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RESEARCH ARTICLE
Contents Vol 35(5)

Philopatry and site fidelity of New Zealand sea lions (Phocarctos hookeri)

B. Louise Chilvers A C and Ian S. Wilkinson A B
+ Author Affiliations
- Author Affiliations

A Marine Conservation Unit, PO Box 10-420, Department of Conservation, Wellington, New Zealand.

B Department of Environment and Conservation, Locked Bag 914, Coffs Harbour, NSW 2450, Australia.

C Corresponding author. Email: lchilvers@doc.govt.nz

Wildlife Research 35(5) 463-470 https://doi.org/10.1071/WR07053
Submitted: 10 May 2007  Accepted: 31 March 2008   Published: 19 August 2008

Abstract

The New Zealand sea lion (NZ sea lion), Phocarctos hookeri, is New Zealand’s only endemic pinniped, and one of the worlds rarest otariids. It is classified as ‘Threatened’ based primarily on the low number of breeding sites and restricted distribution. In New Zealand, a species listed as ‘threatened’ is required to be managed to allow its recovery and removal from the list within 20 years. For NZ sea lions this is dependant on the establishment of new breeding areas. However, understanding the recolonisation processes for pinnipeds is still in its infancy with factors such as philopatry needing more research to understand individual dispersal and the recolonisation process. This paper presents the first quantitative investigation into the level of site fidelity and philopatry to breeding beaches in NZ sea lions. Data from resights of NZ sea lions marked as pups from the northern Auckland Island breeding area suggest that both site fidelity and philopatry are important characteristics of this species. Our results show that overall: (1) females have a higher resighting rate than males, particularly at natal sites; (2) female non-natal resightings are predominantly restricted to locations within the northern Auckland Island breeding area (an area of ~10 km2), whereas male resightings are more widely dispersed (up to 700 km to NZ mainland); and (3) philopatry occurs for both sexes, but is more predominant in females than males, with males displaying delay related to sexual and social maturity. The colonisation of new breeding habitats rarely occurs when philopatry is strong and population density is low, stable or declining such as seen for NZ sea lions. Therefore, this research indicates that management of NZ sea lions needs to minimise anthropogenic mortality and encourage population growth to maximise density at breeding sites and encourage females to disperse to establish new breeding areas.


Acknowledgements

The work was conducted under research and entry permits from the New Zealand Department of Conservation (DOC), and was funded by DOC, Research, Development and Information Unit and Conservation Services Providers. DOC Southland are thanked for their logistical assistance. We thank J. Amey, H. Best, A. Castinel, S. Childerhouse, P. Duignan, W. Hockley, C. Lalas, A. Maloney, S. McConkey, F. Riet Sapriza, B. Robertson, P. Sagar and other people who helped with resighting or reported resights from outside the Auckland Islands. A special thanks to M. Cawthorn for the early tagging and resights of the Auckland Island sites and C. Edkins for graphics help. Approval for work was obtained from DOC Animal Ethics Committee – Approval AEC86 (1 July 1999). I. West and two anonymous reviewers all provided helpful, critical reviews of the manuscript.


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