1

Johanna Ek

Degree project for Master of Science in Biology

Animal Ecology, 45 hec, 2015-2016

Department of Biological and Environmental Sciences

University of Gothenburg

Supervisors: Donald Blomqvist, Frank Götmark and Emil Nilsson

Examiner Charlotta Kvarnemo

The future of the Lesser Spotted Woodpecker

-In the growing municipality of Gothenburg

Foto: Uno Unger

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Abstract

Threats against species is one of the bigger problems concerning preservation of biological

diversity today. In the member states of the EU, this concern has been addressed by the

implementation of the bird directive together with the directive for the conservation of natural

habitats and of wild fauna and flora into their own legislations. In Sweden "the Swedish

protection ordinance" was issued in 2007, making public authorities of all levels responsible

to insure favorable conservation status for species included in the appendices of these

directives, as well as for species on the national red list. In spite of this, the method of

evaluating a species’ conservation status is still poorly developed across Europe and more

research is needed.

The protection of important species is applied partly on a national level and mostly on a local

level and it is of each municipality responsibility to ensure favorable conservation status. This

can result in fragmented habitat protection especially in municipalities with high development

and growing human population. In the municipality of Gothenburg, the second largest city in

Sweden, the rates of development (housing, etc) are high and evaluation is needed to assess

the conservation status of the nationally red listed lesser spotted woodpecker (NT)

(Dendrocopos minor ), the smallest of the indigenous woodpeckers of Sweden. This thesis

aims to investigate if the municipality of Gothenburg's woodpecker population can be

considered to have met all three criteria for favorable conservation status, by locating suitable

habitats and potential breeding territories for the species and analyze its exploitation risks and

landownership. A field study was conducted on randomly selected potential breeding sites

during March-May 2016, to compare the population data with older inventories made before

the initiation of the EU directives.

The results indicate that the Gothenburg woodpecker population seems to be maintaining

itself as a viable unit (criterion a) and that the distribution of the population in the

municipality's different regions has not changed (criterion b), but a tendency for relocation

from central to northern parts can be deducted. The habitat analysis suggests that the

municipality contains 3233 ha of potential breeding habitat which could sustain a range of 32-

162 pairs (criterion c). Only 65% of the area investigated in the field study 2016 was utilized,

thus not all available habitats is used. About 2115 ha within the whole municipality seem be

utilized today. For protection status of the breeding habitat, only 506 ha are located within a

nature reserve or a Nature 2000 area. To conclude, the population of lesser spotted

woodpecker within the municipality fulfills two out of three criteria for favorable

conservation status, but more habitat needs to be preserved to ensure that the species can

persist in a long term basis. If the municipality were to preserve the 2 233 ha of habitat on its

own land as well, fulfillment of all three criteria could be claimed for the population in the

future.

This study shows that it is possible to quantitatively evaluate the conservation status of a

species, though improvements are necessary. More actors across Europe should therefore take

responsibility for evaluating the status of listed species.

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Abstrakt

Förlusten av arter är ett av de större problemen när det gäller bevarandet av den biologiska

mångfalden. I EUs medlemsländer har detta problem hanterats genom utfärdandet av olika

direktiv med syfte att bevara och skydda utsatta arter. Två av dessa är Fågeldirektivet från

1979 och Art- och habitatsdirektivet från 1992. I Sverige har dessa direktiv implementerats in

i Artskyddsförordningen 2007, som bland annat fridlyser alla fågelarter. Denna

implementering gör även alla nivåer av myndigheter ansvariga för att gynnsam

bevarandestatus försäkras för arter som är upptagna i bilagorna till dessa direktiv samt arter på

den svenska rödlistan. Trots detta är metoden för att utvärdera en arts bevarandestatus

fortfarande under utveckling i Europa, och mer forskning behövs.

Skydd av arter implementeras delvis på nationell nivå men implementeras huvudsakligen på

lokal nivå inom kommuner och i kommuner med växande population och hög exploatering är

det extra viktigt att säkerställa känsliga arters habitat. I Göteborgs kommun är

exploateringsgraden hög, och en utvärdering av hur den rödlistade mindre hackspetten (NT)

behövs för att säkerställa att arten inte minskar i antal och uppnår gynnsam bevarandestatus

trots nuvarande och planerade exploateringar. Denna avhandling syftar därför till att

undersöka om kommunens population av mindre hackspett kan anses ha uppfyllt alla tre

kriterier för gynnsam bevarandestatus. Detta studerades genom att lokalisera lämpliga habitat

och potentiella häckningsområden och analysera dess markägarförhållanden och

exploateringsrisk. En fältstudie utfördes på slumpmässigt utvalda lokaler, distribuerade över

hela kommunen under mars-maj 2016. För att utvärdera populationsutvecklingen och

utbredningsområdet jämfördes data med äldre inventeringar som genomfördes före

implementeringen av EU direktiven.

Resultaten visade att populationen inom Göteborg är stabil, och utbredningen mellan

kommunens olika regioner inte har förändrats sedan implementeringen. Men tendenser till

omlokalisering av individer från centrala delar till den norra regionen finns. Analysen av

biotop och häckningsmiljö visade att kommunen totalt sett innehåller 3233 ha av

häckningsbiotop, tillräckligt för 32-162 par. Endast 65 % av den undersökta arean ha i

fältstudien 2016 utnyttjades och visar på att inte all potentiell biotop används idag. Ca 2 115

ha inom hela kommunen uppskattas utnyttjas idag. Mängden skyddad biotop inom

kommunen är endast 506 ha, vilket innebär att populationen av mindre hackspett inom

kommunen uppfyller två av tre kriterier för gynnsam bevaradestatus, men tillräckligt stor yta

av skyddad biotop är inte säkrad för att garantera populationens bevarande på lång sikt. Om

kommunen skulle åta sig att bevara majoriteten av de 2 234 ha biotop lokaliserat på deras

egen mark skulle gynnsam bevarandestatus kunna uppnås i framtiden. Men en närmare

undersökning av kommunala planer behövs innan dessa slutsatser dras för att säkerhetsställa

att inte större områden redan är lagligt bindande till att bli exploaterade.

Denna avhandling har visat att det är möjligt att kvantitativt utvärdera en arts bevarandestatus

även om förbättringar och effektiviseringar är möjliga. Fler aktörer i hela Europa bör därför ta

ett större ansvar och lägga mer insatser på att utvärdera arters bevarandestatus, så att

direktivens syfte kan uppfyllas i framtiden.

