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Eradication of invasive alien vertebrates in the UK

Overseas Territories

A prioritised framework for island restoration to enable the UK Overseas

Territories' Biodiversity Strategy

June 2014

The Royal Society for the Protection of Birds (RSPB)

Funded by the Department for Environment, Food and Rural Affairs

(Defra)

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Contents

EXECUTIVE SUMMARY .............................................................................................................................. 4

ACKNOWLEDGEMENTS ............................................................................................................................. 7

INTRODUCTION ........................................................................................................................................... 9

Aims ........................................................................................................................................................ 10

Scope ...................................................................................................................................................... 11

Limitations ............................................................................................................................................... 12

METHODS .................................................................................................................................................. 14

Data collection ......................................................................................................................................... 14

Island Prioritisation .................................................................................................................................. 16

RESULTS .................................................................................................................................................... 21

Islands in the OTs ................................................................................................................................... 21

Beneficiary species in the OTs................................................................................................................ 21

Invasive Species in the OTs.................................................................................................................... 23

Priority Islands ......................................................................................................................................... 25

TERRITORY-SPECIFIC ACCOUNTS ........................................................................................................ 29

ANGUILLA................................................................................................................................................... 30

BERMUDA .................................................................................................................................................. 32

BRITISH INDIAN OCEAN TERRITORY ..................................................................................................... 33

BRITISH VIRGIN ISLANDS ........................................................................................................................ 35

CAYMAN ISLANDS .................................................................................................................................... 37

FALKLAND ISLANDS ................................................................................................................................. 39

MONTSERRAT ........................................................................................................................................... 41

PITCAIRN ISLANDS ................................................................................................................................... 42

SAINT HELENA, ASCENSION AND TRISTAN DA CUNHA ...................................................................... 43

SOUTH GEORGIA AND THE SOUTH SANDWICH ISLANDS .................................................................. 45

TURKS AND CAICOS ISLANDS ................................................................................................................ 46

NEXT STEPS .............................................................................................................................................. 48

ANNEX 1 – Present and Historical Breeding Status full definitions ............................................................ 50

ANNEX 2 – Full List of Beneficiary Species................................................................................................ 52

ANNEX 3 – Full List of Invasive Alien Vertebrates ..................................................................................... 58

REFERENCES ............................................................................................................................................ 61

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EXECUTIVE SUMMARY

The UK Overseas Territories (OTs) are of considerable importance for biodiversity, holding an estimated 90% of the UKs total biodiversity and over 300 globally threatened species (IUCN 2013). One of the most serious threats identified to this biodiversity is the presence of invasive alien species, in particular invasive mammals and other vertebrates (Hilton and Cuthbert 2010). Invasive vertebrates have been responsible, wholly or partially, for the extinction of eight endemic bird species and for population declines of numerous other native bird and reptile species on OTs (BirdLife 2009; Cuthbert and Hilton 2004; Mitchell et al. 2004). As such, the control, eradication and prevention of establishment of invasive alien species is a key strategic priority in the current OTs Biodiversity Strategy (Defra 2009). Due to the detrimental impact of Invasive Alien Vertebrates on many native island species, eradicating invasive alien vertebrates from islands has become an important management tool to preserve endemic island biodiversity. As eradication techniques have been developed and refined, the number of islands where eradication is possible and would provide a biological conservation benefit is increasing (Brooke et al. 2007). The OTs include a wide range of islands, hosting numerous invasive alien vertebrates as well as native threatened and endemic species. Until now islands selected for eradication and restoration have generally been identified opportunistically, without comparative assessment between islands to weigh the biological benefit of eradicating invasive species, the feasibility and sustainability of restoration. This study provides a strategic assessment to rank all of the OTs’ islands according to the greatest biodiversity benefit resulting from technically feasible invasive vertebrate eradications. This island priority list can then be used to direct actions and make best use of limited resources to support the strategic priorities of the UK Overseas Territories Biodiversity Strategy. Scope and Limitations The study focussed on the 11 island OTs: Anguilla; Bermuda; British Indian Ocean Territory; British Virgin Islands; Cayman Islands; Falkland Islands; Montserrat; Pitcairn Islands; Saint Helena, Ascension and Tristan da Cunha; South Georgia and the South Sandwich Islands and Turks and Caicos Islands. The Cyprus SBAs, Gibraltar and British Antarctic Territory were not included. The potential biodiversity gains of an invasive vertebrate eradication were calculated against a subset of native fauna: all Critically Endangered, Endangered, Vulnerable and Near Threatened terrestrial vertebrates; marine turtles; restricted-range bird species and colonial seabird species. Other taxonomic groups were not included as information on their occurrence, distribution and vulnerability to invasive alien vertebrates is not currently available in sufficient detail for all of the OTs. All terrestrial invasive alien vertebrates were included and the logistical feasibility of eradicating them was assessed for each island and incorporated along with the natural reinvasion risk for rodents. Social feasibility, socio-economic impacts and the anthropogenic reinvasion risk of invasive alien vertebrates were not considered in the study as data was not available in sufficient detail for all islands across the OTs. Island area was not incorporated into the prioritisation, because it mostly affects the cost rather than the feasibility of an eradication, with costs factoring into the planning stage of an eradication rather than the strategic assessment. Prioritisation Method Calculating the priority islands was a multi-step process. First, Potential Conservation Value scores were calculated for each island. This is the maximum conservation value achievable if all invasive alien vertebrates present could be successfully eradicated. The Potential Conservation Value incorporates the threat status, irreplaceability and vulnerability to present invasive vertebrates for all native species on an island.

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Secondly, invasive alien vertebrate species that could technically be eradicated from each island were identified, using human population size as a criterion for technical feasibility, as well as natural re-invasion risk as guidance for which eradications would yield lasting benefits (eradications where natural re-invasion was considered very likely were excluded). The identified species were then theoretically removed from each island, and a Post-eradication Conservation Value was calculated for each island using the same approach as above with a reduced subset of invasive vertebrates remaining on each island. The Actual Conservation Value for each island was the difference between Potential and Post-eradication Conservation Values. This value would be 0 for islands where no invasive alien vertebrates can be eradicated, and very high for islands where many globally threatened and /or endemic species are threatened by invasive alien vertebrates which could all be eradicated. The island with the highest Actual Conservation Value was considered to be the island with the highest eradication priority. Results One hundred and ninety-one islands (of 2499) harboured at least one native threatened or endemic vertebrate species and one invasive alien vertebrate (IAV) that was considered to have a negative impact on a native species. In total, 217 native (beneficiary) species were considered, of which 18 are Critically Endangered, 22 Endangered and 26 Vulnerable. Reptiles were the most numerous group with 27 globally threatened species and another 32 species that are not yet assessed by the IUCN. In total, 85 IAV exist in the study OTs, 30 reptiles, 26 birds, 23 mammals and six amphibians. Rats (Rattus sp.) were the most widespread invasive alien vertebrate species occurring on 470 islands across all the OTs and recorded from another 282 from which they had either been extirpated or where they were currently subject to an on-going eradication. Ten of the 11 OTs in this study have islands in the top 25 priority islands for restoration when ranked by Actual Conservation Value. The majority of islands in the top 25 are from the Caribbean Territories. This is due primarily to the rich endemic reptile fauna found on these islands. Gough Island in the Tristan da Cunha group is the top priority island restoration project in the OTs due to the presence of a large number of globally threatened and globally important breeding seabird species, two endemic land birds and the high impact of predatory house mice (Mus musculus). A number of islands including Cayman Brac and St Helena have very high Potential Conservation Values but do not appear in the final list of priority restoration projects because some invasive alien vertebrates cannot be eradicated given the human population size. In these situations eradication or control of some invasive alien vertebrates could still be very beneficial. This list is based on current information and knowledge. As more information is collected, the prioritisation should be updated. A number of OTs, particularly in the Caribbean, would benefit from further surveys to establish the distribution and impacts of IAV within the Territory.

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Summary of the Top 25 priority islands for invasive vertebrate eradication ranked by Actual Conservation Value.

Rank Island OT Invasive Species to be

removed (feral populations

only)

Examples of native species

that could benefit

1 Gough Saint Helena, Ascension

and Tristan da Cunha

Mice Gough bunting, Tristan albatross

2 Anegada British Virgin Islands Cats, dogs, goats, cattle,

donkeys, mice, feral pigs,

green iguanas, rats

Anegada ground iguana,

Anegada skink

3 Little Cayman Cayman Islands Cat, dogs, mice, rats, green

iguanas

Sisters Islands rock iguana

4 Henderson Pitcairn Islands Rats Henderson petrel, Henderson

fruit dove

5 Guana British Virgin Islands Dogs, cats, sheep Mona Island boa, Hawksbill

turtle

6 = Tristan da

Cunha

Saint Helena, Ascension

and Tristan da Cunha

Mice, rats, sheep Atlantic petrel, Atlantic yellow-

nosed albatross

6 = Norman British Virgin Islands Rats, dogs, goats Virgin Islands bronze skink

8 = Cotton Cay Turks and Caicos Rats, goats Turks Island skink

8 = Necker British Virgin Islands Rats Lesser Virgin Islands skink,

Virgin Gorda blindsnake

10 Big Ambergris

Cay

Turks and Caicos Rats, cats Caicos Islands skink, Bastion

Cay curlytail lizard

11 South Georgia South Georgia and the

South Sandwich Islands

Rats, mice White-chinned petrel, other

breeding seabirds

12 = Pitcairn Pitcairn Islands Rats, cats, goats Pitcairn reed warbler, breeding

seabirds

12 = Jost van Dyke British Virgin Islands Rats, cats, dogs,goats, pigs,

mongooses

Mona Island boa

12 = Little

Ambergris Cay

Turks and Caicos Chickens, rats Hecht's Caribbean gecko

15 Salt Cay Turks and Caicos Cattle, dogs, donkeys, cats,

rats, mice

Turks and Caicos rock iguana

16 New Falkland Islands Rats, cats, mice, rabbits Many breeding seabirds

17 French Cay Turks and Caicos Rats, mice Turks and Caicos rock iguana

18 Little Tobago British Virgin Islands Goats, rats Virgin Islands bronze skink

19 Peter British Virgin Islands Green iguanas, cats, chickens Hawksbill turtle

20 Ascension Saint Helena, Ascension

and Tristan da Cunha

Rats, mice, rabbits, sheep,

donkeys

Ascension frigate bird, other

breeding seabirds

21 Dog Anguilla Goats Anguilla Bank skink, Anguilla

Bank ameiva, breeding seabirds

22 Salt British Virgin Islands Goats, chickens Lesser Virgin Islands skink

23 Montserrat Montserrat Cattle, goats, donkeys, sheep,

pigs

Montserrat oriole, mountain

chicken frog, galliwasp (lizard)

24 Great Dog British Virgin Islands Rats, goats Virgin Islands coqui (frog)

25 Ile de la Passe British Indian Ocean

Territory

Rats Breeding turtles and seabirds

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ACKNOWLEDGEMENTS

This study was funded by the UK Government’s Department for Environment, Food and Rural Affairs (Defra). It would not have been possible without the help and assistance from a wide range of people and organisations. Within the Royal Society for the Protection of Birds (RSPB) particular thanks goes to the OTs Unit of Clare Stringer, James Millett and Jonathan Hall for their continued assistance and guidance, and in Conservation Science Steffen Oppel and Richard Cuthbert for advice on developing the methodology, creating the R code for analysis and in reviewing the report. Many thanks go to Stuart Butchart and Jez Bird (BirdLife International) and Nick Holmes (Island Conservation) for their considerable support and assistance in developing the methodology and data protocols. Dena Spatz and Kelly Newton (University of California, Santa Cruz) for assistance in data collection protocols and GIS; Andrew Budden (RBG-Kew) for collating all of the Falkland Islands data; Richard Lewis (RBG-Kew/ Falklands Conservation) and Rebecca Upson (RBG-Kew) for assistance with collating information on endemic and invasive plant species in the Falkland Islands. Finally, many thanks go to the Project Advisory Group members for their useful input, comments and guidance at various stages during the study and all of the Territories’ Government Departments and Territory NGOs for their cooperation in providing and verifying much of the information necessary to carry out this study. Anguilla Department of the Environment, Government of Anguilla Anguilla National Trust Ascension Ascension Conservation Department, Ascension Island Government (Stedson Stroud, Jolene Sim, Nathan Fowler) Bermuda Department of Conservation Services, Government of Bermuda (Andrew Petit, Alison Copeland) British Indian Ocean Territory Pete Carr British Virgin Islands Department of Conservation and Fisheries, British Virgin Islands Government (Mervin Hastings) British Virgin Islands National Park Trust (Nancy Woodfield Pascoe) Cayman Islands Department of Environment, Cayman Islands Government National Trust for the Cayman Islands (Paul Watler) Falkland Islands Environmental Planning Department, Falkland Islands Government (Nick Rendell) Falklands Conservation (James Fenton, Kalinka Rexer-Huber) Sally Poncet

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Montserrat Department of the Environment, Government of Montserrat Pitcairn Islands Pitcairn Natural Resources Division, Pitcairn Islands Government (Michele Christian) Saint Helena Environmental Management Directorate, St Helena Government St Helena National Trust South Georgia and the South Sandwich Islands Government of South Georgia and the South Sandwich Islands (Jennifer Lee) Tristan da Cunha Tristan da Cunha Conservation Department, Tristan da Cunha Government (Trevor Glass, Katrine Herian – RSPB) Turks and Caicos Islands Department of Environment and Coastal Resources, Turks and Caicos Islands Government (Eric Salamanca, Bryan Naqqi Manco) Turks and Caicos National Trust (Ethlyn Gibbs-Williams) Dr Glenn Gerber – Institution for Conservation Research, San Diego Zoo Project Advisory Group Jez Bird – BirdLife International Lord David Blencathra – Cayman Islands Government Representative in the UK Sarah Brennan – UK Executive Officer Falklands Conservation Jeff Dawson - RSPB Kimberley Durrant – UK Representative for the Government of Bermuda Siôn Griffiths – Foreign and Commonwealth Office Richard Lewis – RBG-Kew and Falklands Conservation Dennison Miller – Cayman Islands Government Representative in the UK James Millett - RSPB Janice Panton MBE – Government of Montserrat UK Representative Trevor Salmon – Department for Environment, Food and Rural Affairs, Defra Clare Stringer - RSPB Tony Weighell – Joint Nature Conservation Committee, JNCC Kedell Worboys MBE – St Helena Government UK Representative

