Work

Heat tolerance of female Yuma Myotis ( Myotis yumanensis ) in the hottest part of their Canadian range

Year: 2026

Type: article

Abstract: High ambient temperatures (Ta) pose a significant challenge to small endotherms that rely on limited water reserves to thermoregulate via evaporative cooling and are exacerbated for species inhabiting poorly insulated microsites. We used flow-through respirometry to investigate the thermoregulatory strategies and capacities of nonreproductive female Yuma Myotis (Myotis yumanensis) from one of the hottest areas of their range. Based on our physiological data and the NicheMapR biophysical model, we also calculated the evaporative cooling requirements and dehydration risk of these females when roosting in artificial structures during a heatwave in 2021 (modeled results) and during the warmest day of our study (measured results). Our results indicated that non-reproductive female M. yumanensis can tolerate a maximum Ta of 44 °C in dry air, adopting a thermoconforming strategy, possibly due to evaporative cooling restrictions imposed by their low water reserves. Our results allude to M. yumanensis using thermal gradients within roosts to avoid high roost temperatures and demonstrate that bats roosting in a South-facing artificial roost exposed to high solar radiation would have faced lethal dehydration during the 2021 heatwave. Our results underscore the importance of natural roosts in the landscape and highlight designing artificial roosts that offer a wide thermal gradient to allow the persistence of this species during current extreme climatic events.

Source: Journal of Mammalogy

DOI: 10.1093/jmammal/gyag070