Female Hummingbirds Look Like Males in Deceptive Mimicry, Anti-Predator Defense

Scientists have discovered a rare instance of deceptive mimicry, which acts as a predator defense for some female hummingbirds.

Young White-necked Jacobin hummingbirds have striking blue-and-white plumage. Males maintain this vibrant pattern as they mature, while most females, at least, adopt a more "muted" green and white color scheme. Surprisingly, 20% of females defy the odds and continue to have male-like plumage as adults.

Postdoctoral researcher Jay Falk at the University of Washington was interested in the changes he had noticed in some of the species females.

In research, Falk and co-authors at the UW, Cornell University, and Columbia University, The white-necked Jacobins, adult females with male-like plumage, are reportedly mimicking male appearance but not male behavior. Their size and strength are also comparable to other females with muted plumage rather than males.

Deceptive Mimicry

According to the study, one in five adult females that have male-like plumage are practicing "deceptive mimicry."

The team of researchers explained that In essence, they're trying to appear masculine while being female. They profit greatly as a result of the process. In contrast to females that have more typical muted plumage, Falk and his colleagues found that females with male-like plumage experience less aggression from males and can spend more time at feeders.

As a postdoctoral fellow at the University of Washington working with co-author Alejandro Rico-Guevara, an assistant professor of biology as well as curator of ornithology at the Burke Museum of Natural History & Culture, Falk continued the research he started as a graduate student at Cornell University.

White-Necked Jacobins

White-necked Jacobins are widespread in the Americas' tropical lowlands. Simply put, the males of this species are bullies. They fight, defend their territories, drive rivals away from sources of food, and pursue females. A fundamental difference in body size and physiology-male Jacobins are larger and more adept at combative flight than dull-colored females-underlies that aggressive behavior.

Comparing Males and Females

Falk's earlier research left open the question of whether the females with male plumage also exhibited male-like flight ability or behavior.

For the study, he captured female and male Jacobins that have both types of plumage for a brief period in a field location in Panama. He discovered that males were slightly larger than females, who had nearly identical wings and body sizes regardless of plumage. Before letting the birds go, Falk tested their "burst power," or muscle endurance during flight, by measuring the height to which they could soar while hoisting a chain of delicate, heavy beads. Males could lift more weight on average, but females, regardless of the types of plumage, had the same burst power.

The team also found that more males fed in a "territorial" pattern, spending more time at fewer feeding sites, according to data from radio-tagged birds in the wild. Regardless of plumage, all females displayed the opposite behavior: they fed more frequently but for shorter amounts of time at locations spread out over a larger territory.

Falk said that male-like females don't appear to act any differently from other females in terms of behavior. Instead, all available evidence suggests that females who resemble males are partaking in deceptive mimicry, Science Daily reports.