KORA Bericht Dispersal 100418.Indd

KORA Bericht Nr. 50 April 2010 ISSN 1422-5123

Expansion of lynx in the Alps

Koordinierte Forschungsprojekte zur Erhaltung und zum Management der Raubtiere in der Schweiz. Coordinated research projects for the conservation and management of carnivores in Switzerland. Projets de recherches coordonnés pour la conservation et la gestion des carnivores en Suisse.

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KORA Bericht Nr. 50 Expansion of lynx in the Alps

Autoren Anja Molinari-Jobin, Ivan Kos, Eric Marboutin, Auteurs Paolo Molinari, Sybille Wölﬂ, Michael Fasel, Authors Christine Breitenmoser, Christian Fuxjäger, Thomas Huber, Iztok Koren, Krzysztof Schmidt, Josip Kusak, Harri Valdmann, Fridolin Zimmer- mann, Manfred Wölﬂ, Urs Breitenmoser

Bearbeitung Anja Molinari-Jobin (Layout) Adaptation Editorial

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Titelbild Luciano Ramires Page de titre Front cover picture

Anzahl Seiten/Pages: 17 ISSN 1422-5123 © KORA April 2010 April 2010 3

Expansion of lynx in the Alps

Anja Molinari-Jobin, Ivan Kos, Eric Marboutin, Paolo Molinari, Sybille Wölﬂ, Michael Fasel, Christine Breitenmoser, Christian Fuxjäger, Thomas Huber, Iztok Koren, Krzysztof Schmidt, Josip Kusak, Harri Valdmann, Fridolin Zimmermann, Manfred Wölﬂ, Urs Breitenmoser 4 KORA Bericht Nr 50

Acknowledgements This review was conducted by the SCALP (Status and Conservation of the Alpine Lynx Population) expert group, and three lynx experts have contributed their unpublished data. This report was ﬁnanced by the Bavarian State Agen- cy of Environment, while SCALP in general receives funding by the MAVA foundation. We thank Andreas Ryser for providing data and expertise about the translocation project. April 2010 5

Expansion of lynx in the Alps

Index

Abstract...... 6

Introduction...... 7

Concepts and deﬁnitions...... 7

Metapopulation...... 7

Population spread/colonization...... 8

Land tenure system...... 9

Dispersal...... 10

Methods...... 10

Present status and trend...... 10

Dispersal...... 10

Survival...... 11

Results...... 11

Present status and trend...... 11

Dispersal...... 12

Survival...... 13

Discussion...... 13

Next steps...... 15

References...... 15 6 KORA Bericht Nr 50

Abstract

The Bavarian State Agency of Envi- the north-eastern Swiss subpopula- In a next step it would be impor- ronment commissioned the SCALP tion is the closest potential source tant to analyze lynx movements in expert group to review existing data to the Bavarian Alps where regular respect to barriers to evaluate the on lynx dispersal and to discuss the reproduction is reported from. With permeability of the barriers created likelihood of a natural recoloniza- a distance of ca. 70 km the Bavar- by highways, as it is important to tion of the Bavarian Alps by lynx. ian Alps are within dispersal range know how often lynx leave their Dispersal data was available from 60 of the north-eastern Swiss subpopu- source habitat patch and “manage” individual lynx. Dispersal distances lation. Yet, the probability that a to cross such barriers, how they in- ranged from remaining philopatric lynx will reach the Bavarian Alps teract and communicate across such to more than 400 km. However, 68% highly depends on the availability barriers, and how they establish in- of documented dispersal distances of suitable habitat and especially its dividual home ranges in new areas were less than 50 km. fragmentation. Since lynx dispersing to predict how the species colonizes In the light of a complete recoloniza- from north-eastern Switzerland to a new patch. And ﬁnally, to predict tion of the Alps (and in particular the the Bavarian Alps have to cross two the future and spread of the Alpine Bavarian Alps), three factors need to highways, it is probable that most of lynx occurrences, we need to model be considered: (1) an analysis of the them will take another dispersal di- the population viability of the pres- closest existing source population, rection. ent lynx occurrences in the Alps by (2) the dispersal capability of lynx, Since the probability that even a means of a spatially explicit demo- their survival probability and asso- single lynx reaches the Bavarian graphic model. Based on the repro- ciated mortality factors, and (3) the Alps is low, a natural recolonization duction and survival data from lynx probability of the establishment of a of this area within the next decades, in the Alps we need to evaluate the population nucleus given successful followed by the successful settle- probability of persistence (or extinc- dispersal or the enlargement of an ment of a viable population nucleus, tion) of existing occurrences. This existing occurrence, respectively. seems very unlikely. The further an would allow us to include different The Alpine lynx population present- animal disperses from its core range management scenarios into the mod- ly consists of 5 more or less isolated the less likely it will ﬁnd a mate later eling. These kinds of analyses would subpopulations or occurrences. Dur- on. A population viability analysis produce the basis for future conser- ing the past 10 years the occupied has revealed that from a demograph- vation and management efforts. area of lynx in all the Alps increased ic viewpoint at least 10 females and by ca. 6000 km2 or 50% based on a 5 males are required for a start that raster grid of 10x10 km. Presently, will develop into a viable population. April 2010 7

