Resident Lynx Research Articles

Long-term changes in habitat selection and prey spectrum in a reintroduced Eurasian lynx (Lynx lynx) population in Switzerland.

When wild‐caught Eurasian lynx (Lynx lynx) from the Slovak Carpathian Mountains were reintroduced to Central Switzerland in the early 1970s and spread through the north‐western Swiss Alps (NWA), they faced a largely unfamiliar landscape with strongly fragmented forests, high elevations, and intense human land use. For more than 30 years, radio‐collared lynx have been monitored during three different project periods (in the 1980s, 1990s, and 2010s). Our study explored, how lynx over generations have learned to adjust to the alpine environment. We predicted that (1) lynx nowadays select more strongly for open habitats, higher elevations, and steep slopes compared to the early stages of recolonization and that (2) consequently, there were significant changes in the Eurasian lynx’ prey spectrum. To test our predictions, we analyzed telemetry data (VHF, GPS) of 13 adult resident lynx in the NWA over 35 years, using Resource Selection Functions. Furthermore, we compared kills recorded from different individuals inhabiting the same region during three project periods. In general, lynx preferred forested areas, but over the years, they avoided open habitat less. Compared to the early stage of the recolonization, lynx in the most recent project period selected for higher elevations and the proportion of chamois in their prey spectrum surmounted that of roe deer. Potential driving factors for the observed changes could be increasing tolerance to human presence, intraspecific competition, or fitness benefits through exploitation of new resources. Long‐term studies like ours provide important insight into how animals can respond to sudden environmental changes, e.g., in the course of translocations into new areas or anthropogenic alterations of their habitats.

Movement patterns and habitat selection during dispersal in Eurasian lynx

Natal dispersal affects the gene flow, distribution, dynamics and social structure of a population. In many solitary mammals, dispersal is often male-biased, while females may remain philopatric. For the Eurasian lynx (Lynx lynx), dispersal distances vary greatly and may be explained by sex or by habitat characteristics, such as fragmentation. Juvenile lynx habitat selection during dispersal has not been studied before, but resident lynx select heterogeneous forested habitats and avoid human settlements and infrastructure through distinct temporal activity patterns. We studied movement patterns and habitat selection during the dispersal of 22 Eurasian lynx (7 females, 15 males) in Finland. We found no differences between the sexes in the onset age, duration, distance, route or route linearity. Dispersal took place mostly during the evening and at night but also during the day. Of the four most used habitats, the mixed forests and transitional woodlands were used more frequently than would be expected according to their availability, and conifer forests and fields less than would be expected. Housing and other human infrastructure, including roads, were the least frequently used categories. There was a highly significant difference between the used and available habitats in general. The lynx selected the habitat more carefully during the day than during the night.

Habitat availability is not limiting the distribution of the Bohemian–Bavarian lynxLynx lynxpopulation

AbstractA population of Eurasian lynxLynx lynxwas established by reintroductions in the Bohemian Forest Ecosystem in the 1970s and 1980s. The most recent information on the population status indicates that the distribution has stagnated since the late 1990s, for unknown reasons. We assessed the availability of suitable habitat along the Austrian–German–Czech border, and hypothesized that the Bohemian–Bavarian lynx population is not in equilibrium with habitat suitability. Based on global positioning system data from 10 radio-collared lynx, we used a maximum entropy approach to model suitable habitat. Variables reflecting anthropogenic influence contributed most to the model and were negatively associated with the occurrence of lynx. We evaluated the model prediction using independent records of lynx from monitoring in Bavaria, Germany. Using our habitat approach we estimated the area of potential habitat, based on a mean annual home range of 445 km2for males and 122 km2for females. Our results indicated there were 12,415 km2of suitable habitat, distributed among 13 patches, for a potential population of c. 142 (93–160) resident lynx. We assessed connectivity via least-cost paths and found that all suitable patches could be reached by the lynx. A comparison with the current distribution of lynx, however, confirms that a significant proportion of suitable habitat is not occupied, which indicates that the distribution is limited by factors other than habitat, with illegal killing being the most likely cause. Our study provides crucial information for the development of a conservation strategy and regional planning for the Bohemian–Bavarian lynx population.

