A. Surlykke et Cf. Moss, Echolocation behavior of big brown bats, Eptesicus fuscus, in the field and the laboratory, J ACOUST SO, 108(5), 2000, pp. 2419-2429
Echolocation signals were recorded from big brown bats, Eptesicus fuscus, f
lying in the field and the laboratory. In open field areas the interpulse i
ntervals (IPI) of search signals were either around 134 ms or twice that va
lue, 270 ms. At long IPI's the signals were of long duration (14 to 18-20 m
s), narrow bandwidth, and low frequency, sweeping down to a minimum frequen
cy (F-min,) of 22-25 kHz. At short IPI's the signals were shorter (6-13 ms)
, of higher frequency, and broader bandwidth. Tn wooded areas only short (6
-11 ms) relatively broadband search signals were emitted at a higher rate (
avg. IPI = 122 ms) with higher F-min (27-30 kHz). In the laboratory the IPI
was even shorter (88 ms), the duration was 3-5 ms, and the F-min 30-35 kHz
, resembling approach phase signals of field recordings. Excluding terminal
phase signals, all signals from all areas showed a negative correlation be
tween signal duration and F-min,, i.e., the shorter the signal, the higher
was F-min. This correlation was reversed in the terminal phase of insect ca
pture sequences, where F-min, decreased with decreasing signal duration. Ov
erall, the signals recorded in the field were longer, with longer IPI's and
greater variability in bandwidth than signals recorded in the laboratory.
(C) 2000 Acoustical Society of America. [S0001-4966(00)03611-0].