1. We collected data on the wing temperature of flying bats using infr
ared thermal imaging to assess the thermoregulatory function of wing m
embranes. 2. Thermographic images of two Egyptian Fruit Bats, Rousettu
s aegyptiacus were captured as they flew along a 12 m length of corrid
or. 3. Body temperature was measured before the first flight and immed
iately after flight sequences using a rectal thermister probe. 4. Temp
eratures across the wing ranged from 34 degrees C near the forearm mus
cle mass, to less than 24 degrees C at the trailing edge (mean ambient
temperature 23 degrees C). The majority of the wing was 1-2 degrees C
above ambient temperature. 5. We found small, but significant changes
in body temperature during flight. These changes did not correlate wi
th changes in wing temperature. (C) 1997 Elsevier Science Ltd.