Spawning salmon disrupt trophic coupling between wolves and ungulate prey in coastal British Columbia

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dc.contributor.authorDarimont, Chris T
dc.contributor.authorPaquet, Paul C.
dc.contributor.authorReimchen, Thomas E.
dc.date.accessioned2014-08-07T20:27:39Z
dc.date.available2014-08-07T20:27:39Z
dc.date.copyright2008en_US
dc.date.issued2008-09-02
dc.descriptionBioMed Centralen_US
dc.description.abstractBackground: As a cross-boundary resource subsidy, spawning salmon can strongly affect consumer and ecosystem ecology. Here we examine whether this marine resource can influence a terrestrial wolf-deer (Canis lupus-Odocoileus hemionus) predator-prey system in coastal British Columbia, Canada. Data on resource availability and resource use among eight wolf groups for three seasons over four years allow us to evaluate competing hypotheses that describe salmon as either an alternate resource, consumed in areas where deer are scarce, or as a targeted resource, consumed as a positive function of its availability. Faecal (n = 2203 wolf scats) and isotopic analyses (n = 60 wolf hair samples) provide independent data sets, also allowing us to examine how consistent these common techniques are in estimating foraging behaviour. Results: At the population level during spring and summer, deer remains occurred in roughly 90 and 95% of faeces respectively. When salmon become available in autumn, however, the population showed a pronounced dietary shift in which deer consumption among groups was negatively correlated (r = -0.77, P < 0.001) with consumption of salmon, which occurred in 40% of all faeces and up to 70% of faeces for some groups. This dietary shift as detected by faecal analysis was correlated with seasonal shifts in δ13C isotopic signatures (r = 0.78; P = 0.008), which were calculated by intra-hair comparisons between segments grown during summer and fall. The magnitude of this seasonal isotopic shift, our proxy for salmon use, was related primarily to estimates of salmon availability, not deer availability, among wolf groups. Conclusion: Concordance of faecal and isotopic data suggests our intra-hair isotopic methodology provides an accurate proxy for salmon consumption, and might reliably track seasonal dietary shifts in other consumer-resource systems. Use of salmon by wolves as a function of its abundance and the adaptive explanations we provide suggest a long-term and widespread association between wolves and salmon. Seasonally, this system departs from the common wolfungulate model. Broad ecological implications include the potential transmission of marine-based disease into terrestrial systems, the effects of marine subsidy on wolf-deer population dynamics, and the distribution of salmon nutrients by wolves into coastal ecosystems.en_US
dc.description.reviewstatusRevieweden_US
dc.description.scholarlevelFacultyen_US
dc.description.sponsorshipWe thank C. Aries, P. Clement, G. Gladstone, J. Gordon-Walker J. Housty, G. Pfleuger, and C. Starr for valuable assistance in the field, the Raincoast Conservation Foundation for primary funding, and J. Gordon-Walker for scat analysis. We also thank the National Geographic Society, Patagonia, and the following foundations for support: Bullitt, McCaw, Summerlee, Vancouver, and Wilburforce. CTD was supported by NSERC Graduate and Postdoctoral Fellowships, PCP by WWF Canada, and TER by NSERC operating grant A2354 and the David Suzuki Foundation.en_US
dc.identifier.citationDarimont et al.: Spawning salmon disrupt trophic coupling between wolves and ungulate prey in coastal British Columbia. BMC Ecology 2008, 8:14en_US
dc.identifier.urihttp://www.biomedcentral.com/1472-6785/8/14
dc.identifier.urihttp://dx.doi.org/10.1186/1472-6785-8-14
dc.identifier.urihttp://hdl.handle.net/1828/5517
dc.language.isoenen_US
dc.publisherBMC Ecologyen_US
dc.subject.departmentDepartment of Biology
dc.titleSpawning salmon disrupt trophic coupling between wolves and ungulate prey in coastal British Columbiaen_US
dc.typeArticleen_US

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