Abstract
Trophic relationships among organisms in terrestrial boreal ecosystems define ecological communities and are important in determining dynamics of energy flow and ecosystem function. We examined trophic relationships between the gray wolf (Canis lupus) and 18 mammalian species from the boreal forest of central Saskatchewan, Canada, using δ13C and δ15N stable isotope values measured in guard hair samples. Variance in isotope values for wolves and other carnivores was investigated as a proxy for variation in diet among individuals. Isosource, an isotopic source partitioning model, quantified the relative range in proportions of five most-likely prey items in the diets of wolves. The distribution of feasible contributions from each source was dominated by elk (Cervus elaphus; mean: 48%, range:11–75%), followed by white-tailed deer (Odocoileus virginianus; mean: 21%, range: 0–54%), moose (Alces alces; mean:14%, range: 0–41%), beaver (Castor canadensis; mean: 8%, range:0–25%) and snowshoe hare (Lepus americanus; mean: 8%, range: 0–24%). Despite social foraging, our results indicate highly variable diets among individuals and we discuss this in terms of individual versus group ecology of boreal wolves.
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Acknowledgements
Many central Saskatchewan fur trappers generously contributed hide samples; special thanks to Henri Giroux, Kelly Barlow and Ken McDaid. We thank Patricia Healy for preparing stable isotope samples. Stable isotope measurements were made at the National Water Research Institute in Saskatoon and the Department of Soil Science, University of Saskatchewan. We also thank C.T. Darimont, R. Feranec, Y.T. Hwang, and an anonymous reviewer for helpful comments on earlier versions of this manuscript. Logistical and financial support was provided by the Canadian Wildlife Service, Parks Canada, University of Saskatchewan, Mountain Equipment Co-op Environment Fund, Saskatchewan Environment, Nature Saskatchewan, Canadian Wildlife Foundation, and Saskatchewan Wildlife Federation.
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Urton, E.J.M., Hobson, K.A. Intrapopulation variation in gray wolf isotope (δ15N and δ13C) profiles: implications for the ecology of individuals. Oecologia 145, 316–325 (2005). https://doi.org/10.1007/s00442-005-0124-2
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DOI: https://doi.org/10.1007/s00442-005-0124-2