Lynx Habitat Suitability In and Near Voyageurs National Park

ABSTRACT: Voyageurs National Park (VNP) is within the historical distribution of Canada lynx (Lynx canadensis), a federally threatened species. Sightings of lynx in and near VNP have existed since the 1970s, and three recent sightings have been confirmed with DNA analysis. However, population status and habitat suitability for lynx in VNP are unknown. We used remote cameras and snow-tracking to search for lynx in and near VNP in 2007 and 2008 and did not document lynx presence. We estimated the density of the lynx's primary prey, snowshoe hare (Lepus americanus), with hare pellet counts, extrapolated hare density to the landscape level, and compared habitat in VNP to habitat in lynx home ranges in northeastern Minnesota. Hare pellet densities in VNP were about half of hare pellet densities in lynx home ranges in northeastern Minnesota. Even though patches of high-density hare habitat exist in the VNP area, the low density of snowshoe hares at the landscape level would not support resident lynx, and most o...

Modeling habitat potential for Canada lynx in Michigan

AbstractIn the ruling to list Canada lynx (Lynx canadensis) as a federally threatened species, the U.S. Fish and Wildlife Service (USFWS) identified the Great Lakes region as an area that historically contained lynx and, hence, could potentially contribute to population recovery. More recent critical habitat designations by the USFWS only recognize Minnesota, USA as important to recovery in the Great Lakes. Although there is no current evidence of a resident lynx population in the Upper Peninsula (UP) of Michigan, USA, trapping and track records over the past century suggest the region was periodically invaded after lynx population irruptions in Canada. In support of state and federal agency efforts in Michigan to provide and conserve lynx habitat, we quantified habitat potential using a spatially explicit, landscape‐level model based on relationships among lynx, their primary prey, snowshoe hare (Lepus americanus), and vegetation attributes. Outputs from the model indicated that habitat in the UP supports low hare densities (<0.07–0.75 hares/ha). Corresponding potential lynx densities ranged from 0/100 km2 in the southern and northeast UP to 5/100 km2 in the central–eastern UP. Model estimates of potential hare density were correlated with winter track‐surveys (R2 = 0.4, P < 0.001). Current absence of a resident lynx population in Michigan is likely attributed to confounding factors (e.g., habitat, competition, status of source population) but our results indicate that current habitat quality, quantity, and spatial configuration are exerting large‐scale negative influences. These results are generally consistent with the USFWS determination that Michigan's UP most likely functions as dispersal habitat. © 2011 The Wildlife Society.

Competition between recolonizing wolves and resident lynx in Sweden

We studied the effect of a recolonizing wolf ( Canis lupus L., 1758) population on a resident lynx ( Lynx lynx (L., 1758)) population in south-central Sweden. Wolf and lynx share the same prey species, western roe deer ( Capreolus capreolus (L., 1758)), and the size difference between the two species suggests a strong potential for interference competition. The spatial distributions of lynx family groups (n = 378) over four winters were not significantly affected by the increase in size and range of the wolf population. Survival of lynx kittens until 9 months of age did not differ significantly inside (54%; n = 37) and outside (62%; n = 42) wolf territories, and female lynx (n = 3) selected natal den sites (n = 19) in the same local area before and after wolf establishment. Furthermore, lynx home-range size (n = 42) did not increase as a result of presence of wolves and space use by female lynx (n = 3) was not affected by wolf establishment. We found no evidence of cleptoparasitism by wolves on roe deer killed by lynx. We conclude that the intensity of interference and exploitation competition between wolves and lynx was low.

