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Extreme weather events influence dispersal of naive northern fur seals

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posted on 2023-05-16, 23:29 authored by Mary-Anne LeaMary-Anne Lea, Johnson, D, Ream, R, Sterling, J, Melin, S, Gelatt, T
Since 1975, northern fur seal (Callorhinus ursinus) numbers at the Pribilof Islands (PI) in the Bering Sea have declined rapidly for unknown reasons. Migratory dispersal and habitat choice may affect first-year survivorship, thereby contributing to this decline. We compared migratory behaviour of 166 naive pups during 2 years from islands with disparate population trends (increasing: Bogoslof and San Miguel Islands; declining: PI), hypothesizing that climatic conditions at weaning may differentially affect dispersal and survival. Atmospheric conditions (Bering Sea) in autumn 2005-2006 were anomalously cold, while 2006-2007 was considerably warmer and less stormy. In 2005, pups departed earlier at all sites, and the majority of PI pups (68-85%) departed within 1 day of Arctic storms and dispersed quickly, travelling southwards through the Aleutian Islands. Tailwinds enabled faster rates of travel than headwinds, a trend not previously shown for marine mammals. Weather effects were less pronounced at Bogoslof Island (approx. 400 km further south), and, at San Miguel Island, (California) departures were more gradual, and only influenced by wind and air pressure in 2005. We suggest that increasingly variable climatic conditions at weaning, particularly timing, frequency and intensity of autumnal storms in the Bering Sea, may alter timing, direction of dispersal and potentially survival of pups. © 2009 The Royal Society.

History

Publication title

Biology Letters

Volume

5

Pagination

252-257

ISSN

1744-9561

Department/School

School of Natural Sciences

Publisher

The Royal Society

Place of publication

United Kingdom

Repository Status

  • Restricted

Socio-economic Objectives

Global effects of climate change (excl. Australia, New Zealand, Antarctica and the South Pacific) (excl. social impacts)

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