Rearing two New Zealand fur seal (Arctocephalus forsteri) pups to weaning
Sacha A. Dowell A , Laura J. Boren A C , Sandra S. Negro A , Chris G. Muller A , Abigail K. Caudron A B and Neil J. Gemmell AA School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand.
B Behavioural Biology Unit, University of Liège, 22 Quai Van Beneden, 4020 Liege, Belgium.
C Corresponding author: Email: seals_n_sealions@yahoo.co.nz
Australian Journal of Zoology 56(1) 33-39 https://doi.org/10.1071/ZO07063
Submitted: 29 November 2007 Accepted: 21 May 2008 Published: 29 July 2008
Abstract
The rearing of two pups to weaning is a rare occurrence in pinnipeds and in many cases it remains unknown whether it is a result of twinning or fostering. This study followed two cases where female New Zealand fur seals (Arctocephalus forsteri) raised two pups, at a colony in Kaikoura, New Zealand. Maternal attendance behaviour was observed, mass and condition of the pups were measured and genetic samples were collected to assess relatedness. In one case, the female gave birth to twins, while the other case was found to be fostering of a second pup. In both cases, the filial pups of each female exhibited significantly lower mass, condition and growth rates than the colony average. The twins’ mother reared both pups to weaning and did not appear to spend a different amount of time ashore compared with single-pup mothers. The current study confirms both fostering and twinning in New Zealand fur seals, with the potential for successfully raising the pups to weaning, despite their well developed recognition system and the energy costs involved.
Acknowledgements
The authors thank Melinda Fowler, Olivier Biémar, Leona Laniewa, John Klavitter, Catherine Gunther-Murphy and the Canterbury University Marine Ecology Research Group for assistance in the field. The New Zealand Department of Conservation provided logistical assistance. Financial assistance was provided by the Minority International Research Training Program, a Canterbury University Doctoral Scholarship and the Whale and Dolphin Adoption Project. Research was carried out under Department of Conservation Permit: Per/10/2002/01. Two anonymous reviewers provided helpful comments on the manuscript.
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