Some agile birds known as kingfishers can catch their favorite food—fish—by diving head-first into the water at speeds of up to 25 miles per hour. They perform this dangerous maneuver over and over again—but how do they do it without getting concussions?
The answer, scientists say, likely lies in their genes. Diving kingfishers have genetic variations that may be linked with their dietary preferences and unique hunting method, according to a paper published in October in the journal Communications Biology.
Not all kingfishers feast on fish—some eat bugs, lizards and even other birds. And past research has found that the dietary preference for fish—and, thus, the plunge-diving hunting style—evolved independently several times, rather than from a shared ancestor.
This revelation was like a gold mine for genetics researchers, because “if a trait evolves a multitude of different times independently, that means you have power to find an overarching explanation for why that is,” says study co-author Shannon Hackett, associate curator of birds at the Field Museum in Chicago, in a statement.
Using frozen specimens from the museum’s collection, researchers sequenced the DNA of 30 different species of kingfishers—including some that ate fish and some that did not. They then compared the birds’ genetic codes to look for variations that the fish-eating kingfishers might share.
The team identified several modified genes among the diving birds, including some related to diet and brain structure. One especially interesting mutation occurred in the MAPT gene, which codes for proteins called tau.
In humans, tau proteins are important because they help stabilize cells in the brain and support healthy brain function. The accumulation of too much tau, however, can be a bad thing: Doctors often see a build-up of tau tangles in the brains of Alzheimer’s patients. Tau is also a hallmark of concussions and traumatic brain injuries.
Researchers don’t know for certain, but they suspect tau may somehow play a protective role in the brains of the plunge-diving kingfishers. Now that they know more about the birds’ genetic underpinnings, they can dig even deeper to understand how those variations play out in their physiology.
“The next question is, what do the mutations in these birds’ genes do to the proteins that are being produced?” says Hackett in the statement. “What shape changes are there? What is going on to compensate in a brain for the concussive forces?”
However, they’ll need to proceed with caution, because the genetic variations they found in the fish-eating kingfishers may have nothing to do with their plunge-diving behavior. Those genes may have mutated randomly, says Tim Sackton, a geneticist at Harvard University who was not involved in the new research, to Science News’ Claudia López Lloreda.
Still, he adds, the theory that tau protein may be mitigating the effects of dives on kingfishers’ brains is an “interesting hypothesis.”
More than 100 different species of kingfishers live across the globe, though they primarily inhabit warm, tropical areas. In North America, the belted kingfisher is the most common. These birds have bluish-gray feathers with a ring of white feathers around their necks and on their breasts. Females also have a rust-colored band of feathers across their breasts.
The birds—which often look like they have mohawks atop their heads—wait patiently on branches above streams and other bodies of water. When they spot a tasty fish, they dive head-first to snatch it with their long, pointy bills.
With more research, scientists might be able to learn from the kingfishers and come up with ways to protect human brains from concussions and other injuries—but any innovation like that would be in the far future.