Nov. 30, 2005 — The sexy sounds emitted by male pigeons send female pigeons into the bird version of rapture, and such vocalizations seem to affect the females more than when they watched a desirous male strut his stuff, a recent study determined.

Since the males usually vocalize and strut at the same time, the findings suggest the strutting may be "redundant," meaning that it serves the same function as the sounds to hammer home a point, which in this case is that the male wants to mate.

Humans communicate using comparable signals, such as when a person might raise his or her eyebrows while at the same time asking someone, "Care to dance?" The eyebrow move alone might be misunderstood or ignored, but together the facial expression and words suggest what the speaker is thinking.

A male pigeon "voice" alone seems to be a big turn on for female pigeons.

"The acoustic signals were very salient to the birds: when the females could hear but not see the males, they responded with some courtship behavior (circle walking and spreading their tails), but most importantly they began to coo," said lead author Sarah Partan, whose research was outlined in a recent issue of the journal Animal Behavior.

Partan, an assistant professor of psychology at the University of South Florida, explained to Animal Planet News that cooing is important because it stimulates ovulation in females.

Humans do not seem to respond to sounds in such a dramatic way, but Partan did say that smells, such as pheromonal cues, do impact human female cycling, such as when a group of closely associated females all start to menstruate at the same time.

Partan and her colleagues studied how six female white Carneaux pigeons reacted to the sounds and visuals of a male that was recorded using audio-visual equipment while he looked at a female pigeon that was placed in a cage next to his.

The camera and sound recorder captured him in typical courtship mode. He bowed and tilted his body forward while puffing out his chest feathers and cooing.

The test females then watched this display without the noise. Some stopped preening themselves to view the male, but others did not and seemed to care less.

The cooing sound alone of the male, however, captured the interest of most of the females. They responded with their tail spreading moves.

The strongest reaction was observed when the females both saw and heard the male, so the apparently redundant male dance still holds importance.

"Animals use redundant signals for emphasis, and also for insurance that the message will still be transmitted even in noisy environments," explained Partan.

George Uetz, a professor of animal behavior, behavioral ecology and arachnology at the University of Cincinnati, told Animal Planet News that he and his colleagues had similar results with video-audio playback for spiders, which are not usually known for their keen sense of hearing.

Both Uetz and Partan cautioned that birds and insects see the world differently than humans do, so video playbacks might be flawed.

A pigeon watching television, for example, would see a lot of flickering, since its sight processing occurs at a faster frequency than what humans experience.

Partan has many related future studies planned to test how multiple signals impact pigeons, other birds and animals. She hinted that a robotic pigeon may help with the effort.

"We are creating life-like robotic animals that simulate the displays we are interested in, and we present these to live animals in real-time, 3-D playback presentation," she explained.

"The goal, as with the video work, is to have the animals 'tell' us what is important about the displays by their responses to the presentations. I am currently working on this with lizards and squirrels, but would like to pursue this in the future with pigeons as well."