Activity patterns and time budgets of the declining sea otter population at Amchitka Island, Alaska

Journal of Wildlife Management
By: , and 

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Abstract

Time budgets of predators may reflect population status if time spent foraging varies with local prey abun- dance. We assumed that the sea otter (Enhydra lutris) population at Amchitka Island, Alaska, USA, had been at equilibrium since the early 1960s and collected time budgets of otters to be used to represent future conditions of currently expanding sea otter populations. We used radiotelemetry to monitor activity-time budgets of otters from August 1992 to March 1994. Sea otter activity was directly linked to sex, age, weather condition, season, and time of day. Sea otters differed in percent time foraging among cohorts but not within cohorts. Percent time foraging ranged from 21% for females with very young (≤ 3weeks of age) dependent pups to 52% for females with old (≥10 weeks of age) pups. Otters foraged more and hauled out more as local sea conditions worsened. Adult males spent less time foraging during winter and spring, consistent with seasonal changes in prey selection. Time spent for- aging was similar to that reported for otters in California and an established population in Prince William Sound, Alaska, but greater than that of otters in recently established populations in Oregon and Alaska. Despite current evidence indicating that the population was in decline during our study, we were unable to recognize this change using time budgets. Our results illustrate the importance of stratifying analyses of activity patterns by age and sex cohorts and the complexity inherent in comparisons of behavioral data between different populations relying on distinct prey bases.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Activity patterns and time budgets of the declining sea otter population at Amchitka Island, Alaska
Series title Journal of Wildlife Management
DOI 10.2307/3802868
Volume 66
Issue 1
Year Published 2002
Language English
Publisher Wildlife Society
Contributing office(s) Western Ecological Research Center
Description 11 p.
First page 29
Last page 39