Habitat use patterns suggest that climate-driven vegetation changes will negatively impact mammal communities in the Amazon

Climate change will affect species persistence and distribution, particularly in high-diversity ecosystems like the Amazon. Studies predict that as temperature and deforestation increase and precipitation patterns change in the Amazon, areas along its southern and eastern borders will suffer large-scale savannization, the conversion of tropical forest to degraded savannah-like vegetation. Here, we aim to identify the terrestrial mammal species potentially most at risk from savannization by studying their use of natural forest and savannah habitats within four protected areas, using camera-trap surveys and community occupancy models. We grouped species into categories according to the overlap of their global distributions with the Amazon and Cerrado biome (Amazon, Cerrado and generalist species) and investigated the effect on their space use of savannah cover within a 100-m buffer, and of the immediate habitat type (continuous forest, riparian forest and savannah) at the camera trap. Both savannah cover and savannah habitat type affected space use of most Amazon and generalist species strongly negatively. Only Cerrado species ever showed strong positive responses to savannah cover. These results suggest that most of the terrestrial mammal community is potentially vulnerable to savannization, including several species typically considered habitat generalists. Negative effects of disturbed savannah-like habitats are likely even stronger than effects of natural savannah reported here. Although less favorable than continuous forest, riparian forest had a strong negative effect for only a small fraction of species, indicating that effects of savannization may be buffered to some extent by riparian forests. Our results suggest that climate change-induced vegetation changes may reduce the ability of protected areas in the southern Brazilian Amazon to safeguard populations of terrestrial mammals and should be considered when assessing potential climate-change effects on these species.