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INTRODUCTION

The UK Overseas Territories (OTs) are: Anguilla; Bermuda; British Antarctic Territory; British Virgin Islands; Cayman Islands; Falkland Islands; Gibraltar; Montserrat; Pitcairn Islands; Saint Helena, Ascension and Tristan da Cunha; South Georgia and the South Sandwich Islands; Turks and Caicos Islands and the Sovereign Base Areas on Cyprus. The OTs are of considerable importance for biodiversity, holding an estimated 90% of biodiversity for which the UK is responsible and more than 300 globally threatened species (those assessed as Critically Endangered, Endangered or Vulnerable on the IUCN Red List; IUCN 2013)1. The number of endemic species in the OTs was estimated as over 300 (Defra 2012) but with over 400 invertebrates on Saint Helena alone this is likely a gross underestimate (RSPB 2013, unpublished data). In relation to birds, the OTs hold 33 of the UK’s 36 globally threatened species placing the UK 19th in the world for numbers of globally threatened bird species ahead of South Africa and Madagascar (Sanders ed. 2008). Seventy-eight Important Bird Areas have been identified in the OTs holding globally and regionally important breeding areas for a number of seabird species. These include arguably some of the most important seabird breeding colonies in the world such as Gough Island in the South Atlantic which is home to millions of breeding seabirds and is the major breeding site of the Critically Endangered Tristan albatross (Diomedea dabbenena). In addition to the native fauna and flora, over 2000 non-native invasive alien species (IAS) have been recorded in the OTs (Defra 2012). IAS are species whose introduction and/or spread outside their natural present or past distribution threatens biodiversity (IUCN 2000). Humans have and continue to introduce IAS, either accidentally or deliberately, with many historical introductions commencing around the same time as European exploration in the 16th Century (Hilton and Cuthbert 2010). IAS are recognised as one of the main threats to biodiversity globally, particularly on islands (IUCN 2000). The issue of IAS is a key target (Aichi Target 9) and a cross-cutting theme in the Convention on Biodiversity 2011-2020 Strategy. The control, eradication and prevention of establishment of IAS is also a key strategic priority of the current OTs Biodiversity Strategy (Defra 2009). The impacts of IAS are wide-ranging and include direct predation on and competition with native species; habitat modification; transmission of disease to both native species and livestock; and economic impacts such as crop damage. Globally some of the most damaging IAS are vertebrates (from here on “IAV”) and in particular mammals. Invasive rodents (notably rats Rattus spp. and house mouse Mus musculus) occur on over 80% of oceanic islands (Russell et al. 2008a) and pose a significant threat to island biodiversity (e.g. Courchamp et al 2003; Jones et al. 2008). Globally, feral cats (Felis catus) have contributed to at least 14% of all bird, mammal and reptile extinctions and the decline of at least 8% of Critically Endangered birds, mammals and reptiles (Medina et al. 2011). Other predators such as feral dogs (Canis familiaris), feral pigs (Sus scrofa) and small Asian mongooses (Herpestes javanicus) are also serious threats with the latter having a major role in the extinction, extirpation and decline of many Caribbean reptile species (Henderson 1992; Powell and Henderson 2005; Hays and Conant 2007). Alongside predators, feral livestock and in particular goats (Capra hircus) can have drastic effects on island ecosystems altering native habitats through herbivory; spreading non-native plant seeds and exacerbating soil erosion (Coblentz 1978). Other IAV introduced to islands include numerous bird, reptile and amphibian species. A potentially serious issue in the Caribbean is the introduction of alien reptile and amphibian

1 The Red List data used for this report was the 2012 list (before the 2013 update was applied). The

Red List categories mentioned in this report may therefore not be the current categories.

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species leading to competition with and predation of native species (Henderson 1992; Pitt et al. 2005; Platenburg 2007). Introduced amphibians also pose another threat by acting as possible carriers and source populations for infectious diseases, such as the fungal disease chytridiomycosis and ranavirus, with the former being arguably the greatest known global disease threat facing any vertebrate group (Wake and Vrendenburg 2008). The negative impacts of IAV are known and have been documented across a range of OTs. Of the 10 endemic bird extinctions in the OTs since 1500, eight have been wholly or partially due to IAV (BirdLife 2009). Native rock iguanas (Cyclura spp.) in the Cayman Islands, British Virgin Islands and Turks and Caicos Islands have suffered population declines in part as a result of feral dog, cat and livestock populations (Iverson 1978; Gerber 1995; Mitchell et al. 2004). Even IAV usually considered less damaging to most native species, such as house mice, have in recent times shown they can evolve devastating predatory behaviour such as observed on Gough Island (Cuthbert and Hilton 2004; Wanless et al. 2007). The eradication of IAV from islands where they are having a damaging impact can result in dramatic recoveries of native species. The eradication of feral cats from Ascension Island between 2002 and 2004 has led to six seabird species recolonising the island, including the Vulnerable Ascension frigatebird (Fregata aquila) in 2012 (Ratcliffe et al. 2009b; pers. comm. Ascension Island Government Conservation Department). On Mokoli’i Island in Hawaii the eradication of rats led to the survival rate of wedge-tailed shearwater (Puffinus pacificus) chicks increasing from one per year pre-eradication to 185 per year in only two years post-eradication (Smith et al. 2006). After removing feral goats and pigs from Sarigan Island in the Northern Mariana Islands there was an increase in plant species richness and in skink numbers (Kessler 2002). The ability to effectively remove IAV from islands is improving as techniques continue to be developed and refined, meaning that the number of islands where IAV eradication is possible and would provide a conservation benefit is increasing (Brooke et al. 2007). This applies to the OTs which comprise a range of islands, IAV, threatened and endemic species. The biological need must be weighed against the feasibility and sustainability of an operation to make best use of the limited resources available. Undertaking a prioritisation exercise for eradication of IAV in the OTs at this time will provide a robust information base to direct actions and resources to support the strategic priorities of the UK Overseas Territories Biodiversity Strategy. Aims The aim of this study was to: 1. Produce a robust priority list of islands for IAV eradications in the OTs based on

potential biodiversity gains, IAV eradication feasibility and natural reinvasion risk of rodents.

2. Identify island management units for future eradications and for islands where incorporating appropriate biosecurity measures into an eradication programme should be considered a priority.

3. Identify data gaps that hamper a full assessment of island restoration priorities, in particular on IAV occurrence, distribution and abundance.

4. Identify specific IAV or beneficiary species concerns within individual OTs. 5. Provide a checklist of next steps to consider when planning to undertake an eradication

project.

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Limitations on this study: 1. The priority list is based on current information and knowledge. As information is

updated and collected the prioritisation should be repeated. 2. The study only incorporates a subset of native biodiversity and IAS (see below and

methods). Additional native taxonomic groups and IAS can be incorporated in future prioritisations as information and knowledge improves.

3. The study does not aim to provide advice on eradication methodologies or biosecurity measures.

Scope The scope of the study was dictated by the level of information available and what could be reasonably collected in the six month timeframe of the study. The study focused on the 11 island OTs: Anguilla; Bermuda; British Indian Ocean Territory; British Virgin Islands; Cayman Islands; Falkland Islands; Montserrat; Pitcairn Islands; Saint Helena, Ascension and Tristan da Cunha; South Georgia and the South Sandwich Islands and Turks and Caicos Islands (see Figure 1).

Figure 1 Map of the 11 OTs included in the study. NB that Saint Helena, Ascension and Tristan da Cunha constitute a single Territory Gibraltar was not included in the study as it is on mainland Europe making any eradication not feasible or sustainable. British Antarctic Territory was omitted as currently it has no terrestrial IAV present. Also excluded were the Cyprus Sovereign Base Areas as they are part of a much larger island and therefore not appropriate for eradication prioritisation in this instance. Various eradication prioritisation exercises have been carried out previously, again focusing on different spatial scales, however these have mostly focused on a single native species group - seabirds (for example Brooke et al. 2007; Ratcliffe et al. 2009a; Capizzi et al. 2010; Harris et al. 2012). Few have looked at incorporating multiple native taxa (see Ecosure 2009) perhaps due to the lack of information regarding population trends in other taxa when compared to seabirds. Incorporating other taxonomic groups is an important consideration

Pitcairn Islands

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for the OTs as they harbour a number of threatened and endemic species, particularly reptiles. Concurrently Island Conservation in partnership with BirdLife International are undertaking a global analysis of island eradication priorities. Although the scope of this global analysis is slightly different, the respective methodologies have been devised in consultation between the RSPB, Island Conservation and BirdLife International. This will ensure that the underlying methods and categories are consistent between methodologies. The potential biodiversity gains of an eradication programme were assessed against a subset of native fauna. Specifically these were: all Critically Endangered, Endangered, Vulnerable and Near Threatened terrestrial vertebrate species (including marine turtles) as defined by the IUCN Red List (IUCN 2012); all restricted-range bird species (defined as an A2 species by BirdLife International) and all colonial seabird species and any other Important Bird Area trigger species. Also included were various reptile species occurring in the Caribbean OTs that have not yet been assessed by IUCN (see methods for selection criteria) as reptiles are an important component of Caribbean biodiversity (Procter and Fleming 1999). Other taxonomic groups were not included as information on their occurrence, distribution and how IAV impact upon them is not currently available in enough detail for all of the OTs. As with native fauna only terrestrial IAV were considered in the study as these are the IAS whose distribution and impact upon native fauna is best known and, for at least some groups, eradication methodologies exist. All invasive invertebrates, freshwater and marine species and plants were omitted as information on their distribution and impacts is poorly known compared to IAV and not equally known across the OTs. Limitations Due to the time scale of the study and the level of information available across all the OTs, some factors were excluded from the study, these being: 1. Social feasibility i.e. how likely it is that Governments and especially local

communities/island owners would support eradications on islands. Having the support or at least agreement of local communities is an essential component of any eradication programme (Oppel et al. 2011). This is likely to vary considerably between and within OTs and requires detailed analysis into people’s values and views surrounding IAV and their removal along with continued consultation and engagement. As such, this should be assessed prior to any proposed eradication on an island by island basis.

2. Anthropogenic reinvasion risk. This is the likelihood of IAV being introduced onto islands either accidentally or deliberately by human activity such as tourists visiting islands and boat landings. This is a potentially important factor and has been incorporated into some previous prioritisation exercises (Capizzi et al. 2010; Harris et al. 2012). Both of these exercises however focussed on a single country with sufficient detailed information to allow suitable proxy criteria for anthropogenic reinvasion risk to be developed. The level of information to allow this to be applied equally across all of the OTs was not readily accessible for all OTs within the study time scale.

3. Socio-economic impacts of IAV. As well as impacting upon native biodiversity IAV can have negative socioeconomic impacts in a variety of areas including agriculture, tourism and water quality (Reaser et al. 2007). The level of information required across all of the OTs to incorporate this into the study was too detailed and complex to collect within the time frame of the study.

4. Island area was not considered a limitation to feasibility in this study as cost is the primary limiting factor in undertaking large island eradications. Whilst cost effectiveness is incorporated into many prioritisation exercises it can be argued that the initial prioritisation should be based on the potential conservation value of an eradication with costs being factored into the planning stage once the necessary detailed information has been collected (Harris et al. 2012). As methods improve and new techniques are

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developed the size of islands where IAV can be effectively eradicated will increase and the cost will most likely decrease in the future.

5. In relation to point 4 the distribution of IAV and beneficiary species on an island was not incorporated into the prioritisation and it was assumed that all IAV and beneficiary species present on the island were distributed across the whole island. This will not be true in many cases, but to incorporate distribution information into a prioritisation would require detailed information which is currently not available for all islands within the OTs. It is also considered important for the prioritisation to highlight islands where there is potential for IAV to impact upon beneficiary species so that proactive action can be taken.

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METHODS

Data collection The eleven island OTs were included in the study, these being: Anguilla; Bermuda; British Indian Ocean Territory; British Virgin Islands; Cayman Islands; Falkland Islands; Montserrat; Pitcairn Islands; Saint Helena, Ascension and Tristan da Cunha; South Georgia and the South Sandwich Islands and Turks and Caicos Islands. Gibraltar, the British Antarctic Territory and the Cyprus Sovereign Base Areas were not included in the study. For each of the eleven OTs data was collected in three main categories: physical and social information for each island; data on all beneficiary species and data on all terrestrial IAV. All internet and document sources from which data was obtained are listed in the reference section. Island Information A list of islands in the OTs was compiled, firstly through using the updated version of the Global Island Database (GID) created by the United Nations Environment Programme – World Conservation Monitoring Centre (UNEP-WCMC 2013).The GID, comprising a global vector layer of islands, is housed and maintained by UNEP World Conservation Monitoring Centre, Cambridge, UK (www.unep-wcmc.org). The GID is originally based on Open Street Map (using a 1:75,000 Landsat product from the US National Geospatial - Intelligence Agency) and has been substantially refined through the work of a number of organisations (e.g. UNEP-WCMC, Island Conservation, BirdLife International, the RSPB, IUCN/SSC ISSG, PIER, Global Island Network). The GID is an intermediate product that is continuously being refined by the user community. Whilst the GID is a good starting point for compiling a list of islands in the OTs, it is not a complete data set. Additional islands were added to this database from a variety of sources including: Google Maps; territory-held GIS layers and the South Georgia GIS (British Antarctic Survey 2008 www.sggis.gov.gs). All islands were given a unique numerical island code. For each island in the OTs the following information was collected: Island name: the commonly used name was recorded when known; using information from Government departments, NGOs within the OTs, various reports, publications, documents and internet sources such as Wikipedia. If there are multiple names commonly used these were also recorded, e.g. Amy Island / Outer Knob. Latitude, Longitude and area: these were all taken from the GID layer in ArcGIS 10.1, with the exception of the Falkland Islands, for which information was taken directly from the Falklands Island Database (Falklands Island Government 2012). Human population: information was collected on the presence of human habitation, human population size and human habitation type. Information was obtained from Government Census reports; Government departments; Wikipedia and other internet sources. Presence of human habitation was classified as: Yes, No or Unknown. Human population size was categorised into minimum and maximum ordinal categories of: None, Unknown, 1-10, 11-100, 101-1000, 1001-10000 and >10000. When known, actual population figures were also recorded. For most individual islands within the OTs, population figures were not available as census data usually refer to the Territory as a whole. In these cases satellite imagery from Google Earth was used to estimate the ordinal category for population size based on the number of buildings on the island. Each building was estimated to house between one and four inhabitants. Therefore, an island with 10 dwellings would be assigned a minimum category of 1-10 and maximum category of 11-100.

