Recruitment probability in a large carnivore: the role of biological and human-related factors in early-life

Abstract

To reach reproduction, individuals must survive the juvenile stage, a critical period of low survival rates in large carnivores. Early-life conditions during this stage can have lasting effects on survival, reproductive maturation, growth, physiology and behaviour. We assessed recruitment probability in Scandinavian wolves, i.e. the probability that a wolf reaches the reproductive stage and has pups surviving at least five months of age. To unravel human-related and biological factors within the natal territory that could affect recruitment probability, we analysed life-history data from 582 Scandinavian wolves Canis lupus identified by DNA as pups or juveniles in their birth territory. Factors considered included main prey density, road density, human density, and proximity to non-breeding zones, as well as sex, inbreeding level and collaring. Among the 582 wolves analysed, 122 produced at least one surviving pup, corresponding to a recruitment probability of 0.21. Recruitment probability was more than twice as high (0.5) for juvenile wolves fitted with GPS-collars compared to non-collared individuals (0.22), and was positively correlated with human population density in the natal territory. We found no significant effects of other biologically or human-related predictors. These results suggest that in this large carnivore population, managed below carrying capacity, individual recruitment probability is primarily influenced by human-related factors, potentially reflecting poaching risk.