Diet and observer bias in scat analysis of gray wolves

Abstract

I analyzed 1,182 gray wolf (Canis lupus) scats, representing summer diet in 1988-1990, collected from 9 packs in northwest Alaska. Using a linear regression model, I determined the biomass of prey species consumed using relative estimated bulk and frequency of occurrence of prey types in scats. There were no significant differences (P < 0.05) between methods in percent biomass of prey consumed and ranking of prey types. Caribou (Rangifer tarandus), moose (Alces alces), microtines, and birds composed 47.0, 21.9, 10.6, and 13.8%, of prey items, respectively. Ungulates composed 90.1%, birds 6.7%, and microtines 0.5% of biomass consumed. Ungulates composed 3.4%, birds 50.4%, and microtines 38.5% of numbers of individuals consumed. Significant (P < 0.05) observer bias was found in the detection and frequency of prey types in the analysis of 1,052 scats by multiple observers.