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Table of contents

Abstract ...................................................................................................................................... 3

1. Introduction ............................................................................................................................ 6

1.1 The Lesser Spotted Woodpecker ...................................................................................... 6

1.2 Bird protection in the European Union and Sweden ........................................................ 7

1.3 Municipality plans and their legal extent ......................................................................... 8

1.4 The municipality of Gothenburg ...................................................................................... 9

1.5 Aim and hypothesis .......................................................................................................... 9

2. Method ................................................................................................................................. 10

2.1 Study species .................................................................................................................. 10

2.1.1 Habitat and mating systems in the Lesser Spotted Woodpecker ............................ 10

2.1.2 Foraging .................................................................................................................. 11

2.1.3 Nesting .................................................................................................................... 12

2.2 Habitat and habitat analysis in present study ................................................................. 12

2.3 Selection of sites for the field study ............................................................................... 13

2.4 Field study ...................................................................................................................... 15

2.5 Statistical analyzes ......................................................................................................... 15

3. Results .................................................................................................................................. 16

3.1 Population dynamics and viability, including range ...................................................... 16

3.2 Habitat conditions .......................................................................................................... 16

3.3 Influences on the probability of detection and residency ............................................... 17

4. Discussion ............................................................................................................................ 19

4.1 Population dynamics and viability ................................................................................. 19

4.2 The Lesser Spotted Woodpeckers range within the municipality .................................. 20

4.3 Habitat conditions .......................................................................................................... 21

4.4 Factors influencing the results ........................................................................................ 22

4.5 The methodology of evaluating FCS ............................................................................. 23

5. Conclusions and summary ................................................................................................... 24

Acknowledgments ................................................................................................................ 24

6. References ............................................................................................................................ 25

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1. Introduction

In Sweden 50 000 species have been registered and are considered to be indigenous. Today 4

273 of these are included in the Swedish red list and 2 029 are considered to be endangered.

20 % of the evaluated species can be found on the red list and this percentage has not

decreased since 2005, making this one of the biggest problems concerning biological diversity

conservation (Swedish Species Information Centre, 2015b). Species connected to woodland

landscapes and agricultural lands are the most affected. 52% of the red listed species utilizes

these types of habitats, and 42% has the forest as their primary home range. In Sweden we

have 257 breeding bird species and the number red listed recently increased from 38 to 52

species (Swedish Species Information Centre, 2015b).This in spite of the fact that all birds are

theoretically protected according to Swedish legislations (SFS: 2007:845. The Species

Protection Ordinance 4 §).

There are currently nine woodpecker species (Piciformes) known to have been indigenous in

Sweden, all connected to the woodland landscape. All but two of these are included in the

national red list (Swedish Species Information Centre, 2016a). Worst off is the middle spotted

woodpecker that has been Regionally Extinct (RE) since the 1980s (Swedish Species

Information Centre, 2016b). Woodpeckers have been known to provide other species with

critical resources and habitats, for example providing nests for secondary hole nesters, by

excavating activities (Martin et al., 2004). If the woodpeckers are eradicated from one area

one may expect reduction in biological diversity. The woodpeckers are therefore considered

to be keystone species, and indicators of high quality habitats (Jones et al., 1994; Mikusinski

et al., 2001).

This thesis aim is to evaluate the conservation status of the lesser spotted woodpecker (LSW)

(Dendrocopos minor), the smallest of the Swedish indigenous woodpeckers, in its natural

environment within the growing municipality of Gothenburg. It also aims to assess whether

the species is declining due to current exploitations or not and to evaluate how the different

criteria for favorable conservation status (FCS) are met within the municipality. This will be

done by investigating the location, extent and owner conditions of their habitat and by

conducting a survey within the municipality, for comparison with data on population

dynamics and -ranges collected from a survey conducted before the initiation of the bird- and

species and habitat directives from the EU.

1.1 The Lesser Spotted Woodpecker

The LSW is the smallest of Swedish woodpeckers, approximately 15 cm with a weight of 21-

28 g (Swedish Species Information Centre, 2015). The LSW is at the moment classified as

Near Threatened (NE) in the Swedish red list, but was in the year 2000 considered to be

worse off an classified as Vulnerable (VU) (Swedish Species Information Centre, 2015a).The

population has fluctuated in the past, and suffered a decrease in population numbers before

the 1990s. In recent years an increase has been observed in the municipality of Gothenburg

(Aronsson, 2009). The current Swedish population of LSW is estimated to be around 7000

pairs (Ottosson et al., 2012). The LSW is considered to be linked to older deciduous, oak

dominated forests with open structures and a high density of snags (Charman et al., 2010;

Wiktander et al., 1992). This type of forest can mainly be found in the southern parts of

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Sweden, but the species is distributed across most of the country (Figure 1). LSW is one of

the model species within the woodpecker family, and a lot of research has already been

conducted on the species (Höntsch, 2005; Olsson, 1998; Rossmanith, 2005; Wiktander,

1998). This makes LSW suitable as a model species for initiating a methodology of

evaluation of FCS in bird species.

Figure 1: To the left is a map of the LSW distribution in Sweden and to the right is registered observations of the

species between the years 1990-2016. Distributed with permission and available at:

http://artfakta.artdatabanken.se/taxon/100048 [Accessed 17 Dec. 2015].

1.2 Bird protection in the European Union and Sweden

The concern for biodiversity has been present in the EU for more than 40 years. In 1979 the

EU council issued the first council directive concerning environmental issues called "The

council directive on the conservation of wild birds (79/409/EEC)". The member states were

obligated according to Article 2 to "take the requisite measures to maintain the population of

the species referred to in Article 1, at a level which corresponds in particular to ecological,

scientific and cultural requirements, while taking account of economic and recreational

requirements, or to adapt the population of these species to that level." In 1992 EU further

issued “The council directive 92/43/EEC of 21 May 1992 on the conservation of natural

habitats and of wild fauna and flora”. Article 6 of this directive states that each member state

of the EU, including Sweden, is obligated to appoint special habitats listed in appendix 1 as

Nature 2000 areas (SFS: 1998:808. Miljöbalken 7: 27 §). In these areas the member states are

obligated to take measures by law enforcement to ensure that the habitats and species

included in appendix 1 and 2 in the directive do not deteriorate in quality or population size.

In November 2005 the Swedish Parliament raised their awareness on environmental issues

and agreed upon a 16th

additional environmental goal, "A rich flora and fauna". This new goal

aims to protect biodiversity and associated natural environments for future generations (SFS:

1998:808. Miljöbalken. Chapter 5). The goal is to apply measures to protect the natural

Missing

Unsure

Available

Extinct

Resident

County wise distribution

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environment on a national, regional and a local level before 2020. The species protection

ordinance is one of several implementations of these EU directives and national goals into

Swedish law, and is also the one most applied and adequate for them (SFS: 2007:845. The

Species Protection Ordinance; Swedish Environmental Protection Agency, 2016). Sweden

hence is legally obligated to make sure that the habitats and species listed in the appendix to

the directives achieve FCS (See citation 1 below). Because of these environmental goals, EU

directives and the content of "The Species Protection Ordinance" the counties and

municipalities of Sweden are obligated to take measures towards securing species and their

habitats in the future. Hence the handbook for the protection ordinance reads that species on

the Swedish red list or species that have declined more than 50% in population size between

the years 1975–2005 are to be prioritized in the same way as the species that are included in

appendix 1 of the bird directive (Swedish environmental protection agency, 2009).