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The type of human habitation was assigned to one of the following categories:

Permanent community: people inhabiting the island all year round in basic or rural but not urban communities.

Seasonal community: the island is not inhabited all year round, but only at certain times of the year e.g. a summer fishing community or a seasonal bar/restaurant.

Military base: the island is solely occupied by military personnel and associates.

Research station: the island is solely occupied by research personnel either permanently or seasonally.

Multiple use: the island is occupied for multiple purposes including urban communities. This is the typical category for most islands with large human populations.

None: island is currently uninhabited, though it may have been inhabited in the past.

Unknown: no information is available regarding human habitation on the island. Ownership: information on island ownership was collected from Government departments or publically available internet sources for the purposes of identifying the contact for any future work on that island. This was classified in one of the following categories:

Government: island is owned entirely by the respective Territory Government.

Private single: island is owned entirely by a single private individual, family or group e.g. National Trust.

Private multiple: island is community owned or owned by multiple private individuals

Military: island is entirely owned by the military.

Mixed: island ownership is a combination of government, private and / or military land ownership which is the typical case for most of the larger islands.

Unknown: island ownership status is unknown. Protection: the protected status of an island was recorded using information from Government departments and publications. This refers only to Government designated protected area status and does not reflect any privately protected islands i.e. islands in private ownership where the owner has designated the island for biological conservation. The protected status of an island was recorded as either:

Fully: the island is wholly under a Government protected site designation.

Partial: the island is partially under a Government protected site designation.

None: the island has no form of Government protected site designation.

Unknown: the protected site designation of the island is unknown. Beneficiary species information Information was collected on all Critically Endangered, Endangered, Vulnerable and Near Threatened terrestrial vertebrate species (including marine turtles) as defined by the IUCN Red List (IUCN 2012) as well as all Least Concern colonial seabird species and restricted-range bird species (defined as an A2 species by BirdLife International). Also included were a number of reptiles occurring in the Caribbean OTs that have not yet been assessed by IUCN. These were selected for inclusion based on the following criteria (following Powell and Henderson 2012): 1) Are a Territory endemic species; or 2) Occur on less than 15 islands across the Caribbean region. Nomenclature for all beneficiary species followed the IUCN Red List. Data was collected from a variety of sources including papers, reports and information held by the relevant government departments within each Territory.

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For each island the presence of a beneficiary species was recorded in terms of its present breeding status (defined as being within the last 20 years) in one of the following categories (for full definitions see Annex 1, which have been developed by Island Conservation, BirdLife International and University of Santa Cruz):

Confirmed: the species has been recorded as breeding on the island.

Probable: the species has not been confirmed but is strongly suspected as breeding on the island based on supporting evidence such as breeding adult found in mist nets, used/abandoned nests, acoustic monitoring.

Potential: unclear records of breeding in the last 20 years but has been recorded as breeding between 21 and 200 years ago.

Data Deficient: no information regarding the species breeding status.

Extirpated: the species is confirmed as being extirpated from the island.

Non-breeding: the species is confirmed but does not breed on the island (e.g. migratory birds, seasonal roosting).

In addition, historical breeding status (defined as between 21 and 200 years ago) for the beneficiary species was recorded in one of the following categories:

Not Applicable: if current breeding status is recorded as Confirmed.

Confirmed: the species has been confirmed as breeding on the island historically.

Probable: the species has not been confirmed but is strongly suspected to have bred on the island in the past based on supporting evidence (as above).

Potential: the breeding status of the species in the last 21 – 200 years is unclear.

Data Deficient: there is no information on the breeding status of the species in the last 21 – 200 years.

Where available, population breeding data was also recorded along with any notes regarding the species breeding on that island, e.g. is the species an island endemic; restricted to a particular location on the island or if it is a globally important breeding population. Invasive species information For every island information was collected on the presence of IAV. Data was collected from reports, publications, local Government departments and comments from experts in the various OTs. Presence was recorded in one of the following categories:

Confirmed: evidence from literature or experts confirms the presence of the invasive species on that island.

Suspected: the invasive species is suspected to be on that island based on evidence from literature or expert opinion. Also used if evidence states the invasive species is not established or not reproducing.

On-going Eradication: invasive species is confirmed as being present on that island and there is a current eradication (but not control programme) in progress.

Extirpated: the invasive species was confirmed as present previously but has now been extirpated due to a successful eradication programme.

Unknown: the IAV is known to occur in the Territory but due to lack of survey information it is not known whether it is or is not present on the island.

Island Prioritisation The final island prioritisation list takes into account the conservation value of eradicating invasive species from an island; the natural reinvasion risk of islands by rodents and the logistical feasibility of eradicating various invasive groups from individual islands based on the human population size and the size of that island. Social feasibility, anthropogenic reinvasion risk and terrain complexity are not incorporated into the prioritisation exercise as the level of detailed data required for each was not available for all islands included in the exercise or possible to collect within the timeframe of the project (see Limitations for further details).

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Potential Conservation Value (PCV) Based on the methodology of Brooke et al. (2007) this represents the conservation value or biodiversity benefit of eradicating all IAV from an island in order to avoid unforeseen secondary effects. PCV incorporates three scores: Threat Status (T): the level of threat facing the beneficiary species based on the IUCN Red List category and scored using both a logarithmic and linear scale.

IUCN Category Log Scale Linear Scale

CR 100 5 EN 10 4 VU 1 3 NT 0.1 2 LC 0.01 1

Unassessed reptile species were categorised as At Risk (AR) and were given a score equivalent to VU for the purposes of analysis. This was chosen as it is the median score for threat status though it is acknowledged that it may, in some cases, be an under or overrepresentation of threat and will need to be adjusted as full Red List assessments are completed for each species. Caribbean skinks (Family Scincidae), although not officially assessed on the IUCN Red List, were assigned a category based on the recommendations made in Hedges and Conn (2012). Irreplaceability (I): a measure of the global importance of a particular island for a beneficiary species. Scored for each beneficiary species per island, based on either the total number of islands supporting the beneficiary species, or the percentage of the species Global Breeding Population or Regional Breeding Population (GBP and RBP respectively) the island supports. This was scored using both a logarithmic and linear scale.

Criteria Log Scale Linear Scale

Single island endemic or island supports >90% of GBP 100 5

Occurs on 2-5 Islands or island supports 50 – 90% of GBP

10 4

Occurs on 6-10 Islands or island supports 1-50% of GBP or 50 – 100% of RBP

1 3

Does not qualify for the above but is a restricted-range species or island supports 1-50% of RBP, or is a seabird island listed as an IBA under criterion A4iii because it is known or thought to hold, on a regular basis, >10,000 pairs of seabirds of one or more species, or is globally or regionally important for wintering / non-breeding congregations of an IBA trigger species

0.1 2

Not any of the above 0.01 1

NB Both log scales for T and I are of the same order of magnitude so as not to weight priority towards one or the other when combined. GBP and RBP were primarily assessed using the 2012 BirdLife IBA data. For multiple island IBAs, containing globally and regionally important breeding populations of a species, each island population was treated as being part of the GBP or RBP and scored accordingly, unless information was provided to the contrary. Additional information regarding breeding population sizes was taken from reports and papers where this had been stated.

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If a beneficiary species could be categorised into two different scores, e.g. it occurs on three islands but one of those islands supports over 90% of the GBP, it was given the highest score for that individual island. Severity of Impact (S): an estimation of the impact of each type of IAV upon each beneficiary species on islands where they both occur. Impact was scored as either: 0, 1 or 2 and was based on either direct evidence of IAV impacts on the beneficiary species or impacts of the IAV on sister / similar species around the globe. Where there is uncertainty of the level of impact a worst case scenario was assumed. The impact scoring system comprised:

2 - the IAV is known, suspected or has the potential to have a detrimental impact upon the beneficiary species causing declines in populations either through direct predation, habitat modification, competition, spreading of disease etc.

1 - the IAV co-exists with the beneficiary species but is likely to prevent the beneficiary species from reaching its maximum potential population due to its presence by, for example, suppressing breeding success or in creating sub-optimal habitat.

0 - no apparent negative impact upon beneficiary species. Calculating an island’s PCV For each beneficiary species whose present breeding status was recorded as confirmed or probable and for those globally important congregations of non-breeding species on that island, four benefit scores (B) are calculated using the following formulas: B = T x I x S The severity of impact (S) score used is the maximum S score affecting that beneficiary species on that island. For example, if there were three IAV on an island scored as having an impact of 2, 1 and 1 respectively, the benefit score for that beneficiary species will use the S score of 2. Only IAV recorded as being confirmed or suspected were considered. Additional benefit scores were also calculated for those species recorded as potentially breeding on the island or that were recorded as having confirmed or probable historical breeding but are now extirpated. This reflects the restoration potential of an island should IAV be eradicated. These benefit scores were calculated in the same way as above but divided by 2 to reflect that this is only a potential benefit of eradicating an island through future recolonisation (either natural or assisted) by those species. As both threat and irreplaceability are scored on two different scales (log or linear), because there is currently no consensus on which scale performs better, the benefit score for each species was calculated in four different ways, using all four possible combinations of log and linear scores of both threat and irreplaceability. This resulted in four non-comparable conservation values, which were all used independently for the priority assessment.

19

All the benefit scores for all native vertebrates on an island were then summed to give the overall island PCV score. The calculation is demonstrated in the example below: Big Island worked example

Beneficiary Species

Threat Status Irreplaceability Severity of Impact Log Linear Log Linear

Sp 1 100 5 100 5 2 Sp 2 10 4 1 3 2 Sp 3 1 3 0.1 2 1 Sp 4 0.01 1 0.1 2 0

Species 1: B1 = 100 x 100 x 2 = 20000 (log-log scale) B2 = 5 x 5 x 2 = 50 (linear-linear scale)

B3 = 100 x 5 x 2 = 1000 (log-linear scale) B4 = 5 x 100 x 2 = 1000 (linear-log scale)

. PCV1 = (Sp1.B1 + Sp2.B1 + Sp3.B1 + Sp4.B1) = 20000 + 20 + .1 + 0 = 20020.1 PCV2 = (Sp1.B2 + Sp2.B2 + Sp3.B2 + Sp4.B2) = 50 + 24 + 6 + 0 = 80 PCV3 = (Sp1.B3 + Sp2.B3 + Sp3.B3 + Sp4.B3) = 1000 + 60 + 2 + 0 = 1062 PCV4 = (Sp1.B4 + Sp2.B4 + Sp3.B4 + Sp4.B4) = 1000 + 8 + 0.3 + 0 = 1008.3 Post-eradication Conservation Value (ECV) On some islands, it may not be possible to eradicate all damaging invasive species and therefore the full PCV will not be achieved. To assess the realistic conservation value of islands, the ECV was calculated for each island using the same methodology as outlined previously, but only including those IAV species that were considered not feasible to eradicate at present. When calculating the ECV, the S score used for each beneficiary species was the highest of those IAV remaining after eradicating all logistically feasible IAV that were unlikely to recolonise the island naturally. To determine which IAV could be logistically eradicated from islands, IAV were classified into six broad categories based on the type of eradication methods used: Rodents (rats, mice and including lagomorphs like rabbits and hares), Predators (mammalian carnivores), Ungulates, Iguana (including monitor lizards), Birds and Other reptiles and amphibians. Logistical eradication feasibility for each class in which an IAV scored a 1 or 2 for impact was then assessed on an island-by-island basis using the following criteria. Rodents: eradication not considered feasible on islands with a human population >1000. Predators, Ungulates, Iguana: eradication not considered feasible on islands with a human population >10000. Birds: applies to various bird species. Chicken eradication not considered feasible on all islands >5km². Eradication of all other bird species e.g. kiskadees (Pitangus sulphuratus), crows (Corvus sp.) and common mynas (Acridotheres tristis) not considered feasible. Although it is acknowledged that invasive bird species have been eradicated from small, isolated islands previously (e.g. mynas in the Seychelles) similar situations do not occur in the OTs. Reptiles and amphibians: eradication not considered feasible due to a current lack of effective methodologies for these species (Pitt et al. 2005; Krause 2009). Two exceptions to this are cane toads (Rhinella marina) on islands <10ha which has successfully been achieved in Bermuda and the red-eared slider (Trachemys scripta elegans) freshwater turtle

20

in Bermuda where eradication is considered feasible (freshwater turtles are also present in other OTs but are not currently considered to impact upon any beneficiary species). These human population figures are based on analysis done by Island Conservation of successful eradications from Oppel et al. (2011) and subsequently agreed with internal and external experts. Natural Reinvasion Risk (NRR) The long-term success of an eradication project can be jeopardized by either natural or human-assisted reinvasion of the eradicated species (Clout & Russell 2008; Russell et al. 2008b; Harris et al. 2012). We considered the reinvasion risk in our prioritization by excluding an eradication as unlikely to yield lasting benefits i.e. if unassisted reinvasion via swimming was likely during or soon after an attempted eradication. Several mammals (e.g., rodents, mustelids, deer, foxes) can swim between islands and may reinvade islands after eradication. However, besides rodents the remaining swimming species inhabited very few islands in our study area, and their reinvasion risk after eradication was negligible for our overall assessment. Rodent eradication on islands within 2 km of an island assessed as being unfeasible for rodent eradication was excluded based on the maximum swimming distance recorded for rodents (Russell et al. 2008a; Russell et al. 2008b). Eradication on these islands may be technically feasible; however, due to the high reinvasion risk they are less likely to maintain the benefit of eradication. Therefore we excluded them from our prioritization. Actual Conservation Value (ACV) The ACV was calculated for each island from the corresponding PCV and ECV scores using the following formula: ACV = (PCV – ECV) For each island, we calculated four different ACV scores, based on the different combinations of log and linear scales in threat and irreplaceability. All islands were ranked according to their ACV scores, which resulted in four ranks for each island due to the four combinations of log and linear scales. The median of these four ranks was then taken to order the islands based on their priority for eradication (see example below). The island with the lowest median ACV rank was the island that would produce the highest conservation benefit from IAV eradication. Final ranking example, the island with the highest eradication priority is highlighted in Red

Island ACV1 Rank

ACV2 Rank

ACV3 Rank

ACV4 Rank

Median ACV Rank

Final Rank

Big Island 2 6 3 4 3.5 3 Little Island 6 5 5 3 5 5 Rat Island 4 1 4 1 2.5 2 Goat Island 1 2 1 2 1.5 1 Cat Island 5 3 2 5 4 4 Sandy Island 3 4 6 6 5 5

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RESULTS

Islands in the OTs In total 2,499 islands, islets and rock stacks were recorded as being present in the eleven study OTs, although this figure will likely change as the GIS mapping of the OTs is improved. The Territory with the most islands is South Georgia and the South Sandwich Islands (n = 1,071, 42.9%). The total land area covered by these Territories is approximately 17,635 km² with the Falkland Islands having the greatest land area (approx. 12,000 km², 68%) and East Falkland the largest single island (6,511 km²). See Table 1 for full details of island physical details. Table 1 Total number of islands and land area by Territory. St Helena, Ascension and Tristan da Cunha are listed separately.