Introduction

The Alpine lynx metapopulation management strategies linked to the to further approach the issue of went extinct during the 19th century. status of brown bear, wolf and lynx “natural recolonization vs. rein- In the 1970s and 1980s, lynx from the (StMUG 2007a, b; 2008). One issue troduction” of lynx in the Alps. Slovak Carpathians were released in controversially discussed centered the Swiss, Austrian and Italian Alps on the presumed low expansion of and in the adjacent Jura Mountains the lynx in the Alps and in particular Concepts and definitions (Switzerland), Vosges (France), around the questions: the Dinaric range (southern Slove- (1) Whether lynx are per se not able Metapopulation: Linnell et al. (2008) nia) and Bavarian-Bohemian Forest to recolonize the Bavarian Alps from recently provided a review of the bio- (Czech Republic). These reintroduc- Switzerland and Slovenia due to the logical and demographic processes tion projects resulted in several local distances from the source populations that underlie the classical concept of populations and isolated occurrenc- and/or the lack of suitable corridors, a population. The basic idea refers es (von Arx et al. 2004, Capt 2007, (2) or do not recolonize the central to a group of individuals that live Molinari-Jobin et al. 2010, Wölfl et Alps because of high mortality in the in the same area and can potentially al. 2001). While lynx populations in two source populations or low demo- interbreed. Linnell et al. (2008) sug- the Jura and Dinaric Mountains, the graphic output, e.g. low fecundity, so gest that the word “metapopulation” Alps and the Bohemian-Bavarian that subadult lynx are not forced to be used to refer to the large scale Forest initially expanded very fast disperse through competition based phenomena that embrace the distri- (Vandel and Stahl 2005, von Arx et mechanisms like food and/or mate bution of individuals with a broadly al. 2004, Wölfl et al. 2001), 20-40 competition. similar genetic structure. Within this years after the reintroductions there To assess these questions the Ba- metapopulation there may be a num- seems to be a stagnation in the ex- varian Environment Agency com- ber of “subpopulations” that consist pansion process, although especially missioned the SCALP (Status and of individuals within a reasonably in the Vosges, eastern Bavaria and Conservation of the Alpine Lynx continuous distribution that interact the Alps suitable habitats are still Population) expert group to prepare with much greater frequency. Fi- available. Forty years after the first a fact-based background document nally, there may be some individuals reintroduction, less than 20% of the to be used for further discussions in or very small groups of animals that suitable habitat of the Alps are recol- the LCMB. occur outside the distribution of any onized (Molinari-Jobin et al. 2010), subpopulation. If they are mobile, and only about one third of the and do not occupy a discrete and Vosges Mountains (von Arx et al. Main questions to be addressed / predictable area, and do not repro- 2004). The same pattern is observed goals of the study: duce, these individuals are termed in the Nordic lynx population that “vagrants”. If they are stable and has considerably expanded its range (1) To clearly define terms/con- occupy a predictable location over southward on broad front since 1990 cepts like metapopulations, several years they can be called an (von Arx et al. 2004). However, in population spread/colonization, “occurrence”. Typically, reproduc- more recent years, expansion, al- and dispersal; tion will only be sporadically docu- though desired, has progressed very (2) To give an explicit overview mented in an occurrence. slowly (Linnell, pers. comm.). about the present status/trends Accordingly, through the fragmen- In 2006, the Bavarian Ministry of of lynx occurrence in the Alps; tation by high Alpine ridges and ur- Environment and Health initiated (3) To describe dispersal patterns banized valley bottoms, the Alps are a process to develop management of lynx in the Alps and compare divided into several subpopulations plans for bear, wolf and lynx. Using a results with dispersal patterns that together can form a metapopula- participatory approach, a Large Car- found across Europe; tion since limited migrations of indi- nivores Management Board (LCMB) (4) To discuss results taking into viduals between the subpopulations has been formed. Within that board, consideration several factors are possible (Zimmermann 2004). a wide variety of administrations, in- (e.g. population status, sex- and Each subpopulation inhabits a dis- terest groups and experts discussed aged linked reproduction/mor- tinct habitat patch that is separated biological and partially sociologi- tality/survival rates); and from neighboring habitat patches cal backgrounds and possible con- (5) Finally to give recommenda- through some kind of natural or ar- flict zones. The LCMB developed tions about possible next steps tificial barrier. 8 KORA Bericht Nr 50

