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

First published online April 23, 2004
Journal of Experimental Biology 207, 1789-1796 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.00967

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 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 Wilson, R. P. Articles by Quintana, F. Search for Related Content PubMed PubMed Citation Articles by Wilson, R. P. Articles by Quintana, F. Social Bookmarking                         What's this?

Surface pauses in relation to dive duration in imperial cormorants; how much time for a breather?

Rory P. Wilson^1,* and Flavio Quintana²

¹ Institut für Meereskunde, Düsternbrooker Weg 20, D-24105 Kiel, Germany
² Centro Nacional Patagonico (Conicet) (9120) Puerto Madryn, Chubut, Argentina

^* Author for correspondence (e-mail: rwilson{at}ifm.uni-kiel.de)

Accepted 8 March 2004

Air-breathing animals diving to forage can optimize time underwater by diving with just enough oxygen for the projected performance underwater. By so doing they surface with minimal body oxygen levels, which leads to maximal rates of oxygen uptake. We examined whether imperial cormorants Phalacrocorax atriceps adhere to this by examining dive:pause ratios in birds diving for extended, continuous periods to constant depths, assuming that the oxygen used underwater was exactly replenished by the periods at the surface. Examination of the cumulative time spent in surface pauses relative to the cumulative time spent in diving showed that surface pauses increase according to a power curve function of time spent in the dive or water depth. In a simplistic model we considered the rate at which birds expended energy underwater to be constant and that the rate of oxygen replenishment during the surface pause was directly proportional to the oxygen deficit. We then worked out values for the rate constant for the surface pause before using this constant to examine bird body oxygen levels immediately pre- and post dive. The model predicted that imperial cormorants do not submerge with just enough oxygen to cover their projected dive performance but rather dive with substantial reserves, although these reserves decrease with increasing dive depth/duration. We speculate that these oxygen reserves may be used to enhance bird survival when rare events, such as the appearance of predators or discovery of large prey requiring extended handling time, occur. The form of the oxygen saturation curve over time at the surface means that the time costs for maintaining constant oxygen reserves become particularly onerous for long, deep dives, so the observed decrease in reserves with increasing dive duration is expected in animals benefiting by optimizing for time.

Key words: diving, imperial cormorant, Phalacrocorax atriceps, oxygen saturation curve, time optimization, surface interval between dives

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

This article has been cited by other articles:

				E. L. C. Shepard, R. P. Wilson, F. Quintana, A. Gomez Laich, and D. W. Forman Pushed for time or saving on fuel: fine-scale energy budgets shed light on currencies in a diving bird Proc R Soc B, September 7, 2009; 276(1670): 3149 - 3155. [Abstract] [Full Text] [PDF]