In the mountainous regions of France—specifically the Jura, Alps, and Vosges—approximately 200 Eurasian lynx are believed to live. These elusive big cats, the largest wild feline in Europe, are difficult to track directly, so scientists rely on indirect signs like footprints, fur, and especially feces to study them. The "Œil de Lynx" project, led by the French Society for the Study and Protection of Mammals (SFEPM), used fecal samples collected between 2019 and 2025 as part of a national plan to conserve the lynx population. The goal of this initiative was to monitor the population and analyze its genetics to improve its conservation status. The findings were published in the journal Global Ecology and Conservation in June 2026, and were led by researchers from the Chrono-environment laboratory at the University of Marie and Louis Pasteur in Besançon. This study was the first large-scale genetic analysis of lynx in France using non-invasive fecal samples. This method avoids the need to harm or kill animals, which is often necessary when collecting blood samples from road-killed or injured lynx. The project relied on over 234 volunteers, including staff from environmental organizations, forest workers, protected area rangers, naturalists, and hunters. These volunteers were trained to recognize lynx feces, which are small, segmented balls with a slight indentation on one side and a rounded, slightly pointed end. The feces often contain hair from roe deer or chamois and may include the remains of small mammals. Volunteers collected the samples following strict guidelines, recording the date and location, storing them in zip-lock bags, and keeping them frozen at -18°C before sending them to the lab for analysis. A total of 729 fecal samples were collected, with 456 used in the study, mostly from the Jura region. Of these, 174 samples were traced back to 74 individual lynx, representing about half of the estimated local population. Genetic analysis showed that the lynx in the area are interbreeding and moving freely, indicating a healthy gene flow. However, the study also found low mitochondrial genetic diversity, suggesting that the current population descended from a small number of ancestors. This genetic limitation is attributed to past reintroduction efforts in the 1970s and 1990s, when lynx from the Carpathian region of Eastern Europe were released without considering genetic diversity. The low genetic diversity, known as a "founder effect," is compounded by physical barriers like highways, urban areas, and canals that restrict lynx movement, and by high mortality rates during dispersal—often due to road accidents. This situation could make the lynx more vulnerable to environmental changes, such as new diseases or climate shifts. To address this, the National Action Plan for lynx conservation plans to release additional lynx in 2027, though the source of these animals has not yet been determined. Conservationists stress the need to carefully choose the origin of the new lynx to prevent repeating the genetic issues from the past. Researchers are planning further studies to track genetic trends over time, while the National Action Plan is set for an evaluation in 2026, with a possible second phase starting soon after.