Territory Number of Islands

Approximate total land area (km²)

% land area of total

Anguilla (AIA) 22 79.13 0.45

Bermuda (BMU) 131 55.73 0.32

British Indian Ocean Territory (BIOT) 56 49.99 0.28

British Virgin Islands (BVI) 57 153.78 0.87

Cayman Islands (CYM) 12 270.26 1.53

Falkland Islands (FLK) 853 11,999.80 68.04

Montserrat (MSR) 2 101.58 0.58

Pitcairn Islands (PCN) 22 48.75 0.28

St Helena, Ascension and Tristan da Cunha

181 400.96 2.27

St Helena (SHN) 103 124.08 0.70

Ascension (ASC) 44 97.80 0.55

Tristan da Cunha (TDC) 34 179.08 1.02

South Georgia and the South Sandwich Islands (SGS)

1,071 3,935.82 22.32

Turks and Caicos Islands (TCI) 92 539.85 3.06

Total 2,499 17,635.44 100

Only 102 islands (3.3%) are classified as having some form of human habitation. Of these, 73 are classed as having permanent or multiple human habitation types; 25 as being seasonally inhabited; three solely comprising research stations (Gough, TDC; South Georgia and Bird Island, SGS) and one as being solely military (Diego Garcia, BIOT). Five islands have human populations over 10,000 (Anguilla; Grand Cayman; Main Island, BMU; Providenciales, TCI; Tortola, BVI) and eight others with populations over 1,000. Beneficiary species in the OTs In total 217 beneficiary species were included in the analysis. Seabirds accounted for the majority of these species (n=92, 42.1%) as Least Concern species were only included in the analysis if they were either a colonial seabird species, restricted-range bird species or an IBA trigger species (see Table 2 for summary and Annex 2 for a full species list). Sixty-six of the beneficiary species are listed by IUCN as globally threatened, of which 18 are Critically Endangered, 22 Endangered and 26 Vulnerable. Reptiles, including four marine turtle

22

species, were the most numerous globally threatened group (n=27, 40.3%; see Table 2 and Figure 2). Of the globally threatened species considered, four are currently considered to be extirpated from the OTs (Roosevelt’s giant anole Anolis roosevelti; Puerto Rican crested toad Peltophryne lemur; giant kingbird Tyrannus cubensis; Cuban crocodile Crocodylus cubensis). Table 2 Number of beneficiary species by IUCN threat status and taxonomic order in the 11 OTs. CR = Critically Endangered, EN = Endangered, VU = Vulnerable, NT = Near Threatened, LC = Least Concern, AR = At Risk.

Taxonomic Order CR EN VU NT LC AR

Seabirds 1 8 7 7 69 0

Land birds 3 3 12 11 31 0

Reptiles 12 9 5 1 0 32

Amphibians 2 2 0 0 0 0

Mammals 0 0 2 0 0 0

OTs Total 18 22 26 19 100 32

Figure 2 Number of globally threatened beneficiary species by taxonomic group in the 11 OTs. St Helena, Ascension and Tristan da Cunha is the Territory with the greatest number of globally threatened species (total of 15, of which 12 occur in the Tristan group) and the BIOT is the Territory with the fewest - namely two marine turtle species (see Table 3). It is likely that the number of globally threatened species occurring in the Caribbean OTs (Anguilla, British Virgin Islands, Cayman Islands, Montserrat, Turks and Caicos Islands) will increase as the region’s herpetofauna is formally assessed by the IUCN. All 32 of the At Risk (AR) reptiles included in this study occur in these five OTs. Montserrat and British Virgin Islands have the greatest number of Critically Endangered species, with six present in each Territory. Two of these have apparently been extirpated from islands in the British Virgin Islands (Anolis roosevelti; Peltophryne lemur).

0

5

10

15

20

25

30

Reptiles Landbirds Seabirds Amphibians Mammals

Nu

mb

er

of

GTS

23

Table 3 Number of globally threatened and endemic terrestrial vertebrates by Territory.

TERRITORY CR EN VU Total

Anguilla (AIA) 2 3 4 9

Bermuda (BMU) 1 3 0 4

British Indian Ocean Territory (BIOT) 1 1 0 2

British Virgin Islands (BVI) 6 8 0 14

Cayman Islands (CYM) 3 3 2 8

Falkland Islands (FLK) 0 1 4 5

Montserrat (MSR) 6 2 3 11

Pitcairn Islands (PCN) 0 4 5 9

St Helena, Ascension and Tristan da Cunha 3 6 6 15

St Helena (SHN) 1 0 0 1

Ascension (ASC) 0 1 1 2

Tristan da Cunha (TDC) 2 5 5 12

South Georgia and the South Sandwich Islands (SGS) 0 1 4 5

Turks and Caicos Islands (TCI) 3 3 2 8

Figure 3 Number of endemic terrestrial vertebrates by Territory. St Helena, Ascension and Tristan da Cunha are listed separately. In total 66 terrestrial vertebrate species are endemic to individual OTs with the Cayman Islands having the largest number at 15 (see Figure 3). Of these endemic species all except three (South Georgia pipit Anthus antarcticus (NT); Tristan thrush Nesocichla eremita (NT); Falkland steamerduck Tachyeres brachypterus (LC)) are either globally threatened or not assessed. Invasive Species in the OTs In total 85 IAV were recorded across the study OTs. Of these 30 were reptiles, 26 birds, 23 mammals and six amphibians. Thirty-eight IAV species (44.7%) were considered to have some form of negative impact upon at least one beneficiary species. This percentage varies

0

2

4

6

8

10

12

14

16

CYM TDC BVI TCI MSR PCN AIA BMU FLK SHN ASC SGS BIOT

Nu

mb

er

of

en

de

mic

sp

eci

es

24

across invasive group with eighteen invasive mammals (78.3%) considered to be having some negative impact on beneficiary species compared to only seven invasive bird species (26.9%) and ten invasive reptile species (32.3%; see Figure 4). A full list of IAV can be seen in Annex 3.

Figure 4 Total number of invasive alien vertebrate species (blue) and number of invasive alien vertebrate species impacting upon at least one beneficiary species (red). The most widespread IAV were rats (Rattus rattus, R. norvegicus, R. exulans) which were recorded as either Confirmed or Suspected on 473 islands (18.9%) across all of the OTs, in addition to 66 islands (2.6%) on which they have been extirpated or are subject to an on-going eradication. At least two of the most damaging IAV classes (Rodents, Predators and Ungulates) occur in all of the OTs (this may soon change as the reindeer population in South Georgia is currently subject to an ongoing eradication). The most widespread predator was the feral cat (Felis catus) occurring on 53 islands (2.1%) across all OTs except SGS and in TDC. Feral goats (Capra hircus) were the most widespread ungulate species, occurring on 28 islands (1.1%) across six OTs (see Table 4). Of the other IAV classes, the cane toad (Rhinella marina) was the most widespread impacting species occuring on 43 islands (1.7%) across six OTs. Other IAV impacting reptile and amphibian species were restricted to the Caribbean, with the most notable example being the Cuban treefrog (Osteopilus septentrionalis). Notable impacting bird species include common myna (Acridotheres tristis), crows (Corvus sp.) and feral chicken (Gallus domesticus).

0

5

10

15

20

25

30

35

Reptiles Birds Mammals Amphibians

Nu

mb

er

of

IAV

sp

eci

es

25

Table 4 Number of Confirmed or Suspected invasive alien vertebrate species by taxonomic order per Territory. St Helena, Ascension and Tristan da Cunha listed separately.

TERRITORY Rodents Predators Ungulates Other Mammals

Birds Reptiles Amphibians

Anguilla 2 3 1 2 2 5 2

Bermuda 3 1 0 0 7 3 1

British Indian Ocean Terr.

1 1 1 0 7 2 1

British Virgin Islands

3 3 5 0 5 6 2

Cayman Islands

3 2 0 1 8 12 2

Falkland Islands

3 2 4 3 1 0 0

Montserrat 2 1 5 2 3 2 1

Pitcairn Islands

1 1 1 0 0 6 0

St Helena 3 1 1 1 9 1 1

Ascension 2 0 2 1 5 3 0

Tristan da Cunha

2 0 3 0 0 0 0

South Georgia and the South Sandwich Is

2 0 0 0 0 0 0

Turks and Caicos Is

2 2 4 0 1 9 3

Priority Islands In total, 191 islands were included in the prioritisation as they harboured at least one beneficiary species and one impacting IAV. All other islands were not included as they either did not meet this criterion or there was insufficient information available for them. Islands were initially prioritised for Potential Conservation Value (PCV) only i.e. the maximum conservation value achievable if all IAV could be successfully eradicated (see table 5). Islands within 30º of the equator account for 18 of the top 20 islands by PCV. This is perhaps unsurprising as biodiversity tends to be greater in tropical regions. Montserrat, a relatively large (> 100km²), tropical island is ranked first due to having a large number of globally threatened species and not yet assessed reptile species that are either single island endemics or are restricted to a few islands. This is also true for many of the other large Caribbean islands such as Anegada, Tortola and the three Cayman Islands. Tristan da Cunha and Gough lie in the temperate region and lack the threatened and restricted herpetofauna of the Caribbean islands but are globally important breeding sites for a large number of seabirds and endemic land birds, many of which are globally threatened.

26

Table 5 Top 25 islands ranked by Potential Conservation Value (PCV) only - this conservation value can only be realised if all invasive alien vertebrate species are eradicated from the beneficiary island (practically not feasible at this stage for all islands).

Rank Island Territory

1 Montserrat Montserrat

2 Gough Saint Helena, Ascension and Tristan da Cunha

3 Cayman Brac Cayman Islands

4 Anegada British Virgin Islands

5 Grand Cayman Cayman Islands

6 Little Cayman Cayman Islands

7 Saint Helena Saint Helena, Ascension and Tristan da Cunha

8 Henderson Pitcairn Islands

9 Tortola British Virgin Islands

10 Guana Island British Virgin Islands

11 Little Thatch Island British Virgin Islands

12 Tristan da Cunha Saint Helena, Ascension and Tristan da Cunha

13 Norman Island British Virgin Islands

14 Virgin Gorda British Virgin Islands

15= Cotton Cay Turks and Caicos Islands

15= Gibb’s Cay Turks and Caicos Islands

17= Anguilla Anguilla

17= Necker Island British Virgin Islands

19= Jost Van Dyke British Virgin Islands

19= Grand Turk Turks and Caicos Islands

21 East Caicos Turks and Caicos Islands

22 Big Ambergris Cay Turks and Caicos Islands

23 Pitcairn Pitcairn Islands

24 Scrub Island Anguilla

25 South Georgia South Georgia and the South Sandwich Islands

When filtered for IAV eradication feasibility, 11 islands were considered not to be feasible for eradication due to either human population size or IAV groups present. Out of the top 20 islands ranked by PCV Grand Cayman, Tortola, and Anguilla all have human populations of over 10,000. No invasive species group on these islands is considered feasible to eradicate and they therefore drop out of the prioritisation. Other islands with human populations of over 1,000 from which rodents, specifically rats, cannot be eradicated drop substantially in the final (ACV) prioritisation list. These include Cayman Brac, Saint Helena, Virgin Gorda and Grand Turk. Table 6 lists the top 25 priority islands when ranked by Actual Conservation Value (ACV)2. Ten of the 11 OTs included in this study are represented in these top 25 islands, but the list is dominated by islands from the Turks and Caicos Islands and British Virgin Islands, with

2 The full list of islands ranked by ACV and PCV is available from the RSPB on request.

27

five and nine respectively. This is due primarily to the rich endemic herpetofauna found in the Caribbean and in these Territories. Further detail on specific islands and key beneficiary species can be seen in the individual Territory sections. Of the top 20 islands, most have small permanent human habitation with the largest population being on Jost Van Dyke (297; 2008 Census data). Island area is currently the biggest determinant of eradication cost, along with complexity (number of species to be eradicated) and isolation. Estimating costs for individual operations was not considered constructive at this stage, as these can vary so significantly between Territories (e.g. from the Falklands where a low-cost ground-based methodology has been developed and no project has cost more than £20,000 to implement, to Henderson Island where aerial techniques were used at a cost of c£1.5 million for an eradication attempt in 2011).

