Long-term reproductive costs of snare injuries in a keystone terrestrial by-catch species

Abstract

Extensive bushmeat hunting is a major threat to wildlife conservation worldwide, particularly when unselective methods such as wire snares kill target and non-target species (by-catch). Animals that escape from snares have injuries of varying severity, with effects on performance that are largely unknown, as most studies typically focus on immediate mortality caused by snaring. Here, we assessed the life-history costs of debilitating snare injuries in individually known female spotted hyenas Crocuta crocuta in three clans in the Serengeti National Park, Tanzania. This keystone predator is a regular by-catch of illegal bushmeat hunting of herbivores in the Serengeti ecosystem. We monitored individuals which escaped from snares between May 1987 and March 2020 and survived long enough to return to their clan territories from commuting trips in the park and surrounding protected areas. Snares that inflicted debilitating injuries on females did not reduce longevity but did delay age at first reproduction and reduced both litter size and offspring survival to the age of 1 year. This long-term decrease in reproductive performance likely resulted from increased inflammatory and immune responses to the snare injury and/or a decreased ability to travel the long distances necessary to feed on migratory herbivores. While our results are based on a relatively small sample of females with debilitating injuries, they suggest that the total population-level costs of wire snares in terrestrial by-catch species may be underestimated and that future studies may need to account for the potential reproductive costs of sublethal snare injuries.