Costa's male hummingbirds attract females with high-speed dives in which they sing with their tail feathers. But these birds also add a twist to improve their chances. Unlike other species of hummingbirds, Costa does his dives next to the females instead of facing them.
Researchers have now discovered that these side dives allow males to manipulate the speed of their dives, making them see faster than they really are. . The strategy basically minimizes the Doppler sound that is created during dives. Doppler sound is an acoustic indicator that would otherwise reveal the actual speed of your dives. Researchers describe this phenomenon as the sudden change in the tone of an ambulance siren when the vehicle passes.
"Recent studies in birds and other animals suggest that women prefer higher speeds during male athletic exhibitions.While hiding their speed, men do not necessarily cheat, but have developed this location of trajectory outside of female choice. " The study's lead author Christopher Clark of the University of California at Riverside said
that Clark and his colleague used a camera to record Costa's hummingbird dives inside a specialized wind tunnel and analyzed how their speed and direction affect the sound they make. The videos showed that men can rotate their tails up to 90 degrees, which amplifies their chirping and makes the Doppler shift less audible. The researchers were surprised to discover that it was difficult to measure the speed of Costa's immersion from the sound they produced.
"Once I realized that it was not trivial for a scientist to measure, I realized that it would not be trivial for a woman to measure anyone," Clark said.
Although researchers do not know exactly how this acrobatic maneuver sounds for female hummingbirds, it certainly manipulates the way they perceive the male's athletic display.
says Christopher Clark. "Most research has focused on static male attributes, such as bright colors and elongated tails, but our research shows that dynamic displays can be just as important and men strategically control these performances to show themselves in the best possible way."