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Table 6 Top 25 islands for invasive alien vertebrate eradication ranked by Actual Conservation Value (ACV), which incorporates natural reinvasion risk and assumes that only those IAV for which technically and logistically feasible eradication techniques currently exist (as of January 2013) are included. Rank Island OT

Island Area (km2)

1 Gough Saint Helena, Ascension and Tristan da

Cunha

65.58

2 Anegada British Virgin Islands 38.44

3 Little Cayman Cayman Islands 28.90

4 Henderson Pitcairn Islands 43.18

5 Guana British Virgin Islands 2.93

6 = Tristan da Cunha Saint Helena, Ascension and Tristan da

Cunha

2.50

6 = Norman British Virgin Islands 96.16

8 = Cotton Cay Turks and Caicos 1.08

8 = Necker British Virgin Islands 0.32

10 Big Ambergris Cay Turks and Caicos 4.17

11 South Georgia South Georgia and the South Sandwich

Islands

3605.42

12 = Pitcairn Pitcairn Islands 4.05

12 = Jost van Dyke British Virgin Islands 8.52

12 = Little Ambergris Cay Turks and Caicos 3.20

15 Salt Cay Turks and Caicos 6.67

16 New Falkland Islands 23.63

17 French Cay Turks and Caicos 0.11

18 Little Tobago British Virgin Islands 0.25

19 Peter British Virgin Islands 4.27

20 Ascension Saint Helena, Ascension and Tristan da

Cunha

97.71

21 Dog Anguilla 1.96

22 Salt British Virgin Islands 0.78

23 Montserrat Montserrat 101.57

24 Great Dog British Virgin Islands 0.36

25 Ile de la Passe British Indian Ocean Territory 0.21

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TERRITORY-SPECIFIC ACCOUNTS

30

ANGUILLA

Top-ranked islands

Island Key IAV Species Key Beneficiary Species

Dog Island Goat Anguilla bank skink (VU); Anguilla bank ameiva (AR); laughing gull (GBP); sooty tern (GBP); brown booby (GBP); bridled tern, brown noddy, magnificent frigatebird, masked booby, red-billed tropicbird (all RBP)

Prickly Pear East (PPE) and Prickly Pear West (PPW)

Black rat PPE: Anguilla bank ameiva (AR); laughing gull (GBP); brown booby, least tern, red-billed tropicbird (all RBP)

PPW: Laughing gull (GBP); brown booby, brown pelican, red-billed tropicbird (all RBP)

GBP = Globally Important Breeding Population RBP = Regionally Important Breeding Population

Discussion Management

The top priority site in Anguilla for invasive vertebrate eradication is Dog Island where eradication of rats has already been successful. Removing goats from this site could bring substantial addtional conservation benefits.

Prickly Pear East and West should be considered as a single management unit when undertaking a rat eradication due to their close proximity to each other in order to reduce the risk of natural reinvasion.

The Anguilla mainland has a number of globally threatened species including the Endangered Anguilla racer (Alsophis rijgersmaei) and Lesser Antillean iguana (Iguana

31

delicatissima) along with a range of IAV including rats, feral cats and dogs, green iguana and goats. It is ranked 17th amongst the OT islands for PCV, illustrating its high biodiversity value. However, due to its high human population, eradication of invasive vertebrates is not considered feasible at present. Many native species on Anguilla could benefit from sustained control of feral mammalian predators, goats and green iguana.

Scrub Island, which is ranked 24th for PCV, lies very close to the Anguilla mainland (< 600m) so there is a high risk of natural reinvasion by rats. Because of this, the eradication of rats from Scrub Island is not currently considered likely to be a sustainable project.

Research

The distribution of rats on the islands of Anguilla is general poorly known and further investigation into their distribution is needed. It would be useful to investigate the gene-flow between populations of rats on the mainland of Anguilla and the off-islands – this could give a good indication as to whether eradication efforts would be sustainable or whether there would be constant reinvasion. Similar work has been carried out in the Falkland Islands and has been useful in guiding project selection (S Poncet, pers. comm.).

Red cornsnakes (Pantherophis guttatus) have been recorded on Anguilla. A common pet trade species, the red cornsnake has been identified as potentially having a severe detrimental impact on native fauna through predation and competition in the US Virgin Islands and Australia (Platenberg and Boulon 2006; Fisher and Csurhes 2009). They have also been identified as a significant threat to the endemic subspecies of brown-headed nuthatch (Sitta pusilla insularis) in the Bahamas (Hayes et al. 2004). Studying the impact of red cornsnake on native fauna in Anguilla, particularly on the Anguilla racer, would be widely beneficial as little is known about their impacts in the Caribbean due to their relative recent arrival. Limiting their spread within Anguilla and preventing their establishment on the other islands should be considered a priority as eradication would be extremely difficult if not impossible (Fisher and Csurhes 2009).

Biosecurity

Preventing rats establishing on Sombrero and Little Scrub Island should be considered a priority due to the presence of two endemic reptile species on Sombrero (Sombrero ameiva Ameiva corvina and Sombrero dwarf gecko Sphaerodactylus sp.) and one endemic reptile species on Little Scrub Island (Censky’s ameiva Ameiva corax).

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BERMUDA

Discussion

As all of Bermuda’s off-islands lie within 2 kilometres of the mainland where eradication of IAV is not considered feasible, this study has not identified any priority vertebrate eradication projects in Bermuda.

Bermudian conservationists have already successfully restored inshore islands for conservation (e.g. Nonsuch Island). Constant rat control is required on these islands to prevent reestablishment. It is likely that the Castle Islands would be a high priority for this sort of ongoing control.

Research

Improving knowledge of the distribution of rats (and other IAV) on the smaller islands of Bermuda would benefit future conservation action.

The native Near Threatened diamond terrapin (Malaclemys terrapin) is currently found in only three ponds on Main Island and could most likely benefit from the eradication of the invasive red-eared slider. Further research is needed on the best approach and likely benefits.

Eradication of kiskadees (Pitangus sulphuratus) and American crows (Corvus brachyrhynchos) is not likely to be feasible at present but control could benefit native species including the Critically Endangered Bermuda skink (Plestiodon longirostris) and diamondback terrapin. Further research is needed on the best approach and likely benefits.

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BRITISH INDIAN OCEAN TERRITORY

Top-ranked islands

Island Key IAV Species Key Beneficiary Species

Ile de la Passe (Peros Banhos)

Black rat Hawksbill turtle (CR); green turtle (EN), nesting seabirds

Ile Yeye Black rat Hawksbill turtle (CR); green turtle (EN), nesting seabirds

Ile Diamant

Petite Soeur

Grande Ile Mapou

Ile Pierre

Black rat Hawksbill turtle (CR); green turtle (EN)

Ile Cipaille

Ile Lubine

Black rat Hawksbill turtle (CR); green turtle (EN)

Eagle Island Black rat Hawksbill turtle (CR); green turtle (EN)

Ile Vache Marine Black rat Hawksbill turtle (CR); green turtle (EN)

Discussion Management

Ile Diamant, Grande Ile Mapou, Ile Pierre and Petite Soeur (Peros Banhos) should be considered as a single management unit if undertaking a rat eradication due to their close proximity to each other to reduce the risk of natural reinvasion.

Ile Cipaille and Ile Lubine (Egmont Islands) are effectively connected so should be treated as a single management unit if undertaking a rat eradication.

The largest island in the BIOT, Diego Garcia, has significant seabird colonies and restoration potential. It also has feral cats, donkeys and black rats. Due to the size of the resident human population, eradication of rats is not currently considered feasible.

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However implementing sustained control of IAV on Diego Garcia could benefit the number of important nesting seabird colonies as well as nesting turtles and native forest.

A rat eradication project has recently been undertaken on Ile Vache Marine, led by the Chagos Conservation Trust (CCT, pers.comm). If this succeeds, there are plans to take work forward on other, larger islands such as Yeye and Eagle Island.

Biosecurity

Many islands in the BIOT have no impacting IAV present and biosecurity for these islands should be given the highest priority.

Nelson, Sea Cow and Danger Island are all Important Bird Areas and have feral chickens present which, although unlikely to impact upon breeding seabirds, would benefit from monitoring.

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BRITISH VIRGIN ISLANDS

Top-ranked islands

Island Key IAV Species Key Beneficiary Species

Anegada Feral cat; dog; goat; cow;, sheep; donkey; pig; brown rat; green iguana; Cuban treefrog

Anegada ground iguana (CR); Anegada skink (CR); roseate tern (GBP); leatherback (CR); hawksbill turtle (CR; green turtle (EN); laughing gull, least tern, royal tern, sandwich tern, brown pelican (all RBP)

Guana Island Feral cat; dog; sheep; Cuban treefrog

Anegada ground iguana (CR); Mona Island boa (EN); Lesser Virgin Islands skink (EN); hawksbill turtle (CR)

Norman Island Feral dog; goat; black rat Anegada ground iguana (CR); Virgin Islands bronze skink (EN)

Necker Island Black rat; Cuban treefrog Anegada ground iguana (CR); Lesser Virgin Island skink (EN); laughing gull and bridled tern (RBP)

Jost Van Dyke Feral cat; dog; goat; pig; small Asian mongoose; black rat; Cuban treefrog

Mona Island boa (EN); Virgin Islands coqui (EN); yellow mottled coqui (EN); hawksbill turtle (CR)

Little Tobago Black rat; goat Virgin Islands bronze skink (EN); brown booby (RBP)

Peter Island Green iguana; feral cat; feral chicken

Virgin Islands bronze skink (EN; hawksbill turtle (CR)

Salt Island Goat; feral chicken Lesser Virgin Island skink (EN); Virgin Islands bronze skink (EN;

Great Dog Island Black rat, goat Virgin Islands coqui (EN) GBP = Globally Important Breeding Population RBP = Regionally Important Breeding Population

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Summary Management

The highest priority invasive vertebrate eradication project in the BVI at present is on Anegada (ranked 2nd across all the OT islands) where feral cats and other IAV are having a severe impact on threatened reptiles and on seabirds. There would need to be full community support for any project on Anegada as the island has substantial private ownership.

Guana Island does not have rodents present, but is a high priority for the eradication of cats and other feral animals.

Jost Van Dyke, Little Jost Van Dyke, Green Cay and Sandy Spit would need to be treated as a single management unit if undertaking a rodent eradication due to their close proximity to each other to reduce the risk of natural reinvasion.

Both Tortola and Virgin Gorda ranked very highly for PCV (9 and 14, respectively) but due to their high human population sizes eradication of most IAV groups is not considered feasible. Control of small Asian mongoose (Herpestes javanicus) and other IAV predators on these islands could be highly beneficial for native fauna, especially the endemic Virgin Islands dwarf gecko (Sphaerodactylus parthenopion; currently unassessed). Similarly for Little Thatch (ranked 11 for PCV) which, due to its close proximity to Tortola, is unlikely to represent a sustainable eradication project but again IAV control could deliver conservation benefits.

Research

Cuban treefrogs (Osteopilus septentrionalis) occur on many islands in BVI including Anegada, Guana, Great Camanoe, Necker, Little Thatch and Jost Van Dyke. These large frogs are voracious predators and have been implicated in declines of native frog species in the US Virgin Islands and Florida through predation and resource competition (Platenberg and Boulon 2006; Glorioso et al. 2012). At present, there is no known eradication method and monitoring their extent of distribution, impact upon native fauna and removal where possible would be considered highly beneficial.

Red cornsnakes (Pantherophis guttatus) have been recorded from Tortola and Peter Island, though these may be waifs and a non-breeding population. A common pet trade species, the red cornsnake has been identified as potentially having a severe detrimental impact on native fauna through predation and competition in the US Virgin Islands and Australia (Platenberg and Boulon 2006; Fisher and Csurhes 2009). They have also been identified as a significant threat to the endemic subspecies of brown-headed nuthatch (Sitta pusilla insularis) in the Bahamas (Hayes et al. 2004). Implementing suitable measures to prevent the establishment of red cornsnakes in BVI would be considered very beneficial as eradication would be extremely difficult if not impossible (Fisher and Csurhes 2009).

Surveys to establish a more detailed understanding of the distribution and impacts of IAV in BVI would be of significant benefit to future conservation actions within the territory.

Biosecurity

Rats are not recorded as being present on Guana Island but it lies close to Tortola (500m). Implementing appropriate biosecurity measures to prevent rats colonising Guana Island should be a high priority.

Prevention of rats, mongoose and feral cats establishing on Mosquito Island should be a high priority, as it is the only predator-free refuge for the Virgin Islands dwarf gecko.

Mongoose distribution is currently limited to Tortola, Virgin Gorda, Jost Van Dyke, Little Jost Van Dyke and Beef Island. Preventing the colonisation of other islands should be considered a priority as mongooses are known to have particularly devastating impacts on native reptile species (Barun et al. 2011; Hedges and Conn 2012).

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CAYMAN ISLANDS

Top-ranked island

Island Key IAV Species Key Beneficiary Species

Little Cayman Feral cat; dog; black rat; green iguana

Sister Islands rock iguana (CR); 5 endemic reptiles; West Indian whistling duck (VU); red-footed booby (GBP); green turtle (EN); loggerhead (EN)

GBP = Globally Important Breeding Population

Summary Management

Little Cayman is ranked the 3rd most important IAV eradication project in the OTs (ACV) due to its populations of Sister Islands rock iguana and other endemic reptiles and its low human population (c. 200 permanent residents). This island is clearly very important for biodiversity, and exploring the potential for IAV control should be a high priority, as well as ensuring new IAV do not become established.

Cayman Brac is ranked 3 for PCV due to its endemic reptile population. For ACV, its ranking is low due to its large human population which rules out rat eradication. Control of feral predators could still deliver substantial conservation benefits on the Brac.

Grand Cayman ranked 5 overall in terms of PCV due in part to the presence of the Endangered Cayman blue iguana (Cyclura lewisi) and four other endemic reptile species. Due to the high human population, eradication of IAV is not considered feasible on Grand Cayman. However, localised control of feral IAV predators could be highly beneficial to biodiversity.

