Female hummingbirds can “dress” like males to avoid being harassed, allowing them to get more food, a new study suggests.
Male white-necked Jacobin hummingbirds of Panama have bright and flashy colors, with iridescent blue heads, bright white tails, and white bellies, while females tend to be drabber, with muted green grey or black colours that help them blend into the environment.
However, US researchers discovered that one in five of the adult females kept their juvenile flashy colours even when they reached reproductive age.
Researchers were puzzled why they would select for a trait that made them less attractive to the opposite sex and therefore less able to reproduce.
To find out, they designed an experiment in which stuffed female hummingbirds were placed on feeders to see how their plumage affected how real birds interacted with them.
The team discovered that the flashier females were left alone with the food while the more drab birds were pecked and body slammed by the males.
Previously, plumage colour was always thought to be linked to mating, but the researchers believe that it can also be connected to competition for food resources.
And they think such an adaptation may be more useful for hummingbirds because they have such fast metabolisms and so need a lot of energy.
Writing in the journal Current Biology, the authors from Cornell University and the Smithsonian Tropical Research Institute concluded: “(Male mimicking) females avoid harassment while feeding, enabling them to access food more than those with non-ornamented plumage.
“For species with the highest mass-specific demands of any vertebrate, selection traits that maximise feeding in the face of intense resource competition for any other bird may explain why (the adaptation) has evolved so often in hummingbirds yet so rarely in other avian species.”
Dr Jay Falk, now at the University of Washington in the United States, added: “Hummingbirds are such beloved animals by many people, but there are still mysteries we have not noticed or studied.”