Spatial density estimates of Eurasian lynx (Lynx lynx) in the French Jura and Vosges Mountains

Abstract

Obtaining estimates of animal population density is a key step in providing sound conservation and management strategies for wildlife. For many large carnivores however, estimating density is difficult because these species are elusive and wide-ranging. Here, we focus on providing the first density estimates of the Eurasian lynx (Lynx lynx) in the French Jura and Vosges mountains. We sampled a total of 413 camera trapping sites (with 2 cameras per site) between January 2011 and April 2016 in seven study areas across seven counties of the French Jura and Vosges mountains. We obtained 592 lynx detections over 19,035 trap days in the Jura mountain and 0 detection over 6,804 trap days in the Vosges mountain. Based on coat patterns, we identified a total number of 92 unique individuals from photographs, including 16 females, 13 males and 63 individuals of unknown sex. Using spatial capture-recapture (SCR) models, we estimated abundance in the study areas between 5 (SE = 0.1) and 29 (0.2) lynx and density between 0.24 (SE = 0.02) and 0.91 (SE = 0.03) lynx per 100 km2. We also provide a comparison with non-spatial density estimates and discuss the expected discrepancies. Our study is yet another example of the advantage of combining SCR methods and non-invasive sampling techniques to estimate density for elusive and wide-ranging species, like large carnivores. While the estimated densities in the French Jura mountain are comparable to other lynx populations in Europe, the fact that we detected no lynx in the Vosges mountain is alarming. Connectivity should be encouraged between the French Jura mountain, the Vosges mountain and the Palatinate Forest in Germany where a reintroduction program is currently ongoing. Our density estimates will help in setting a baseline conservation status for the lynx population in France.