Research and biosecurity

Green iguanas (Iguana iguana) are present on all islands (although not yet well established on Cayman Brac or Little Cayman). They potentially compete with native Cyclura species though their impacts are not well investigated. Preventing further establishment of green iguanas on Little Cayman and Cayman Brac should be a high priority.

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Red cornsnakes (Pantherophis guttatus) have established populations on Grand Cayman. A common pet trade species, the red cornsnake has been identified as potentially having a severe detrimental impact on native fauna through predation and competition in the US Virgin Islands and Australia (Platenberg and Boulon 2006; Fisher and Csurhes 2009). They have also been identified as a significant threat to the endemic subspecies of brown-headed nuthatch (Sitta pusilla insularis) in the Bahamas (Hayes et al. 2004). Studying the impact of red cornsnake on native fauna in Grand Cayman would be widely beneficial, as little is known about their impacts in the Caribbean due to their relative recent arrival. Limiting their spread within Grand Cayman and preventing their establishment on the Little Cayman and Cayman Brac should be a high priority as eradication would be extremely difficult if not impossible (Fisher and Csurhes 2009).

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FALKLAND ISLANDS

Top-ranked islands

Island Key IAV Species Key Beneficiary Species

New Island Feral cat; black rat; house mouse; rabbit

Black-browed albatross (EN, GBP); white-chinned petrel (VU); southern rockhopper penguin (VU); gentoo penguin (GBP); imperial shag (GBP); thin-billed prion (GBP); seabird IBA

Steeple Jason House mouse Black-browed albatross (EN, GBP); seabird IBA GBP = Globally Important Breeding Population

Discussion The Falkland Islands have led amongst the Overseas Territories in developing a local programme of invasive vertebrate eradication projects. These have included attempted rodent eradications from more than 30 individual islands, as well as projects to remove foxes from several sites. Unlike many of the other Territories, the majority of land in the Falklands is in private ownership, including many privately owned islands. Falklands stakeholders have previously developed their own priority list of islands for future eradications, and the criteria used incuded owner acceptance and enthusiasm as a key factor. The current project has not taken this into account, so the resulting list should only be considered along with a local priority list. Management

New Island is ranked 16 for ACV, and would require a multi-species eradication effort. It has a number of offshore islands in close proximity that would need to be considered during any eradication attempt.

Steeple Jason is ranked relatively low for ACV (38) as it only has house mice present and they are considered to have a much lower impact than either rats or cats on the Globally Threatened birds considered in this analysis. However, the eradication of mice from Steeple Jason could remove the main biosecurity threat to the Jason Islands group where all other islands are rodent-free and important refugia for small seabirds and

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invertebrates. Mice are known to be having an impact on small birds and invertebrates on Steeple Jason. This island may therefore carry a higher local priority than apparent from this exercise.

Research and biosecurity

Assessment of IAV distribution on West and East Falkland would be very beneficial to identify isolated IAV populations that are feasible for eradication now, thus limiting their spread in the future. Rabbits are one species that currently occur in small isolated populations that could be dealt with before they spread further with potentially damaging impacts on native vegetation and potential impact on agriculture.

In general, all islands within 2km of each other should be treated as a single management unit when undertaking a rodent eradication to reduce the risk of natural reinvasion. In some circumstances it may be appropriate to “control” rodents on islands, accepting some level of reinvasion risk. A discussion on the appropriateness of this approach would need to be held locally.

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MONTSERRAT

Top-ranked Island

Island Key IAV Species Key Beneficiary Species

Montserrat Feral pig; goat; cow, feral cat; black rat; cane toad

Montserrat oriole (CR); mountain chicken (CR); Montserrat galliwasp (CR); Montserrat skink (CR); forest thrush (VU); leatherback turtle (CR); hawksbill turtle (CR); green turtle (EN) and 3 other endemic reptiles

GBP = Globally Important Breeding Population

Discussion

Based on PCV only, Montserrat is the top-ranking island in the OTs. Its ACV ranking however is significantly lower as its human population size means that rat eradication is not considered feasible (island size and topography would also make this exceptionally expensive).

Predator and ungulate control is, within the scales of this assessment, theoretically feasible. However, given the social conditions on the island (e.g. recreational hunting being a popular activity amongst some members of the community) and the inaccessibility of a large part of the island due to ongoing volcanic activity, eradication is clearly not feasible at present. Control of feral ungulate populations, as is currently being undertaken in and around the Centre Hills and should be continued as this area is where most of the key beneficiary species occur. In addition, turtle populations could benefit significantly from control of pigs on nesting beaches.

Biosecurity should be a high priority for Montserrat, to prevent the establishment of more IAV species.

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PITCAIRN ISLANDS

Key Islands

Island Key IAV Species Key Beneficiary Species

Henderson Polynesian rat Henderson petrel (EN); Henderson crake (VU); Henderson reed-warbler (VU), Henderson lorikeet (VU); Henderson fruit-dove (VU); Murphy’s petrel (GBP) Herald petrel (GBP); Kermadec petrel (GBP); green turtle (EN, RBP)

Pitcairn Feral cat; Polynesian rat; goat

Phoenix petrel (EN); Pitcairn reed-warbler (EN)

GBP = Globally Important Breeding Population RBP = Regionally Important Breeding Population

Discussion

Henderson Island is ranked 4 across the Overseas Territories for ACV. A second attempt to eradicate Polynesian rats (Rattus exulans) from Henderson Island should therefore be a high priority.

Pitcairn Island is ranked 12 for ACV. The eradication of invasive vertebrates on Pitcairn Island should be considered a high priority. Eradication of feral goats is currently being planned, and this should have substantial benefits for Pitcairn’s endemic plants.

Biosecurity should be a high priority – this should include preventing new IAV reaching pest-free Oeno and Ducie Atolls as well as preventing new IAV reaching Henderson Island and Pitcairn Island.

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SAINT HELENA, ASCENSION AND TRISTAN DA CUNHA

Top-ranked Islands

Island Key IAV Species Key Beneficiary Species

Gough House mouse Tristan albatross (CR); Gough bunting (CR); Atlantic yellow-nosed albatross (EN); sooty albatross (EN); Atlantic petrel (EN); Gough moorhen (VU); 11 other seabird GBPs

Tristan da Cunha Black rat; house mouse; cow; sheep

Atlantic yellow-nosed albatross (EN); sooty albatross (EN); Atlantic petrel (EN); Gough moorhen (VU); number of potential breeding seabirds including Tristan albatross (CR)

Ascension Black rat; house mouse; rabbit; sheep; common myna; donkey

Ascension frigatebird (VU); red-billed tropicbird (GBP); sooty tern (GBP); black noddy (GBP); green turtle (EN)

GBP = Globally Important Breeding Population

Discussion

Gough Island is the top priority IAV eradication project in the OTs due to the presence of a large number of globally threatened and globally important breeding seabird species and two endemic land birds. The high impact of predatory house mice is currently driving two Critically Endangered species towards extinction, as well as having a substantial negative impact on breeding seabirds.

Tristan da Cunha is ranked 7 for ACV. The eradication of rodents could benefit both existing seabird populations and the restoration potential for other seabirds, in particular the Critically Endangered Tristan albatross (Diomedea dabbenea).

St Helena scored 7 for PCV, solely due to the presence of a single island endemic - the Critically Endangered St Helena plover (Charadrius sanctaehelenae).However St Helena is low on the ACV list as the eradication of rats is not considered feasible due to the human population size. Feral cat control has been shown to be beneficial in semi-

Inaccessible

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desert areas but to have only a marginal impact on pasture land. Control of common myna (Acridotheres tristis) could also be of potential benefit.

Ascension is ranked 20 for ACV. The eradication of rodents, rabbits and sheep could enable further seabird recolonisation of Ascension as well as having substantial benefits for plants and invertebrates.

Implementing appropriate biosecurity measures to prevent rats reaching Gough and the other uninvaded islands of the Tristan group should be a high priority, as well as continuing the robust biosecurity measures to prevent the reestablishment of feral cats on Ascension.

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SOUTH GEORGIA AND THE SOUTH SANDWICH ISLANDS

Key Islands

Island Key IAV Species Key Beneficiary Species

South Georgia Brown rat; house mouse; reindeer

Black-browed albatross (EN); grey-headed albatross (VU); South Georgia pipit (NT); 20 other seabird GBPs

GBP = Globally Important Breeding Population

Discussion

South Georgia ranks highly for both ACV and PCV due to its globally important breeding seabird populations which include a number of globally threatened species.

Completing the programme of rodent and reindeer eradication that has been started in South Georgia should be a high priority.

Preventing rodents and other IAV reaching and colonising the rodent-free areas of South Georgia through the adoption and implementation of robust biosecurity measures is of the utmost importance.

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TURKS AND CAICOS ISLANDS

Key Islands

Island Key IAV Species Key Beneficiary Species

Cotton Cay Black rat; goat Turks Island skink (CR); Potential - Turks and Caicos rock iguana (CR); hawksbill turtle (CR)

Big Ambergris Cay Black rat; feral cat; Cuban treefrog

Turks and Caicos rock iguana (CR); Caicos Island skink (VU); Caicos gecko (AR); Caicos Island dwarf boa (AR); Turks Island boa (AR); hawksbill turtle (CR)

Little Ambergris Cay Black rat, feral chicken Turks and Caicos rock iguana (CR); Caicos Island skink (VU); Caicos gecko (AR); Turks Island boa (AR); roseate tern (GBP)

Salt Cay Black rat; feral cat; dog; cattle, donkeys, mice

Turks and Caicos rock iguana (CR); Underwood’s dwarf gecko (AR); least tern (GBP)

French Cay Black rat, mice Turks and Caicos rock iguana (CR); Caicos gecko (AR); brown noddy (GBP)

GBP = Globally Important Breeding Population

Discussion Key islands

The Turks and Caicos Islands have nine endemic reptile species, many of which have not been assessed by IUCN and these are the main contributors to the high rankings of many islands in this Territory. Of particular conservation concern is the Turks Islands skink (Spondylurus turksae, recommended as Critically Endangered by Hedges and Conn 2012) which is only known from three islands, but considered extirpated from one of those (Grand Turk). Eradication of invasive vertebrates and the restoration of Cotton Cay would be highly beneficial for this species.

If IAV were eradicated, Cotton Cay could be a suitable site for reintroduction of the Turks and Caicos rock iguana (Cyclura carinata), which is currently recorded as absent from the island but was present previously.

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Due to the close proximity of all of the large Caicos Islands (East Caicos, Middle Caicos, North Caicos) to each other, to the other Cays (Joe Grant’s Cay, Pine Cay, Dellis Cay, Little Water Cay) and to Providenciales with a human population of more than 20,000, a sustainable IAV “eradication” project is not considered feasible on these islands. However, these islands clearly hold very important biodiversity, and the prospects for sustained control of key IAV should be explored in order to reduce the risks to endemic species.

Further research

The distribution of IAV, especially rats, in the Turks and Caicos is poorly known. Due to a lack of surveys, rats are only confirmed present on some islands but are strongly suspected as being present on many others. It would therefore be highly beneficial for future conservation action to carry out surveys to accurately assess the presence and distribution of IAV in the Turks and Caicos.

Red cornsnake (Pantherophis guttatus) is suspected on Grand Turk. A common pet trade species, the red cornsnake has been identified as potentially having a severe detrimental impact on native fauna through predation and competition in the US Virgin Islands and Australia (Platenberg and Boulon 2006; Fisher and Csurhes 2009). They have also been identified as a significant threat to the endemic subspecies of brown-headed nuthatch (Sitta pusilla insularis) in the Bahamas (Hayes et al. 2004). Implementing suitable measures to prevent the establishment of red cornsnakes in the Turks and Caicos would be considered very beneficial as eradication would be extremely difficult if not impossible (Fisher and Csurhes 2009).

Cuban treefrogs (Osteopilus septentrionalis) are confirmed on Middle Caicos, North Caicos, Pine Cay and Parrot Cay and suspected on Big Ambergris Cay. These large frogs are voracious predators and have been implicated in declines of native frog species in the US Virgin Islands and Florida through predation and resource competition (Platenberg and Boulon, 2006; Glorioso et al. 2012). At present, there is no known eradication method but monitoring their extent of distribution, impact upon native fauna should be considered.

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NEXT STEPS

This section outlines some of the key steps, information to collect and points to consider when proposing to undertake an eradication programme. In addition, the Pacific Invasives Initiative has produced a user-friendly, practical guide to planning and implementing rodent and cat eradications. This is a highly recommended resource for those wishing to carry out eradications in the OTs and a link is provided below. Social engagement. Having the support of local communities is an essential component

of any eradication programme. Engaging with island owners, communities and other relevant stakeholder groups and facilitating their participation is essential at all stages of project implementation from information gathering, to consultation, to decision making, to eradication work and evaluation (Oppel et al. 2011).

Confirm the presence and extent of an IAV on the island. For some of the priority islands the presence of IAV (usually rodents) is only suspected due to a lack of recent survey so confirming whether a particular IAV is present is key. For all islands, establishing the extent and population size of IAV is vital as this will influence the methodology and cost of an eradication. Work to establish the connectivity of island rodent populations would also be useful to determine whether island populations are truly isolated (and therefore whether eradication is really possible).

Collect information on the status of native species and / or vegetation cover. It is important to have information on the status of native species that will benefit from the eradication of IAV and habitat prior to an eradication to provide a baseline against which operational success can be assessed.

Assess whether there are any non-target species (i.e. not the IAV being eradicated) that may be affected by the proposed eradication. Some islands will have native species, livestock or domestic pets that may be affected by an IAV eradication. Such effects may be accidental poisoning through consumption of bait or by eating poisoned animals or accidental shooting. A thorough assessment of the risk to non-target species and, if required, development of a mitigation strategy should be carried out.

Undertake a feasibility study to assess whether eradication is feasible and eradication methodologies that may be used. This will depend upon various factors including the type of IAV to be eradicated; size and topography of the island and presence of susceptible non-target species. A review and assessment of all possible eradication methodologies should be conducted prior to deciding the most appropriate methodology.

