Observer bias and analysis of gray wolf diets from scats

The most widely used method to determine diets of carnivores is seat analys is, which allows the identification of prey species from teeth, bones, feat hers, and the cuticular scale and medullary characteristics of hair found i n seats. Because the influence of observer bias in seat analysis has not be en addressed, our objective was to compare analyses of the same gray wolf ( Canis lupus) seat samples by 3 observers to estimate error attributable to individual observer bias. We found significant observer bias when comparing detection of prey types and percentage of occurrence found by multiple obs ervers who analyzed 1,002 seats. It is important that observers be trained to thoroughly dissect and examine seats and use a reference collection.