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.

Early‐life adversity predicts performance and fitness in a wild social carnivore

“…Female cubs of young mothers had a reduced growth rate, whereas both young and old mothers had a reduced longevity and LRS. In a previous study, young and old mothers produced smaller litters which were less likely to survive to the age of 1 year, suggesting an important effect of maternal age on reproductive success in hyenas (Benhaiem et al, 2022). In ungulates and pinnipeds, young females produce smaller offspring with a lower survival than older females (Bowen, 2009; Côté & Festa‐Bianchet, 2001; Green & Rothstein, 1991).…”

“…Hofer & East, 2003). (iii) Maternal age: Maternal inexperience and/or an expected decline in performance with age may decrease litter size and offspring survival (Benhaiem et al, 2022). (iv) Litter size and within‐litter dominance status (hereafter ‘cub status’): The dominant sibling in twin litters and singleton cubs receive more maternal milk and grow faster than subordinate cubs in twin litters (Hofer et al, 2016; Hofer & East, 1997, 2008).…”

Effects of environmental change on population growth: monitoring time-varying carrying capacity in free-ranging spotted hyenas

“…The spotted hyena ( Crocuta crocuta ) is a large social carnivore that plays an important role in the African savannah ecosystem as a regulator of herbivore disease (Packer et al, 2003), a competitor of other large carnivores (Höner et al, 2002), and as a species capable of digesting large bones and thus releasing calcium and phosphorus concentrated within bones back into the ecosystem (Abraham et al, 2022). Although the spotted hyena is categorised as a species of ‘Least Concern’, many populations are declining due to impacts of human activity such as culling, poisoning, snares, and roadkill (Benhaiem et al, 2023; Bohm and Höner, 2015; Naciri et al, 2023). Spotted hyenas form clans, consisting of multiple matrilines organized into a relatively stable linear dominance hierarchy (Kruuk, 1972), where cubs obtain a social rank within the dominance hierarchy directly below that of their mother and above older siblings (Frank, 1986; Vullioud et al, 2019).…”