Citation 1: Excerpts from Article 1 of the Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural

habitats and of wild fauna and flora, listing the 3 criteria that need to be fulfilled to achieve FCS.

1.3 Municipality plans and their legal extent

In Sweden building permits and plans to exploit new areas are regulated and approved in

accordance to larger municipal plans. These are called municipal comprehensive plan and

local plans (in Swedish Översiktsplan and Detaljplan respectively). The Municipal

comprehensive plan is mandatory for every municipality and has to cover all land and water

areas in that municipality (SFS: 2010:900. Plan- och bygglag. 3:1 §). This plan is meant to

work as guidance to the approval board for the long term development within the

municipalities (SFS: 2010:900. Plan- och bygglag. 3:2 §). However the Municipal

comprehensive plan is not legally binding and exceptions can be made (SFS: 2010:900. Plan-

och bygglag 3:3 §). Currently unexploited areas that for example fulfills the LSW habitat

requirements can be threatened if it is listed in a "Municipal comprehensive plan" as an area

that the municipality plans to develop (industrial buildings/ apartments/ parks e.g.) unless

sufficient compensation measure is installed.

In smaller areas within the municipality where exploitation rates are high, the municipality

can choose to install a local plan which is more specific about what will take place in that

area. Here borders of public grounds and the future usage are specified. The local plan is

Species are considered to have favorable conservation status according to the Council

Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of

wild fauna and flora, Article 1(i) when:

"a. population dynamics data on the species concerned indicate

that it is maintaining itself on a long-term basis as a viable

component of its natural habitats, and

b. the natural range of the species is neither being reduced for the

foreseeable future, and

c. there is, and will probably continue to be, a sufficiently large habitat to maintain its

populations on a long-term basis."

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legally binding, and means that exploitation will occur. (SFS: 2010:900. Plan- och bygglag.

Chapter 4-6). When looking at future perspectives for the LSW this would mean that a

neighborhood with a local plan is excluded as possible habitat if the plan means to exploit the

area and no compensation measures are in place.

1.4 The municipality of Gothenburg

The municipality of Gothenburg is located on the west coast of Sweden. Since it is the second

largest city in the country it is also a growing city, and with that comes elevated exploitation

(Mehner, 2016). This means that the land use and vegetation landscape will change rapidly in

this area. This could influence species linked to intended development areas. One of the

species that the municipality of Gothenburg has an elevated concern for when planning and

approving new exploitations is the LSW. As the LSW is currently red listed (Swedish Species

Information Centre, 2015), has an important ecological function (Jones et al., 1994;

Mikusinski et al., 2001) and is included in article 1 in the Council Directive on the

conservation of wild birds (2009/147/EC), the municipality is responsible for the conservation

of the local LSW population. They therefore need to evaluate the species status before new

exploitations can occur within the municipality.

Several previous surveys and assessments of smaller sites within the Gothenburg municipality

have been conducted, with the purpose of evaluating LSW distribution and if they have the

potential to be inhabited by the LSW (Calluna AB, 2012; Norconsult AB, 2013; Svedholm,

2013; Svedholm, 2015; Åhlund and Ahlén, 2001; Åhlund and Ahlén, 2011; Åhlund and

Ahlén, 2012; Åhlund and Ahlén, 2013). These together with nationwide inventories

(Aronsson, 2009) have been used to estimate the population distribution across the

municipality. The current estimate is calculated to 40 pairs, but this is a rough estimate based

on limited data (Åhlund and Ahlén, 2011).

1.5 Aim and hypothesis

The aim of this thesis is to assess if the LSW population within the municipality of

Gothenburg can be considered to have met all three criteria for FCS and to evaluate and locate

suitable habitats and potential breeding territories for LSW within the municipality. Also

aiming to assess potential risks of future exploitations of LSW breeding habitat by determine

land owner conditions. To do this a field study was conducted during 2016 to compare with

previous population dynamics data from a survey conducted in the 1970-80´s before the

initiation of the bird, and species, and habitat directives (Aronsson, 2009). This gave an

indication if the LSW is decreasing or increasing in population and range, and if the preferred

habitat is expected to be exploited or remain intact in the future. The hypothesis from the

municipality's side is that LSW has reached FCS within the municipality (Lennart Gustafsson,

Municipality ecologist, 2016, pers. comm., 2 February). Their hypothesis is based on

observations of the species (Artportalen.se, 2016) and that compensation efforts are installed

if a new exploitation in a known LSW habitat is approved (Hansson et al., 2009).

I also investigated the alternative hypothesis that the LSW population has not reached all

the criteria for FCS. The alternative hypothesis is supported by general knowledge about

specialists like the LSW. Specialists are often less adaptable and more affected then

generalists when introduced to more fragmented, unnatural and exploited areas with a

reduction of their own natural habitat (Matthews et al, 2014).

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2. Method

2.1 Study species

2.1.1 Habitat and mating systems in the Lesser Spotted Woodpecker The LSW is a residential bird and during the breeding season, the male and female defend the

same territory together, an area to which they stay very faithful. For the rest of the year

however, they live relatively solitary (Olsson, 1998; Wiktander, 1998). A Swedish study

conducted during several years, showed that 94% of all the LSW stayed in their original

territories and only 1% moved out of the studied area during this time, 5% changed to a

neighboring territory, but only if a vacancy occurred (Olsson, 1998).

The relationship between the female and the male of LSW is complicated, polyandry is

relatively common and has been estimated to occur in 8.5 % -9.7 % of the pairs (Wiktander et

al., 2000; Rossmanith, 2005). A socially polyandrous mating system, where the female nests

with multiple males, makes the species breeding territory complicated to survey with respect

to how many successful breeding pairs there are. This number is therefore frequently

overestimated. Polygyny can also occur within the species but is not as common. LSW are

monogamous in 77.9 % of the cases when examined over several years and polygyny and

polyandry is only registered in years where there is a skewed sex ratio (Wiktander et al.,

2000). The female LSW also have a lower survival rate, therefore a male skewed sex ratio

occurs more frequently (Wiktander, 1998). When polyandry occurs the number of fledged

chicks and nests varies between males and females (Wiktander et al., 2000).

Höntch (2005) hypothesized that LSW is likely to have no close neighbors, because of their

large home range and low density. This would comply with Wiktanders field observation

"that couples with an isolated territory show low levels of territorial behavior" (Wiktander,

2016, pers. comm. in Swedish, 23 February). In Sweden there have been records of

neighboring territories where 2-4 territories can border each other and at some areas even

overlap. Concerning polyandrous females, their territories are usually modified so that all

male territories are included in them (Wiktander et al., 2000; Wiktander, 1998). In Sweden

the habitat of the LSW shrinks during the year with an average of 742 ha during winter and

43 ha (max: 100 ha, min: 20 ha) during nestling season (Wiktander et al., 2001a). These are

hence the estimates that this thesis will utilize in the habitat analysis.