If a species is not found in an area, subadult survival, and factors affect- or barriers followed by successful it might be either because the patch ing them is crucial to many areas in establishment of a population (e.g. is not suitable, or because it was un- ecology and conservation. island colonization) is caused by able to immigrate. Metapopulation jump dispersal. Dispersal plays a theory has therefore focused on the Population spread/colonization: key role in both types of coloniza- importance of dispersal for patch Population spread happens when an tion processes. colonization (Hanski and Gaggiotti organism arrives somewhere beyond Since dispersal allows the avoidance 2004). In classic metapopulation its previous range. The beginning of competition, it was thought for models (e.g. Hanski 2000), coloniza- of population spread includes the a long time that density dependent tion ability is measured as the prob- arrival of individuals of a species dispersal should always be positive ability of an empty patch becoming in a new locality and its successful (Clobert 2009). The hypothesis that colonized per unit time. A number establishment. Both the enlargement population pressure will result in an of factors inﬂuence this parameter. of existing home ranges or dispersal expansion of the occupied area im- These include (1) the mean distance may lead to an expansion of the dis- plies two assumptions: the popula- over which individuals disperse; (2) tribution area. Since in an expanding tion expands through dispersal, and the total number of dispersers in a population unexploited resources are dispersal is positively density depen- population, which in turn is a func- at the edge of or outside the colonized dent. Comparing lynx dispersal rates tion of the number of offspring pro- area, home range expansion (e.g. and distances from the Jura Moun- duced per individual and population Breitenmoser and Haller 1993) and tains with the Alps, Zimmermann et density; and (3) the amount and dis- dispersal both regulate abundance by al. (2007) failed to detect any positive tribution of suitable habitat (Freckle- expanding distribution (Dieckmann density dependence in lynx dispersal ton et al. 2005). Wrong assumptions et al. 1999). Within the gradient of and hence were not able to conﬁrm about dispersal behavior and surviv- colonization processes (McShea and the hypothesis that high population al affect the accuracy of individual- Madison 1992), we can distinguish density will systematically encour- based simulation models of popula- between two different extreme colo- age the expansion of the population. tion dynamics (South 1999, Cooper nization types: (1) Diffusion is the Negative correlations between dis- et al. 2002), metapopulation models gradual movement of a population persal probability and density have (Trenham et al. 2001), and conse- across hospitable terrain and may be been observed in several other spe- quently regional conservation and caused through home range enlarge- cies (voles, Lambin 1994, Andreas- management plans. Thus, improv- ment and dispersal processes, while sen & Ims 2001; brown bear, Stoen ing our knowledge in lynx dispersal, (2) movement across long distances et al. 2006; European hare, Bray et al. 2007; for a review, Matthysen 2005). In this respect it is worth analyzing the potential of the lynx occurrence in the north-western Swiss Alps to expand. Within the Swiss large carnivore management unit north-western Swiss Alps (Fig. 1), the lynx distribution area has increased after 1995, decreased to a low in 2002 and then increased again (Fig. 2). According to the population pressure hypothesis lynx should disperse and thus expand the distribution in the area adjacent to the management unit north- western Swiss Alps. While we can observe a considerable increase in the distribution area from 1998 until 2001 in the management unit Valais Fig. 1. Swiss large carnivore management units and the distribution of lynx signs of presence that lies south of the north-western from 1999-2001. Each point observation is buffered with a radius of 5 km. The lynx occur- Swiss Alps, in the management unit rence in the Jura Mountains is not shown. Central Switzerland West we did not April 2010 9

