US biologists have studied the behaviour in the swamp sparrow species by creating a robot from a dead bird.
Scientists at Duke University in North Carolina worked with engineering students and a taxidermist to operate the wings of a deceased swamp sparrow.
They programmed simple Picaxe computer chips, and built a tiny linear motor to fit inside the cavity of the bird they named Robosparrow.
They were studying male aggressive behaviour among the species.
The experiment, carried out over a period of two months, confirmed to the researchers that wing-flapping is a sign of male aggression, Dr Rindy Anderson, who led the study, said.
Getting the robotics right took around nine months, she told the BBC.
"We had to be able to use computer software to control the motor, to programme it to move the wings at particular intervals," she said.
"It's not a random movement. Ultimately what was really difficult was getting everything so small," she added.
Once the motor was in place and the robot chip was programmed, the mounted bird was put in the wild along with a discreet sound system playing swamp sparrow calls to attract others.
The wing-waving robot lasted for two months but was regularly attacked, said Dr Anderson.
The living male birds were equally aggressive to Robosparrow whether its wing movements were activated or not, the researchers found.
The research is published in the journal Behavioral Ecology and Sociobiology. (ANI)