Meeting Abstract
S6.7 Tuesday, Jan. 5 A Unique Adaptation of Bats in the Family Molossidae for Long-distance Foraging and Migration KUNZ, Thomas H.*; REICHARD, Jonathan D; PRAJAPATI, Surech I; AUSTAD, Steven N; KELLER, Charles; Boston University; Boston University; University of Texas Health Center; University of Texas Health Center; University of Texas Health Center kunz@bu.edu
Heat generated as a byproduct of energetically costly flight must be dissipated to avoid hyperthermia. Brazilian free-tailed bats, Tadarida brasiliensis, dissipate large amounts of heat from the head and body. However, wings and the tail membrane remain significantly cooler than air temperature during flight, reducing their ability to dissipate heat. Thermal infrared (TIR) imaging of free-ranging T. brasiliensis revealed thermal windows on the flanks and proximal portions of the wing that are uniquely vascularized and hairless, but are absent from syntopic cave myotis, Myotis velifer. The anatomy of these regions was analyzed with light and TIR imaging, microscopic x-ray computed tomography (microCT), and light microscopy to characterize form and function. Two branches from the ulnar artery in Brazilian free-tailed bats are uniquely developed, creating a specialized thermal radiator. We postulate that these radiators facilitate thermoregulation and water balance through localized heat loss. Transcutaneous water loss through the hairless wing membranes is reduced while blood is shunted away from flight membranes to fuel flight muscle activity. Countercurrent exchange may also play an important role in thermoregulation at lower air temperatures such as those encountered at high altitude. Comparative analysis of 133 fluid-preserved Chiropteran species from 15 families suggests that similar anatomy is present only in the Molossidae, many of which are known to undertake extended foraging flights and migration in warmer geographic regions. We suggest that this thermal radiator is a unique adaptation for long-distance foraging and migration in the family Molossidae.