There have been several studies investigating habitat requirements for the LSW. In Sweden

Wiktander et al. (1992) found that the probability for LSW to appear in large areas (200 ha) is

dependent on the amount of deciduous woods available in that region. If there were less than

17 ha available, they found LSW in 24% of the areas and if there were between 17 -38 ha the

probability increased to 62%. If more than 38 ha were present they found LSW in 80 % of

them, showing that the LSW is closely linked to deciduous forests. Charman et al. (2012b)

also found during her studies in England, that the LSW were more likely to be present in

areas where snag density is high (>10/ha) and the trees were older than 75 years. Oak-

dominated stands with open structures is the preferred choice, but birch and aspen were also

utilized. In contrast a Swiss study concluded that the LSW was more likely to be abundant if

snags were fewer and softwoods (conifers) were more frequent. Their abundance was also

more probable if the distance to a lake or river was small and the elevation was low (Miranda

and Pasinelli, 2001; Cramp 1985). In Belgium the preferred habitat were younger stands with

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a higher percentage of oak and a high density of snags and deadwood (9 m3/ha) (Delaheye et

al., 2010). Difference between studies can be due to local variations and preference of the

different subspecies of the LSW. But generally all studies more or less agree on that LSW

seem to seek out areas with older deciduous woods with a higher percentage of oak and

deadwood, generally in damp landscapes.

During the end of March LSW start to form pairs and defend their territories together. They

find a location for their nesting tree and excavate a nest together (Olsson 1998; Wiktander

1998). In the years when polyandry is observed a chick's condition does not seem to be

affected by the mother´s number of partners. But in the Wiktander et al. (2000) study a female

biased sex ratio also occurred and two males (2.9%) were observed being polygynous. Here

the young appeared to suffer and their weights were the lowest recorded during the entire

study, suggesting that the conditions of the chicks are more dependent of the male attendance

than the females. Even if breeding attempts are not successful divorce rates also seems to be

fairly low within the LSW and only one couple (3.4%) during a several year long study in

Sweden divorced (Wiktander et al., 2000).

2.1.2 Foraging LSW can be considered to be a specialist when it comes to foraging, in contrast to its bigger

relative the Great spotted woodpecker (Dendrocopos major). The LSW exclusively forages

on dead smaller branches (1-5 cm) on still living trees for wood-living insects (primarily

long-horn beetles, Cerambycidae) during autumn to early spring (Charman et al., 2012b;

Cramp, 1985; Olsson, 1998; Smith, 2007). In 80 % of the cases the LSW was primarily

foraging in oak trees, and beech was the secondary choice (Charman et al, 2012b). Olsson

(1998) however found during his long term studies that the preferred tree species fluctuated

between years depending on the availability of food sources. This can explain variations

between different studies, and give an indication that the species is able to change its foraging

behavior to increase food intake and decrease predation risks. The LSW has also been found

to forage in the afternoon, an indication that their food source is reliable (Olsson et al., 2000).

LSW residing in territories of lower quality spend more time foraging than individuals

residing in superior ones (Olsson et al., 2000).

Feeding rates of LSW chicks in Sweden is more intense during the later nestling stages, in

socially monogamous pairs. At these stages the males in general take a higher responsibility

in rearing the chicks; some females (42%) in a Swedish population ceased feedings all

together during this period (Wiktander et al., 2000). If the female still provided food in the

later stages no difference in feeding rates was found between sexes (Wiktander et al., 2000).

In polyandrous females the feeding rate between her nests do not differ and if feeding by the

female stops the overall feeding rates do not decrease. In England similar tendencies has been

observed (Charman et al, 2012a). In Swedish populations this is due to that the male is almost

fully able to compensate for the absence of the female (Wiktander et al., 2000). But in

England it has been noticed that if the conditions are unfavorable, the male cannot fully

compensate, which leads to reduced breeding successes (Charman et al., 2012a).

Wiktander (1998) found that females have a higher mortality rate during the egg laying and

this could be because they forage significantly more during this period than the males. During

foraging there is a high risks of predation and therefore the females pay a higher cost for their

energy intake. If this is the case LSW with lower quality territories also have an elevated risk

of predation because they spend more time foraging (Olsson et al., 2000). Populations in

poorer quality regions therefore are more vulnerable for elevated mortality rates. The male is

12

usually able to compensate for when the female cease to feed the young during later stages of

nestling but in poorer habitats this ability decreases and can lead to fewer numbers of new

recruits (Wiktander et al., 2000; Wiktander et al., 2001b; Charman et al, 2012

a). It has been

observed that the number of pairs that raise fledglings goes down to 33% (from 76%) in years

with particularly cold and wet weather during the nestling season (Wiktander et al., 1994).

This can be a concern since current climate changes have the potential to produce extreme

weather conditions (IPCC, 2014).

2.1.3 Nesting In Sweden the average date for the female to lay the first egg is between 5-19 May (95%) and

usually all females lay their first egg within a 7-15 day period (Wiktander, et al., 2001a;

Wiktander et al., 1994). The start of the first laid egg is highly correlated with the date when

50% of the oaks buds have bursted and the eggs will be laid within 2.9 ± 2.13 days after this

occurs (Wiktander et al., 1994). This is thought to be an adaptation to synchronize the

beginning of the nestling period to the peak of abundant food recourses (Rossmanith et al.,

2007).The entire nestling period lasts between 19-21 days (Wiktander et al., 1994). Nesting

seems to rely on bi-parental care even if the male takes on the bigger role and this is

strengthen by the fact that when a LSW lose its partner the bird ceases the breeding attempt

(Wiktander, 1998).

2.2 Habitat and habitat analysis in present study

To locate habitat preferred by LSW within the municipally of Gothenburg, digital vegetation

maps were analyzed in ArcGIS 10.3 and MapInfo Professional 11.5. Ten different inventories

of mainly deciduous stands in the municipality were utilized (GSK, 2013). The ten digitalized

inventories were edited by only selecting areas that represented deciduous stands separately,

and then converted into a new joined layer using ArcGIS. The new joined layer was then

dissolved so that partially overlapping stands from different inventories would fuse together.

Stands smaller than 20 ha and further away from the nearest neighboring habitat than 1 km

were then removed, so locations with no ability to host the LSW were eliminated (Wiktander

et al., 2001a). This then produced a map illustrating the extent and locations of suitable habitat

for the LSW within the municipality.

To validate the GIS selection of suitable habitats, the Atlas survey from 1973-1984 (for

further details see below) was added to the habitat map to analyze how much habitat

coincided with the "Secure" and "Likely" breeding areas (squared shaped) in this survey. This

resulted in a count of 15 squares or areas with the status of "Secure" or "Likely” within the

municipality and a total sum of 2 304 ha within these and a mean of 153.6 ha SD ± 130.50

(range: 2.5- 430.7 ha) in known areas, enough for a breeding LSW couple.