yet observe an increase (Fig. 2). In 2000 at least eight individuals were known to have been killed illegally (Breitenmoser-Würsten et al. 2001) and four animals were removed as stock raiders during 1997–2001. In addition, six lynx were taken from the north-western Swiss Alps in 2001 for a translocation programme into the north eastern Swiss Alps (Molinari-Jobin et al. 2001). All of these removals led to a considerable reduction in abundance and a decrease in the distribution area in the north-western Swiss Alps (Fig. 2). Thereafter, the area of lynx presence increased again in the north- western Swiss Alps. While in the Valais the lynx distribution area Fig. 2. Area occupied by lynx in three Swiss large carnivore management units (blue = north- continued to decline, in the manage- western Swiss Alps, green = Valais, red = central Switzerland West). The size of the distribu- ment unit Central Switzerland West tion area was estimated using circular buffers with a radius of 5 km around each conﬁrmed we observed a considerable increase. sign of lynx presence. Since 1998 we also have conﬁrmed signs of presence from the western part of the management unit Gri- may vary depending on habitat type, aged 211 km2 (range 71-450 km2) sons (Fig. 1). Overall, during the composition of prey community and and of 17 radio-tagged females 101 past 10 years the distribution area of density of prey (Molinari-Jobin et al. km2 (range 35-210 km2; Haller and the north-western Alps occurrence 2007). In the Alps, home range sizes Breitenmoser 1986, Breitenmoser- has increased by 1960 km2 or 27%. of 15 radio-tagged male lynx aver- Würsten et al. 2001, Ryser et al. 2004). Whether the pressure in the core of the population or the dynamics at the edge of the population has led to this increase cannot be evaluated with the data available. In fact, already Williamson (1996) stated that in al- most all cases, the rate of spread is mostly determined by processes at the fringe of the population and does not involve the population behind the front to any great extent, but this might be modulated according to the species characteristics regarding its ability to disperse.

Land tenure system: Lynx are soli- tary living animals, except for females with the offspring of the year. Both males and females occupy individual territories. Home ranges of males are larger than those of females. Generally, adult males share Figure 3. We used the case of the north-western Swiss Alps where 14 female (red) and 9 male their home ranges with one or two lynx (blue) were radio-collared to illustrate the land tenure system (from Breitenmoser-Würs- females (Fig. 3). Home range sizes ten et al. 2001). 10 KORA Bericht Nr 50

along the Brenner freeway (Trento- Innsbruck; Zimmermann 2004). To distinguish specifically between vagrants (spatially isolated observations of individuals the status of which is unknown) and occurrences/ subpopulations (assembled observations indicating a closed pool of sed- entary individuals, i.e. a population), we also described the population range of the lynx using the 95% kernel area of confirmed lynx signs of presence (Worton 1989, Seaman & Powell 1996). For the smoothing factor (also referred to as the bandwidth or h statistic, which controls how wide the probability mass is spread around a point and the smoothness or roughness of the density estimate) we applied 15.000 of the user de- fined option in the GIS program Arc- Fig. 4. Confirmed lynx signs of presence in the Alps (red dots). Each point observation is buf- View 3.3 (ESRI 1996a,b) and Ani- fered with a radius of 5 km. The dark grey area is the 95% Kernel estimate. In yellow is shown mal Movement extension (Hooghe the longest reported dispersal of a lynx in the Alps from its place of birth (star) to its present et. al. 1999). home range (ellipse; April 2010). Assuming that not every lynx is detected each year, we pooled 3 years in one distribution map. We analyzed Mating takes place from February to tition for mates, and avoidance of the trend using data from 1995-1997 mid-April. After 67-74 days, usually close inbreeding (Greenwood 1980, to 2005-2007. From 1995 to 2007, in late May, 2-3 kittens are born. The Johnson and Gaines 1990, Pusey and lynx experts confirmed a total of number of kittens may vary from 0- Wolf 1996). Dispersal behavior may 8748 signs of lynx presence that were 5. Kittens follow their mother until depend on several interacting fac- used for this analysis. The point data the next mating season. The onset of tors rather than on a single one, and of these presence signs was georefe- dispersal occurs generally at the age the various hypotheses proposed are renced and mapped using ArcView of 9-11 months (February to April) not necessarily mutually exclusive 3.3 (ESRI 1996a,b). and after 250 days, at the most, dis- (Dobson and Jones 1985). persal is completed (Zimmermann et al. 2005). Dispersal Methods Dispersal: We follow Howard’s We compiled data from published (1960) definition of dispersal as the Present status and trend reports of lynx dispersal, as well as movements by an animal from its available anecdotal observations point of origin to another area where We estimated the distribution area from ongoing research projects from it might reproduce. This implies that of lynx in the Alps from the location the Baltic population, the Dinaric dispersal is a behavioral attribute of its presence signs by computing Mountains and the Bavarian-Bohe- of certain individuals that make the annual maps using a 10x10 km grid, mian Forest. Dispersal data came decision to move, with important the reporting format adopted by the mainly from radio-telemetry; ad- implications for their individual fit- E.C. Habitats Committee (European ditional information was available ness (Van Vuren 1998). Three major Commission 2006). If a presence sign from cubs tagged at the den or “cap- hypotheses have been proposed to is reported within a given grid cell, tured” in a camera trap when still to- explain the ultimate causes of dis- this cell is illuminated. We divided gether with the mother and later cap- persal in a wide range of species: the Alpine lynx metapopulation into tured, “pictured” in a camera trap, or competition for resources, compe- a western and an eastern occurrence found dead. The three broad lynx age April 2010 11

