Factors affecting lynx predation on sheep in the French Jura.
Abstract
1. In regions where sheep are kept in fenced pastures and do not graze unattended in carnivore habitats, sheep losses vary greatly between sites and livestock farms. To assess the factors that may predispose farms to lynx predation in the French Jura, we compared sheep availability and environmental characteristics between pastures with and without attacks in a 1800-km2 study area. Nine lynx were radio-tracked in the same area for a total of 21 lynx years to estimate individual killing rates on sheep and to identify possible habitual livestock killers. 2. Depending on individual and year, lynx predation rate on sheep within lynx home ranges varied between 0 and 12.4 attacks 100 days-1. Predation rate on sheep was not related to sheep abundance nor sheep dispersion in lynx home ranges. Two individuals became habitual sheep killers during, respectively, their third and fourth year of monitoring. Other lynx that had access to the same flocks were only occasional sheep killers. No obvious causal factor (e.g. sex, reproductive status, physical debilitation) explained the differential individual propensity for lynx to kill livestock. 3. We found no difference in sheep availability between pastures with and without attacks, but strong differences in their environmental characteristics. In only 5.1% of 98 pastures >250 m from a forest were sheep attacked by lynx. In 228 pastures adjacent or connected to forests by cover, 39.1% sustained attacks on sheep by lynx (P<0.01). For these latter pastures, logistic regression showed a positive effect of their proximity to major forested areas (P<0.01), absence of human dwellings (P<0.01), local abundance of roe deer (P=0.01) and the presence of attacked pastures in their vicinity (P=0.03). 4. These results suggests that lynx damage locally can be explained by a predictable set of habitat features that expose sheep on some pastures to risk, and by an unpredictable event, i.e. an individual developing regular predation on sheep. 5. In grazing systems like the Jura, where unattended sheep are distributed patchily and individual problem lynx may appear, removing lynx or lowering density without differentiating individuals will be insufficient to limit conflicts. Selective removals could temporarily reduce predation but the site effect implies that durable management can arise only through improved shepherding. This might include guard dogs in the few local sites at risk and providing shelter for sheep at night when attacks are on the increase.