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23 November 2023 Non-Breeding-Season Site Fidelity and Evidence of Migration of Steller Sea Lions (Eumetopias jubatus)
Grey W. Pendleton, Lauri A. Jemison
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Most research that has been done regarding Steller sea lions (SSLs; Eumetopias jubatus) has been during the breeding season. Adult SSLs are known to have high among-year breeding-season site fidelity, typically with movement away from breeding-season locations during non-breeding seasons. Using non-breeding-season sighting data of permanently marked SSLs from four areas in Alaska and broad-scale breeding-season sightings, we estimated among-year non-breeding-season site fidelity (i.e., the probability a SSL moves from its breeding-season location to a specific non-breeding-season area). Some SSLs, especially females, have high site fidelity to non-breeding-season areas; fidelity is markedly lower for males. We found no evidence that site fidelity varied among natal rookeries, but our sample sizes were relatively small, possibly limiting our ability to determine such effects. With our estimates of non-breeding-season site fidelity, coupled with previously demonstrated breeding-season site fidelity, we concluded that SSLs should be considered partial migrants (i.e., migratory behavior exhibited by only some individuals in a population) with at least some individual SSLs, particularly females, exhibiting migratory behavior.

Grey W. Pendleton and Lauri A. Jemison "Non-Breeding-Season Site Fidelity and Evidence of Migration of Steller Sea Lions (Eumetopias jubatus)," Northwest Science 96(3-4), 136-146, (23 November 2023).
Received: 25 April 2022; Accepted: 11 July 2022; Published: 23 November 2023
Eumetopias jubatus
Non-breeding season
site fidelity
Steller sea lion
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