Christine Breitenmoser-Würsten

People and Wildlife: Non-lethal techniques for reducing depredation

INTRODUCTION Ever since humans domesticated the first animals several thousand years ago, there have been conflicts with large carnivores attacking livestock (Kruuk 2002). Every year, thousands of cattle, sheep, goats, poultry or farmed fish are killed by wild carnivores worldwide (Thirgood et al ., Chapter 2) (Table 4.1). The farmers, in turn, kill the predators. Lethal control of stock-raiders is common in all cultures and has a devastating impact on many populations of large carnivores (Woodroffe et al ., Chapter 1). Retaliatory killing was the most important reason for the historic eradication of large carnivores in large areas (Breitenmoser 1998). In addition to killing the predators, herdsmen have tried to protect their livestock, mainly because lethal control alone rarely reduced depredation to an acceptable level. For a traditional society, the investment in terms of labour and resources for the protection of livestock was high (Kruuk 2002). Rural cultures have consequently adopted a combination of non-lethal measures, lethal control and – strongly varying between cultures – an acceptance of losses. The application of non-lethal techniques was mainly a matter of technology and of cost–benefit considerations. From the perspective of modern society, there are two more reasons to propagate preventive measures: conservation (lethal control threatens many carnivore populations), and ethical arguments (moral reservation against the killing of predators and against livestock being exposed to pain and suffering).

Spatial and Social stability of a Eurasian lynx Lynx lynx population: an assessment of 10 years of observation in the Jura Mountains

Abstract A total of 18 Eurasian lynx Lynx lynx were radio-tagged between March 1988 and June 1998 in the Swiss Jura Mountains, and during 1995-1997 eight animals were radio-tagged on the French side of the mountain chain. Adult males occupied larger long-term home ranges than adult females (283 km2 vs 185 km2). Neighbouring males shared 7.3% of their home ranges and females 0.2%. The mean distance between males and females living in the same area for fixes taken the same day was 10.94 ± 8.61 km, underlining the solitary character of the species. Consecutive individual annual home ranges overlapped 71.7 ± 7.3% for females and 77.5 ± 7.9% for males, indicating high spatial stability over time. In the Swiss study area, two adult animals were followed for seven and nine years, respectively, and another two lynx were observed in the study area for nine years. Range size did not vary across three distinct periods, P1-P3, but the sex ratio did. Generally, males covered the ranges of 1-2 females, but during the second period, P2, the range of a single male overlapped with those of six females. Dead females were all immediately replaced, but dead males were not. Two poached males were only replaced after three and five years, respectively. Population density, ranging within 0.7-0.8 adult resident lynx/100 km2, did not vary significantly over time in Switzerland. Including kittens and subadults, the density was 1.1-1.6 lynx/100 km2. Our study in the Jura Mountains indicated that there is long-term stability in the social and spatial structure of the lynx population, but this stability was temporarily disturbed by the lack of adult resident males.

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 predators 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

Demography of lynx Lynx lynx in the Jura Mountains

Abstract We radio-collared a total of 29 lynx in the Swiss Jura Mountains and collected data on demography during 1988-1998. We were able to observe 10 2-14 year-old females for 32 female years. Lynx kittens were born between 12 May and 13 June (26 May ± 9 days). One female gave birth to a litter on 26 August after she had lost her first litter born in May. The average litter size was 2.00 ± 0.75 kittens (range: 1-3). The sex ratio of 1.67 females:1 male did not differ significantly from the expected ratio of 1:1. On average, 81% of adult females reproduced each year. The overall reproduction rate was 1.67 kittens/female year. Of 49 kittens, 43-49% survived until independence at the age of about 10 months. The survival rate of subadults and adults was 53 and 76%, respectively. Litter size and survival of kittens and subadults varied considerably between three observation periods, i.e. P1-P3 (P1: 1988-1991, P2: 1992-1994, P3: 1995-1997), characterised by substantial changes in the social structure of the population. During P2 only one resident male was present in the main study area, and during this period, the average litter size was lowest with 1.50 kittens only. The survival of kittens was with 37-44% lowest as well, mainly because of the high proportion of litters where all kittens were lost. However, the survival of subadults was highest during P2, when observed animals survived to adulthood. During 1974-2002, 124 mortalities were documented for the whole of the Jura Mountains. Human related mortalities were responsible for 70% of known losses. An estimation based on the radio-collared lynx suggested that poaching may have been responsible for as much as 32% of total mortality. In contrast to other study areas, traffic accidents were very important in the Jura Mountains. They might represent as much as 29% of mortality. During our 10-year study period, no significant spatial expansion of the population was recorded in Switzerland. We suppose that the high human-related mortalities limited the population, which also would explain the lack of a numerical response to an increase in prey abundance observed during the same period in the study area in Switzerland.

