While most female white-necked jacobin hummingbirds don't have showy colors like the pictured male hummingbird, all females have them early in life and the brighter appearance helps them avoid harassment when they aren't looking for mates. Photo by Andy Wraithmell/Flickr
Aug. 26 (UPI) -- Female white-necked jacobin hummingbirds are less likely to be harassed at feeding time if they have the brightly colored ornamentation of their male counterparts, a new study has found.
Like other bird species, female white-necked jacobin hummingbirds tend to have more subdued coloring.
But the study, published Thursday in the journal Current Biology, found that over a quarter of female white-necked jacobin hummingbirds have the same flashy colors of males -- that include luminous blue heads, and bright white tails and bellies.
Brighter colored females are less likely to experience pecking and body-slamming from males during feeding, according to the study, based on observations of the hummingbirds in Panama.
The brighter colors of many male bird species have been chalked up to helping them attract a female mate.
By finding that the hummingbirds' coloring can arise from purely "nonsexual social selection," the study is the latest to explore the complexity around avian appearances.
Researchers at the University of Wisconsin-Milwaukee in 2015 found that male and female birds adopted increasingly similar coloring to blend into their environment and avoid predators.
However, researchers at the University of Melbourne found in 2019 that brightly colored fairy Wrens were not more likely to be eaten in the wild.
A key moment in the most recent study was the realization that all juvenile females hummingbirds had showy colors, Jay Falk, who led the research as a part of the Cornell Lab of Ornithology and Smithsonian Tropical Research Institute, said in a statement.
That's notable because in almost all bird species juveniles typically have the more muted coloring of the adult females, he said. Females and males adopt different coloring as they mature.
"It was unusual to find one where the juveniles looked like the males," he said. "So it was clear something was at play."
To find out why some females kept the bright colors, researchers set up taxidermied mounts of the birds at feeders. The mounts included different combinations of sexes and coloring.
Researchers observed that real hummingbirds mainly harassed the females with subdued coloring. Additionally, researchers found that electronically tagged females with bright coloring accessed feeders more than those with drab coloring.
However, the researchers say it remains unclear whether the difference in the hummingbirds' coloring is genetic, caused by environmental factors or is the choice of the hummingbird.
"Alternatively, social harassment -- either as detrimental sexual attention or aggression toward heterochrome mounts -- could favor the evolution of ornamentation in females via nonsexual social selection," researchers wrote in the study.