Birds pick up new gut bacteria as they travel

Inside of every animal, there is an entire community of gut bacteria which contribute to digestion and fighting off disease. Without these “microbiomes,” complex, multicellular organisms would be far worse off. Now, a recent study is shedding light on the variety of compositions these microbiomes might take on within a single animal over the course of a year. 

The study examined the migration and biology of Kirtland’s Warbler by sampling a key resource for ecologists – scat. The selected population of Kirtland’s Warbler migrates every year from Michigan (in spring) to the Bahamas (in the winter). Researchers from the Field Museum, the Smithsonian, and Georgetown University sampled the warbler’s poop in both locales. 

“This study shows how much we can learn about even foundational aspects of bird biology, such as migration, from the combination of new and old technologies – fieldwork and following birds in their breeding, migrating, and wintering habitats, to newer technologies of radiotelemetry and next-generation DNA sequencing,” explained study co-author Shannon Hackett.

By utilizing old and new methodologies, the team discovered that the bird’s gut microbiomes changed as they traveled. 

“We’ve seen in other animals that microbiomes can be influenced by the places their hosts live. Lots of birds migrate, and they experience different environments at different points of their migratory cycle. We didn’t know how these different environments affected the birds’ microbiomes,” said study lead author Heather Skeen.

The relative rarity of Kirtland’s Warbler allowed them to track individual birds, and over a much smaller geographic area. Using twelve radio towers in Michigan, they were able to pinpoint the birds’ locations after they were tagged. 

“One of the most important parts about this study is that we were able to recapture birds at different portions of the annual cycle in different locations, and we have this one-to-one comparison of the same population and the same individuals and how their microbiomes changed,” said Skeen.

This study’s results are important because birds have a much more flexible microbiome content than mammals. By tracking changes as populations move, due to migration or, potentially, climate change, we can have a better understanding of how changes correspond to changes in geography. 

“An animal’s gut microbiome is an additional level of molecular diversity, and as global climate change alters ecosystems, the gut microbiome might be one of the avenues in which animals can adapt to the changing environment,” said Skeen. “The gut microbiome has its own unique ecosystem, and it’s ripe for discoveries.”

The study is published in the journal Molecular Ecology.

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By Alex Ruger, Earth.com Staff Writer