classes were (1) cubs dependent on their mothers; (2) subadults as independent but not yet of breeding age, thus lynx in their second year of life; and (3) adult lynx being older than 2 years. Thus, our analysis includes all subadult individuals, including philopatric ones. Dispersal distance for radio-collared individuals was deﬁned as the distance from the arithmetic centre of a progeny’s natal home range to the arithmetic centre of its independent home range (Zimmermann et al. 2005). The area a lynx used for ≥6 consecutive months without sub- sequent change in location was re- garded as independent home range. When complete dispersal information was not available, dispersal distance was calculated based on one of the following combinations: natal centre to mortality site or last location, or capture site to independent centre, mortality site, last location, or recapture site.

Survival

The survival rates of dispersing lynx was calculated as S = 1 – (deaths/ number of dispersing individuals). Fig. 5. Estimated lynx distribution range in the Alps (adjacent ranges are not considered) based We used only data from radio-col- on a 10x10 km grid for the 1995-1997 period (top) and the 2005-2007 period (bottom). lared individuals, excluding those whose transmitters failed before the animal was at least 2 years old, so as to avoid bias towards survival (White second nucleus in the south-eastern eastern subpopulation during these and Garrott 1990). Since not all pub- Alps (Italy and Slovenia, stretch- three years. The number of lynx es- lications give detailed information ing into Austria). A third nucleus of timated in the Alps ranged from 85- on dispersal and survival, sample similar size was founded in north- 130 (France: 15, Italy: 10-15, Swit- sizes may vary considerably. eastern Switzerland between 2001 zerland: 50-80, Liechtenstein: 0-1, and 2008 with the translocation of Germany: 0, Austria: 5-10, Slovenia: 12 lynx (Ryser et al. 2004, Ryser, 5-10), which roughly averaged about Results in prep.). The fourth nucleus lies in a hundred of animals. the Kalkalpen region (Upper Aus- In the 10x10 km raster, the number Present status and trend tria) and a very small nucleus in of occupied grid cells increased in the French Alps (Fig. 4). However, the 10-year period from 1995-1997 A kernel analysis of conﬁrmed re- during 2005-2007 reproduction has to 2005-2007 (Fig. 5). The trend cords from 2005-2007 illustrated only been reported in three areas: the lines show an increase in the area that the most important lynx area north-western Alps, the French Alps occupied until the 2002-2004 period, is located in the north-western Alps and north-eastern Switzerland. No with a slight decrease in recent years (western Switzerland). There is a reproduction was reported from the (Fig. 6). The western area of occur- 12 KORA Bericht Nr 50

rence was about twice as large as the eastern one. The western occurrence covered the largest area in the 2002- 2004 period, and the eastern occurrence one year later (Fig. 6). Overall, during the past 10 years the area occupied in the Alps increased by 4300 km2 or 35% through natural expansion and another 2000 km2 or 15% through the translocation of 12 lynx to north-eastern Switzerland.

Dispersal Fig. 6. Trend of the area occupied by lynx based on the 10x10 km grid (green line = whole Alps, blue line = western subpopula�ons, red line = eastern subpopula�on). Dispersal data was available from the north-western Swiss Alps (NWSA) and the Jura Mountains (JM), the Baltic population (BP), and the Nor- dic population (NP), and anecdotal observations are available from north-eastern Switzerland (NECH), the Bavarian-Bohemian Forest (BBF), and the Dinaric Mountains (DM). Thus, the dispersal data (1-22 individuals per study area) stem from 7 different populations or subpopulations (Table 1), in total from 60 individuals. The overall mean dispersal distance was 39 km, the median 27 km. 68% of documented dispersal distances were less than 50 km (Fig. 7). In the Alps, subadult lynx showed a great variety of dispersal Fig. 7. Dispersal distances of lynx from 7 diﬀerent popula�ons or subpopula�ons (JM = Jura types, from remaining philopatric Mountains, CN = Central Norway, NWSA = north-western Swiss Alps, BPF = Bialowieza Prime- to long-distance dispersal of up to val Forest, DM = Dinaric Mountains, BBF = Bavarian Bohemian Forest, NECH = north-eastern 200 km (Table 1, Fig. 8). However, Switzerland). from the Nordic population dispersal

