widespread amphibian extin-ctions from epidemic disease driven by global warming Na-ture 439, 161-167

• Proctor, D.L. (1994) Grain storage techniques: FAO agricultu-ral Services Bulletin No. 109. Food and Agriculture Organiza-tion of the United States Nations: Rome, Italy

• Pyšek, P., Hulme, P.E. & Nentwig, W., (2009) Glossary of themain technical terms used in the handbook. Handbook ofAlien Species in Europe (ed. DAISIE), pp. 375-379. Springer,Berlin

• Pyšek P., Richardson D. M., Pergl J., Jarošík V., Sixtová Z. &Weber E. (2008): Geographical and taxonomic biases in inva-sion ecology. – Trends in Ecology and Evolution 23: 237–244

• Pyšek, P., Richardson, D.M., Rejmanek, M., Williamson, M., Kir-shner, J. (2004) Alien plants in checklists and floras: towardsbetter communication between taxonomists and ecologists.Taxon 53:131-143

• Nogales, M. & F.M. Medina, 1996. A review of the diet of fe-ral domestic cats (Felis sylvestris f. catus) on the Canary Is-

26

Page 27: Impronte specie aliene inglese

lands, with new data from the laurel forest of La Gomera. Z.Säugetierkunde, 61: 1-6

• Occhipinti-Ambrogi A., Galil BS (2004) A uniform terminolo-gy on bioinvasions: a chimera or an operative tool? Mar PollNull 49:688-694

• Orians, G. H. 1986. Site characteristics favoring invasions. Pp.133-148 In: H. A. Mooney and J. A. Drake, eds. Ecology ofBiological Invasions of North America and Hawaii. Springer-Verlag, New York, NY.

• Rajagopal, D: (2008) Implications of India’s biofuel policiesfor food, water and the poor. Water policy 10 Supplement1:95-106

• Rejmánek, M. (2000) Invasive plants: approaches and predic-tions. Austral Ecology, 25, 497-506

• Richardson, D. M., Pyšek, P. and Carlton, J. T. (2010) A Com-pendium of Essential Concepts and Terminology in InvasionEcology, in Fifty Years of Invasion Ecology: The Legacy ofCharles Elton (ed D. M. Richardson), Wiley-Blackwell, Oxford,UK. doi: 10.1002/9781444329988.ch30

• Schmidt, R.H., (1989) “Vertebrate Pest Control and AnimalWelfare,” in Vertebrate Pest Control and Management Mate-rials: 6th Volume, ASTM STP 1055, Kathleen A. Fagerstone andRichard D. Curnow, Eds, American Society for Testing andMaterials, Philadelphia, pp 63-68.

• Roemer, G.W., Donlan, C.J., Courchamp, F. (2002). Golden ea-gles, feral pigs and island foxes: how exotic species turn nati-ve predators into prey. Proceedings of the National Academyof Sciences, USA 99, 791-796.

• Ruffino, L., Bourgeois, K., Vidal, E., Duhem, C., Paracuellos, M.,Escribano, F., Sposimo, P., Baccetti, N., Pascal, M., Oro, D.(2009). Invasive rats and seabirds after 2,000 years of an un-wanted coexistence on Mediterannean islands. Biological In-vasions 11:1631-1651 doi:10.1007/s10530-008-9394-z

• Seabloom, E.W., van der Valk, A.G. (2003). Plant diversity,composition, and invasion of restored and natural prairie po-thole wetlands: implications for restoration. Wetlands, Vol.23. No 1, pp. 1-12

• Seaman, G.A. (1952). The mongoose and Caribbean wildlife.Transactions of the North American Wildlife Conference 17,188-197

• Sharma, G.P, Esler, K.J, Blignaut, J.N. (2009), Determining therelationship between invasive alien species density and acountry’s socio-economic status, South African Journal ofScience, Vol. 106. No 3/4, pp. 1-6

• Shigesada, N. and K. Kawasaki. 1997. Biological Invasions:Theory and Practice. Oxford University Press, New York, NY.

