Vertebrate animals are known to consume other species' faeces, yet the role of such coprophagy in species dynamics remains unknown, not least due to the methodological challenges of documenting it. In a large-scale metabarcoding study of red fox and pine marten scats, we document a high occurrence of domestic dog DNA in red fox scats and investigate if it can be attributed to interspecific coprophagia. We tested whether experimental artifacts or other sources of DNA could account for dog DNA, regressed dog occurrence in the diet of fox against that of the fox’s main prey, short-tailed field voles, and consider whether predation or scavenging could explain the presence of dog DNA. Additionally, we determined the calorific value of dog faeces through calorimetric explosion. The high occurrence of dog DNA in the diet of fox, the timing of its increase, and the negative relationship between dog and the fox's main prey, point to dog faeces as the source of DNA in fox scats. Dog faeces being highly calorific, we found that foxes, but not pine martens, regularly exploit them, seemingly as an alternative resource to fluctuating prey. Scattered accounts from the literature may suggest that interspecific coprophagia is a potentially frequent and widespread form of interaction among vertebrates. However, further work should address its prevalence in other systems and the implications for ecological communities. Tools such as metabarcoding offer a way forward.
We are deeply grateful to the Cairngorms Connect, Forestry and Land Scotland, Wildland Ltd., the Royal Society for the Protection of Birds and NatureScot and their staff for their ongoing support. Particularly, to Thomas MacDonell for encouraging us to investigate the occurrence of dog DNA. Two anonymous reviewers contributed to improve an earlier version of this manuscript as did Thomas Cornulier and Jennifer Smart. This study was funded by Forestry and Land Scotland, the School of Biological Sciences of Aberdeen University and Wildland Ltd.
Data Availability StatementThe data and code used in this study is presented within or available from the Dryad Data Repository: https://doi.org/10.5061/dryad.qz612jmj4.
- red fox
- species interactions
- domestic dog
- interspecific coprophagia