Spatial Ecology of a Canada Lynx Population in Northern Maine

Canada lynx (Lynx canadensis) were listed as a federally threatened species in 14 states at the southern extent of their geographic range in March 2000, with Maine being the only state in the northeastern United States known to support a resident population. Relatively little information is known about the ecology of lynx living at the southern edge of their range, including range requirements, movements, and spatial organization. Basic knowledge of lynx ecology is needed for federal recovery planning efforts. Between 1999 and 2004, we trapped and radiocollared 43 lynx (21 M, 22 F) in northern Maine in an intensively managed and predominantly early successional forested landscape. We estimated diurnal annual and seasonal home-range size for male and female lynx using the 85% fixed-kernel home-range estimator. Annual home ranges of adult male lynx (x̄ = 53.6 km2) were more than twice the size of adult female home ranges (x̄ = 25.7 km2). Home ranges of adult females during snow periods (x̄ = 38.3 km2) were nearly 3 times larger than their snow-free-period ranges (x̄ = 14.3 km2), whereas, snow-free ranges of adult males (x̄ = 58.8 km2) were slightly larger than their snow-period ranges (x̄ = 45.2 km2). We observed a limited amount of home-range overlap among lynx of the same sex (F: x̄ = 17.2%; M: x̄ = 11.8%). Lynx of opposite sex showed more extensive overlap (x̄ = 24.3%). Most home-range shifts of resident lynx were typically not extensive. Based on territory mapping, we estimated a minimum lynx density of 9.2–13.0 lynx/100 km2. We observed lynx spatial ecology and densities that were more similar to northern lynx populations when hares were abundant than to other southern lynx populations, suggesting that region-specific studies under varying habitat conditions and hare densities are needed to ensure realistic recovery goals and effective management of lynx at the southern extent of their range.

Prey density, environmental productivity and home‐range size in the Eurasian lynx ( Lynx lynx )

Variation in size of home range is among the most important parameters required for effective conservation and management of a species. However, the fact that home ranges can vary widely within a species makes data transfer between study areas difficult. Home ranges of Eurasian lynx Lynx lynx vary by a factor of 10 between different study areas in Europe. This study aims to try and explain this variation in terms of readily available indices of prey density and environmental productivity. On an individual scale we related the sizes of 52 home ranges, derived from 23 (9:14 male:female) individual resident lynx obtained from south-eastern Norway, with an index of density of roe deer Capreolus capreolus. This index was obtained from the density of harvested roe deer within the municipalities covered by the lynx home ranges. We found a significant negative relationship between harvest density and home-range size for both sexes. On a European level we related the sizes of 111 lynx (48:63 male: female) from 10 study sites to estimates derived from remote sensing of environmental productivity and seasonality. A multiple linear regression model indicated that productivity of the study site had a clear negative relationship with home-range size. At both scales, sex emerged as a significant explanatory variable with males having larger home ranges than females. In addition, the size of male home-ranges increased faster with decreasing prey density than for females. These analyses support widely held predictions that variation in home-range size is due to variation in prey density.

Assessing the suitability of central European landscapes for the reintroduction of Eurasian lynx

Summary After an absence of almost 100 years, the Eurasian lynx Lynx lynx is slowly recovering in Germany along the German–Czech border. Additionally, many reintroduction schemes have been discussed, albeit controversially, for various locations. We present a habitat suitability model for lynx in Germany as a basis for further management and conservation efforts aimed at recolonization and population development. We developed a statistical habitat model using logistic regression to quantify the factors that describe lynx home ranges in a fragmented landscape. As no data were available for lynx distribution in Germany, we used data from the Swiss Jura Mountains for model development and validated the habitat model with telemetry data from the Czech Republic and Slovenia. We derived several variables describing land use and fragmentation, also introducing variables that described the connectivity of forested and non‐forested semi‐natural areas on a larger scale than the map resolution. We obtained a model with only one significant variable that described the connectivity of forested and non‐forested semi‐natural areas on a scale of about 80 km2. This result is biologically meaningful, reflecting the absence of intensive human land use on the scale of an average female lynx home range. Model testing at a cut‐off level of P > 0·5 correctly classified more than 80% of the Czech and Slovenian telemetry location data of resident lynx. Application of the model to Germany showed that the most suitable habitats for lynx were large‐forested low mountain ranges and the large forests in east Germany. Our approach illustrates how information on habitat fragmentation on a large scale can be linked with local data to the potential benefit of lynx conservation in central Europe. Spatially explicit models like ours can form the basis for further assessing the population viability of species of conservation concern in suitable patches.

