Scientists Discover an Animal That Can Sense When a Tornado Will Strike

Tiny golden-winged warblers detect infrasound that heralds the coming of massive storms so they can fly out of harm's way.

(Photo: Willoughby Owen/Getty Images)

Dec 18, 2014· 2 MIN READ
Katharine Gammon has written for Nature, Wired, Discover, and Popular Science. A new mom, she lives in Santa Monica.

When the forest suddenly gets quiet and birds take flight, it might be time to worry about a brewing storm. New research published Wednesday shows that tiny birds sensed a giant storm developing in late April 2014—a weather event that spawned 84 tornadoes, killing 35 people.

The scientists stumbled on the finding when they were studying golden-winged warblers—small birds that weigh less than a third of an ounce. Henry Streby, a postdoctoral researcher at the University of California, Berkeley, said that the team was testing if the birds could carry tiny backpack transmitters.

The warblers are the smallest species ever tracked, and when the researchers retrieved the transmitters from five birds, they discovered something strange: The birds had all moved away from their breeding grounds a day before the storm, flying nearly 1,000 miles—even though the tornado was still hundreds of miles away.

“The week prior, every bird was in the place we expected, but then something happened,” said Streby. “We of course assumed we had done something wrong in analyzing the data, so we spent a while editing that out before we came to the conclusion that the birds were getting away from the storm.”

The researchers think that the birds were sensing infrasound—acoustic waves that occur at frequencies below 20 hertz. While humans can’t hear such a low level of sound, it’s known that birds and other animals can.

Streby stressed that the researchers are only looking at correlations—but it’s a strong correlation. “All signs point toward infrasound, and we know that this kind of sound affects birds from previous research,” he said.

The team’s findings were published in the journal Current Biology.

So is it time to fire the meteorologists and start looking to the sky for storm predictions?

Not quite yet.

“Birds are really good at predicting storms, but they’re not a good replacement for satellites and radar, and a meteorologist is usually going to be better than the birds,” Streby said.

He noted that a storm already has to be forming nearby before the birds can sense the infrasound, whereas humans reading satellite data can discern where storms are developing thousands of miles away.

There is one situation, though, where Streby said that birds could beat humans: “If you were all alone in the forest and all the birds left, you should be worried about it.”

When storms force birds to flee, it can put pressure on their ability to breed. As storms become more powerful and frequent with climate change, those disruptions will grow.

“They wouldn’t do this with a normal thunderstorm, but if it comes to big storms arriving every year and birds losing four to five days of breeding season, it would be a big problem for their conservation,” said Streby.

Golden-winged warblers have suffered one of the steepest population drops of any songbird species in the past 45 years, according to the Cornell Lab of Ornithology. Conservationists are working on a plan to stop the decline and grow the population 50 percent by 2050.

Streby is continuing his research and plans to put backpacks on 500 golden-winged warblers and related species that range from North Carolina to Manitoba, Canada. The goal, he says, is to connect data on the places the birds breed with the places they avoid during the winter to coordinate conservation efforts. But he’s open to more serendipitous discoveries along the way.