A new home is a death trap: Reinforcement at a translocation release site leads to fatalities in an endangered primate species

Abstract

The confiscation and release of animals into the wild are common conservation responses to the illegal wildlife trade, yet their effectiveness remains uncertain, especially for cryptic and territorial species. We assessed the post-release survival and spatial ecology of nine confiscated Bengal slow lorises (Nycticebus bengalensis) translocated to a fragmented forest patch in northeastern Bangladesh. Using radio telemetry, we tracked individuals for 138 nights across eight months. Only two lorises (22.2 %) survived beyond six months, while the others died within days to weeks, including four individuals to fatal intraspecific aggression. Survivors exhibited significantly larger home ranges (95 % KDE: male = 187.7 ha, female = 57.5 ha) than deceased individuals. Activity budgets revealed higher alertness and reduced locomotion in lorises that died, suggesting chronic stress and poor habitat adaptation. Survival was negatively correlated with duration in captivity prior to release. Our findings highlight critical challenges in translocating highly territorial nocturnal animals, including territorial conflict and inadequate release protocols. We recommend rigorous site assessments, long-term monitoring, and species-specific rehabilitation guidelines to improve outcomes of welfare-based translocations for slow lorises and similar species.