Conservation of the lynx Lynx lynx in the Swiss Jura Mountains

Abstract Lynx Lynx lynx returned to a semi-natural, human dominated landscape in the Jura Mountains in France and Switzerland after reintroductions in the early 1970s. Controversy has resulted from lynx attacking sheep and preying on game species such as roe deer Capreolus capreolus and chamois Rupicapra rupicapra. We review the history of the lynx, the transition of the landscape and fauna in the Jura Mountains, and recent findings from long-term field studies on the species. Possible threats to the survival of the population are assessed. The ecological conditions for the existence of the lynx in the Jura Mountains have improved since the species was eradicated in the 19th century. Both habitat and prey base are suitable for maintaining the population. Immediate threats include traffic accidents and illegal killings. Long-term threats include small population size and genetic impoverishment as a result of the post-reintroduction bottleneck. We recommend conservation and management that involve local people and cooperation at national and international scales. Fragmentation of the habitat and the management system should be avoided, and landscape linkages from the Jura Mountains to adjacent mountain ranges should be established to promote a lynx metapopulation.

Characterisation of Eurasian lynx Lynx lynx den sites and kitten survival

Abstract We retrospectively investigated characteristics of den structures and den sites used by female Eurasian lynx Lynx lynx in the Jura Mountains and the northwestern Alps of Switzerland. During 1983-2000, we discovered 30 natal and 40 maternal dens belonging to 26 females. Important den structures were closed, i.e. provided good shelter, had few entrances, and measured 1 m2. Dens were found in rocky places, caves and wooden surroundings. Most dens were located in mixed forests with relatively open vegetation allowing for a visibility of 10-20 m. Contrary to our expectations, natal and maternal dens were equally exposed to human disturbance and were found in terrain which could be dangerous for the kittens. Overall, the two den types barely differed. While concealment did not seem to play a very important part at natal dens and while natal dens were almost never open structures, maternal dens were surrounded by a large number of hiding places and the dens and surroundings were rich in visual contrasts providing good camouflage options. Dens in the Alps and in the Jura Mountains were located in steeper terrain than available on average. The quality of the den sites did not seem to affect the survival of young lynx. Well-suited den sites are so abundant in the Alps and the Jura Mountains that females obviously have no problems finding good den sites.

Importance of dispersal for the expansion of a Eurasian lynx Lynx lynx population in a fragmented landscape

Dispersal allows recolonization of previous areas of habitat following severe depression of a popu- lation but the significance of this is not clear in felids. There is little evidence to support the general belief that subadult felids will colonize new areas, although this is a crucial assumption in reintroduction or recovery projects. Eurasian lynx Lynx lynx were reintroduced into the Swiss Alps and have subsequently spread over part of their potential range but the expansion halted in the mid 1980s. We postulated that high lynx densities would lead to an expansion of the population, and to assess the potential of this population to expand we compared the dispersal characteristics of 22 subadults from the north- west Swiss Alps, where an increase in lynx abundance occurred from 1995 onwards, to 17 individuals from the Jura Mountains, an area with a lower lynx density. Dispersal data came mainly from radio-telemetry. Dis- persal rates and distances for subadults that completed dispersal were lower in the north-west Swiss Alps than in the Jura Mountains. In general, subadults exhibited little ability to cross major barriers such as highways. The hypothesis that high density alone will foster the expansion of the population was therefore not confirmed. This has consequences for the reintroduction and recovery of carnivores in fragmented landscapes. To establish only one strong source population may not be an optimal strategy, and population nuclei should therefore be founded in several neighbouring patches.

Robust monitoring of the Eurasian lynx Lynx lynx in the Slovak Carpathians reveals lower numbers than officially reported

The Eurasian lynx Lynx lynx population in the Carpathian Mountains is considered to be one of the best preserved and largest in Europe and hence is a source for past and current reintroduction projects in central Europe. However, its status in Slovakia has been reported to the European Commission on the basis of hunters´ reports and expert estimates that have never been validated by a robust scientific approach. We conducted the first camera-trapping surveys to estimate the density of Eurasian lynx in Slovakia by means of spatial capture–recapture models in two reference areas during 2011–2015. We estimated population density per 100 km2 of suitable lynx habitat (posterior SD) as 0.58 ± SD 0.13 independent individuals (adults and subadults) in the Stiavnica Mountains and 0.81 ± SD 0.29 in Veľka Fatra National Park and surroundings. These are the lowest densities estimated using spatial capture–recapture models so far reported for the species, suggesting the lynx population in Slovakia is below carrying capacity. We suspect that low densities may be attributable to undetected human-caused mortality. Our results imply that official game statistics are substantially overestimated. Moreover, the lynx population in Slovakia may not be at favourable conservation status as required by the EU Habitats Directive. We therefore call for a thorough assessment of the density and trend of the Slovak Carpathian lynx population, and the establishment of a scientifically robust monitoring system.