Restoring ecological function: Interactions between vertebrates and latrines in a reintroduced population of Rhinoceros unicornis

Reintroduction is a highly effective strategy for rebuilding wildlife populations and restoring their ecosystem functions, but impacts on function are poorly documented. We addressed this gap by comparing the species richness and visit rate of mammals and birds that interact with rhino (Rhinoceros unicornis) latrines at two locations in Nepal: Chitwan National Park, with a stable rhino population, and Shuklaphanta National Park, where a rhino reintroduction program was conducted from 2003 to 2018. Camera-traps were used to monitor visitors to 30 latrines in both parks from 2020 to 2021 (669 camera-trap days). The reintroduction of rhinos to Shuklaphanta National Park has played a crucial role in restoring an important resource for other mammal and bird species. Despite a large difference in rhino abundance, and differences in the size, quality and some of the nutritional contents of latrines between sites, there were no significant differences in species richness of latrine visitors and in the frequency of most behaviours at the latrines. Visit rates of animals were higher at the reintroduction site, confirming latrines to be important, limited resources. Overall, 4 mammal and 4 bird species used the latrines to consume the dung, or insects and plants growing on and around the dung; a further two mammal species interacted only indirectly with the latrines. These findings provide evidence that even at low population densities, rhino reintroduction can successfully restore an important ecological function and provide vital resources for other species. Our study supports the rewilding of large-bodied animals to mitigate ecosystem deterioration.