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Study: Wolves will eat salmon if ungulate prey is scarce

[large thumbnail url=”study-wolves-will-eat-salmon-if-ungulate-prey-is-scarce” filename=”science” year=”2010″ month=”05″ day=”04″] [thumbnail icon url=”study-wolves-will-eat-salmon-if-ungulate-prey-is-scarce” filename=”science” year=”2010″ month=”05″ day=”04″] The Denali wolves are subject to many studies, but one of the most recent shows that wolves will resort to eating fish in areas where their more traditional prey is only available in limited numbers.

It’s something biologists have known for some time. That wolves will eat salmon. During winter, wolves will hang out in salmon-spawning areas. What scientists haven’t been able to do til now is quantify the observation.

Layne Adams, a USGS Alaska Science Center biologist, wrote a paper which appeared in the January issue of  Ecological Applications which talked about the new study which is the first to investigate how inland wolves eating salmon is related to, and impacts the relationship between wolf-ungulate populations.

An abstract for the paper Are inland wolf-ungulate systems influenced by marine subsidies of Pacific Salmon?  is found below:

Wolves (Canis lupus) in North America are considered obligate predators of ungulates with other food resources playing little role in wolf population dynamics or wolf–prey relations. However, spawning Pacific salmon (Oncorhyncus spp.) are common throughout wolf range in northwestern North America and may provide a marine subsidy affecting inland wolf–ungulate food webs far from the coast. We conducted stable-isotope analyses for nitrogen and carbon to evaluate the contribution of salmon to diets of wolves in Denali National Park and Preserve, 1200 river-km from tidewater in interior Alaska, USA. We analyzed bone collagen from 73 wolves equipped with radio collars during 1986–2002 and evaluated estimates of salmon in their diets relative to the availability of salmon and ungulates within their home ranges. We compared wolf densities and ungulate:wolf ratios among regions with differing salmon and ungulate availability to assess subsidizing effects of salmon on these wolf–ungulate systems. Wolves in the northwestern flats of the study area had access to spawning salmon but low ungulate availability and consumed more salmon (17% ± 7% [mean ± SD]) than in upland regions, where ungulates were sixfold more abundant and wolves did or did not have salmon spawning areas within their home ranges (8% ± 6% and 3% ± 3%, respectively). Wolves were only 17% less abundant on the northwestern flats compared to the remainder of the study area, even though ungulate densities were 78% lower. We estimated that biomass from fall runs of chum (O. keta) and coho (O. kisutch) salmon on the northwestern flats was comparable to the ungulate biomass there, and the contribution of salmon to wolf diets was similar to estimates reported for coastal wolves in southeast Alaska. Given the ubiquitous consumption of salmon by wolves on the northwestern flats and the abundance of salmon there, we conclude that wolf numbers in this region were enhanced by the allochthonous subsidy provided by salmon and discuss implications for wolf–ungulate relations.

ESA Journals – www.esajournals.org

Tim Mowry, of the Fairbanks Daily News-Miner, wrote up a detailed story based on the paper and also talked to Layne Adams.

FAIRBANKS — Moose and caribou are the food of choice for wolves in Interior Alaska, but salmon also can be an important item on their menu, at least for wolves in part of Denali National Park and Preserve.

A recent study using old wolf bones revealed that some living in the northwest portion of the park, near salmon-spawning beds, rely on the fish for a third of their diet. On average, salmon make up about a sixth of the diet of wolves in the area.

“That’s quite a bit for an animal that’s supposed to be relying on ungulates,” said Layne Adams, a longtime biologist with the U.S. Geological Survey’s Alaska Science Center.

Adams co-wrote a paper about the study for the journal Ecological Applications. It appeared two months ago…

Read the entire article – Study: Wolves prefer moose or caribou, but salmon will do in a pinch

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