A call for urban greening: High forest thresholds for the endangered northern maned sloth in urbanized landscapes

Habitat loss is a major driver of species decline, often producing non-linear responses with critical thresholds. We used drone-based thermal surveys and occupancy models to evaluate the effects of forest and urban cover on the endangered northern maned sloth ( Bradypus torquatus ) in peri-urban landscapes of the Atlantic Forest, Bahia, Brazil. Results revealed a positive, non-linear relationship between forest cover and occupancy, with a critical decline around 50%, and occupancy approaching zero below 31% forest cover. These values are higher than thresholds previously reported in agricultural areas. Urban cover had a negative non-linear effect on occupancy at intermediate forest levels (∼40%), indicating that urbanization amplifies the negative effects of habitat loss in such conditions. Our findings demonstrate that the deforestation levels currently permitted within peri-urban and urban zones by Brazilian environmental law are insufficient to ensure sloth persistence. Given accelerating real estate speculation, urban expansion, and the limited extent of protected areas within the species’ range, a paradigm shift in urban and peri-urban planning is urgently needed. Integrating biodiversity conservation into city planning and active management of urban risks is essential to ensure the conservation of this threatened mammal in such areas and its coexistence with humans.