Age-related reproductive variation in a wild marine mammal population

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Authors

Postma, Martin
Bester, Marthan Nieuwoudt
De Bruyn, P.J. Nico

Journal Title

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Volume Title

Publisher

Springer

Abstract

Life history theory predicts a change in reproduction success with age as energy resources are limited and must be allocated effectively to maximise reproduction and survival. In this study we use three reproductive performance measures; maternal expenditure, offspring weaning mass and first year survival to investigate the role maternal age plays in successful reproduction. Long-term uninterrupted life history data available for Marion Island’s southern elephant seals and mass change estimates from photogrammetry data allow for assessment of age related reproduction performance and trade-offs. Known-aged adult females were photographed for photogrammetric mass estimation (n=29) and their pups weighed at weaning during the 2009 breeding season. Maternal age and proportional mass loss positively influenced pup weaning mass. In turn first year pup return rates (as a proxy for survival) were assessed through the intensive mark-recapture program. Pup survival increased with female age and weaning mass. Pups of young females aged 3 to 6 years have a lower 1st year survival probability compared to pups of older and larger females.

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Keywords

Southern elephant seals, Mirounga leonina, Photogrammetry, Age-specific reproduction, Pup survival, Life history theory

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Citation

Postma, M, Bester, MN & De Bruyn, PJN 2013, 'Age-related reproductive variation in a wild marine mammal population', Polar Biology, vol. 36, no. 3, pp. 719-729.