Thursday, December 18, 2014

Birds heard deadly storms coming and escaped before they hit

ByMichael Casey CBS News December 18, 2014

Much as humans have early warning systems to predict tornadoes and hurricanes, birds are showing they have their own ways of sidestepping deadly super storms.

Researchers studying golden-winged warblers found that they flew 932 miles out of their way -- from Tennessee down to Florida and as far away as Cuba -- to escape an incoming a powerful storm in April that spawned dozen of tornadoes and killed 35 people.

"It is the first time we've documented this type of storm avoidance behavior in birds during breeding season," said Henry Streby, a National Science Foundation postdoctoral fellow at the University of California, Berkeley.

"We know that birds can alter their route to avoid things during regular migration, but it hadn't been shown until our study that they would leave once the migration is over and they'd established their breeding territory to escape severe weather," said Streby, who co-authored a study on the findings that appeared Thursday's issue of Current Biology.


"It's exciting and new because they sensed it coming long before all the other things about storms that we thought birds used," Streby said. "We know they use changes in barometric pressure, temperature and wind speed to feel the front of storming coming. But in this case, they evacuated long before any of that stuff happened."

Known as infrasound waves, these are sounds which are indiscernible to the human ear and can travel thousand of miles from their source. Events like volcanic eruptions or ocean waves crashing onto shorelines create higher frequency sounds that humans can hear but they also throw off infrasound waves that can travel great distances.


Streby said his findings could help explain why animals have reportedly acted strange in past disasters, such as the 2004 tsunami. It could also help scientists better understand the stress facing birds, since such evasive action are taxing.

"There's growing research that shows that tornadoes are becoming more common and severe with climate change, so evasive actions like the ones the warbler took might become more necessary," said Streby. "It could come at a cost, though, since such actions place added energetic and reproductive stress on populations that are already struggling."

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