Meeting Abstract
P3.216 Tuesday, Jan. 6 Thermoregulation during Flight in the Brazilian free-tailed Bat REICHARD, J.D.*; FELLOWS, S.R.; KUNZ, T.H.; Boston University; Boston University; Boston University reichard@bu.edu
Body temperature (Tb) is intimately linked to an animals form and function. Although flight permits bats to forage over large areas, metabolic heat produced as a byproduct of flight may lead to hyperthermia that can inhibit metabolic pathways or damage tissues. Body surface temperatures (Ts) of free-ranging Brazilian free-tailed bats, Tadarida brasiliensis, were measured with infrared thermography over a range of ambient temperatures (Ta). Mean Ts was determined for the body, head, wings, and tail membrane during emergence flights at dusk and during return flights at midnight and dawn. Ts increased with Ta for all body regions (p<0.0001). At dusk, only the body was 0.06C warmer than Ta; all other regions were cooler. During midnight return flights, the body and head were warmer than Ta by 1.3C and 0.8C, respectively. Wings and tail were both 1.0C below Ta. Similarly at dawn, the body and head were 1.2C and 0.6C above Ta, respectively, and the wings and tail were each 2.1C below Ta. Cool membranes may result from bats flying in cool air immediately prior to measurements or from evaporative cooling. Mean internal Tb decreased between emergence flights (36.8C) and return flights (34.4C). However, Tb increased from 5.4C to 9.0C above Ta between emergence and return flights, suggesting increased heat production during this time. The sides beneath the wings were the warmest body regions, providing high potential for heat loss. At ground level, cool wings would not facilitate heat dissipation. By shunting blood away from naked wings during flight, bats reduce potential water loss that would otherwise result from blood flow to these membranes. At the same time, warmer regions on the body dissipate heat from flight muscles.