Table 1. Number of Eurasian lynx from 7 European areas followed during dispersal, sorted from low to high maximum dispersal distance. Location Mean dispersal Max. observed n References distance dispersal distance Dinaric population 22 3 Kos pers. comm., Kusak pers. comm. Bavarian-Bohemian Forest 50 1 Wölﬂ pers. comm. North-western Swiss Alps 26 56 22 Zimmermann et al. 2005, 2007 Nordic population 42 79 5 Sunde et al. 2000 Jura Mountains 63 97 17 Zimmermann et al. 2005, 2007

Baltic population 41 129 9 Schmidt 1998, Schmidt pers. comm., Valdmann pers. comm. North-eastern Switzerland 200 3 Haller 2009, Ryser et al. 2004, 2006 April 2010 13

distances of more than 400 km are documented (Linnell, pers. comm.). The median dispersal distance in the Alps was lower than in the Jura Mountains but higher than in the Baltic population. Most long range dispersals concerned males, the longest recorded dispersal distance of a female was 81 km (Fig. 9).

Survival

The fate of 58 lynx during their second year of life was reported. Of these, 57% completed dispersal and Fig. 8. Median (and range) dispersal distance in 6 diﬀerent popula�ons (DM = Dinaric Moun- potentially reproduced. The fate of tains, BP = Bal�c popula�on, NP = Nordic popula�on, Alps = data from the north-western 11 individuals was unknown due to Swiss Alps and north-eastern Switzerland combined, JM = Jura Mountains, BBF = Bavarian collar failure. Overall, the survival Bohemian Forest). rate of subadult lynx was 0.72. Re- garding the Alps, the survival rate of 18 subadult lynx in the north-western Swiss Alps was even higher: 0.83. Sample size was very small for analyzing differences in mortality factors (n = 14). Disease was most important, followed by human caused mortalities (trafﬁc accidents, illegal killings and legal harvest). Two subadult lynx were killed by other predators (one by a lynx, the other by an unknown predator), and one lynx starved. The cause of death of two subadults was unknown (Ta- ble 2).

Discussion Fig. 9. Dispersal distances of males (left) and females (right).

Based on their ability to survive, Table 2. Causes of mortalities in different populations (JM = Jura Mountains, BP = Baltic disperse and subsequently repro- population, NP = Nordic population, BBF = Bavarian-Bohemian Forest, DM = Dinaric duce, subadults play a vital role in Mountains). the restoration of lynx populations Alps JM BP NP BBF DM Total and range expansions. However, it is Starvation 1 1 difficult and time consuming to ob- Disease 1 2 3 tain data on dispersal. In addition, it Traffic 1 1 2 is often impossible to determine the fate of dispersing individuals and Illegal killing 2 2 the proportion that become breed- Predation 2 2 ers (Vitalis 2002). A consequence of Quota hunting 2 2 these limitations is that many field Unknown 1 1 2 studies on large carnivores yield Total 3 5 2 2 1 1 14 only anecdotal information on dis- 14 KORA Bericht Nr 50