The total ha of LSW breeding habitat in the municipality was subsequently divided by 20 and

100, representing the smallest and largest area needed for holding a breeding LSW couple

according to Wiktander et al., (2001a). This produced a range of the number of potential

breeding territories within the municipality.

To evaluate the level of certainty of persistence of the LSW potential breeding habitat, the

land ownership was examined by comparing the LSW habitat overlaps with protected areas,

public lands, private lands and national interests. This produced new layers of habitat, sorted

by the land conditions both for the entire potential breeding habitat and for the randomly

13

selected sites for the field study (see allocation process below). The potential breeding

territories within Gothenburg were then compared with the amount of ha that is protected in

the municipality. After confirming breeding sites in the field study this numbers was then

used to estimate the number of ha the estimated current Gothenburg population would utilize

during optimal conditions (Wiktander et al, 2001a). This was done to evaluate criteria c., if the

level of secured habitat is enough to sustain the population in the long hale.

A comparison with a newly taken orthophoto (air-photo) provided by the municipality was

also performed on the randomly selected sites for field study. Areas no longer covered with

forest stands were calculated, to estimate how much of the breeding habitat within the entire

municipality that have the potential to already be exploited by humans.

2.3 Selection of sites for the field study

To determine if the LSW population has increased or decreased since the bird directive was

initiated, a previous survey was utilized to compare with the field results of 2016. This so

called Atlas survey was performed between 1973-1984 (Aronsson, 2009). This survey method

divides the country in to "Atlas square" of 5x5 km, where ornithologists classified their

assigned square as either a secure, likely, possible (in Swedish "säker, trolig and möjlig"

respectively), or no existing breeding area for each bird species based on the criteria met in

their area and square (for more details see Aronsson, 2009). To estimate if the viability and

range of the LSW (criteria a. and b.) is unchanged or improving within the sites selected for

the field study a comparison with this survey was performed.

To select which sites to survey during the 2016 field season a grouping tool was used on the

LSW breeding habitat layer in ArcGIS 10.3. This tool aggregates and sorts the different

stands (patches) into a set number of groups depending on their four closest neighboring

stands. The first selection of habitat generated about 4 470 ha of suitable habitat within the

municipality. The number of groups was consequently set to 104 sites (4 470 ha / mean

breeding territory size 43 ha). A digitalization of the Atlas survey square system from 1973-

84 was then imported on top of the 104 sites to determine which groups that were mainly

inside a previously known site (within a "secure" or "likely" square) and which were mainly

inside an unknown breeding area (within a "possible" or "unknown" square).

To acquire 15 "previously known sites" and 15 "unknown sites" more evenly distributed over

the municipality's regions (Figure 2) a stratified random selection was enforced to obtain 10

sites in each region (five unknown and five known) using Microsoft Office Excel 2007. Using

the RAND. BETWEEN function a list randomly sorted with the 104 groups was produced.

This list was then used to select groups to survey by including the first groups/sites that had

an area higher or equal to 20 ha and were dispersed in a smaller area than 200 ha (Wiktander

et al., 2001a). If a randomly chosen set within a region was not complete with five known

sites and five unknown, the first site that was discarded due to that its own region set was

completed was included instead. So that 15 sites of each abundance status in total could be

acquired for the field season.

14

During the early stages of the field

season some of the areas classified as

suitable habitat in the GIS selection

were inaccurate. These areas were

identified as unproductive land with a

low tree coverage and no possibility to

hold breeding LSW. Five of the

selected sites (four unknown and one

known) were mainly or completely

made up of this particular type of stands

and therefore had to be excluded from

the study. The areas with this type of

stands were then also excluded from the

habitat map and the new number of

suitable habitat was recalculated to 3

318 ha. Hence 77 groups should have

been pre-set in the grouping tool in

ArcGIS (3 318/43≈ 77) instead of the

104 groups selected. These settings

were then subsequently used to allocate

two new unknown sites, to even out

numbers between the different

abundance statuses. The new sites were

visited in the breeding season together

with the other selected sites, producing

a total number of 27 sites, 14 known

and 13 unknown.

To balance the effort of the survey and locate coordinates for playback use, in the differently

shaped sites, circles with a 100 m radius and with minimal overlaps were produced using

ArcGIS 10.3 (Figure 3). This produced a distance of about 200 m between each playback

point (Kosinski and Kempas, 2007). The midpoint of these circles was then converted into

GPS coordinates and imported to a GPS device (GARMIN GPSmap 60CSx).

Figure 3: An illustration of the working process of allocating the playback points in site 51.

Figur 2: A map illustrating the different regions of Gothenburg

in this survey.

15

2.4 Field study

The field study was conducted between 21 March and 6 May. Each stratified randomly

selected site was visited 3 times during this period if no LSW was detected in the previous

visits. Unoccupied sites were visited at least one time in the morning and one time in the

evening. This produces about a 91% chance of registering an inhabited site (Charman et al.,

2010). The sites were visited 30 minutes after dawn and the survey continued for four hours.

In the evening the survey started approximately four hours before dusk or so that one site

could be completed in time for scheduled sunset. If bad weather was predicted (> 0,5 mm/h

rainfall or > 7 m/s wind) inventories were not conducted that day, due to decreased detection

chances (Wiktander pers. communications 16 Mars). Presence of LSW or not, way of

detection and time of day were registered for each site.

In each site the predetermined GPS-point was used to allocate the positions where playback

was performed. It has been proven as an effective method for allocating LSWs in the period

between Mars and end of April (Miranda and Pasinelli, 2001; Rassati, 2015). The playback

of drumming and calls was performed for one minute using a portable speaker (PHILIPS

BT6000W). Recordings of LSW response, movement and sightings were then noted during

one minute before moving on to the next GPS-point.

During the field study a third of the existing LSW breeding habitat in the municipality was

examined (1 067.2 ha) with a total sum of 160 hours spent in the field (80 h in walking time

and 80 h of observation time at the playback GPS-points) adding up to a walked distance of

550 km, during the 7 weeks of field work. A mean of 3 h and 41 min SD ± 1h 53 min

(Maximum: 11 h 36 min, Minimum: 2 h 0 min) was spent in each site at one visit.

2.5 Statistical analyzes

Statistical analysis was performed using SPSS statistical software (version 24, IBM Corp). To

establish if the abundance of the LSW had changed overall and for each region since the

1970-80´s sign-tests were performed on the ordinal abundance data. To establish if the size of

occupied sites differed from unoccupied ones a Permutation test was performed on the sizes

of the different abundance areas. To examine whether date and site size influenced the

probability of detection of LSW a binominal logistic regression and a Wald-chi2-test were

performed.

16

3. Results

3.1 Population dynamics and viability, including range

16 of 27 investigated sites were inhabited by a territorial LSW. Estimating the density of pairs

in Gothenburg to 0,015 pairs/ ha. In 15 of the 27 sites the abundance status had not changed

since the Atlas survey. Seven sites that had not been holding LSW before were now inhabited

and 5 inhabited before, were now uninhabited. The change in abundance in the investigated

sites between 2016 and the Atlas survey was not significant between the different time

periods (sign-test, P=0.766, n=12). In the excluded (from sign-test) sites, 56% (n=15) the

abundance remained unchanged. There was however tendencies towards an increase in

occurrence in the northern regions and a decrease in the central region (Figure 4).