Programme timeline. A detailed project timeline will aid the effective completion of an eradication programme. It is important to carry out any eradication at the most appropriate time of year to avoid severe weather, maximise bait uptake etc. and factor this into the timeline.

Develop an Operational Plan. Each eradication programme will have its own set of logistical requirements and constraints. An important factor is the remoteness of the island to be eradicated. Islands further away from major ports of airports will have a much higher cost than those closer. Most eradication projects in the OTs will require external expertise being brought in which will be identified at the methodology consultation phase. Using local expertise where available and ensuring that local practitioners receive training during the eradication programme will aid future eradications.

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Collect accurate cost information. There are many costs associated with these projects, and these can vary widely depending on technique, remoteness, non-target issues, island ownership, livestock, etc. It is important that sufficient resources are secured to see any project through to completion.

Post-eradication monitoring. This is an essential part of any eradication programme in order to assess and evaluate the success and effectiveness of the programme. It should include monitoring for the presence of IAV and of those native species against which there is a baseline. This should be factored into the programme timeline and costs.

Biosecurity measures. These measures will depend upon an array of factors but are vital to ensure the long term sustainability of any eradication programme.

Resource Documents Pacific Invasives Initiative Resource Kit for Rodent and Cat Eradication http://rce.pacificinvasivesinitiative.org/ There are currently no guides for ungulate eradications but principles outlined here and in the above document are universally applicable to all proposed eradication projects.

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ANNEX 1 – Present and Historical Breeding Status full definitions

Parameter Criteria Criteria definition

Present Breeding Status

Confirmed Birds, Bats: Confirmed breeding found including evidence: "pairs", nests, live/dead fledglings, eggs (whole or fragments), adults flying into crevices or burrows with fish/insects, female with egg in oviduct, Adults flying with nesting materials in mouth, singing/calling make, bird and/or pair holding territory, "colony".

Amphibian, Mammal, Reptiles: 1 - Species observed, recorded, surveyed; or 2 - remains found on the island; reported in a publication within the last 20 years but no record or survey year is available; or 3 - expert confirms on island and has been recorded in last 20 years (no years or evidence provided).

Probable Birds, Bats: Breeding not confirmed but is suspected based on a number of factors and evidence: (BIRDS) breeding adult found in mist-nets (female without egg in oviduct), breeding adult fall-outs, radar surveys, spot-light surveys, acoustic monitoring, guano scents, bones, used/abandoned nests; expert confirms species but record years unclear; (BATS) "probable colony"; breeding island mentioned in paper; species is endemic to the region; species is non-migratory.

Amphibian, Mammal, Reptiles: THIS IS NOT AN OPTION.

Potential Breeding

Birds, Bats: Species recorded as past breeder but status unclear (Inconclusive surveys, searches, or data; Inconclusive or no survey but researcher found suitable breeding; at-sea survey recorded breeders near a specific island; expert confirms past breeding but does not provide or know the record/account of evidence type or year of record) OR species is confirmed/potentially extirpated.

Amphibian, Mammal, Reptiles: Species recorded as past breeder (21 - 200 years ago) but species is currently extirpated or status unclear. Most recent survey yielded no evidence of breeding; island or species has not been surveyed within the last 20 years or unclear if surveyed or observed; bones from species found on island but undated.

Data Deficient

Birds, Bats: Island with species recorded as Data Deficient or Potential Breeding in historic breeding status and status has not been updated in the past 20 years; not enough data to extrapolate exact island location, breeding island not provided in data or communication with experts; data from the last 20 years is not available.

Amphibian, Mammal, Reptiles: Island with species recorded as Data Deficient or Potential Breeding in historic breeding status and status has not been updated in the past 20 years; not enough data to extrapolate exact island location, breeding island not provided in data or communication with experts; data from the last 20 years is not available.

Extirpated Confirmed extirpation from the island.

Non Breeding

Birds only: Species recorded on island but is known not to breed e.g. wintering migrants, seabirds or land birds seen flying / foraging only on island.

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Historic Breeding Status

Confirmed Birds, Bats: Confirmed breeding found including evidence: "pairs", nests, live/dead fledglings, eggs (whole or fragments), adults flying into crevices or burrows with fish/insects, female with egg in oviduct, Adults flying with nesting materials in mouth, singing/calling make, bird and/or pair holding territory, "colony".

Amphibian, Mammal, Reptiles: 1- Species observed, recorded, surveyed; or 2- remains found on the island; reported in a publication within the last 20 years but no record or survey year is available; or 3 - expert confirms on island and has been recorded in last 20 years (no years or evidence provided).

Probable Birds, Bats: Breeding not confirmed but is suspected based on a number of factors and evidence: (BIRDS)breeding adult found in mist-nets (female without egg in oviduct), breeding adult fall-outs, radar surveys, spot-light surveys, acoustic monitoring, guano scents, bones, used/abandoned nests; expert confirms species but record years unclear; (BATS) "probable colony"; breeding island mentioned in paper; species is endemic to the region; species is non-migratory.

Amphibian, Mammal, Reptiles: THIS IS NOT AN OPTION

Potential Breeding

Birds, Bats: Status unclear. Status unclear (Inconclusive surveys, searches, or data; Inconclusive or no survey but researcher found suitable breeding; at-sea survey recorded breeders near a specific island; expert confirms past breeding but does not provide or know the record/account of evidence type or year of record) OR species is confirmed/potentially extirpated.

Amphibian, Mammal, Reptiles: Status unclear (Inconclusive surveys, searches, or data) or extirpated.

Data Deficient

Birds, Bats: Island with species recorded as Data deficient, Probable or Potential Breeding in present breeding status but there is no record or history on island in the last 21 - 200 years; not enough data to extrapolate exact island location; data from the last 21 - 200 years is not available.

Amphibian, Mammal, Reptiles: Species recorded as Data deficient or Potential Breeding in present breeding status but there is no record or history on island in the last 21 - 200 years; not enough data to extrapolate exact island location; data from the last 21 - 200 years is not available.

NA All Species: Species listed as Confirmed (native or introduced) for Present Breeding Status OR was translocated in the last 20 years but is no longer on the island.

Definitions developed by Island Conservation, BirdLife International and University of California, Santa Cruz.

52

ANNEX 2 – Full List of Beneficiary Species

Key: AG – Anguilla; AS – Ascension; BM – Bermuda; IO – British Indian Ocean Territory; BV – British Virgin Islands; CY – Cayman Islands; FK – Falkland Islands; M – Montserrat; P – Pitcairn Islands; SH – St Helena; SG – South Georgia and the South Sandwich Islands; TR – Tristan da Cunha; TC – Turks and Caicos Islands

Scientific name Common name IUCN

status Taxonomic group

Territory

Acrocephalus taiti Henderson reed-warbler VU Land bird P

Acrocephalus vaughani Pitcairn reed-warbler EN Land bird P

Alsophis manselli Montserrat racer AR Reptile M

Alsophis rijgersmaei Leeward Island racer EN Reptile AG

Amazona leucocephala Cuban amazon NT Land bird CY

Ameiva corax Censky's ameiva VU Reptile AG

Ameiva corvina Sombrero ameiva VU Reptile AG

Ameiva plei Anguilla bank ameiva AR Reptile AG

Ameiva pluvianotata Montserrat ground lizard AR Reptile M

Amphisbaena fenestrata Cope's worm lizard AR Reptile CY

Anas bahamensis White-cheeked pintail LC Land bird TC

Anas georgica Yellow-billed pintail LC Land bird SG

Anolis conspersus Caymans blue-fanned anole AR Reptile CY

Anolis ernestwilliamsi Carrot Rock anole AR Reptile BV

Anolis lividus Montserrat anole AR Reptile M

Anolis luteosignifer Cayman Brac anole AR Reptile CY

Anolis maynardii Cayman green anole AR Reptile CY

Anolis pogus Bearded anole VU Reptile AG

Anolis roosevelti Roosevelt's giant anole CR Reptile BV

Anous minutus Black noddy LC Seabird AS, P, SH

Anous stolidus Brown noddy LC Seabird AG, IO, BV, P, SH, TC, TR

Anous tenuirostris Lesser noddy LC Seabird IO

Anthracothorax dominicus Antillean mango LC Land bird BV

Anthus antarcticus South Georgia pipit NT Land bird SG

Aptenodytes patagonicus King penguin LC Seabird FK, SG

Aristelliger hechti Hecht's Caribbean gecko AR Reptile TC

Atlantisia rogersi Inaccessible rail VU Land bird TR

Bulweria bulwerii Bulwer's petrel LC Seabird SH

Calidris fusicollis White-rumped sandpiper LC Land bird FK

Calidris minutilla Least sandpiper LC Land bird TC

Calidris pusilla Semipalmated sandpiper NT Land bird AG, BM, BV, CY, M

Calliphlox evelynae Bahama woodstar LC Land bird TC

Caretta caretta Loggerhead EN Reptile BM, BV, CY, M, TC

Celestus maculatus Cayman Island galliwasp AR Reptile CY

Chaetura pelagica Chimney swift NT Land bird BM, CY

Charadrius melodus Piping plover NT Land bird BM, BV

Charadrius sanctaehelenae St Helena plover CR Land bird SH

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Charadrius wilsonia Wilson's plover LC Land bird TC

Chelonia mydas Green turtle EN Reptile AG, AS, BM, IO, BV, CY, M, P, TC

Chionis albus Snowy sheathbill LC Seabird SG

Chiroderma improvisum Guadeloupean big-eyed bat VU Mammal M

Chloephaga rubidiceps Ruddy-headed goose LC Land bird FK

Cinclocerthia ruficauda Brown trembler LC Land bird M

Cinclodes antarcticus Tussacbird LC Land bird FK

Crocodylus acutus American crocodile VU Reptile CY

Crocodylus rhombifer Cuban crocodile CR Reptile CY

Cubophis caymanus Grand Cayman racer AR Reptile CY

Cubophis fuscicauda Cayman Brac racer AR Reptile CY

Cubophis ruttyi Little Cayman racer AR Reptile CY

Cyclura carinata Turks and Caicos rock iguana CR Reptile TC

Cyclura lewisi Grand Cayman blue iguana EN Reptile CY

Cyclura nubila caymanensis

Sister Islands rock iguana CR Reptile CY

Cyclura pinguis Anegada rock iguana CR Reptile AG

Daption capense Cape petrel LC Seabird SG

Dendrocygna arborea West Indian whistling-duck VU Land bird CY, TC

Dendroica vitellina Vitelline warbler NT Land bird CY

Dermochelys coriacea Leatherback CR Reptile AG, M , TC

Diomedea dabbenena Tristan albatross CR Seabird TR

Diomedea exulans Wandering albatross VU Seabird SG

Diploglossus montisserrati Montserrat galliwasp CR Reptile M

Egretta rufescens Reddish egret NT Land bird CY, M, TC

Elaenia martinica Caribbean elaenia LC Land bird AG, BV, CY, M

Eleutherodactylus lentus Yellow-mouthed coqui EN Amphibian BV

Eleutherodactylus schwartzi Virgin Islands coqui EN Amphibian BV

Epicrates chrysogaster chrysogaster

Turks Island boa AR Reptile TC

Epicrates monensis granti Mona Island boa EN Reptile BV

Eretmochelys imbricata Hawksbill turtle CR Reptile AG, IO, BV, CY, M, TC

Eudyptes chrysocome Southern rockhopper penguin VU Seabird FK

Eudyptes chrysolophus Macaroni penguin VU Seabird FK, SG

Eudyptes moseleyi Northern rockhopper penguin EN Seabird TR

Eulampis holosericeus Green-throated carib LC Land bird AG, BV, M

Eulampis jugularis Purple-throated carib LC Land bird M

Euphonia musica Antillean euphonia LC Land bird M

Fregata aquila Ascension frigatebird VU Seabird AS

Fregata ariel Lesser frigatebird LC Seabird IO, SH

Fregata magnificens Magnificent frigatebird LC Seabird AG, BV, CY, M, TC

Fregata minor Greater frigatebird LC Seabird IO, P, SH

Fregetta grallaria White-bellied storm-petrel LC Seabird TR

Fregetta tropica Black-bellied storm-petrel LC Seabird SG

Fulmarus glacialoides Southern fulmar LC Seabird SG

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Gallinula nesiotis Gough moorhen VU Land bird TR

Garrodia nereis Grey-backed storm-petrel LC Seabird FK

Geotrygon mystacea Bridled quail-dove LC Land bird BV, M

Grus canadensis Sandhill crane LC Land bird TC

Gygis alba White tern LC Seabird AS, P, SH

Halobaena caerulea Blue petrel LC Seabird SG

Icterus oberi Montserrat oriole CR Land bird M

Iguana delicatissima Lesser Antillean iguana EN Reptile AG

Larus atricilla Laughing gull LC Seabird AG, BV, TC

Larus dominicanus Kelp gull LC Seabird FK

Larus maculipennis Brown-hooded gull LC Seabird FK

Leiocephalus psammodromus

Turks and Caicos curlytail AR Reptile TC

Leptodactylus fallax Mountain chicken CR Amphibian M

Leucophaeus scoresbii Dolphin gull LC Seabird FK

Limnodromus griseus Short-billed dowitcher LC Land bird TC

Loxigilla noctis Lesser Antillean bullfinch LC Land bird AG, BV, M

Lugensa brevirostris Kerguelen petrel LC Seabird TR

Mabuya montserratae Montserrat skink CR Reptile M

Macronectes giganteus Southern giant petrel LC Seabird FK, SG, TR

Macronectes halli Northern giant petrel LC Seabird SG

Malaclemys terrapin Diamondback terrapin NT Reptile BM

Margarops fuscatus Pearly-eyed thrasher LC Land bird AG, BV, M, TC

Margarops fuscus Scaly-breasted thrasher LC Land bird M

Melanodera melanodera White-bridled finch LC Land bird FK

Mimus gundlachii Bahama mockingbird LC Land bird TC

Myiarchus antillarum Puerto Rican flycatcher LC Land bird BV

Nesocichla eremita Tristan thrush NT Land bird TR

Nesospiza acunhae Inaccessible bunting VU Land bird TR

Nesospiza questi Nightingale bunting VU Land bird TR

Nesospiza wilkinsi Wilkin's bunting EN Land bird TR

Numenius tahitiensis Bristled-thighed curlew VU Land bird P

Oceanites oceanicus Wilson's storm-petrel LC Seabird SG

Oceanodroma castro Madeiran storm-petrel LC Seabird AS, SH

Orthorhyncus cristatus Antillean crested-hummingbird LC Land bird AG, BV, M

Pachyptila belcheri Thin-billed prion LC Seabird FK

Pachyptila desolata Antarctic petrel LC Seabird SG

Pachyptila turtur Fairy prion LC Seabird FK

Pachyptila vittata Broad-billed prion LC Seabird TR

Pagodroma nivea Snow petrel LC Seabird SG

Patagioenas leucocephala White-crowned pigeon NT Land bird AG, BV, CY

Pelagodroma marina White-faced storm-petrel LC Seabird SH, TR

Pelecanoides georgicus South Georgia diving-petrel LC Seabird SG

Pelecanoides magellani Magellan diving-petrel LC Seabird FK

Pelecanoides urinatrix Common diving Petrel LC Seabird FK, SG, TR

Pelecanus occidentalis Brown pelican LC Seabird AG, BV, M, TC

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Peltophryne lemur Puerto Rican crested toad CR Amphibian BV

