In the world of Costa’s hummingbirds, it’s not size that matters—it’s sound. During breeding season, male Costa’s perform a high-speed dive during which they “sing” to potential mates using their tail feathers.
In the world of Costa’s hummingbirds, it’s not size that matters—it’s sound. During breeding season, male Costa’s perform a high-speed dive during which they “sing” to potential mates using their tail feathers.
Unlike related hummingbird species, Costa’s perform their dives to the side of females, rather than in front of them. In a paper published today in Current Biology, researchers at the University of California, Riverside show this trajectory minimizes an audible Doppler sound that occurs when the Costa’s dive. The Doppler effect is familiar to most people as the change in tone of an ambulance siren as the vehicle passes by.
The findings suggest that males can strategically manipulate the way females perceive their displays by minimizing the Doppler sound. This deprives females of an acoustic indicator that would otherwise reveal the speed of their dives.
“Recent studies in birds and other animals suggest that females prefer higher speeds during male athletic displays. By concealing their speed, males are not necessarily cheating, but instead have evolved this placement of trajectory out of female choice,” said Christopher Clark, who led the study. Clark is an assistant professor of biology in UCR’s College of Natural and Agricultural Sciences.
Read more at University of California - Riverside
Image: Male Costa's hummingbirds, like the one shown here, court females using a high-speed dive in which they sing with their tail feathers. (Credit: Christopher Clark, UC Riverside)
