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Seasonal foraging strategies of Alaskan gray wolves (Canis lupus) in an ecosystem subsidized by Pacific salmon (Oncorhynchus spp.). Stanek AE, Wolf N, Hilderbrand GV, Mangipane B, Causey D, Welker JM. Canadian Journal of Zoology. 2017
ABSTRACT
Despite frequent observations of wolves (Canis lupus L., 1758) using non-ungulate prey, the seasonal and inter-annual variation in the use and relative importance of alternative prey sources to gray wolf diets have not been studied at the individual scale. We used stable isotope analysis (δ13C and δ15N) of guard hair and blood components (clot and serum) collected over four years to examine the occurrence, extent, and temporal variation of salmon as a food resource by both individual wolves and social groups in Lake Clark National Park and Preserve in southwestern Alaska. Our results demonstrate substantial variability in the use of salmon over time. During summer, diets of five wolves consisted of at least 50% salmon while the diets of 17 wolves consisted of primarily terrestrial prey. Over three years, one group of wolves consistently consumed salmon in summer and switched to terrestrial prey in winter. Prey choices were generally similar within social groups; however, the degree to which individuals consumed salmon was highly variable. The use of salmon as exhibited by wolves in Lake Clark is likely widespread where salmon are abundant and this finding should be taken into consideration in the conservation and management of wolves and their prey.
By Yereth Rosen
Wolves, as readers of fairy tales know, have enduring reputations as big, bad predators. But a growing body of evidence shows that wolf diets can be diverse and extend beyond the big animals that they hunt down.In Alaska in particular, the studies say, many wolves dine on a daintier dish — salmon.
Two recent studies focusing on coastal areas of Southwest Alaska fill in details about those food choices, quantifying the proportion of salmon in wolf diets in different locations and times of the year.
One study, newly published in the Canadian Journal of Zoology, studied wolves in Lake Clark National Park over four years — 22 wolves from nine social groups roaming the park. Researchers examined the chemistry of hair and blood samples, which revealed the chemical fingerprint of food eaten by the animals.
Of the test subjects, five had summer diets that were at least half salmon. The others ate mostly food from land in that season.
Use of salmon varied widely between individuals and groups and between seasons and years, and there was a lot of evidence of diet switching as seasons changed and years progressed, the study said. Estimated proportions of salmon in individual wolves’ diets ranged from 1 percent to 89 percent in different seasons and locations.