Natal dispersal of tree sloths in a human-dominated landscape: implications for tropical biodiversity conservation.
Abstract
Habitat loss and fragmentation caused by the conversion of tropical forests are among the most important threats to biodiversity globally. Habitat specialists and species with low dispersal capacity are expected to be the most sensitive to such changes. Relatively little is known, however, about how habitat change and life history interact to impact natal dispersal and population viability in tropical species. Here, we characterized natal dispersal patterns, habitat selection and survival rates in two-toed (Choloepus hoffmanni) and three-toed (Bradypus variegatus) sloths within a human-dominated tropical landscape in Costa Rica consisting of a shade-grown cacao plantation surrounded by riparian forests and cattle pastures. Radio-marked individuals of both species preferentially selected tropical forests during natal dispersal and were commonly observed using riparian forest buffers for dispersal. The more specialized and sedentary three-toed sloth, however, avoided both pastures and shade-grown cacao for dispersal, whereas two-toed sloths only avoided pastures. Juvenile survival was lower for three-toed than two-toed sloths, and was lowest immediately following maternal independence for both species. However, despite interspecific differences, juvenile survival was high and sufficient to maintain stable populations of both species. Synthesis and applications. Our results indicate that tropical forest conversion is more likely to impact the natal dispersal success of specialized and dispersal-limited species. Moreover, riparian forest buffers appear to provide critical corridors for maintaining such species, and biodiversity more broadly, in modified tropical landscapes.