Figure 4: Bar-charts illustrating the abundance of LSW in the municipality's different regions in the year's 1970-80´s

and 2016.

3.2 Habitat conditions

The ArcGIS analysis generated an estimate of 3 318 ha available, potential LSW breeding

habitat in the municipality of Gothenburg, 506 ha of LSW breeding habitat is protected to

some extent. Inventoried area in 2016 was 1 067 ha (≈32% of the total area) and 312 ha of

this consisted of protected lands (Table 1). The optical examination of the inventoried habitat

showed that about 2.6% of the selected sites already were exploited, mostly by new houses

and their adjoining gardens. If this number is used for the entire municipality's LSW breeding

habitat, 85 ha could already be exploited, leaving the remaining breeding habitat to be about 3

233 ha. The estimated remaining potential breeding habitat for the LSW in the municipality (3

233 ha) is enough for approximately 32-162 pairs of LSW (Wiktander et al., 2001a), 75 pairs

if a mean of 43 ha/ pair is utilized. In 2016 only 59 % (n=16) of the investigated sites were

defended by a LSW. The defended areas were 65 % (n=698) of the total area in ha, meaning

that potentially not all of the estimated LSW breeding habitat inventoried in 2016 is utilized

as breeding territories. If similar percentages are utilized in the entire municipality by the

LSW an estimate of 46 sites or 2 170 ha are used.

17

Inventoried sites 2016 Municipality of

Gothenburg

Protected land 312,5 ha 506,3 ha

Municipally land 622,3 ha 2 234,3 ha

- National interests for

nature and recreation

23,5 ha 229,3 ha

Private land

- National interests for

nature and recreation

214,2 ha

98,1 ha

578,5 ha

183,7 ha

Total habitat (ha) available 1 067,2 ha 3 317,9 ha

3.3 Influences on the probability of detection and residency

Factors that could bias or affect the results of the field study were examined. Mean size of site

did not differ for sites that were occupied in 2016, and unoccupied (Permutation test P=0.27,

n=27) (Figure 5A). In a Binomial logistic regression of the size of an inventoried area and

probability of detection there was a tendency towards a positive correlation (Wald

Chi2=1.241, P= 0.265, B= 0.030±0.027, df=1, n=27) (Figure 5B).

Figure 5: A) Box-plot illustrating the mean size (ha) of occupied and unoccupied sites in 2016 error bars displaying

range of variation of the outlying minimum and maximum 25% of area examined. B) Scatter plot illustrating the

probability of detection of LSW in relation site size.

When taking a closer examination at the sites where the abundance did change between the

Atlas inventories and the field study 2016, the mean inventoried area did not differ in a

significant way either (Permutation test, P= 0.43, n=12) (Figure 6).

Table 1: Table reporting the result from the habitat analyses in ArcGIS.

18

Figure 6: A box plot illustrating the size difference between sites where the LSW either disappeared or arrived

between the different inventories error bars displaying range of variation of the outlying minimum and maximum

25% of area examined.

Probability of detecting a LSW dependent on date was examined in a Binomial logistic

regression and showed a significant negative impact, on the probability of detection later in

the season (Wald chi2=5.862, P= 0.015, B= -0.130±0.054, df=1, n=27) (Figure 7).

Figure 7: A Scatter plot illustrating the probability of detecting a LSW during the 2016 field study dependent on day

of survey where day 0 is 21 March.

19

4. Discussion

4.1 Population dynamics and viability

The results indicate that the population numbers are steady and if given more time they could

increase in a significant manner. This is in accordance to previous observations where the

population had the ability to increase almost 50% over the course of 25-30 years (Aronsson

2009). This would mean that criteria a. of the FCS is fulfilled. However, the population size

within the municipality is small and limited to specific habitat, and therefore is more

vulnerable to stochastic events. Wiktander, et al., (1994) noted during a year with bad weather

conditions fledging success dropped from 76% in a normal year to as low as 33%. But during

steady circumstances the population in Gothenburg seems to be maintaining itself on an

acceptable level. Reasons for this could be that even though small pieces of habitat are

exploited each year, compensation measures are installed in accordance to the municipality's

guidelines (Hansson et al., 2009). Another explanation could be that more stands reach ages

where deadwood are self-produced each year, and thereby reach the potential to host LSW

pairs. This ultimately could sustain and help the LSW to adapt to the smaller habitats and

territories. As shown in Olsson´s (1998) research the LSW seems to be adaptable to changing

foraging conditions. This could be a vital component in its survival with current exploitations.

The LSW is also adaptable in the size range of breeding territory (Wiktander et al., 2001a). If

efficient compensation measures are not installed, the risk is that the quality of the habitat is

too low to compensate for areal losses, and an area could run the risk of not being sufficient

for a LSW breeding. One crucial reason might be the mating system for LSW, where the male

sometimes is unable to compensate, if the female leaves the nest and stops feeding the

nestlings. This has been seen as the main problem in England (Charman et al.,2012a). Some

evidence indicates that the same occurs in Sweden, since reduced quality of territories seem to

affect LSW reproduction, resulting in lower numbers of new recruits (Wiktander, et al,

2001b). If habitat quality is reduced the female is also prone to forage for a longer period of

time. This increases her predation risks, elevating the risk that a LSW breeding will cease due

to loss of partner (Wiktander, 1998).

The LSW mating system makes it difficult to estimate how many pairs there is within

Gothenburg, since there could be several areas that are occupied and defended by a male

LSW but his female is shared with another neighboring male. Having this in mind the

estimated population size and effective population size could be worse of and therefore affect

the total amount of protected land needed to claim that the population has FCS. Population

viability analysis models have tested the different life styles of monogamy and polyandry in

the LSW. The models found that polyandry can enhance the populations´ persistence and

actually lowering the minimum size for a viable population from 410 in a strict monogamous

population to 290 if a high-cost polyandrous system is in place or 220 if no cost is connected

with a polyandrous system (Rossmanith et al., 2006). Hence, the population number in

Sweden as a whole is efficient in any mating system constellation but the maximum

population number of 162 pairs is not sufficient to be viable on its own and could thereby be

dependent on neighboring municipalities’ populations. Another study on woodpeckers

however concluded that polyandry should lower fitness due to the high risk that the mate will

find out that he has been cuckolded when they are fertile such a short time prior to egg laying

(Pechacek et al., 2005a). It is also suggested that polyandry is a way for the female LSW to

increase her fitness when the male´s is superior, but that this mating system is only

20

sustainable when the male is able to compensate for the loss of female care that the polyandry

mating system entails (Pechacek et al., 2005b). This would imply that polyandry should be

lower in areas where the male has been seen not to manage this (Charman et al., 2012a).

