Skipping meals is a way to go, and the kangaroo and grizzly bear of the world have learned to eat meat without ever pecking at the bones. Now scientists say some birds could have figured out a similarly innovative way to forage — gut bacteria that can clog their digestive systems.
New research from researchers at the University of Surrey in the United Kingdom suggests that vulture bee populations are becoming more genetically adapted to eating a diet rich in bovine stomach acids, meaning the birds may be able to break down more quickly and take in more juicy innards.
Researchers analyzed the gut bacteria of high-fat diets for about 550 beaked vultures, and found they were more resistant to stomach acid than a control group of lower-fat meals.
Dormancy is the main biological defense against stomach acid, and all humans have retained parts of their gut microbial communities in a form that is capable of supporting gut microbes. But in addition to being constantly digging into these preserved communities, humans produce an enzyme called PER3 to convert stomach acid into glucose.
The scientists found vulture bees reacted differently. The bee gut bacteria produced PER3 in their level of digestion activity. But they also maintained the ability to damage the intestinal walls of mice by turning gut acids into glucose, which can release the intestinal waste product methane.
“Bees can cope better with a longer digestive cycle if they eat a diet more concentrated in the acid-digesting components of human stomach acid,” Robert Meadowcroft, who conducted the study as a postdoctoral fellow in the Department of Biology, University of Surrey, said in a statement. “This highlights the importance of gut bacteria in the immunity of vultures, especially as these insect-eating birds rely on the bovine stomach acid, which is in short supply due to the over-dependence on grass, which lacks acid producing species.”
In a similar but separate experiment, researchers from the University of California Davis found that red-legged vultures are more likely to put down their bill, swallow a small stone and raise their babies with the soil and plants they find in the forest where they hunt.
Study author Sam Pearlman, a postdoctoral researcher in the Department of Wildlife Conservation Biology at UC Davis, said the vultures feed on the soil that is laid down by animals that have driven out other hunters and changed the ecosystem.
“Red-legged vultures have been known to live the equivalent of a year on a single mango,” Pearlman said in a statement. “In addition to eating underground, this means they are picking up a range of beneficial species from the ground, which they use as food.”