persal. Nevertheless, we were able project of north-eastern Switzerland: lynx will reach the Bavarian Alps to collect (including unpublished A female lynx was killed in a traffic highly depends on the availability material) data on 60 lynx that were accident 46 km south of the mother’s of suitable habitat and especially its partly or completely followed dur- home range (Ryser, in prep.) and a fragmentation. Zimmermann et al. ing their first year of independence male lynx was captured at the Swiss- (2007) have found that highways and it is possible to draw some first Italian border, fit with a GPS/GSM were important barriers to dispersal, conclusions. collar and subsequently followed on as three out of four dispersing lynx In the light of a complete recoloni- his dispersal (Haller 2009). He estab- did not cross highways and turned sation of the Alps (and in particular lished a home range in the Trentino back after they spent a few days in the Bavarian Alps), we need to con- region (Fig. 4; since this lynx arrived their vicinity. Thus habitat restric- sider 3 factors: (1) an analysis of the in the Trentino during spring 2008, tions (a lack of suitable habitat as closest existing source population, he does not show up on the map of well as linear barriers) led to circular (2) the fragmentation and the disper- Fig. 5 as it compiles only data up to dispersal in males in the north-west- sal capability of lynx, their survival 2007). There is no confirmation that ern Swiss Alps. Zimmermann et al. probability and associated mortality the Trentino region is presently fre- (2007) concluded that the lynx’ low factors, and (3) the probability of the quented by a second lynx. The third ability to cross major barriers such establishment of a population nucle- lynx who has left the perimeter of as fenced highways hampers the us given successful dispersal or the the translocation project was one of colonization in a fragmented land- enlargement of an existing occur- the translocated female lynx who es- scape such as the Alps. Since lynx rence, respectively. tablished a home range in the south dispersing from north-eastern Swit- Potential sources for the coloniza- but it is supposed that she never had zerland to the Bavarian Alps have to tion of the Bavarian Alps are the contact with a male lynx since she cross two highways (A13 Sargans- north-eastern Swiss subpopula- never had kittens (Ryser, in prep.). St. Margrethen in Switzerland, A14 tion, the Kalkalpen and the south- In the Kalkalpen region of Upper Bregenz-Bludenz in Austria), it is eastern Alps occurrences (Fig. 4), Austria there is another isolated oc- probable that most of them will take and the Bohemian-Bavarian Forest currence of 1-2 individuals with un- another dispersal direction. population. The north-eastern Swiss known origin. No reproduction was With only 14 documented cases of subpopulation is of special inter- ever reported from the Kalkalpen deaths the sample size is too small est in this respect as it was founded region and although reproduction is to compare different mortality fac- through the translocation of 12 lynx. suspected to occur in the south-east- tors of subadult lynx. However, the This case study allows us to look at ern Alps, during the past 3 years no survival of subadult lynx based on the likelihood of successful coloni- signs of reproduction were detected this analysis with 47 individuals was zation of a new habitat patch, given neither in this area. Although within 0.72. Andren et al. (2006) have ana- dispersal. We here therefore outline dispersal distance, the recolonisation lyzed the survival of subadult lynx in the fate of the translocated lynx and of the Bavarian Alps by the Bavarian different parts of the Nordic popula- their progeny (see Ryser in prep. for Bohemian Forest lynx population is tion, where the survival ranged from a detailed assessment): From 2001 to highly unlikely due to the lack of a 0.43 to 0.90, depending on the re- 2009 a total of 7 female and 5 male suitable corridor. Therefore, the only gion. With 0.83, the survival of sub- lynx were translocated. Three of the possible source population for the adult lynx in the north-west Swiss females have never reproduced. Of Bavarian Alps presently is the north- Alps does not seem to be a limiting the remaining 4 females a total of eastern Swiss subpopulation. factor to colonization, contrary to 9 litters are reported (data analyzed The straight-line distance a lynx habitat structure. until end of 2009), of which at least has to travel from the core area of Since the probability that even a sin- 7 lynx have reached the age of inde- the north-eastern Swiss Alps across gle lynx reaches the Bavarian Alps pendence (Ryser, in prep.). Although Vorarlberg in Austria to the Bavar- is low, a natural recolonisation of there have at times been rumors of ian Alps is about 70 km. Of the 41 the Bavarian Alps within the next signs of lynx presence in adjacent lynx of which full dispersal data decades, followed by the success- Liechtenstein (Fasel 2006), Vorarl- were available 7 (17%) dispersed ful settlement of a viable population berg (Laass et al. 2006), the cantons 70 km or further (Fig. 7). Besides, nucleus, seems very unlikely. The of Glarus and Grisons (Ryser in prep., in the Nordic population straight- further an animal disperses from its Zimmermann et al. 2009), only three line dispersal distances of more than core range the less likely it will find lynx in 9 years are confirmed to have 400 km are known (Linnell, pers. a mate. Kramer-Schadt et al. (2005), left the perimeter of the translocation comm.). Yet, the probability that a who conducted a population viabil- April 2010 15

