Molecular technology can identify species noninvasively from faeces found in the field. We describe a fast and reliable genetic method that differentiates faeces of five potentially sympatric North American canids without using multiple primer sets or restriction enzyme digestion. Our primer set amplifies a short fragment (237–288 bp) of the mitochondrial d-loop that is a different length in each species: kit fox (Vulpes macrotis), red fox (Vulpes vulpes), gray fox (Urocyon cinereoargenteus), coyote (Canis latrans), and dog (Canis familiaris). We extensively tested our technique using published and novel d-loop sequences and then applied it to two large faecal data sets collected in California and Virginia. It provides an efficient tool for noninvasively distinguishing sympatric canids in diverse regions of North America.
