Dog faeces form a significant part of red foxes' diets, a new study by University of Aberdeen scientists shows

A new study has revealed that dog faeces form a significant part of the diet of red foxes in the Highlands.

Scientists analysed the diets of red foxes found in the pine forests of the Cairngorms – marking the first time such a connection has been detected anywhere in the world.

They found that dog faeces have a calorific content on par with the foxes’ wild prey, but are far easier to “hunt” and consume, especially when wild prey is naturally scarce.

The study had initially set out to characterise the diet of foxes and pine martens to better understand how these two predators coexist despite very similar eating habits and their impacts on prey.

Using a technique known as “metabarcoding” – which is based on DNA-based identification and rapid DNA sequencing – they found that domestic dog DNA was the second most frequent species in fox stool samples (nearly 40%), while being virtually absent in pine marten samples.

Several options were considered to explain this, including a possible confusion between fox and dog DNA since the two are closely related species, however researchers concluded that dog faeces have become an important food source for foxes to fall back on in times of scarcity.

Scientists at the University of Aberdeen’s School of Biological Sciences, the Laboratory of Alpine Ecology at University of Grenoble Alps, Cairngorms Connect and Forestry and Land Scotland said that the findings alter general understanding of how the behaviour of foxes living in the pine forests of the Cairngorms are affected by visits from people and their pets.

Cristian Navarro, a PhD student from the University of Aberdeen’s School of Biological Sciences and co-author of the study, called the findings “unprecedented”.

He added: “Rabbits and other related species are well-known to consume their own faeces but consumption of the faeces of another species has seldom been documented and likely represents an overlooked interaction among wild animals.

“This phenomenon would be undetectable through traditional diet study methods, but by using DNA-based techniques our study has revealed this interaction for the first time, leading to important questions about how human activities are affecting wildlife.”

Mr Navarro co-authored the study published in the journal Ecology and Evolution with Professor Xavier Lambin, Dr Catherine Hambly, Kenny Kortland, Dr Eric Coissac and Dr Pierre Taberlet.

Professor Lambin added: “Just like how bird feeders in gardens benefit some species of birds while others are displaced, dog faeces may benefit foxes over their competitors or prey species.

“In addition, the availability of dog faeces and their consumption by wild animals creates risks of disease and parasite transmission, and of introducing new pathogens.

“This highlights the need for a holistic management approach, including the need for measures to help ensure the appropriate use of outdoor spaces by dog walkers, given the potential impacts.”