Integrating climate, ecophysiology, and forest cover to estimate the vulnerability of sloths to climate change

Abstract

Global change imposes multiple challenges on species and, thus, a reliable prediction of current and future vulnerability of species must consider multiple stressors and intrinsic traits of species. Climate, physiology, and forest cover, for example, are required to evaluate threat to thermolabile forest-dependent species, such as sloths (Bradypus spp.; Mammalia: Xenarthra). Here, we estimated future changes in the distribution of three sloth species using a metabolic-hybrid model focused on climate (climatic only, i.e., CO approach) and adding forest cover constraints to distribution of species (climate plus land cover, i.e., CL approach). We used an innovative method to generate estimates of physiological parameters for endotherms, validated with field data. The CF approach predicted a future net expansion of distribution of B. torquatus and B. variegatus, and a future net contraction of distribution of B. tridactylus. The inclusion of forest cover constraints, however, reversed the predictions for B. torquatus, with a predicted net distribution contraction. It also reduced expansion of B. variegatus, although still showing a large net expansion. Thus, B. variegatus is not predicted to be threatened in the future; B. tridactylus emerges as the species most vulnerable to climate change, but with no considerable forest losses, while B. torquatus shows the opposite pattern. Our study highlights the importance of incorporating multiple stressors in predictive models in general. To increase resilience of species to climate change, it is key to control deforestation in the Amazon for B. tridactylus, and to promote reforestation in the Atlantic Forest for B. torquatus.

Combined effect of ambient temperature and solar radiation on maned sloths' behaviour and detectability

“…It is possible that a warmer and drier future in the already warm northern Atlantic Forest may bring some changes in maned sloths' behaviours and challenges to this species that rely on thermoregulatory behaviours to control body temperature (Kearney et al, 2009). Maned sloths are vulnerable to habitat loss and a myriad of anthropogenic pressures (Chiarello & Moraes‐Barros, 2014; Santos et al, 2019; Tourinho et al, 2022), and such future conditions could be an additional threatening factor, which may affect their physiology, metabolism and behaviour (Cliffe et al, 2018; Deutsch et al, 2008; Kearney et al, 2009). We offer information that can be combined with climate data to spatially predict the future impacts of climate change on its distribution and behaviour.…”

“…In this scenario, sloths may be exposed to conditions in which thermoregulatory behaviours will no longer be effective to avoid overheating or even maintain a positive energy and water balance, an issue to be investigated. This is even more worrying when we consider the recent revision of B. torquatus taxonomy and the projections of future suitable areas for the species, which indicate more restrict distribution range and no future expansion in their habitat, respectively (Miranda et al, 2022; Tourinho et al, 2022).…”

“…| 1357 WEATHER EFFECTS MANED SLOTHS BEHAVIOR Tourinho al., 2022), and such future conditions could be an additional threatening factor, which may affect their physiology, metabolism and behaviour (Cliffe et al, 2018;Deutsch et al, 2008;Kearney et al, 2009). We offer information that can be combined with climate data to spatially predict the future impacts of climate change on its distribution and behaviour.…”

“…Although the effects of ambient temperature and sun condition (sunny, cloudy, or rainy) on sloths' behaviour have been previously studied (Britton & Atkinson, 1938;Cliffe et al, 2018;Giné et al, 2015;Montgomery & Sunquist, 1978), the joint effect of these variables has never been statistically evaluated in free-ranging sloths. As the three-toed sloths are potentially sensitive to fluctuations in temperature and sun conditions, the maned sloth may be particularly vulnerable in the face of global climate changes and landscape changes occurring in the Atlantic Forest (Santos et al, 2019(Santos et al, , 2022Tourinho et al, 2022). Particularly, behavioural changes driven by climate change (activity levels, forest strata selection and frequency of postures adopted) might make them more detectable and vulnerable to human pressures, such as hunting.…”

Juçara palm ecological interactions threatened by climate and land‐cover changes

“…Considering that a reliable prediction of current and future vulnerability of species should include multiple stressors and biological interactions (Araújo & Luoto, 2007; Tourinho, Sinervo, et al, 2022; Urban et al, 2016), the objective of this study was to evaluate whether the overlap of the distribution of the E. edulis with its seed dispersers and seed predators would change under future climate change, discussing possible consequences for the species' viability in the future.…”