Abstract
The wolf population (Canis lupus) in France is monitored annually by the wolf-lynx network, led by the French Biodiversity Agency. This technical report presents an update on demographic parameters and population size following the 2023/24 winter field campaign. The genotyping of DNA from collected biological samples (feces, hair, urine, blood, and tissue from dead wolves) provides the genetic identity of individuals and forms the basis for estimating demographic parameters and population size. As in previous years, capture-recapture methods were used to account for the imperfect detection of individuals in the population.The 2023/24 winter field campaign was characterized by increased sampling effort, resulting in a larger volume of genetically analyzed biological samples. A new sampling protocol, that was based on a goal in terms of number of biological samples collected per grid cell, allowed the homogenization of the collection of samples across the population range, and increased the probability of detecting individuals compared to previous winters.As in previous years, there was a strong individual heterogeneity in detection probability. The annual survival probability decreased from 71% (95% confidence interval: 66-77%) during the 2014-18 period to 62% (95% CI: 56-69%) during the 2019-24 period. The last period corresponded to a change in derogatory culling regime, which increased from about 10% of the population during 2014-18 to 19% during 2019-24.The analysis indicated that wolf population size in France during the winter 2023/24 was likely between 920 and 1125 individuals. These two values correspond to the lower and upper bounds of the 95% confidence interval. There was a marked increase in the precision of the estimates compared to previous years, which was mostly caused by the larger field effort and by better accounting for various sources of heterogeneity in detection probability.Since the winter 2021/22, population estimates have remained within a similar range (825-1635 in 2021/22; 750-1344 in 2022/23; 920-1125 in 2023/24). Conclusions on the demographic trend of the population should be drawn from multi-year timeseries to identify demographic trajectories, particularly given the degree of uncertainty associated with these estimates. In this regard, understanding the underlying demographic parameters is crucial for interpreting these trends: the observed decrease in survival, which is at the threshold of maximum mortality tolerable to maintain stable growth, suggests a trend towards a stable population size.