Document Detail

Consumption of salmon by Alaskan brown bears: a trade-off between nutritional requirements and the risk of infanticide?
MedLine Citation:
PMID:  14673639     Owner:  NLM     Status:  MEDLINE    
The risk of infanticide may alter foraging decisions made by females, which otherwise would have been based on nutritional requirements and forage quality and availability. In systems where meat resources are spatially aggregated in late summer and fall, female brown bears (Ursus arctos) would be faced with a trade-off situation. The need of reproductive females to accumulate adequate fat stores would likely result in a decision to frequent salmon streams and consume the protein- and lipid-rich spawning salmon. In contrast, aggregations of bears along salmon streams would create conditions of high risk of infanticide. We investigated consumption of salmon by brown bears on Admiralty and Chichagof Islands in Southeast Alaska from 1982 to 2000 using stable isotope analysis and radiotelemetry. While nearly all males (22 of 23) consumed relatively large amounts of salmon (i.e., >10% relative contribution to seasonal diet), not all females (n=56) did so. Five of 26 females for which we had reproductive data, occupied home ranges that had no access to salmon and thus did not consume salmon when they were mated or accompanied by young. Of females that had access to salmon streams (n=21), all mated individuals (n=16) had delta(15)N values indicative of salmon consumption. In contrast, 4 out of 16 females with cubs avoided consuming salmon altogether, and of the other 12, 3 consumed less salmon than they did when they were mated. For 11 of 21 females with access to salmon streams we had data encompassing both reproductive states. Five of those altered foraging strategies and exhibited significantly lower values of delta(15)N when accompanied by young than when mated, while 6 did not. Radiotelemetry data indicated that females with spring cubs were found, on average, further away from streams during the spawning season compared with females with no young, but both did not differ from males and females with yearlings and 2-year-olds. Females with young that avoided salmon streams were significantly lighter indicating that female choice to avoid consumption of salmon carries a cost that may translate to lower female or cub survivorship. The role of the social hierarchy of males and females, mating history, and paternity in affecting the risk of infanticide and foraging decisions of female brown bears merit further investigation.
Merav Ben-David; Kimberly Titus; LaVern R Beier
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2003-12-13
Journal Detail:
Title:  Oecologia     Volume:  138     ISSN:  0029-8549     ISO Abbreviation:  Oecologia     Publication Date:  2004 Feb 
Date Detail:
Created Date:  2004-01-27     Completed Date:  2004-05-27     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0150372     Medline TA:  Oecologia     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  465-74     Citation Subset:  IM    
Department of Zoology and Physiology, University of Wyoming, P.O. Box 3166, Laramie, WY 82071, USA.
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MeSH Terms
Adipose Tissue
Animals, Newborn
Behavior, Animal*
Body Composition
Feeding Behavior*
Nutritional Requirements
Risk Factors
Social Dominance*

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