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

Reliable density estimates are the cornerstone of effective conservation and management planning. For large carnivores however, estimating density is difficult because these species are elusive and wide-ranging. Here, we focus on the Eurasian lynx (Lynx lynx) in the French Jura and Vosges Mountains (Mts) and provide the first density estimates. We set up 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 Mts. We obtained 592 lynx detections over 19,035 trap days in the Jura Mts and 0 detection over 6,804 trap days in the Vosges Mts. 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. 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 Mts are comparable to other lynx populations in Europe, the situation in the Vosges Mts is alarming. Connectivity should be encouraged between the French Jura Mts 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.