Testing environmental DNA from wolf snow tracks for species, sex, and individual identification

Abstract

Monitoring elusive, relatively low-density, large predators, such as the grey wolf (Canis lupus), has often been accomplished by live-capture and radiocollaring. Increasingly, non-invasive methods are considered best practice whenever it is possible to use them. Recently, environmental DNA (eDNA) deposited in snow tracks was demonstrated as useful for identifying lynx (Lynx canadensis), fisher (Pekania pennanti), wolverine (Gulo gulo), sika deer (Cervus nippon), red fox (Vulpes vulpes), and the Japanese marten (Martes melampus) to species level using mitochondrial DNA (mtDNA) markers. We tested whether eDNA from fresh wolf snow tracks collected in the Superior National Forest, Minnesota, USA during winter 2019 could be used to identify species, sex, and individual. Seven of the 8 snow track samples were successfully identified to “wolf-dog” species using mtDNA, with alleles amplifying in 5 of the samples at 1 or both of loci u250 and FH2096 in the allele range for wolves for this population. None yielded enough high-quality DNA to obtain genotypes to determine individual or sex. We recommend additional field trials to determine the minimum number of tracks required per individual to obtain sufficient, high-quality eDNA, as well as collecting associated urine or blood (from estrus) when possible. If individual wolves could be identified and sexed by the eDNA in their snow tracks, researchers should be able to determine population and family or group metrics with greater precision and less effort than typically required when conducting winter scat or hair-based genetic field studies of low density, elusive carnivores. Furthermore, this method would have applications to other areas of research and management, such as hunting quota determinations, validation of field methods and, in particular regards to wolves and other predators, livestock depredation issues. Overall, this technique holds significant future promise as field and laboratory methods are further refined for greater precision and optimized regarding the varying collection, filtration, and extraction protocols for different species in various environments.