Bird droppings reveal that intestinal bacteria change as birds move

The trillions of bacteria that live in our gut play an important role in our ability to digest food and fight disease. All other animals also have a community of bacteria that scientists call the microflora, and by learning about them, scientists can get a more complete picture of how those animals interact with the world. I can.In a new study of the journal Molecular ecologyResearchers used a small radio tracker to track the movement of birds moving between the Bahamas and Michigan, and found that the intestinal bacteria of the same individual bird differed in two places. And to understand that, scientists had to approach and personalize a lot of bird droppings.

“In other animals, we have identified that the microbial flora can be affected by the host’s place of residence. bird Migrate and experience different environments at different points in the migration cycle.How are these Various environments He influenced the bird’s microbiome, “said a doctoral student at the Field Museum and the University of Chicago, and the lead author of molecular ecology studies with John Bates and Shannon Hackett at the Field Museum and Nathan Cooper at the Smithsonian. Heather Squin said. Peter Marra of the Conservation Biology Institute and Georgetown University.

“This study combines old and new technologies such as fieldwork, breeding, migration, and bird tracking in wintering habitats for radiotelemetry and next-generation DNA sequencing,” said Hackett, an associate curator at the Field Museum. say.

Thousands Bird seeds During the transition, Skeen and her colleagues honed only one for this study. It is the warbler of Cartland, one of the rarest birds in the world. Kirtland’s Warblers are small yellow-breasted chatters that spend the winter in the Bahamas and move to northern Michigan in the spring and breed only in young jack pine forests. They were almost extinct in the 20th century, leaving only 167 males in the wild in 1987, but the population is Breeding ground..

Still, they are rare in the bird world, and their rarity, combined with their extreme annoyance in breeding grounds, has made them the ideal subject of this study. “I chose the Kurtland Warbler because there are so few types of birds that can be tracked. Individual birds We capture from non-breeding grounds and in breeding grounds, “says Skeen. Attempting to track a very common and widely distributed bird individual, such as Robin, was like trying to find a needle in a haystack. The warblers in Cartland have much smaller haystacks to choose from, spread over a much smaller geographical area.

The researchers started by doing fieldwork in the Bahamas. There, he seduced the Japanese bush warbler with a recorded bird song and installed a small radio tracking device. The bird itself is small, about 0.5 ounces, so the geolocator weighed less than 0.5 grams. (In context, a penny weighs about 2.5 grams.) After installing the tracker, Skeen and her colleagues put the bird in a bag of wax paper for a few minutes. The birds quickly turned the bag into their own bathroom. The warbler was then released and Skeen went into a bag to collect stool samples.

A few months later, when the bird moved from the Bahamas to Michigan, Skeen and her colleagues used the exact same individual sampled at The using a large network of automated towers called the Motus Wildlife Tracking System. I found a bird. Bahamas. “There are 12 radio towers throughout the bird breeding range of Michigan, and when one of the bird tracking devices pings near the tower, it uses a portable radio antenna to drive within the range and look for birds. “It was,” says Skeen. “Once the signal was received, I got out of the car and walked around, trying to attract the birds using recordings of bird songs.” Scientists released the birds again when they flew into the nets set up by the researchers. I repeated the paper bag procedure before.

Armed with samples from the same individual birds as nearly 200 bird droppings samples in both the Bahamas and Michigan, researchers Bacteria Exists in poop. They found that the bacteria present in Michigan dung differ from those in the Bahamian dung. But more importantly, the same individual bird had different bacteria in the gastrointestinal tract, depending on where the dung was collected.

“One of the most important parts of this study was the ability to recapture birds at different locations and at different parts of the annual cycle. A one-to-one comparison of the same population and the same individual and how to do it. Compare. The microbial flora has changed, “says Skeen. “When we tested different individual birds, we couldn’t be sure that the changes we saw were due to location or differences between populations. We were looking at the exact same birds. So these results are much more supported. “

A study found that bird microbiota varies from place to place, helping scientists understand how bird microbiota work, even within the same individual. “We know that bird microbiota is different from most mammals, but we don’t know the exact method or reason,” says Skeen. In most mammals, the types of gut microbiota that are present are closely related to the species and evolutionary history of the animal, but in birds, those relationships appear to be loose. Instead, previous studies have shown that the intestinal microflora of birds is more related to where they live than what species they are. “Our study found that there were probably several groups of transient bacteria. Birds acquired bacteria from food, produced feces, and they were gone,” says Skeen. “These bacteria do not colonize birds and enter and exit.”

Skeen also states that the climate crisis can make the gut microbiota particularly important as animals try to survive in changing environments. “Animal’s Gut microbiota Is an additional level of molecular diversity, and as global climate change changes ecosystems, the gut microbiota may become one of the means by which animals can adapt to changing environments, “Skeen said. Says. Microbiota It has its own ecosystem and the opportunity for discovery is ripe. ”

For more information:
Repeated sampling of individuals reveals the effects of tropical and temperate habitats on migratory bird microflora. Molecular ecology (2021).