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The Scientific World Journal
Volume 2012, Article ID 128695, 15 pages
Research Article

Simple Syllabic Calls Accompany Discrete Behavior Patterns in Captive Pteronotus parnellii: An Illustration of the Motivation-Structure Hypothesis

1Laboratory for Auditory Communication and Cognition, Department of Physiology and Biophysics, Georgetown University Medical Center, 3900 Reservoir Road, NW, Washington, DC 20057-1460, USA
2Department of Neurology, Georgetown University Medical Center, 3900 Reservoir Road, NW, Washington, DC 20057-1460, USA

Received 1 November 2011; Accepted 3 January 2012

Academic Editors: M. L. Fine, R. Heffner, M. Huotilainen, and P. H. S. Jen

Copyright © 2012 Matthew J. Clement and Jagmeet S. Kanwal. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Mustached bats, Pteronotus parnellii, are highly social and vocal. Individuals of this species roost in tight clusters, and emit an acoustically rich repertoire of calls whose behavioral significance is largely unknown. We recorded their social and vocal behaviors within a colony housed under semi-natural conditions. We also quantified the spatial spread of each bat’s roosting location and discovered that this was relatively fixed and roughly confined to an individual’s body width. The spatial precision in roosting was accompanied by an equally remarkable match between specific vocalizations and well-timed, discrete, identifiable postures/behaviors, as revealed by logistic regression analysis. The bodily behaviors included crouching, marking, yawning, nipping, flicking, fighting, kissing, inspecting, and fly-bys. Two echolocation-like calls were used to maintain spacing in the colony, two noisy broadband calls were emitted during fights, two tonal calls conveyed fear, and another tonal call signaled appeasement. Overall, the results establish that mustached bats exhibit complex social interactions common to other social mammals. The correspondence of relatively low frequency and noisy, broadband calls with aggression, and of tonal, high frequency calls with fear supports Morton’s Motivation-Structure hypothesis, and establishes a link between motivation and the acoustic structure of social calls emitted by mustached bats.