Birds Hear Tornadoes - Researchers have detected that while humans are oblivious to infrasounds, birds can hear storms coming from 250-560 miles away and flee a day or two before it hits.
Ecologists from the University of California in Berkeley made the accidental discovery that birds can hear tornadoes while tracking the migratory pattern of a population of golden winged warblers for a year.
The birds spend winter in Central and South American and then travel back to the Great Lakes and Appalachian Mountain of North America to breed.
Berkeley Ornithologist Henry Streby, the lead researcher of the project, says the birds fled their breeding grounds about one to two days before a powerful storm swept through central and southern US in April 2014.
While the birds were able to hear the storms coming, human could not. Reports indicate that about 35 people were killed and over $1 billion worth of property damaged in the supercell storms that generated at least 84 tornadoes across the area.
"It is the first time we've documented this type of storm avoidance behavior in birds during breeding season," said Streby. "The warblers in our study flew at least 1,500 kilometers (9932 miles in total) to avoid a severe weather system. They then came right back home after the storm passed."
In the study published on Dec. 18th in the journal Current Biology, researchers tied the ability of birds to hear tornadoes to acoustic waves occurring at frequencies below 20 hertz (cycles per second). These waves were grouped under the infrasound range that storms emit, which are far below normal human hearing limits. However, birds and other animals can hear these infrasounds and respond to it.
The birds, which weigh only about 9 grams, were being tracked through a half-gram geolocator. Out of about 20 birds which were tagged and tracked throughout the entire year, only five of the retrieved geolocator's where useable.
The golden song birds packed up and fled while the storms was still about 250-560 miles away - around this time there had been no atmospheric changes in the weather.
"At the same time that metrologists on the Weather Channel were telling us this storm was headed in our direction, the birds were apparently already packing their bags and evacuating their area," Streby said.
