Roost selection by the solitary, foliage-roosting hoary bat (Lasiurus cinereus) during lactation

Abstract

Nests, roosts, and dens are an important facet of life for many animals and often provide refuge from weather and predators. Reproduction, particularly lactation, is energetically expensive. Many small mammals form maternity colonies in sheltered locations, which provides protection for offspring and mitigates the cost of staying warm. However, lasiurine bats give birth in roosts that superficially appear to offer relatively little thermal buffer. Given the consequences of a cold environment on offspring growth and the high energetic demand of thermoregulating and lactating concurrently, choosing roosts with certain microclimatic properties would be beneficial. We investigated the influence of microclimate on roost selection by lactating hoary bats ( Lasiurus cinereus (Beauvois, 1796)), a solitary foliage-roosting species. We found that roosts chosen by bats offered shelter from the wind and exposure to sunlight, and consistently had an opening that faced south. We suggest that lactating L. cinereus choose roosts based largely on a microclimate that reduces convective cooling and increases radiant heating, thereby mitigating the cost of thermoregulation and promoting rapid growth of offspring.