How long does a dive last? Foraging decisions by breath-hold divers in a patchy environment: a test of a simple model

Carol E. Sparling, Jean-Yves Georges, Susan L. Gallon, Mike Fedak, Dave Thompson

Research output: Contribution to journalArticlepeer-review

50 Citations (Scopus)

Abstract

Many theoretical models have been proposed to explain and predict the behaviour of air-breathing divers exploiting a food resource underwater. Many field observations of the behaviour of divers do not fit with the prediction that to maximize energetic gain divers should dive close to their aerobic diving limits. In an attempt to explain this paradox, Thompson & Fedak (2001, Animal Behaviour, 61, 286-297) proposed a model of diving behaviour that takes into account patchily distributed prey patches of varying quality. We tested this model experimentally in a simulated foraging set-up. We measured the diving behaviour of grey seals, Halichoerus grypus, diving to patches of varying prey density and distance from the surface. Our results were equivocal with respect to the model predictions. Seals responded to prey density, leaving low-quality patches earlier. However, this pattern was still evident at long dive distances, contrary to the prediction that during deep dives seals should stay at a patch regardless of prey density. While seals maximized dive durations at high prey densities and long distances, they did not do so at short distances. The apparent quitting strategy of the seals always produced higher net rates of energy gain than would have been achieved if they had remained at the foraging site up to their aerobic dive limit on every dive. These results indicate that seals' diving behaviour, particularly bottom duration, may indicate the relative prey availability in their environment. (c) 2007 The Association for the Study of Animal Behaviour Published by Elsevier Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)207-218
Number of pages12
JournalAnimal Behaviour
Volume74
DOIs
Publication statusPublished - Aug 2007

Keywords

  • diving behaviour
  • foraging
  • grey seal
  • Halichoerus grypus
  • WEDDELL SEALS
  • GRAY SEALS
  • OPTIMAL ALLOCATION
  • DIVING BEHAVIOR
  • METABOLIC-RATES
  • MARINE PREDATOR
  • GREY SEALS
  • RESPONSES
  • TIME
  • MOVEMENTS

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