In birds, males are often the ones to sport showy, colorful feathers—the better to attract and entice females. It’s peacocks, not peahens, that get to fan out flamboyant blue-and-green tails. Male cardinals get bright red plumage, while females are pale brown. And the male white-necked jacobin, a tiny tropical hummingbird, has a deep blue head and vibrant green back, whereas females are generally drab.

But not always. Researchers studying white-necked jacobins in Panama noticed that nearly 30 percent of the more than 120 females they captured and sexed between 2015 and 2019 turned out to be females that looked like males.

A study published today in Current Biology sheds light on why. It turns out that mimicking male coloration helps