Molecular testing of observer identification of carnivore feces in the field

Collection of carnivore feces is common in wildlife ecology studies, but misidentification of scats can compromise data quality. We tested the ability of observers to identify coyote (Canis latrans) feces in the Alaska Range from 2000–2002. We extracted DNA from 834 fecal samples and used an unambiguous mtDNA analysis to differentiate coyote scats from those of sympatric carnivores. We successfully amplified DNA from 78% of the extracts, and 92% of these samples were from coyotes. We rated our certainty level when collecting scats in the field, and the proportion correctly identified matched well with expected proportions. For example, 100% of scats that we rated “100% certain” were from coyotes (n = 129), 96% of scats rated “95% certain” were from coyotes (n = 174), and 88% of scats rated “90% certain” were from coyotes (n = 62). Thus, we demonstrate that trained observers can identify coyote scats in the field with accuracy that should be sufficient for diet studies, even in the presence of other similar-sized carnivores. Rating observer certainty is useful for later analyses because researchers can decide what level of uncertainty is acceptable for their purposes and exclude samples accordingly.