Songbirds tagged by scientists fled their breeding grounds in the Appalachians just before fierce tornadoes struck the area, suggesting that they “heard it coming,” according to a new study.
Researchers from the universities of Tennessee, Minnesota and Berkeley fitted a number of golden-winged warblers, who nested in north-eastern Tennessee for part of the year, with geo-locating devices.
After a tornado hit the area in April this year, scientists managed to locate the birds and retrieve the trackers. The data stored on the devices showed that the birds had taken significant evasive action to avoid the storms.
“It is the first time we’ve documented this type of storm avoidance behavior in birds during breeding season,” said Dr. Henry Streby, of UC Berkeley, quoted in a release from the university. “The warblers in our study flew at least 1,500 kilometers (932 miles) total to avoid a severe weather system. They then came right back home after the storm passed,” he added.
The animals were likely alerted to the approaching danger by the deep rumble that tornadoes create, a noise that falls within the 'infrasound' range, which is outside of human beings' range of hearing.
Noises in this range can travel thousands of miles, and serve as an early warning system for creatures capable of hearing it, according to a BBC report.
"This suggests that these birds can detect severe weather at great distances," wildlife biologist David Andersen of the U.S. Geological Survey and the University of Minnesota, one of the researchers in the study published in the journal Current Biology, told Reuters.
"We hypothesize that the birds were detecting infrasound from tornadoes that were already occurring when the storm was still quite distant from our study site," he added.
All the more remarkable was the fact that the tagged birds had just completed a 1,500 mile migration, but showed no hesitation in leaving their nesting grounds, despite their presumed fatigue, as the storms approached, according to Nature World News.
The storm the birds fled spawned in 84 tornadoes, and resulted in the deaths of 35 people, according to the Los Angeles Times.
However, in the study, published in the scientific journal Current Biology, researchers stressed that infrasound from the storms was a “probable cue” to the birds' escape, and that the exact reason for their flight was still unclear, according to National Geographic.