E113 英文朗读 | Why some female hummingbirds masquerade as males

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PHOTOGRAPH BY JOEL SARTORE, NATIONAL GEOGRAPHIC PHOTO ARK

New research shines light on the benefit of female white-necked jacobins having flashy, colorful plumage like males, instead of their more usual brown.

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Why some female hummingbirds masquerade as males

00:09①In birds, males are often the ones to sport showy, colorful feathers—the better to attract and entice females.

00:19②It's peacocks, not peahens, that get to fan out flamboyant blue-and-green tails.

00:28③And the male white-necked jacobin, a tiny tropical hummingbird, has a deep blue head and vibrant green back, whereas females are generally drab. 

00:42④But 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.

01:06⑤A study published in Current Biology sheds light on why. It turns out that mimicking male coloration helps female white-necked jacobins avoid social harassment from other hummingbirds while feeding. 

01:23⑥"The [bright] coloration on the bird is associated with aggression," says Jay Falk, the study's lead author. "Just looking like males seems to deter bullies," allowing females better access to nectar.

01:40⑦With such benefits, why don't all females develop ornamentation?

01:46⑧Flamboyant plumage is not just high maintenance, but it's also risky.

01:54⑨"if you're brightly colored and sitting on a brown nest in a green tree, you're going to stand out," says Dustin Rubenstein, the study's co-author. "It's much more easy to be eaten."

原文链接 

https://www.nationalgeographic.com/animals/article/why-some-female-hummingbirds-masquerade-as-males