Although they may appear friendly and charming, hummingbirds are known for their aggressive nature. It appears that some female hummingbirds have adapted to this behavior by adopting the bright plumage and colors of their male counterparts.
More than 400 white-necked Jacobin Hummingbirds were captured by US researchers in Panama.
Surprisingly, more than 25% of female Jacobins had the same ostentatious plumage, bright white tails and white bellies as their male counterparts. The female Jacobins are typically duller than their male counterparts, with muted green, grey, or black hues that blend in with the environment.
The researchers found that flashy, male-like garb was able to help females avoid male aggressive behaviours such as body slamming and pecking during food preparations.
The researchers found that all of the juvenile Jacobins had flashy colors when they examined the birds. In general, most birds have juvenile birds that look like the adult birds.
Jay Falk, the first author of the study, was a postdoctoral researcher at Washington University. He also led the research as part of Smithsonian Tropical Research Institute's Cornell Lab of Ornithology.
Each male and female start off looking the same as their adult male counterparts. As they age, approximately 20% of females retain their plumage and then the rest shift to the dull plumage.
Most people believe that ornamental and flashy plumage is a result of competition for mates. He noted that most of the females didn't retain their colourful plumage after they became sexually mature and were looking for mates. This was an indication that sexual selection wasn't the cause.
Falk and his coworkers tried to find out why some female Jacobins resembled males as adults. They left stuffed hummingbirds on feeders for male-like females, male-like males, and drab females. Then they watched as real hummingbirds interacted in different places in Panama.
According to the current biology study, they found that the majority of sexual behavior by male hummingbirds was directed towards stuffed drab females. This reinforced the notion that sexual selection is not the correct explanation.
The researchers discovered that the aggression between real and stuffed hummingbirds was more common in the stuffed drab females than the stuffed flashy ones. Falk said that this kind of suggests that the aggression is related to social selection and competition for food rather than competition for mates.
He said that people tend to think of hummingbirds simply as little fairies who drink nectar from flowers. They are constantly in conflict with one another and aggression is a major part of their daily lives.