QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online May 1, 2006
Journal of Experimental Biology 209, 1816-1826 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02194

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JEB Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Holderied, M. W. Articles by von Helversen, O. Search for Related Content PubMed PubMed Citation Articles by Holderied, M. W. Articles by von Helversen, O. Social Bookmarking                         What's this?

Flight and echolocation behaviour of whiskered bats commuting along a hedgerow: range-dependent sonar signal design, Doppler tolerance and evidence for `acoustic focussing'

Marc W. Holderied^1,2,*, Gareth Jones¹ and Otto von Helversen²

¹ School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK
² Department of Zoology II, University of Erlangen, Staudtstr. 5, 91058 Erlangen, Germany

^* Author for correspondence (e-mail: mholderi{at}biologie.uni-erlangen.de)

Accepted 28 February 2006

Echolocating bats obtain three-dimensional images of their surroundings in complete darkness by emitting sonar signals and evaluating returning echoes. When flying close to objects, bats risk collision and therefore depend on the accuracy of images – particularly in the perceived distance of obstacles, which is coded by the time delay between call and echo. Yet, during flight, such accuracy is perturbed first because bats call and receive echoes at different positions and second because echoes are modified by Doppler shifts. Certain call designs avoid both sources of ranging error, but only for a limited range of distances [the `distance of focus' (DOF)]. Here, we show that whiskered bats (Myotis mystacinus) using broadband echolocation calls adjust call design in a range-dependent manner so that nearby obstacles are localised accurately. Such behaviour is adaptive because it reduces collision risk. The bats also reduced call duration to some extent as they approached obstacles so that most returning echoes arrived after they finished calling. This reduction in call duration during the approach to obstacles was neither the only nor the main factor that influenced DOF. Indeed, both duration and bandwidth of calls influenced DOF independently, with lower bandwidths and longer durations giving greater DOF. Our findings give a new perspective on the adaptive significance of echolocation call design in nature and have implications for sonar engineering.

Key words: bat echolocation, acoustic flight path tracking, sonar signal design, Doppler-errors, ranging, distance of focus, Myotis mystacinus

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

Related articles in JEB:

BATS MODULATE CALLS FOR INCREASED ACCURACY

Kathryn Phillips
JEB 2006 209: i. [Full Text]  

This article has been cited by other articles:

				M. W. Holderied, C. J. Baker, M. Vespe, and G. Jones Understanding signal design during the pursuit of aerial insects by echolocating bats: tools and applications Integr. Comp. Biol., July 1, 2008; 48(1): 74 - 84. [Abstract] [Full Text] [PDF]

				N. Ulanovsky and C. F. Moss What the bat's voice tells the bat's brain PNAS, June 24, 2008; 105(25): 8491 - 8498. [Abstract] [Full Text] [PDF]

				G. Jones and M. W Holderied Bat echolocation calls: adaptation and convergent evolution Proc R Soc B, April 7, 2007; 274(1612): 905 - 912. [Abstract] [Full Text] [PDF]

				K. Phillips BATS MODULATE CALLS FOR INCREASED ACCURACY J. Exp. Biol., May 15, 2006; 209(10): i - i. [Full Text] [PDF]