A 2022 study published in Ecology and Evolution sheds light on a surprising behaviour among wild red foxes (Vulpes vulpes): the frequent consumption of domestic dog faeces. This behaviour, known as interspecific coprophagy, has traditionally been difficult to document, but advances in DNA metabarcoding have made it possible to explore this phenomenon in greater detail. By analysing fox and pine marten scats, the researchers uncovered a potentially widespread commensal relationship among vertebrates, offering new perspectives on how species interact. Additionally, we propose a theory that this behaviour may reflect foxes’ adaptive response to environmental changes, such as the loss of plant biodiversity, and could even be a form of self-medication.
The Study: Exploring Fox Diets Through DNA Metabarcoding
The researchers conducted a large-scale DNA metabarcoding study on scat samples from red foxes and pine martens, focusing on identifying the sources of DNA present in the animals’ diets. One of the most surprising findings was the high occurrence of domestic dog DNA in the red fox scats. To determine whether this was the result of experimental contamination or an actual dietary choice, the team rigorously tested various hypotheses, including predation, scavenging, and environmental contamination.
The results pointed towards interspecific coprophagy as the most likely explanation for the presence of dog DNA in fox scats. The timing of the increase in dog DNA coincided with decreases in the availability of the fox’s main prey, the short-tailed field vole. The research team also assessed the calorific value of dog faeces and found that it offered substantial nutritional content. Thus, the consumption of dog faeces appeared to provide foxes with an alternative food source when prey was scarce.
The Role of Coprophagy in Species Interactions
While coprophagy, the consumption of faeces, is known in various animal species, its role in shaping species dynamics is still largely unexplored. This study contributes to a growing body of evidence that suggests interspecific coprophagy may be more widespread than previously thought, and it could be an important form of commensalism in some ecosystems. The foxes' use of dog faeces as an additional resource, particularly during periods of prey scarcity, highlights how animals can adapt their foraging strategies based on environmental conditions.
A New Theory: Foxes Self-Medicating Due to Environmental Stress
Building on the study's findings, we propose an additional theory: red foxes may not only be consuming dog faeces for its calorific value alone, but also as a form of self-medication. As urbanisation and agricultural expansion reduce plant biodiversity, wild animals may struggle to find the plants they would naturally consume to support their health, particularly those with medicinal properties. Ingesting faeces from domestic animals like dogs, which may contain remnants of plant matter or even medications (such as anti-parasitic drugs), could help foxes compensate for these lost resources.
The reduction in plant biodiversity due to habitat degradation and human development could also be limiting the availability of certain nutritional components. Foxes might be turning to dog faeces not just as an emergency food source, but as a means to acquire nutrients they are no longer able to find in their natural environment. Parasite management is a key concern for wild animals, and the presence of pharmaceutical residues in the faeces of domestic dogs may offer some medicinal benefits to foxes. This theory is supported by observations of similar behaviours in other species, where animals are known to seek out particular plants or other organic material as a way to self-medicate against parasites or nutritional deficiencies.
Implications for Wildlife and Urban Ecology
The study has broad implications for how we understand wildlife behaviour in increasingly urbanised environments. Foxes are highly adaptable creatures, capable of modifying their behaviour in response to changes in food availability. The frequent consumption of dog faeces as an alternative resource highlights the resourcefulness of foxes, but it also raises questions about how environmental pressures, such as biodiversity loss, may be influencing their behaviour in unexpected ways.
Moreover, the potential for interspecific coprophagy to play a role in nutrient cycling and disease transmission between domestic and wild animals warrants further investigation. If foxes are routinely consuming dog faeces in urban environments, it could create new pathways for the transmission of parasites or pathogens between species. On the other hand, this behaviour could also provide insights into how wildlife is adapting to human-altered landscapes.
Summary
This study marks a significant step forward in understanding the diet and behaviour of red foxes, revealing that interspecific coprophagy may be a widespread and adaptive strategy. The high calorific value of dog faeces and the timing of its consumption suggest that red foxes are using this resource when prey is scarce. However, the potential for self-medication through coprophagy, especially in response to environmental stressors like the loss of plant biodiversity, is a promising avenue for future research.
As cities continue to expand and natural habitats diminish, the ability of wild animals to adapt to new ecological pressures will become increasingly important. Studies like this provide valuable insights into the complex dynamics of species interactions in urban and suburban environments, offering a deeper understanding of how wildlife survives in human-dominated landscapes.
Further research into the prevalence of interspecific coprophagy, as well as its long-term effects on species health and behaviour, could significantly enhance our knowledge of animal ecology and welfare in rapidly changing environments.
Source:
