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 (2018 : Seattle, Wash.)
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
Genre/Form
presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Killer whale--Behavior--Salish Sea (B.C. and Wash.); Killer whale--Food --Salish Sea (B.C. and Wash.); Killer whale--Mortality--Salish Sea (B.C. and Wash.)
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
Included in
Fresh Water Studies Commons, Marine Biology Commons, Natural Resources and Conservation Commons, Terrestrial and Aquatic Ecology Commons
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.
