Click here to read more about my research into White Nose Syndrome affecting bats in New England.

Population size estimation is fundamental to all ecological investigations. In our lab, we have focused on measuring colony sizes of Brazilian free-tailed bats inhabiting several caves in South-central Texas. Although colonies at these caves appear to be reduced compared to historic estimates (see our publication in Journal of Mammalogy ), redistribution of colonies to alternate roost sites, highway bridges, and other structures may explain localized declines.

Colony size fluctuations are closely linked to age and reproductive conditions of bats in the colony. We are interested in synchrony of reproductive cycles in these colonies. Additionally, the large sizes of Brazilian free-tailed bat colonies reveal foraging behaviors specific to the extrinsic conditions of climate and light conditions as well as intrinsic factors related to energetic demands and flight ability.

Bat flight presents intriguing questions with respect to heat balance. Although flight is efficient per unit distance, it is inefficient per unit time. Thus, bats face possible hyperthermia as much of the energy expended during flight generates waste heat. However, the extended naked flight membranes of bats provide a large surface area to volume ration beneficial to heat dissipation. Excessive water loss may accompany necessary heat loss, resulting in physiological and behavioral characteristics that help to maintain energy equilibrium.

Brazilian Free-tailed bats are small bats that fly high and fast. Thus, tracking their flight trajectories, whether nightly or seasonally, has been difficult. Historic banding studies with less than 2% recapture success provide much of our knowledge about there migratory movements. We are currently analyzing stable isotopes of hydrogen, nitrogen, and carbon in bat hair and skin in order to confirm these patterns and identify the summer ranges of Brazilian free-tailed bats using important winter roost sites.

Brazilian free-tailed bats often forage over artificially nutrient rich agricultural lands and roost amidst potentially nutrient poor native landscapes. As large numbers of bats disperse from roosts to forage each night, they consume insects and defecate during flight, thus redistributing nutrients over the landscape. We are actively attempting to quantify this ecosystem service provided by bats.