• Shore, R.F., Birks, J.D.S., Freestone, P., (1999) Exposure of non-target vertebrate to second generation rodenticides in Bri-tain, with particular reference to the polecat Mustelaputorius. New Zealand Journal of Ecology 23: 199-206

• Shore, R.F., Birks, J.D.S., Freestone, P., Kitchener, A.C. (1996)Second generation rodenticides and polecats Mustela puto-rius. Environmental Pollution 91: 279-282

• Sindaco R. Doria G., Razzetti E., Bernini F. (Eds 2006), Atlantedegli Anfibi e dei Rettili d’Italia /

• Atlas of Italian Amphibians and Reptiles. Societas Herpetolo-gica Italica, Edizioni Polistampa, Firenze

• Soulé, M.E., (1990) The onslaught of Alien Species, and OtherChallages in the Coming Decades, Conservation Biology, Vo-lume 4, Number 3,

• Smal, C.M. 1988. The american mink Mustela vison in Ireland.Mammal Rev., 18: 201-208.

• Spagnesi M., Toso, S. (eds), 1999 – Iconografia dei Mammiferid’Italia. Ministero dell’Ambiente – Servizio Conservazione Na-tura e Istituto Nazionale per la Fauna Selvatica

• Stephenson, B.H., Minot, E.O., Armstrong, D.P. (1999) Fate ofmoreporks (Nimox novaseelandie) during a pest control ope-ration on Mokoia Island, Late Roturua, New Zealand. NewZealand Journal of Ecology 23: 233-240

• Stone, W.B., Okoniewski, J.C., Stedelin, J.R., (1999) Poisoningof Wildlife with Anticoagulant Rodentices in New York. Jour-nal of Wildlife Diseases 35(2): 187-193

• Surtsey, The Surtsey Research Society. www.surtsey.is

• Taylor, R.H. (1979a). How the Macquarie Island parakeet be-came extinct New Zealand Journal of Ecology 2, 42-45.Thi-riet, D. (2007). The welfare of introduced animals in Australia.Environmental and Planning Law Journal 24: 417-426

• Towns, D.R. (2008). Eradications as reverse invasions: lessonsfrom Pacific rat (Rattus exulans) removals on New Zealandislands. Biological Invasions. Doi:10.1007/s10530-008-9399-7

• Tyndale-Biscoe, C.H., (1994) Virus-vectored immunocontra-ception of feral mammals. Reproduction, Fertility and Deve-lopment, 6, 281-287

• Vermeij, G.J. (1991). When biotas meet: Understanding bioticinterchange. Science 253, 1099-1104. Doi10.112/scien-ce.253.5025.1099

• Warburton, B., and Norton, B.G. (2009). Towards a knowled-ge-based ethic for lethal control of nuisance wildlife. Journalof Wildlife Management 73: 158-164

• Wauters, L.A., (1997) The Ecology of the red squirrel (Sciurusvulgaris) in fragmented habitats: a review. In: Gurnell, J.,Lurz, P. (Eds), The conservation of Red Squirrels, Sciurus vul-garis L. People Trust for Endangered Species, pp. 5-12

• Webster, K.H. (2009) Validation of a prothrombin time (PT)assay for assessment of brodifacoum, exposure in Japanesequail and barn owls. Thesis. Simon Fraser University

• Weihong Ji, (2009) A review of the potential of fertility con-trol to manage brushtail possums in New Zealand. Universityof Nebraska - Lincoln. Internet Center for Wildlife DamageManagement

• Wilcove, D.S., Rothstein, D., Dubow, J., Phillips, A., and Losos,E. (1998). Quantifying threats to imperiled species in the Uni-ted States. BioScience 48: 607-615

• Williamson, M.H. and Fitter, A. (1996) The characters of suc-cessful invaders. Biol. Conservation 78: 163-170

• Williamson, M.H. and Fitter, A. (1996) The varying success ofinvaders. Ecology, 77, 1661-1666

• Wilson, E.O. 1992 The diversity of life. Harvard UniversityPress, Cambridge, Massachusetts

• Woods. B., Hagenstein, R., Waldman, B. (2009). News Release.Reports from Rat Island Reflect Successes and Concerns. USFish and Wildlife Service. http://www.fw.gov/news/NewsRe-leases/showNews.cfm?newsld=D1853646-F27F-23F3-9E027F384A3AF96D

• Zavaleta, E. S. 2002. It’s often better to eradicate, but can weeradicate better? Pp. 393-404 in C. R. Veitch and M. N. Clout(Eds.) Turning the Tide: The Eradication of Invasive Species.Gland, Switzerland: The World Conservation Union (IUCN).

27

Page 28: Impronte specie aliene inglese

Recommended