Age-related reproductive variation in a wild marine mammal population

• Published in: Polar Biology
• Main Authors: Postma, Martin, Bester, Marthan Nieuwoudt, De Bruyn, P.J. Nico
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer 2013
• Subjects: Southern elephant seals; Mirounga leonina; Photogrammetry; Age-specific reproduction; Pup survival; Life history theory; Elephant Seals; Polar Biology; Southern Elephant Seals
• Online Access: http://hdl.handle.net/2263/39828; https://doi.org/10.1007/s00300-013-1298-4

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. http://link.springer.com/journal/300 hb2014