Birds and bats have strange gut bacteria, and it might help them fly

January 8, 2020, 1:54 p.m.

We humans are relatively obsessed with the state of our gut bacteria. We have somewhere between 300 to 500 types of bacteria living in our digestive system, reports WebMD. Known as the microbiota, or the microbiome, research shows they impact everything from our moods to our immune systems.

Researchers recently compared the microbiomes of nearly 900 vertebrate species by analyzing fecal samples collected from institutions around the world. They found that bats and birds had similar gut bacteria, and surprisingly, they didn't seem to rely on it to support normal digestion.

The researchers believe it's the creatures' shared ability to fly that links their digestive bacteria.

"If you're carrying a lot of bacteria in your gut, it can be pretty heavy and may take resources away from you," coauthor Holly Lutz, Ph.D., a postdoctoral researcher at the University of California San Diego School of Medicine and research associate at Chicago's Field Museum, said in a statement. "So if you're an animal that has really high energetic demands, say because you're flying, you may not be able to afford to carry all those bacteria around, and you may not be able to afford to feed them or deal with them."

A lifestyle link

white-throated swallows Carrying too much bacteria may make it difficult for birds and bats to fly. (Photo: Sumarie Slabber [CC BY-ND 2.0]/Flickr)

Researchers originally thought that animals would share a similar microbiome when they had similar diets or it would be shared ancestry that linked their gut bacteria.

Although birds and bats are very distantly related, it's their shared lifestyles that is the link, researchers say. They have much shorter guts than comparably-sized land mammals and they have fewer bacteria. There's the chance, too, that their bodies aren't supplying enough food to their gut bacteria to make the relationship beneficial for the bacteria.

Another important finding is that with birds and bats there seems to be a haphazard collection of types of gut bacteria versus other mammals that have specific patterns of bacteria.

"It's almost like they're just picking up whatever's around them and they don't really need their microbes to help them in ways that we do," says Lutz.

The research, which published in the journal mBio, could be a stepping stone. Scientists hope that uncovering more about the microbiomes of birds, bats and other animals will help us learn more about our own. It's particularly illuminating to learn from the species that don't rely on their gut bacteria like we do, Lutz says.

"If we ever are putting ourselves in some kind of extreme situation where we're disrupting our microbiome, there is something that we can learn from animals that don't need their microbiomes as much."