Ecology and Vulnerability

Little Brown Bat

Little information was found about the biological responses of the Northeast’s bat RSGCN to climate change. However, bats in the northeastern U.S. will likely be especially sensitive to climate change because much of their biology, including reproduction and hibernation, is closely related to temperature (Loeb and Winters, 2013). For instance, increasing winter temperatures will likely cause warmer microsites where bats hibernate (Boyles et al., 2017), and variation in ambient microsite temperature increases energy expenditure by hibernating bats (Boyles and McKechnie, 2010). Hibernacula near cave entrances are quickly affected by outside temperatures, as opposed to sites deeper in more shielded caves (Boyles et al., 2017). However, even small temperature variations can significantly increase energy expenditure across winter (Boyles and McKechnie, 2010), so areas with a large range of microclimates may hold on to their bat populations while those with a more limited range may not (Boyles et al., 2017). Despite that, some evidence suggests that ambient temperature may not be the most important factor in energy conservation during hibernation, as behavior, humidity, and initial fat mass were also important factors for Tricolored Bats (McGuire et al., 2021) and Tricolored Bats experimentally held in varying temperatures during hibernation showed no difference in metabolic rate when hibernation ended (Boyles et al., 2022).

Shifts in Range, Elevation, or Depth

Though outside of the northeastern region, Little Brown Bats did not appear to alter their
elevational range in the Rocky Mountains from 1996 to 2016, despite an increase of 1.8°C over
that time period in the study area (Adams, 2017). This suggests that their flexibility in shifting
roost sites, as opposed to other myotis species in the area may be allowing them to remain at the
same elevations while others are starting to shift elevations (Adams 2017). However, less
precipitation during the summer months may lead to higher mortality rates (Frick et al., 2010)
due to decreased abundance of insects for feeding.