Presentation Abstract

An individual's ecological environment affects its mortality risk, which in turn has fundamental consequences for life-history evolution and population viability. In many species, social relationships are likely to be an important component of an individual's environment, and therefore mortality risk. Here, we examine the relationship between social position and mortality risk in Southern resident killer whales (Orcinus orca) using over three decades of social and demographic data. We find that the social position of male, but not female, killer whales in their social unit predicts their mortality risk. More socially integrated males have a significantly lower risk of mortality than socially peripheral males, particularly in years of low salmon abundance, suggesting that social position mediates access to resources. Male killer whales are larger and require more resources than females, increasing their vulnerability to starvation in years of low salmon abundance. More socially integrated males are likely to have better access to social information and food-sharing opportunities which may enhance their survival in years of low prey abundance. Our results show that observable variation in the social environment is linked to variation in mortality risk. Furthermore, our results highlight the importance of considering sex differences in social effects on survival when developing conservation strategies for long-lived social mammals.

Session Title

Cumulative Effects on Southern Resident Killer Whales (Orcinus orca)

Keywords

Killer whale, Social behavior

Conference Track

SSE9: Transboundary Management and Policy

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE9-450

Start Date

4-4-2018 2:15 PM

End Date

4-4-2018 2:30 PM

Type of Presentation

Oral

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

text

Language

English

Format

application/pdf

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Apr 4th, 2:15 PM Apr 4th, 2:30 PM

Mortality risk and social network position in southern resident killer whales (Orcinus orca): sex differences and the importance of salmon abundance

An individual's ecological environment affects its mortality risk, which in turn has fundamental consequences for life-history evolution and population viability. In many species, social relationships are likely to be an important component of an individual's environment, and therefore mortality risk. Here, we examine the relationship between social position and mortality risk in Southern resident killer whales (Orcinus orca) using over three decades of social and demographic data. We find that the social position of male, but not female, killer whales in their social unit predicts their mortality risk. More socially integrated males have a significantly lower risk of mortality than socially peripheral males, particularly in years of low salmon abundance, suggesting that social position mediates access to resources. Male killer whales are larger and require more resources than females, increasing their vulnerability to starvation in years of low salmon abundance. More socially integrated males are likely to have better access to social information and food-sharing opportunities which may enhance their survival in years of low prey abundance. Our results show that observable variation in the social environment is linked to variation in mortality risk. Furthermore, our results highlight the importance of considering sex differences in social effects on survival when developing conservation strategies for long-lived social mammals.