How birds pick up predator alerts
Tuesday, March 20, 2007
WHEN the black-capped chickadee chirps out a warning of predators closing in, not only its closest feathered friends pay attention.
The red-breasted nuthatch, another small native North American songbird, is also listening in and can interpret the finer points of the chickadees' early warning system.
"They can figure out how dangerous the predator is from the type of call," explained Christopher Templeton, co-author of the study released yesterday.
Black-capped chickadees are one of the most common backyard birds in North America, but their vocalisations are among the most complex in the animal kingdom.
A slight variation in their song can convey whether a predator is flying or perched, and whether the predator is large or small.
When a chickadee spots a stationary or perched predator, it uses a loud, wide-spectrum chick-a-dee-dee-dee alarm to recruit other birds to harass, or mob, the predator and chase it off.
Its unique acoustic capabilities make the chickadee a valuable sentinel. But the nuthatch is no slouch.
While dozens of other birds eavesdrop on the chickadee's alarm calls, only the nuthatch has figured out how to decode all of the intelligence encoded in the calls, according to researchers at the University of Washington.
When Templeton played recordings of the chickadees' mobbing calls over speakers in the woods of Missoula, Montana, nuthatches reacted differently depending on whether the call was coded for a smaller pygmy owl, or for a great horned owl, a larger predator.
The nuthatches responded to the pygmy owl alarm in greater numbers, flew closer to the speaker, and appeared to be more agitated by flicking their wings than when they heard the great horned owl call.
"It turns out these animals are pretty smart," said Templeton, himself a pretty smart postgraduate student at the University of Washington in Seattle.
AFP
The red-breasted nuthatch, another small native North American songbird, is also listening in and can interpret the finer points of the chickadees' early warning system.
"They can figure out how dangerous the predator is from the type of call," explained Christopher Templeton, co-author of the study released yesterday.
Black-capped chickadees are one of the most common backyard birds in North America, but their vocalisations are among the most complex in the animal kingdom.
A slight variation in their song can convey whether a predator is flying or perched, and whether the predator is large or small.
When a chickadee spots a stationary or perched predator, it uses a loud, wide-spectrum chick-a-dee-dee-dee alarm to recruit other birds to harass, or mob, the predator and chase it off.
Its unique acoustic capabilities make the chickadee a valuable sentinel. But the nuthatch is no slouch.
While dozens of other birds eavesdrop on the chickadee's alarm calls, only the nuthatch has figured out how to decode all of the intelligence encoded in the calls, according to researchers at the University of Washington.
When Templeton played recordings of the chickadees' mobbing calls over speakers in the woods of Missoula, Montana, nuthatches reacted differently depending on whether the call was coded for a smaller pygmy owl, or for a great horned owl, a larger predator.
The nuthatches responded to the pygmy owl alarm in greater numbers, flew closer to the speaker, and appeared to be more agitated by flicking their wings than when they heard the great horned owl call.
"It turns out these animals are pretty smart," said Templeton, himself a pretty smart postgraduate student at the University of Washington in Seattle.
AFP
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