Golden-winged warblers that live in the mountains of eastern Tennessee were spotted fleeing their breeding grounds ahead of the arrival of the powerful supercell storm.
And the discovery was made by accident while researchers were testing whether the warblers – which weigh less than two small coins – could carry geolocators on their backs.
It turned out they could.
With a big storm brewing, the birds were seen taking off from their breeding ground, where they had only just arrived, as part of an unplanned migratory event.
The birds were alerted when the storm was 900km away, causing them to flee to Cuba before making the return trip once the storm had passed.
Overall, the warblers travelled 1,500km in just five days to avoid the deadly storms.
Dr Henry Streby, of the University of California, Berkeley, said, “The most curious finding is that the birds left long before the storm arrived. At the same time that meteorologists on The Weather Channel were telling us this storm was headed in our direction, the birds were apparently already packing their bags and evacuating the area.”
Dr Streby and his colleagues found the birds fled from their breeding territories more than 24 hours before the arrival of the storm.
The researchers suspect that the birds did it by listening to infrasound associated with the severe weather, at a level well below the range of human hearing.
Dr Streby said, “Meteorologists and physicists have known for decades that tornadic storms make very strong infrasound that can travel thousands of kilometres from the storm.”
He said while the birds might pick up on some other cue, the infrasound from severe storms travels at exactly the same frequency the birds are most sensitive to hearing.
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