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Behavioral evidence of thermal stress from over-heating in UK breeding gray seals

Twiss, S.D.; Wright, N.C.; Dunstone, N.; Redman, P.; Moss, S.; Pomeroy, P.P.

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N.C. Wright

N. Dunstone

P. Redman

S. Moss

P.P. Pomeroy


Gray seals (Halichoerus grpus) in the UK exhibit clear preferences for pupping close to pools of water on inland breeding sites. The reasons for this are unclear as seals are thought to derive all their water requirements from the metabolism of fat. Likewise, the prospect of seals overheating during the UK's cool, damp, autumnal breeding seasons, has seemed unlikely, but has not been previously explored. Here, we provide preliminary behavioral evidence of thermal stress in female gray seals breeding on the island of North Rona, Scotland. Video footage provided measures of proximity to, and the proportion of animals bathing in, pools in relation to meteorological data (temperature, mean sea-level pressure, rainfall, wind speed and direction) on four dates spread through a single breeding season. The proportion of females close to pools increased with pressure (warmer, drier conditions) and decreased on wetter days. In addition, analyses of colony-wide patterns of seal dispersion showed that females tended to be closer to pools of water at higher pressures and temperatures and at lower wind-speeds. These results provide the first evidence of thermal stress and behavioral thermoregulation through access to pools of water in a phocid breeding in temperate autumnal conditions.

Journal Article Type Article
Publication Date Apr 1, 2002
Deposit Date Mar 17, 2014
Publicly Available Date Mar 17, 2014
Journal Marine Mammal Science
Print ISSN 0824-0469
Electronic ISSN 1748-7692
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 18
Issue 2
Pages 455-468
Keywords Gray seal, Halichoerus grypus, Behavioral thermoregulation, Breeding habitat, North Rona.
Public URL


Accepted Journal Article (220 Kb)

Copyright Statement
This is the peer reviewed version of the following article: Twiss, S. D., Wright, N. C., Dunstone, N., Redman, P., Moss, S. and Pomeroy, P. P. (2002), Behavioral evidence of thermal stress from over-heating in UK breeding gray seals, Marine Mammal Science, 18 (2): 455–468, which has been published in final form at This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.

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