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Kays and Feranec 2011 captive vs. wild wolf isotopes

Kays, R. and R.S. Feranec  2011. Using stable carbon isotopes to distinguish wild from captive wolves. Northeast Naturalist, 18, 253-264.
Abstract - Morphological and genetic techniques for distinguishing captive vs. wild
stock are often insuffi cient. We found differences in carbon isotope values from Canis
latrans (Coyote) and Canis lupus (Wolf) eating wild vs. domestic diets. Wild canids in
the Northeast have lower d13C values because they eat prey that mainly feed on C3 plants.
However, canids eating typical domestic diets have more positive d13C values (˜+6‰)
because of the Zea mays (Corn; a C4 plant) fed to domestic stock and used in dog foods.
We applied this technique to hair and bone samples from eight Wolves in the northeastern
USA, where no natural Wolf populations are known. Three Wolves had strongly negative
d13C values, typical of a wild-food diet, while the other fi ve Wolves had more positive
values typical of captive animals. As expected, we found no signifi cant difference in
d15N isotope values between captive and wild animals. This new evidence suggests that,
while some Wolves are escaping from captivity, at least three animals have apparently
dispersed into the area. This fi nding adds new urgency to the preparation of conservation
plans for the potential natural recovery of this endangered species in the region.