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The effects of body size and climate on post-weaning survival of elephant seals at Heard Island

Citation

McMahon, CR and New, LF and Fairley, EJ and Hindell, MA and Burton, HR, The effects of body size and climate on post-weaning survival of elephant seals at Heard Island, Journal of Zoology, 297, (4) pp. 301-308. ISSN 0952-8369 (2015) [Refereed Article]

Copyright Statement

Copyright 2015 The Zoological Society of London

DOI: doi:10.1111/jzo.12279

Abstract

The population size of southern elephant seals in the southern Indian and Pacific Oceans decreased precipitously between the 1950s and 1990s. To investigate the reasons behind this, we studied the population of southern elephant seals at Heard Island between 1949 and 1954, using data collected by the early Australian National Antarctic Research Expeditions. Seals were marked and measured (lengths) as weaned pups, and resighted at Heard and Marion islands and in the Vestfold Hills, Antarctica in subsequent years. Bayesian state-space mark-recapture models were used to determine post-weaning survival. Yearling survival was consistently lower (ϕy: 0.280.40) than sub-adult survival (ϕs: 0.790.83). We found evidence for constant sub-adult survival and time-dependent resight probabilities. Weaning length was an important determinate of yearling survival, with the probability of survival increasing with individual length. There was some suggestion that the Southern Annular Mode influenced yearling survival but this evidence was not strong. Nonetheless, our results provide further support showing that size at independence affects yearling survival. Given the known sensitivity of southern elephant seal populations to survival early in life, it is possible that the decline in population size at Heard Island between the 1950s and 1990s like that at Macquarie Island was due to low yearling survival mediated through maternal ability to produce large pups and the dominant environmental conditions mothers experience during pregnancy.

Item Details

Item Type:Refereed Article
Keywords:survival, climate, body size, seals
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Marine and Estuarine Ecology (incl. Marine Ichthyology)
Objective Division:Environment
Objective Group:Ecosystem Assessment and Management
Objective Field:Ecosystem Assessment and Management of Antarctic and Sub-Antarctic Environments
Author:Hindell, MA (Professor Mark Hindell)
ID Code:106513
Year Published:2015
Deposited By:IMAS Research and Education Centre
Deposited On:2016-02-12
Last Modified:2016-11-16
Downloads:0

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