'Smart' mockingbirds can tell human friends from foes

Washington, May 19 (ANI): Mockingbirds may look alike to humans, but they can remember people who have threatened them and even start dive-bombing them if they've previously posed a threat to their nests, a study has found.

According to University of Florida biologists, the white-and-grey songbirds spot their unwelcome guests, they screech, dive bomb and even sometimes graze the visitors' heads - while ignoring other passers-by or nearby strangers.

"We tend to view all mockingbirds as equal, but the feeling is not mutual," said Doug Levey, a UF professor of biology. Mockingbirds certainly do not view all humans as equal," the researcher added.

The study is to be published in the Proceedings of the National Academy of Sciences.

"The real puzzle in the field of urban ecology is to figure out why certain species thrive around humans. One of the hypotheses is that they have some innate ability to adapt and innovate in ways that other species don't," Levey said.

For the research, student volunteers walked up to the birds' nests, reached through the foliage and gently touched the nests' edges, then walked away. The same volunteers repeated the same visits again the next day, and again for two more days.

On the fifth day, however, different volunteers approached thenests. All told, 10 volunteers tested 24 nests at least five times last spring and summer, during the mockingbird nesting season.

It didn't take a bird's eye view to spot the resulting pattern, Levey said.

On the third and fourth days, the birds flushed from their nests more rapidly each time the increasingly familiar students appeared - even though the students took different paths toward the nests on successive days and wore different clothes.

The birds also gave more alarm calls and flew more and aggressively each succeeding day, with some especially defensive birds even grazing intruders' heads - not exactly deadly, but annoying, because the birds tend to hit the same spot repeatedly, Levey said.

And yet when different students approached the nests on the fifth day, the birds hardly ruffled their feathers, waiting to flush until last moment. They also gave fewer alarm calls and attacked much less than on the previous day with the familiar intruder. (ANI)