Vegetation structure and prey abundance requirements of the Iberian lynx: implications for the design of reserves and corridors

Summary Habitat alteration and fragmentation are two of the greatest threats to biodiversity. The conservation of most species in highly encroached areas requires reserves that are connected by suitable habitat corridors to increase the effectiveness of the area under protection. However, the quality required for such corridors is still debated. This study investigated the habitat characteristics (vegetation structure and prey abundance) of sites used by resident and dispersing Iberian lynx in south‐western Spain. Vegetation structure and an index of rabbit abundance (the staple prey of lynx) were measured at sites used by radio‐collared lynx in 1996 and 1997. Data from 128 plots used by resident lynx and 310 plots used by dispersing individuals were compared with data from 162 randomly located plots in sites considered to be unused by lynx.3. Resident sites had a lower percentage of tree cover, shorter tree height, higher percentage of tall shrub cover, higher percentage of overall understorey and higher number of rabbit pellets than both dispersal and unused sites. The height of the short shrub layer was taller and the rabbit abundance index was higher in dispersing sites than in unused sites. Gender did not affect habitat selection by lynx. During dispersal, lynx frequently (50% of cases) used vegetation patches narrower than 300 m. In these cases, sites used by lynx had higher understorey cover and taller shrub height than adjacent unused sites. The percentage of short shrub cover used by lynx increased with the length of time taken to disperse; this was the only variable that changed over time. Range size of resident individuals declined significantly with the index of rabbit abundance but increased with the percentage of short shrub cover. Both variables were good predictors of range size. The study shows that corridors connecting reserves do not have to be prime habitats; they can even support moderate habitat degradation due to human activity. This result has implications both for the conservation of existing corridors, and for the restoration of the many corridors between reserves that have been lost.

Spatial organization of a lynx population

I examined the home-range relationships and spatial organization of an untrapped lynx (Lynx canadensis) population in the southern Northwest Territories, Canada. I determined annual home ranges and static and dynamic interactions among 30 radio-collared adult lynx from April 1989 to April 1993. Densities of snowshoe hares (Lepus americanus), the main prey, declined during winter 1990–1991. There was extensive range overlap between sexes, and between certain pairs of female lynx. Ranges among most males and among other individual or pairs of females were more exclusive. Most intrasexual dynamic interactions indicated neither attraction nor avoidance, suggesting that home-range boundaries were maintained by passive means. Two male–female pairs showed some positive attraction during the early part of the first winter of low hare density. Home ranges of three male and three female lynx monitored for 3 consecutive years were stable. Spatial organization broke down during winter 1991 – 1992, when all resident lynx died or dispersed; this was concomitant with the first full winter of low hare density. Spatial organization observed prior to low hare densities may be described as a land-tenure system, based on prior residency, and may have served to regulate the density of this untrapped population during peak prey levels.

Predators of Cyclic Prey: Is the Canada Lynx Victim or Profiteer of the Snowshoe Hare Cycle?

Most populations of predators of cyclic prey fluctuate as their reproductive output and survival is a function of prey availability. The predator's response to a given prey density, however, may alter from the increase to the decrease phase. In cycles, the development of the prey population is predictable, and more sophisticated strategies can evolve. We develop an hypothesis on the life history strategy of the Canada lynx (Lynx canadensis). We propose that resident lynx form a core population and occupy large and stable home ranges throughout the cycle. Their reproductive output is maximized with increasing prey availability, but reduced in the decline phase before the investment threatens the long-term survival of the residents