It takes smarts to be a bird

'Birdbrain' hardly seems an insult, research shows

Science & Research

December 10, 2004|By Dennis O'Brien | Dennis O'Brien,Sun Staff

Sparrows can learn complicated songs by hearing just a few notes. The swift -- a bird equally adept at sleeping and catching insects in flight -- uses the same aeronautical principles as fighter jets and insects do.

And, while their brains have evolved in different directions, crows and ravens display as much intelligence as apes and chimpanzees.

That news from the avian world appeared in three scientific reports this week, shedding new light on how birds fly and learn to sing and on their level of intelligence.

Scientists and engineers have studied birds for a century, finding inspiration in their wings and tapered bodies for the earliest airplanes. But many of the habits and abilities of the world's 9,000 known species remain a mystery.

"When it comes to birds, we've learned a lot, but we still know very little," said John J. Videler, a biologist at the University of Groningen in Haren, Netherlands.

Videler created models of swift wings in his lab with plaster and enamel-like materials that he uses to make jewelry in his spare time. He tested the models in a water tunnel installed years ago at the university to study motion in aquatic animals.

The results, published today in the journal Science, show that by sweeping back its wing tips at an area known as the hand wing, the swift creates "a leading edge vortex," or a tornado-shaped current of air that sweeps around the wing and lifts the bird.

Videler said other birds and airplanes may create lift in other ways, but that insects and some fighter jets use similar vortices. The phenomenon has never been documented among birds in such detail before, he said.

"People learned to fly from studying birds. But nobody ever looked at how this hand wing cuts through the air to create this vortex," Videler said.

How birds learn to sing is another story.

Gary Rose, a biologist at the University of Utah, captured dozens of white-crowned sparrow nestlings in the Utah mountains, and with researcher Stephanie Plamondon, hand-fed them and raised them in soundproof cages to examine how they learned to sing.

When the birds were 2 weeks old, they played digital recordings of their own species, which include a trilling, a buzzing and a whistling sound, for 90 minutes twice a day for two months. But Rose broke up the recorded songs into five segments and played the segments individually and in pairs to assess the effects on song learning.

When the segments were played individually for one set of sparrows, they failed to learn the songs. But when the segments were played in pairs of two for other sets, the birds were able to piece together a complete tune.

Rose said when the sparrows heard two sounds together they made sense of what they were hearing and learned the rules for putting songs together, just as children learn a language by hearing consonants and vowels together.

"They hear a lot of stuff out there and they have to be able to identify components with one another to be able to put it all together," Rose said.

Crows: problem solvers

Another research group concluded this week that when it comes to intelligence, one familiar family of birds is greatly underrated.

Crows, ravens and other corvids, a family that includes the jay, are about as smart as apes and chimpanzees, according to researchers at the University of Cambridge in England.

The scientists, who reviewed dozens of scientific studies, argue in today's Science that corvids show the same abilities as apes to use tools, learn tasks and manage food supplies -- despite the lack of a prefrontal cortex, the area of a primate's brain responsible for problem solving and complex thought.

They note that while the birds have very different brain structures, their brains are the same size in relation to their overall body as chimpanzee brains.

"There are many aspects of corvid and ape cognition that appear to use the same cognitive tool kit," writes Nathan J. Emery and Nicola S. Clayton, husband and wife experts in animal behavior.

Other researchers agree that crows and other corvids may be the smartest of birds.

"There's no reason to believe that primates are going to be the best at everything," said Kevin McGowan, an ornithologist at Cornell University who has tagged and studied 1,200 crows near campus.

Crows will shape twigs, wires and leaves into probes that can reach food buried in holes. Studies of the western jay, another corvid, show it can learn when buried caches of food will spoil and dig them up before they turn.

Ravens, which tend to be larger and more solitary than the crows, use their beaks and talons to pull meat dangling from a string up to their perches.

"It's a pretty impressive task," said Bernd Heinrich, a biologist at the University of Vermont who has written extensively on ravens.

Human applications

Researchers say the studies have implications for human health and the design of airliners.

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