Phaethon aethereus Red-billed tropicbird LC Seabird AG, AS, BV, M, SH

Phaethon lepturus White-tailed tropicbird LC Seabird AS, AG, BM, IO, BV, CY, TC

Phaethon rubricauda Red-tailed tropicbird LC Seabird IO, P

Phalacrocorax atriceps Imperial shag LC Seabird FK, SG

Phalacrocorax magellanicus

Rock shag LC Seabird FK

Phalcoboenus australis Striated caracara NT Land bird FK

Phoebetria fusca Sooty albatross EN Seabird TR

Phoebetria palpebrata Light-mantled albatross NT Seabird SG

Phoenicopterus ruber American flamingo LC Land bird TC

Plestiodon longirostris Bermuda skink CR Reptile BM

Pluvialis squatarola Grey plover LC Land bird TC

Porzana atra Henderson crake VU Land bird P

Procellaria aequinoctialis White-chinned petrel VU Seabird FK, SG

Procellaria cinerea Grey petrel NT Seabird TR

Procellaria conspicillata Spectacled petrel VU Seabird TR

Procelsterna cerulea Blue noddy LC Seabird P

Pterodroma alba Phoenix petrel EN Seabird P

Pterodroma atrata Henderson petrel EN Seabird P

Pterodroma cahow Bermuda petrel EN Seabird BM

Pterodroma heraldica Herald petrel LC Seabird P

Pterodroma incerta Atlantic petrel EN Seabird TR

Pterodroma macroptera Great-winged petrel LC Seabird TR

Pterodroma mollis Soft-plumaged petrel LC Seabird TR

Pterodroma neglecta Kermadec petrel LC Seabird P

Pterodroma ultima Murphy's petrel NT Seabird P

Ptilinopus insularis Henderson fruit-dove VU Land bird P

Puffinus assimilis Little shearwater LC Seabird TR

Puffinus gravis Great shearwater LC Seabird FK, TR

Puffinus griseus Sooty shearwater NT Seabird FK, TR

Puffinus lherminieri Audubon's shearwater LC Seabird AG, AS, IO, BV, M, SH, TC

Puffinus nativitatis Christmas Island shearwater LC Seabird P

Puffinus pacificus Wedge-tailed shearwater LC Seabird IO

Pygoscelis adeliae Adelie penguin NT Seabird SG

Pygoscelis antarcticus Chinstrap penguin LC Seabird SG

Pygoscelis papua Gentoo penguin NT Seabird FK, SG

Rowettia goughensis Gough bunting CR Land bird TR

Sphaerodactylus argivus Cayman Islands dwarf gecko AR Reptile CY

Sphaerodactylus caicosensis

Caicos dwarf gecko AR Reptile CY

Sphaerodactylus parthenopion

Virgin Islands dwarf gecko AR Reptile BV

Sphaerodactylus sp. 1 Sombrero dwarf gecko AR Reptile AG

Sphaerodactylus sp. 2 Carval Rock dwarf gecko AR Reptile BV

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Sphaerodactylus underwoodi

Underwood's dwarf gecko AR Reptile TC

Spheniscus magellanicus Magellanic penguin NT Seabird FK

Spondylurus anegadae Anegada skink CR Reptile BV

Spondylurus caicosae Caicos Islands skink VU Reptile TC

Spondylurus macleani Carrot Rock skink EN Reptile BV

Spondylurus powelli Anguilla Bank skink AR Reptile AG

Spondylurus semitaeniatus Lesser Virgin Islands skink EN Reptile BV

Spondylurus sloanii Virgin Islands bronze skink EN Reptile BV

Spondylurus turksae Turks Islands skink CR Reptile TC

Stercorarius antarcticus Southern skua LC Seabird TR

Stercorarius lonnbergi Brown skua LC Seabird FK, SG

Sterna albifrons Little tern LC Seabird IO

Sterna anaethetus Bridled tern LC Seabird AG, IO, BV, CY, TC

Sterna antillarum Least tern LC Seabird AG, BV, CY, M, TC

Sterna bergii Great crested tern LC Seabird IO

Sterna dougallii Roseate tern LC Seabird AG, IO, BV, TC

Sterna fuscata Sooty tern LC Seabird AG, AS, IO, BV, P, SH, TC

Sterna hirundinacea South American tern LC Seabird FK

Sterna hirundo Common tern LC Seabird BV, TC

Sterna maxima Royal tern LC Seabird AG, BV, M, TC

Sterna nilotica Gull-billed tern LC Seabird BV, TC

Sterna sandvicensis Sandwich tern LC Seabird AG, BV, TC

Sterna sumatrana Black-naped tern LC Seabird IO

Sterna vittata Antarctic tern LC Seabird SG, TR

Sturnira thomasi Thomas's yellow-shouldered bat VU Mammal M

Sula dactylatra Masked booby LC Seabird AG, AS, IO, P, SH

Sula leucogaster Brown booby LC Seabird AG, AS, IO, BV, CY, M, SH, TC

Sula sula Red-footed booby LC Seabird AG, AS, IO, BV, CY, P, SH

Tachyeres brachypterus Falkland steamerduck LC Land bird FK

Thalassarche chlororhynchos

Atlantic yellow-nosed albatross EN Seabird TR

Thalassarche chrysostoma Grey-headed albatross VU Seabird SG

Thalassarche melanophrys Black-browed albatross EN Seabird FK, SG

Tringa flavipes Lesser yellowlegs LC Land bird TC

Tringa melanolceuca Greater yellowlegs LC Land bird TC

Troglodytes cobbi Cobb's wren VU Land bird FK

Tropidophis caymanensis Grand Cayman dwarf boa AR Reptile CY

Tropidophis greenwayi Caicos Islands dwarf boa AR Reptile TC

Tropidophis parkeri Little Cayman dwarf boa AR Reptile CY

Tropidophis schwartzi Cayman Brac dwarf boa AR Reptile CY

Tryngites subruficollis Buff-breasted sandpiper NT Land bird BM

Turdus lherminieri Forest thrush VU Land bird M

Typhlops catapontus Erica's worm snake AR Reptile BV

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Typhlops caymanensis Grand Cayman blindsnake AR Reptile CY

Typhlops epactius Cayman Brac blindsnake AR Reptile CY

Typhlops monastus Montserrat blindsnake AR Reptile M

Typhlops naugus Virgin Gorda blindsnake AR Reptile BV

Tyrannus cubensis Giant kingbird EN Land bird TC

Vini stepheni Henderson lorikeet VU Land bird P

Vireo crassirostris Thick-billed vireo LC Land bird CY, TC

Vireo magister Yucatan vireo LC Land bird CY

IUCN rankings from the 2012 Red List

58

ANNEX 3 – Full List of Invasive Alien Vertebrates

Key: AG – Anguilla; AS – Ascension; BM – Bermuda; IO – British Indian Ocean Territory; BV – British Virgin Islands; CY – Cayman Islands; FK – Falkland Islands; M – Montserrat; P – Pitcairn Islands; SH – St Helena; SG – South Georgia and the South Sandwich Islands; TR – Tristan da Cunha; TC – Turks and Caicos Islands Scientific name Common name Taxonomic

Group Territory

Acridotheres tristis Common myna Bird AS, IO, SH

Aix sponsa Wood puck Bird CY

Alectoris chukar Chukar partridge Bird SH

Amazona ochrocephala Yellow-crowned parrot Bird CY

Anas platyrhynchos Mallard Bird BM, CY

Anolis carolinensis Green anole Reptile AG, CY

Anolis equestris Knight anole Reptile TC

Anolis garmani Jamaican giant anole Reptile CY

Anolis sagrei Brown anole Reptile CY

Anser anser Goose Bird FK

Aratinga erythrogenys Red-masked parakeet Bird CY

Bos taurus Feral cow Mammal BV, FK, M, TC, TR

Bulbucus ibis Cattle egret Bird IO

Cairina moschata Muschovy duck Bird BV

Canis familiaris Feral dog Mammal AG, BV, CY, TC

Capra hircus Goat Mammal AG, BV, FK, M, P, TC

Carlotes versicolor Bloodsucker Reptile IO

Centrochelys sulcata African spurred tortoise Reptile BV

Chlorocebus sabaeus Green monkey Mammal AG

Columba livia Rock dove Bird AG, BM, BV, CY, M, SH

Corvus brachyrhynchos American crow Bird BM

Corvus splendens House crow Bird IO

Cryptoblepharus poecilopleurus

Mottled snake-eyed skink Reptile P

Dasyprocta antillensis Saint Lucia agouti Mammal M

Dasyprocta punctata Central American agouti Mammal CY

Diadophis punctatus Southern ringneck snake Reptile CY

Didelphis marsupialis Common opossum Mammal M

Eleutherodactylus johnstonei Lesser Antillean tree frog Amphibian AG, BV

Eleutherodactylus planirostris Greenhouse frog Amphibian TC

Emoia cyanura Copper-tailed skink Reptile P

Equus asinus Donkey Mammal AS, IO, BV, M, SH, TC, TR

Equus caballus Feral horse Mammal TC

Estrilda astrild Common waxbill Bird AS, SH

Felis catus Feral cat Mammal AG, BM, IO, BV, CY, FK, M, P, SH, TC

Foudia madagascariensis Madagascar fody Bird IO, SH

Francolinus afer Red-necked francolin Bird SH

59

Gallus gallus domesticus Feral chicken Bird AG, BM, IO, BV, CY, M, TC

Gastrophryne carolinensis Eastern narrowmouth toad Amphibian CY

Gehyra mutilata Four-clawed gecko Reptile P

Geochelone carbonaria Red-footed tortoise Reptile M

Geopelia striata Zebra dove Bird IO, SH

Gonatodes albogularis Yellow-headed gecko Reptile CY

Hemidactylus frenatus Asian house gecko Reptile AS, BM, SH

Hemidactylus mabouia Afro-American house gecko Reptile AG, BV, CY, M, TC

Hemidactylus mercatorius Coconut-palm gecko Reptile AS

Hemidactylus turcicus Turkish house gecko Reptile BM

Hemiphyllodactylus typus Indopacific tree gecko Reptile P

Herpestes javanicus Small Asian mongoose Mammal BV

Iguana iguana Green iguana Reptile AG, BV, CY, TC

Lama guanico Guanaco Mammal FK

Lepidodactylus lugubris Mourning gecko Reptile IO, P

Lepus europaeus European hare Mammal FK

Liolaemus wiegmani Iguana species Reptile AS

Lipinia noctua Moth skink Reptile P

Lycalopex griseus South American gray fox Mammal FK

Mus musculus House mouse Mammal AG, AS, BM, BV, CY, FK, SH, SG, TC, TR

Nesoenas picturata Madagascar turtle-dove Bird IO

Ophisaurus ventralis Eastern glass lizard Reptile CY

Oryctolagus cuniculus European rabbit Mammal AG, AS, FK, SH

Osteopilus septentrionalis Cuban treefrog Amphibian AG, BV, TC

Ovis aries Sheep Mammal AS, BV, M, SH

Padda oryzivora Java sparrow Bird SH

Pantherophis guttatus Red cornsnake Reptile AG, BV, CY, TC

Passer domesticus House sparrow Bird AS, BM, BV

Phasianus colchicus Ring-necked pheasant Bird SH

Pitangus sulphuratus Kiskadee Bird BM

Pseudemys nelsoni Florida red-bellied turtle Reptile BV

Psittacula krameri Rose-ringed parakeet Bird CY

Ramphotyphlops braminus Brahminy blindsnake Reptile AG, CY, TC

Rangifer tarandus Reindeer Mammal FK, SG

Rattus exulans Polynesian rat Mammal P

Rattus norvegicus Brown rat Mammal AG, BM, BV, CY, FK, M, SH, SG

Rattus rattus Black rat Mammal AG, AS, BM, IO, BV, CY, FK, M, SH, TC, TR

Rhinella marina Cane toad Amphibian AG, BM, IO, CY, M, TC

Serinus flaviventris Yellow canary Bird AS, SH

Sphaerodactylus mariguanae Dwarf skink species Reptile TC

Stongylopus grayii Gray's stream frog Amphibian SH

Streptopelia decaocto Eurasian collared-dove Bird BV, CY, M

Sturnus vulgaris Common starling Bird BM

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Sus scrofa Feral pig Mammal BV, M

Sylvilagus floridanus North American cotton-tail rabbit

Mammal FK

Trachemys decussata North Antillean slider Reptile CY

Trachemys scripta elegans Red-eared slider Reptile BM, BV, CY, TC

Trachemys stejnegeri malonei Inagua slider Reptile TC

Varanus exanthematicus Savannah monitor Reptile TC

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