One could argue that it takes a while for species to decline after a disturbance in its connected

nature and habitat, and that the population number will not begin to decline within the time

range this thesis has focused on. But during the period of 1970-2016 there have been close to

insignificant exploitation on larger deciduous stands in the municipality (Prof. Lars

Arvidsson, Municipality ecologist, 2016, pers. comm., 17 February) and several generations

of LSW have had the ability to respond to these kinds of triggers if any have existed.

Therefore the result should reflect a correct status of how the LSW population has evolved in

this area since the initiation of the bird directive. Furthermore a third of the available habitat

has been evaluated in this thesis and therefore it is likely that the results are accurate.

In relation to the public authority's internet page for species reports "Artportalen.se" the

results do not majorly contradict each other. But in one of the sites, a LSW has been spotted

foraging by an ornithologist and in the field season no LSW responded to drum or song

recordings or made themselves visible during my 3 visits in this area. This could be explained

by a closely located known territory, or that LSW could have been present but did not have

the impulse to reply due to that it was not a part of the birds primary breeding territory.

However three sites were classified as in habituated where there were no previous records

according to "Artportalen.se". This could potentially be because of little effort has been made

in finding a LSW within that site. Another reason could be incorrect species identification.

This indicates that new information of LSW distribution in the municipality has been added

where 16 instead of 13 territories was inhabited. Also notable is if some of the known

inventoried sites in 2016 were in reality not inhabited during the 1970-80 inventories and only

had this abundance status given to them, due to that other adjacent territories within the same

relatively big Atlas square (2 500 ha) were inhabited. This could mean that the LSW are

doing even better today than the results indicate, because more areas are repopulated than

estimated in this thesis.

4.2 The Lesser Spotted Woodpeckers range within the municipality

The LSW range had no noticeable changes in the regions when comparing the previous

survey and the one made during 2016. There was however a tendency towards an increase in

the north region and a decrease in the central region. This means that criterion b. for FSC is

seemingly fulfilled as well, at least for the time being. The lower number in the central region

could be an indication that city densification is affecting LSW (Prof. Lars Arvidsson,

Municipality ecologist, 2016, pers. comm., 17 February; Brunnkvist et al., 2014). This can

pose a future threat for the LSW and could reduce the available habitat to a critical level. This

can also result in isolation between pairs in the central region of the municipality and thereby

limit re-colonization of these areas. This could mean that the range in the central region is

reduced which may result in population reduction and ultimately lead to that criteria b. for

FCS is unfulfilled. This would make breeding pairs in this region of the highest concern,

when it comes to compensation measures. A recommendation would be to not approve

dispensations for exploitations in the central areas, where there are known successful LSW

breeding’s. Especially if the municipally wants to preserve FCS for the LSW in the future –

and preserve green central areas in general, linked to the concept of green infrastructure.

21

Continental bird species that are not island residential generally are highly mobile, and can re-

colonize new areas without larger oceans limiting them, therefore population numbers and

range could be positively affected by individuals outside the municipality's borders. This

means that even if the central region would lose its pairs in the future, the area could be re-

colonized by new individuals either from the municipality itself or from adjacent

municipalities. The range of the LSW probably depends on the range of their preferred

habitat. This is an additional reason to why the qualities of LSW breeding habitats in the

central region of Gothenburg should be conserved or improved in quality, so that the area can

be desirable for new recruits in worse case scenarios.

4.3 Habitat conditions

To maintain the population number found during the 2016 survey (n=16) the municipality of

Gothenburg would need to preserve 320-1600 ha. If the mean breeding territory size is 43 ha

one could claim that an area of 688 ha would be sufficient. But according to the findings of

this study only about 59 % of the assessed sites was inhabited and only 65 % of the total area

inventoried. As a precautionary measure it would be recommended that at least twice that

amount of potential breeding habitat should be protected to ensure that the LSW population is

not negatively affected. The LSW territory also increases during winter from 211 to 742 ha

(Höntch, 2005; Wiktander et al., 2001a), and the LSW of Gothenburg might need a larger area

than 320-1600 ha to be able to expand their territories during winter without bigger overlaps.

But the winter territories have been observed to overlap, with 2-4 shared territorial grounds

(Wiktander et al., 2000; Wiktander, 1998). However during the winter the LSW has been

shown to alter its habitat preference and can utilize other areas within the municipality that

has not been defined as LSW habitat in this thesis. This could also be a part of the explanation

why only 59% of the inventoried sites and 65 % of the areal inventoried in the spring of 2016

were occupied and not all 77 sites within the municipality are estimated to be utilized. Other

reasons could be bias in habitat requirements defined for the LSW, or species competition that

excludes LSW from the area.

Today 506 ha of the municipality's estimated 3233 ha of LSW potential breeding habitat are

protected (≈16%) within either a Nature 2000 area or a Nature reserve. In the ArcGIS analysis

2 234 ha of their habitat was located on municipal land and therefore could be preserved if the

municipality of Gothenburg has the ambition and means to leave these areas unexploited.

Unfortunately the municipality is not only faced with the responsibility to achieve FCS for

species connected to natural areas. They are also faced with other conflicting responsibilities

like the growing human population number and housing problems (Brunnkvist et al., 2014).

If all 2 234 ha of municipal land were to be preserved together with the already protected 506

ha the municipality has control of 2 740 ha of LSW habitat. This is well over the 2 170 ha

estimated to be utilized today and enough for 27-137 LSW pairs, also if not all of the habitat

is occupied. This could indicate that if the municipality were urged they could ensure an

adequate amount of habitat to approach fulfillment of criteria c. for FCS. However, further

analyses of municipality plans are required to get a more detailed picture of the area that

realistically could be preserved and /or reinforced for the LSW, due to the high likelihood that

large areas of LSW breeding habitat are included in local plans and may be exploited.

Currently 506 ha are protected, which is in the smaller range of what is needed to secure the

16 pairs found in this thesis. As shown above, not all available habitats seem to be utilized.

22

Therefore the amount of protected area is not sufficient to fulfill criteria c. for FCS for all the

birds within the municipality.

4.4 Factors influencing the results

The amount of time spent in each site varied in this study. This could have a possible effect

on the results but since there was no significance found in probability of detection dependent

on size, the result should be valid. Bigger areas had more playback points and therefore had a

longer survey time. But more playbacks per ha was not performed in bigger areas. Playback-

points per ha was more dependent on the shape of the site rather then the size of it. Long, thin

and dispersed stands had to have more playback points in them so the majority of the area was

within a distance lesser or equal to 200 m away from a playback-point and optimally only one

point was within this distance. In more round shaped sites playback-point could cover areas in

each direction, and fewer points was needed. Therefore the effort should be equivalent in sites

independent on size or shape.

