Why Might a Female Hummingbird Have Male Plumage?

The "glass ceiling" may be a human construct, but the animal kingdom is also rife with examples of when it's easier to be a male – or appear to be one, at least.

To study the phenomenon of female hummingbirds sporting male-type plumage, researchers from the Cornell Lab of Ornithology and the Smithsonian Tropical Research Institute studied 400 white-necked Jacobin hummingbirds in Panama. Strikingly, they noted that over 25 percent of the females had developed physical characteristics typically present only in males, including white bellies and tails, and iridescent blue heads.

Usually, the females of this species are rather drab by comparison, with feathers in muted colors. The researchers believe that evolution has allowed some female hummingbirds to develop a more male appearance in order to have better access to food, and to feed without having to endure pecking and body slamming, which female hummingbirds are often subjected to by their male counterparts.

The scientists added that the change in plumage points to a little-understood truth about these small-but-tough birds: “They’re constantly fighting with each other … aggression is a big part of their lives," study author Jay Falk said.

Some humdingers about hummingbirds: