Evaluating the reliability of field identification and morphometric classifications for carnivore scats confirmed with genetic analysis

Abstract

ABSTRACTScat surveys are commonly used to monitor carnivore populations. Scats of sympatric carnivores can be difficult to differentiate and field‐based identification can be misleading. We evaluated the success of field‐based species identification for scats of 2 sympatric carnivores—coyotes (Canis latrans) and kit foxes (Vulpes macrotis). We conducted scat surveys in the Great Basin desert of Utah, USA, during the winter and summer of 2013, and we detected 1,680 carnivore scats. We classified scats based on field identification, recorded morphometric measurements, and collected fecal DNA samples for molecular species identification. We subsequently evaluated the classification success of field identification and the predictive power of 2 nonparametric classification techniques—k‐nearest neighbors and classification trees—based on scat measurements. Overall, 12.2% of scats were misclassified by field identification, but misclassifications were not equitable between species. Only 7.1% of the scats identified as coyote with field identification were misclassified, compared with 22.9% of scats identified as kit fox. Results from both k‐nearest neighbor and classification‐tree analyses suggest that morphometric measurements provided an objective alternative to field identification that improved classification of rarer species. Overall misclassification rates for k‐nearest neighbor and classification‐tree analyses were 11.7% and 7.5%, respectively. Using classification trees, misclassification was reduced for kit foxes (8.5%) and remained similar for coyotes (7.2%), relative to field identification. Although molecular techniques provide unambiguous species identification, classification approaches may offer a cost‐effective alternative. We recommend that monitoring programs employing scat surveys utilize molecular species identification to develop training data sets and evaluate the accuracy of field‐based and statistical classification approaches. © 2015 The Wildlife Society.