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Evidence for density dependent population regulation in southern elephant seals in the southern Indian Ocean

Evidence for density dependent population regulation in southern elephant seals in the southern... The means by which populations are regulated form a central theme in conservation biology, and much debate has revolved around density dependence as a mechanism driving population change. Marion Island (46°54‘S, 37°45‘E) is host to a relatively small breeding population of southern elephant seals, which like its counterparts in the southern Indian and southern Pacific Oceans, have declined precipitously over the past few decades. An intensive mark–recapture study, which commenced in 1983, has yielded a long time-series of resight data on this population. We used the program MARK to estimate adult female survival in this population from resight data collected over the period 1986–1999. Including concurrent population counts as covariates significantly improved our mark–recapture models and suggests density dependent population regulation to be operational in the population. Although predation may have been involved, it is far more likely that density dependent regulation has been based on a limited food supply. A significant increase in adult female survival was evident which is likely to have given rise to recent changes in population growth. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png African Zoology Taylor & Francis

Evidence for density dependent population regulation in southern elephant seals in the southern Indian Ocean

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Evidence for density dependent population regulation in southern elephant seals in the southern Indian Ocean

Abstract

The means by which populations are regulated form a central theme in conservation biology, and much debate has revolved around density dependence as a mechanism driving population change. Marion Island (46°54‘S, 37°45‘E) is host to a relatively small breeding population of southern elephant seals, which like its counterparts in the southern Indian and southern Pacific Oceans, have declined precipitously over the past few decades. An intensive mark–recapture study,...
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Publisher
Taylor & Francis
Copyright
© Zoological Society of Southern Africa
ISSN
2224-073X
eISSN
1562-7020
DOI
10.1080/15627020.2008.11407409
Publisher site
See Article on Publisher Site

Abstract

The means by which populations are regulated form a central theme in conservation biology, and much debate has revolved around density dependence as a mechanism driving population change. Marion Island (46°54‘S, 37°45‘E) is host to a relatively small breeding population of southern elephant seals, which like its counterparts in the southern Indian and southern Pacific Oceans, have declined precipitously over the past few decades. An intensive mark–recapture study, which commenced in 1983, has yielded a long time-series of resight data on this population. We used the program MARK to estimate adult female survival in this population from resight data collected over the period 1986–1999. Including concurrent population counts as covariates significantly improved our mark–recapture models and suggests density dependent population regulation to be operational in the population. Although predation may have been involved, it is far more likely that density dependent regulation has been based on a limited food supply. A significant increase in adult female survival was evident which is likely to have given rise to recent changes in population growth.

Journal

African Zoology – Taylor & Francis

Published: Apr 1, 2008

Keywords: density dependence; southern elephant seals; Marion Island; population regulation

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