ity analysis for lynx in Germany, highways and more data on survival and the traditional land users. Two concluded that from a demographic and mortality of subadult lynx. Some issues are commonly of most con- viewpoint at least 10 females and 5 radio-tagged lynx are known to have cern when lynx newly arrive in an males are required for a start that will e. g. crossed high-speed freeways, area: the predation impact on the develop into a viable population with but the significance of such barriers local ungulate community and the an extinction probability of less than for the spread of the population is question, how many lynx frequent 5% in 50 years. Nevertheless, in Slo- difficult to evaluate. Lynx are able to the area. We recommend to include venia a lynx population was founded climb a fence, or cross a stripe of ag- local people into the monitoring based on 3 males and 3 females only ricultural land. However, it is impor- of lynx to improve mutual trust, (Cop and Frkovic 1998), and in the tant to know how often lynx leave as monitoring is at the base of any Vosges based on 4 females and 6 their source habitat patch, how they management or conservation mea- males (Vandel et al. 2006). Based on interact and communicate across sure and the data basis needs to be a deterministic matrix-based model, such barriers, and how they establish accepted by all partners. Vandel et al. (2006) have found that individual home ranges in new areas the probability was very low for a to predict how the species colonizes population growth based on such a new patch. References few founder individuals, as a very And finally, to predict the future low percentage of the simulated tra- of the Alpine lynx occurrences, we Andren, H., J.D.C. Linnell, O. Li- jectories (i.e. less than 50%) would need to model the population viabil- berg, R. Andersen, A. Danell, J. attain the observed growth (with ity of the present lynx metapopula- Karlsson, J. Odden, P.F. Moa, P. or without poaching) as long as the tion in the Alps by means of a spa- Ahlqvist, T. Kvam, R. Franzen, adult survival rate was not close to tially explicit demographic model. and P. Segerstrom 2006. Surviv- 0.90. However, the extinction risk Based on the reproduction and sur- al rates and causes of mortality decreases sharply with increas- vival data from lynx in the Alps we in Eurasian lynx (Lynx lynx) in ing immigration rate (e.g. Enneson need to evaluate the probability of multi-use landscapes. Biological and Litzgus 2009). Marboutin et al. persistence (or extinction) of existing Conservation 131: 23-32. (2006) have shown that lynx occur- subpopulations. This would allow Andreassen, H.P. and R.A. Ims 2001. rences have a higher probability of us to include different management Dispersal in patchy vole popula- persistence if they are demographi- scenarios into the modeling. These tions: role of patch configuration, cally connected with each other. kinds of analyses would produce density dependence, and demog- However, if in the next decade the the basis for future conservation and raphy. Ecology 82: 2911-2926. expansion will continue as observed management efforts. Although lynx Breitenmoser, U. and H. Haller during the past decade, in 2017 only in the north-western Swiss Alps 1993. Patterns of predation by re- 28.000 km2 will be colonized. This have gained some territory, overall introduced European lynx in the is less than 20% of the Alps follow- the colonization has stagnated (Fig. Swiss Alps. Journal of Wildlife ing the definition of the Alpine Con- 6). As a possible management sce- Management 57: 135-144. vention. nario we may have to consider the Breitenmoser-Würsten, Ch., F. Zim- artificial transfer of individuals to mermann, A. Ryser, S. Capt, J. several neighboring patches, rather Laass, A. Siegenthaler and U. Next steps than creating one population. Thus, Breitenmoser 2001. Untersuch- dispersing animals may encounter ungen zur Luchspopulation in Due to the importance of connectiv- conspecifics when moving away den Nordwestalpen der Schweiz ity for the persistence of subpopula- from the place of origin (Zimmer- 1997-2000. KORA Bericht 9: 1- tions, in a next step it would be im- mann et al. 2007). 88. portant to analyze lynx movements A prerequisite for the successful es- Bray, Y., S. Devillard, E. Marbou- in respect to barriers to evaluate the tablishment of lynx in a new habitat tin, B. Mauvy and R. Peroux 2007. permeability of the barriers created patch or the maintenance in already Natal dispersal of European hare in by the highways A13 and A14, and colonized areas is the social accep- France. Journal of Zoology: 1-7. others in the whole Alps. Recent ad- tance by local stakeholders. The re- Capt, S. 2007. Monitoring and pres- vances in technology, such as GPS/ covery of lynx is a complicated and ent status of the lynx Lynx lynx GSM collars, will aid in getting more lasting process, and it is important in the Jura Mountains. Wildlife accurate data on the ability of lynx to to develop strategies to mitigate the Biology 13: 356-364. overcome physical barriers such as conflict between the returning lynx Clobert, J., J.F. LeGalliard, J. Cote, 16 KORA Bericht Nr 50

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