A recent study has highlighted the benefits of coprophagy, or the consumption of faeces, among birds.
Published in Biological Reviews and led by researchers from the University of South Australia (UniSA), the research outlines how coprophagy influences the gut biota (the bacteria in the digestive system) of wild birds.
Gut biota boosted by coprophagy allows birds to absorb nutrients more efficiently and respond to changes in food availability over the seasons.
A migratory bird such as a Black Redstart could benefit from coprophagy, but consuming faeces in urban environments could be bad for gut health (R Thew).
Why eating faeces works
Coprophagy helps migratory birds to bridge periods of fasting and refuelling during their journeys. Consuming faeces alters the microbial composition within a bird's digestive tract, allowing them to settle in to new surroundings.
Emerging evidence suggests that coprophagy could serve as a form of self-medication, boosting birds' defences against infections, although further research is needed.
Alongside its benefits, coprophagy increases the risk of disease transmission between birds and may also increase their exposure to antimicrobials, particularly pesticides and cleaning products, which lead to antimicrobial resistance and compromised gut biota.
Dr Barbara Drigo, a UniSA microbial ecologist and lead author of the study said: "Birds foraging in human environments are exposed to chemicals and metals from waste, sewage and refuse, which can alter their microbiota, potentially leading to antimicrobial resistance."
Bread is known to have a similar damaging effect on the health of birds' digestive systems, meaning their gut biota faces multiple threats in areas where birds come into contact with people.
Dr Drigo said: "Depending on their geographical range, behaviour and interactions with other animals and environments, birds – especially migratory ones – can efficiently spread pathogens around the world."
The study highlights the need for further research into the impacts of coprophagy on avian gut microbiomes and how human environments and substances could play into bird health.
Dr Drigo said: "There's an urgent need to thoroughly explore how various forms of coprophagy impact avian gut microbiomes, affecting bird health across their different life stages and environments."
Reference
Dunbar, A, Drigo, B, Djordjevic, S P, Donner, E, and Hoye, B J. 2023. Impacts of coprophagic foraging behaviour on the avian gut microbiome. Biological Reviews, 99(2), 582. DOI: https://doi.org/10.1111/brv.13036
