Forbes Magazine Fiona McMillan July 31, 2018
Male Costa’s hummingbirds (Calypte costae) go to elaborate lengths to attract the attention of a potential mate, even if that means including a little bit of colorful deception.
With a green and white body, and an iridescent purple head and throat, male Costa’s have quite a striking appearance. The iridescent plumage is the result of optical nanostructures in the feathers that reflect and scatter light. Consequently, the color appears to change with the angle of incident light and the movement of the bird.
Brilliant color is something that the female Costa’s appear to prefer, so the males show off their shimmering accouterments as much as they can during their signature ‘shuttle dance’.
Of course, this presents a challenge for male Costa’s that may not shimmer as brightly as their peers. Now a new study published in the journal Ecology Letters shows that these males try to compensate by altering their shuttle dance so that they literally present themselves in the best possible light.
Richard Simpson and Kevin McGraw at Arizona State University filmed male Costa’s during their shuttle dances and examined the males’ position relative to the sun and relative to the female Costa’s they were trying to impress. The researchers then used this information to determine how the males’ feathers might have appeared from the point of view of the females.
Males who positioned themselves so that they directly faced the sun during their dance were the ones who appeared brightest, even if they normally did not have the most impressive plumage.By taking advantage of the way the sunlight bounced off their feathers, male Costa’s were essentially able to compensate for their looks with some dazzling dance moves.
(It’s not just what you have, but how you use it: solar‐positional and behavioural effects on hummingbird colour appearance during courtship) (Simpson R and McGraw K Original research)