Recent research has revealed that the gut microbiome significantly impacts the health of wild birds, potentially affecting their survival rates and population sizes.

A groundbreaking study published in Proceedings of the National Academy of Sciences (PNAS), led by researchers at University College Cork (UCC), included contributions from Dr. Caroline McKeon of Trinity’s School of Natural Sciences and the Climate + Biodiversity + Water Co-Centre. This research provides direct evidence of the gut microbiome's role in the ecology and evolution of natural bird populations.

To investigate this, researchers manipulated the microbiome of great tits by introducing Lactobacillus kimchicus, a beneficial bacterium. They cultured large quantities of this bacterium from the gut microbiomes of nestling birds in 2020 and prepared it as a freeze-dried powder. In a woodland area of West Cork, researchers placed pots of mealworms outside bird nests, with some pots containing plain mealworms and others coated with the freeze-dried bacteria. Parent birds fed both themselves and their nestlings from these pots.

Throughout the nesting period, the researchers measured the nestlings' weights and collected fecal samples to analyse their gut microbiota. The findings indicated that nestlings fed with the added Lactobacillus had a distinct gut microbiome composition and were heavier during the crucial growth phase before fledging.

“While laboratory studies have shown the microbiome's impact on the health of rodents and humans, there has been limited research on wild animals,” said lead author Dr. Shane Somers, who conducted this study as part of his PhD at UCC. “In the wild, obtaining calories is challenging, so any advantage can significantly enhance survival. Our findings highlight that the gut microbiome may confer a survival advantage.”

Professor John Quinn from UCC noted, “Culturing bacteria from wild hosts is difficult, as most probiotics are generic and not tailored to specific animals. This study stands out because we isolated and fed a strain directly from wild bird feces. While the specific benefits of this strain remain unclear, our analysis indicates it likely relates to carbohydrate and protein metabolism.”

Co-author Dr. Gabrielle Davidson from the University of East Anglia emphasised, “Our research suggests that replenishing essential gut microbes could be crucial for helping wildlife adapt and thrive. Probiotics may become an essential tool for wildlife conservation moving forward.”

Professor Paul Ross, Director of APC Microbiome Ireland, added, “Lactobacillus kimchicus was isolated from a wild bird in Professor Catherine Stanton’s lab at Teagasc Moorepark Food Research Centre, where it was characterised for this study. This publication is significant as it showcases a rare ability to positively manipulate the gut microbiome of a wild animal.”

Dr. Caroline McKeon from Trinity remarked, “This research exemplifies the benefits of collaborative work, combining expertise in fieldwork, lab work, sequencing, bioinformatics, statistical analysis, and ecological theory, contributing significantly to our understanding of the microbiome's role in ecology and evolution.”