|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
First published online January 5, 2005
Journal of Experimental Biology 208, 181-194 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01327
Biosonar performance of foraging beaked whales (Mesoplodon densirostris)
1 Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
2 La Laguna University, Tenerife, Canary Islands, Spain
3 NATO Undersea Research Center, viale San Bartolomeo 400, 19138 La Spezia,
Italy
* Author for correspondence (e-mail: pmadsen{at}whoi.edu)
Accepted 11 October 2004
Toothed whales (Cetacea, odontoceti) emit sound pulses to probe their surroundings by active echolocation. Non-invasive, acoustic Dtags were placed on deep-diving Blainville's beaked whales (Mesoplodon densirostris) to record their ultrasonic clicks and the returning echoes from prey items, providing a unique view on how a whale operates its biosonar during foraging in the wild. The process of echolocation during prey capture in this species can be divided into search, approach and terminal phases, as in echolocating bats. The approach phase, defined by the onset of detectable echoes recorded on the tag for click sequences terminated by a buzz, has interclick intervals (ICI) of 300-400 ms. These ICIs are more than a magnitude longer than the decreasing two-way travel time to the targets, showing that ICIs are not given by the two-way-travel times plus a fixed, short lag time. During the approach phase, the received echo energy increases by 10.4(±2) dB when the target range is halved, demonstrating that the whales do not employ range-compensating gain control of the transmitter, as has been implicated for some bats and dolphins. The terminal/buzz phase with ICIs of around 10 ms is initiated when one or more targets are within approximately a body length of the whale (2-5 m), so that strong echo returns in the approach phase are traded for rapid updates in the terminal phase. It is suggested that stable ICIs in the search and approach phases facilitate auditory scene analysis in a complex multi-target environment, and that a concomitant low click rate allows the whales to maintain high sound pressure outputs for prey detection and discrimination with a pneumatically driven, bi-modal sound generator.
Key words: beaked whale, Mesoplodon densirostris, echolocation, biosonar, automatic gain control, foraging, click interval, sound production
This article has been cited by other articles:
|
|
 |
|
  H. B. Schack, H. Malte, and P. T. Madsen The responses of Atlantic cod (Gadus morhua L.) to ultrasound-emitting predators: stress, behavioural changes or debilitation? J. Exp. Biol., July 1, 2008; 211(13): 2079 - 2086. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Villadsgaard, M. Wahlberg, and J. Tougaard Echolocation signals of wild harbour porpoises, Phocoena phocoena J. Exp. Biol., January 1, 2007; 210(1): 56 - 64. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Johnson, P. T. Madsen, W. M. X. Zimmer, N. A. de Soto, and P. L. Tyack Foraging Blainville's beaked whales (Mesoplodon densirostris) produce distinct click types matched to different phases of echolocation J. Exp. Biol., December 15, 2006; 209(24): 5038 - 5050. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. L. Tyack, M. Johnson, N. A. Soto, A. Sturlese, and P. T. Madsen Extreme diving of beaked whales J. Exp. Biol., November 1, 2006; 209(21): 4238 - 4253. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. A. Goldbogen, J. Calambokidis, R. E. Shadwick, E. M. Oleson, M. A. McDonald, and J. A. Hildebrand Kinematics of foraging dives and lunge-feeding in fin whales J. Exp. Biol., April 1, 2006; 209(7): 1231 - 1244. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
U. K. Verfuss, L. A. Miller, and H.-U. Schnitzler Spatial orientation in echolocating harbour porpoises (Phocoena phocoena) J. Exp. Biol., September 1, 2005; 208(17): 3385 - 3394. [Abstract] [Full Text] [PDF]
|
|