No difference was detected between occupied and unoccupied site sizes in 2016. This was

also the case if you looked at the sites where a change in abundance had occurred between

1973-1984 and the 2016 survey. However these results are not unexpected and are an

indication that the site size chosen in the survey 2016 are within the LSW natural range. As

previously shown by Wiktander et al., (2001a), the LSW has the ability to breed in both bigger

and smaller sites. Maybe the quality of the territory is more of a determining factor of how

big a breeding territory constitutes, whereas the actual area available is of less importance. If

this is the case then compensation efforts paid by the exploiter as the guidelines constitutes

today (Hansson et al., 2009) is an effective method to lessen the pressure of the LSW during

exploitations. But important to keep in mind is that the LSW probably has a threshold of how

minimal a territory can be to successfully raise fledglings, even if the quality of that area is

elevated.

The probability to find a LSW within a site did not increase dependent on size but a bigger

area had a slight positive effect. This result however implies that size might have some

influence on their abundance. If a site or area has a higher count of hectare the chances are

that several higher quality patches can occur within that area and that these patches have

different food sources available in them. This could be preferable if the regular primary food

source is limited in certain years and an alteration to the diet is required. This would then

make a bigger area more attractable for a LSW individual and is maybe thereby chosen if

given a choice. But the cost of defending that area will also increase with the amount of

hectare and together with elevated predation risk of flying between more patches and more

open areas, could be the reasons why LSW breeding habitat are seldom bigger than 100 ha

(Wiktander et al., 2001a).

The effect on detection probability was dependent on day of surveying. The significant impact

later in the season suggests that the period a site was visited influenced the chance of finding

a LSW individual. This might mean that sites investigated later in the field season had a lower

detection probability than site investigated early. Reasons for this could be that the LSW were

less likely to respond to playbacks after finding a partner and only visually investigated the

area making them harder to detect. Especially since bud bursts of other tree species than oak

increased throughout the season. But the last day of survey was the 6th of May, the beginning

of when first egg laying is expected (5-19 May). So few individuals are expected to not

23

defend their territories during the inventory time-line and the survey also ended 2-3 days

before the first budburst of the majority of the oaks within the municipality (Wiktander et al.,

1994). This result could more likely be due to the fact that in the later stages of the study only

sites that already had been visited one or two times before were investigated. The majority of

the LSW found in the field study 2016 (n=13) were located in the first visit to a site (an

indication of high detection probability). In the later stages of the field study a lower count of

sites was classified as occupied, due to that most occupied sites already was detected. This is

also an indication that detection probability estimated to 91% in Charman et al., (2010) study

with three visits in an area, was a good estimate in general and during this survey the

detection probability was even higher with 94% probability on the second visit (reliant on that

all occupied sites were detected in 2016). Charman et al., (2010) detection probability was

estimated without performing playbacks at the investigated sites and this probably elevated

the detection rate in this thesis, as the LSW has been registered to be the most responsive to

playbacks out of several woodpecker species (Rassati, 2015).

4.5 The methodology of evaluating FCS

Continental bird populations, compared to for example bird populations living residentially

on isolated island have been found to be one of the least sensitive groups in terms of global

extinction (Loehle and Eschenbach, 2011), and this could explain why the LSW are

maintaining in stable population numbers. In general continental bird populations have been

found to have a low rate of extinction and over the last 500 years only six species have been

lost (Loehle and Eschenbach, 2011). Even if the municipality have or will lose LSW pairs in

isolated locations, re-colonization is very likely due to their high mobility compared to other

animal groups. This along with that birds are one of the more well-studied groups makes

LSW one of the more favorable species to initiate methods for establishing conservation

status.

This present method could facilitate estimations of FCS for other species with previously

known breeding territories and habitat preferences as well. This makes this thesis interesting

for governments all across the European Union and their corresponding county

administrations and municipalities. As far as the author is informed the methodology of

estimating a species conservation status is highly limited even though all EU countries have a

legal obligation to ensure it, and this is a first step in doing so. But a need for better

population data prior the initiation of the directives would help creating a better baseline for

other species. Birds in general have better population data due to the bigger public interest

ornithologists provide and therefore are one of the more favorable groups to evaluate. More

studies on habitat requirements, territory sizes and other critical population parameters such

as mortality and fertility are also needed in the future to easier and quicker have all the facts

needed for an evaluation.

Even if the bird directive and the conservation of natural habitats and wild fauna and flora

directives are legally binding in several of the EU countries, no large effort in evaluating

conservation status is in place. This thesis has shown that it is possible even if it is only on a

local level and the methodology needs empirical trials. In Sweden the work of assessing FCS

is limited as in other countries, thereby making the municipality of Gothenburg at the

forefront in addressing these obligations. Hopefully more municipalities in Sweden and

countries as a whole will start to take these obligations more seriously in the future.

24

5. Conclusions and summary

The LSW population within the municipality of Gothenburg does not fulfill all the criteria for

FCS. The population seems to be maintaining itself, maybe due to their ability to adapt to

smaller areas and changing foraging conditions. Or partially due to that compensation efforts,

to improve the quality of remaining habitats are installed with new exploitations. The range is

also still distributed across the different regions in the municipality, but it is important to

conserve habitat in the central region to reassure equal future distribution. The amount of

habitat that is protected today is barely enough to retain the 16 pairs found in this thesis and

therefore in the long run is probably not enough to secure the entire population within the

municipality. Especially when taking into account that only about 65 % of the area within the

municipality is estimated to be utilized, thereby failing criteria c. for achieving FCS. If the

municipality was to secure the majority of its own land with preferable LSW habitats FCS

could be claimed in the future, but an analysis of municipality plans is needed. What is

needed is reduction of exploitation in sensitive areas and an increase in protection of natural

habitats but this is hard to achieve because of conflict of interests. This study shows that it is

possible to investigate conservation status for the LSW and that it could be applied to other

animals even if improvements can be made. This is a field more municipalities and countries

should be focused on so that the aims of the EU directives can be achieved in the future.

Figure 8: A summary of the criteria for FCS and which of them the LSW within the municipality of Gothenburg

fulfill.

Acknowledgments I would like to thank my supervisors Frank Götmark and Emil Nilsson for support in the writing

process of this thesis. My supervisor Donald Blomqvist for input in my statistical analyses and help

with my method development. Ola Hammarstöm and Mikael Finsberg at the municipally Park and

Nature Department for helping me find the material I needed for this project and help with

understanding the new computer systems as well. I would also like to thank Ulf Wiktander for his

advice during my field study and the now retired Lars Arvidsson and Lennart Gustafson at the Park

and Nature department that initiated this project. At last by not least I would like to thank my fellow

officemate and Master student at the University, Anton Larsson for trying to keep up my good spirits

when things went south.

a. population dynamics data on the species concerned indicate

that it is maintaining itself on a long-term basis as a viable

component of its natural habitats, and

b. the natural range of the species is neither being reduced for the foreseeable future, and

c. there is, and will probably continue to be, a sufficiently large habitat to maintain its populations on a long-term basis."

25

6. References

Aronsson, N. (2009). Fågelatlas över Göteborg med kranskommuner. Fåglar på Västkusten, supplement 34,

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