From the Google cache of Dear Kitty ModBlog:
Date: 6/23/05 at 9:45PM
From ABC in the USA:
WASHINGTON Jun 23, 2005 — The chirp of the chickadee [small North American songbirds, related to species like the blue tit in Europe] is charming to humans.
To other chickadees, it can convey a lot of vital information.
When the little black-capped songbird whistles “chick-a-dee-dee” it can warn flock mates to watch out: A predator is near.
Christopher N. Templeton and colleagues recorded the chickadee songs [specifically, of the black-capped chickadee], analyzed them by situation, studied the calls on acoustic instruments, and watched the birds react when the songs were played back.
The researchers’ findings are reported in Friday’s issue of the journal Science.
“These birds are passing on way more information than anyone ever dreamed possible, and only by carefully looking at these calls can we really appreciate how sophisticated these animals are,” Templeton said in a telephone interview.
“They change a bunch of different features about the call, subtle acoustic features, the spacing between the notes, things we can’t hear,” he said.
One thing humans can hear, Templeton said, is the number of “dee” notes at the end of the call. “The more they add, the more dangerous the predator,” he said.
The familiar “chick-a-dee” can indicate a stationary predator.
Variations can convey how dangerous it is, whether it flies or is a snake or a mammal such as a ferret, and where it is, he said.
“We had no idea that any animal was able to distinguish between predators that seem similar,” Templeton said.
“It’s life of death for them. It’s just a fun bird-watching tool for us.”
The call even differed slightly depending on whether the predator was a large great horned owl or a pygmy owl.
Despite their large hooked beak and big talons, the large owls are not as much of a concern because they are slow and the chickadees can outmaneuver them.
The fast and maneuverable pygmy owl, however, specializes in small birds.
When a pygmy owl perched nearby, Templeton recorded as many as 23 added “dee” notes to the chickadee call.
Hear black-capped chickadee here.
Spatial memory of chickadees: here.