Antonio Guillén-Servent and Carlos Ibáñez (2007): Unusual echolocation behavior
in a small molossid bat, Molossops temminckii, that forages near background
clutter. Behav Ecol Sociobiol 61, 1599–1613.
Abstract: When searching for flying insects, Molossops temminckii uses unusual
echolocation calls characterized by upward modulation of frequency vs time
(UFM). Call frequency increases asymptotically in the relatively long (∼8 ms)
pulses from a starting frequency of ∼40 kHz to a long narrowband tail at ∼50
kHz. When approaching a prey, the bat progressively increases the duration of
calls and intersperses in the sequence broadband downwardly frequency-modulated
signals with a terminal frequency of about 53 kHz, which totally replaces the
UFM signals at the end of the approach phase. The sequence progresses to a
capture buzz resembling those from other molossid and vespertilionid bats. The
M. temminckii wing morphology is characterized by an average aspect ratio and a
high wing loading, suggesting that it is more maneuverable than the typical
Molossidae but less than typical Vespertilionidae. M. temminckii regularly
forages near clutter, where it needs to pay attention to the background and
might face forward and backward masking of signals. We hypothesize that the UFM
echolocation signals of M. temminckii represent an adaptation to foraging near
background clutter in a not very maneuverable bat needing a broad attention
window. The broadband component of the signal might serve for the perception of
the background and the narrowband tail for detection and perhaps classification
of prey. Bats may solve the signal masking problems by separating emission and
echoes in the frequency domain. The echolocation behavior of M. temminckii may
shed light on the evolution of the narrowband frequency analysis echolocation
systems adopted by some bats foraging within clutter.
For reprints please contact Antonio Guillén-Servent (Email:
URL:http://www.springerlink.com/content/v946426426476711/
Kind regards
Sonja
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University of Vienna, Dept. of Behavioural Biology
Sonja Amoser
PhD
Althanstrasse 14
1090 Vienna
Austria
tel: +43 (1) 4277 54467
fax: +43 (1) 4277 54506
mobile: +43 (664) 500 61 06
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