May 22, 2022

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Females of a hummingbird species imitate the appearance of males to avoid harassment |  Science

Females of a hummingbird species imitate the appearance of males to avoid harassment | Science

White-collar Jacobins are a Types of hummingbirds that live in Central and South America. As with other species, adult males and females have a different appearance. When this dimorphism occurs in the bird world, the young usually resemble the adult female, but this type is called Florisoga Millifora, has two properties. The first is that immature individuals have a similar appearance to adult males. The second is that when they grow up, not all females change their plumage as they should. About 20% acquire the colors that correspond to them. The researchers don’t know if this is due to genetic or environmental factors, but they did discover that female males experience less social harassment than other individuals.

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The young of this species are distinguished by bright colors on the head and wings, have an orange spot on the neck, and the tail and chest are speckled with green. The adult males share the main colors very similar to the young, although in this case the tail and chest are almost entirely white. Females, for the most part, tend to wear more muted tones, such as gray, green and even black, and green is dominant in both the tail and chest. Those females who adopt a masculine appearance do so when they reach adulthood, but cannot do so later. Once they disguise themselves, they cannot restore the feather color that corresponds to them.

The researchers’ observations were conducted between July 2015 and June 2019 in Gamboa (Panama), selecting 436 white-necked Jacobins. Through a series of feeders they studied how the different samples interacted with each other. Thus, experts discovered that harassment came mainly from males and was more frequent towards females of their usual colors. This abuse is usually manifested in aggressive situations in social interactions or during feeding. In some cases, there were even presses and blows to the body. In 269 hunts in which at least one male-looking individual (regardless of gender) participated, this was the persecutor on most occasions. In contrast, in the 90 recorded persecutions in which an individual of female appearance participated, those persecuted 10 out of 11 times. In this way, female disguise They can safely access nutrients more often and for longer periods.

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From left to right, plumage and appearance of a female, male and white-necked Jacob’s boyGillian Dettner

Experts from the beginning rejected the idea that these new colors would make it easier for the female to find a mate more quickly. In fact, they point out that when females have those striking tones it is exactly when they have not yet matured and cannot reproduce. This researchers’ theory was later reinforced by their own articles. In all the tests conducted by the team Cornell UniversityWhenever there is a female of her usual colors, the males approach her first. When there were two females and males, they seemed to have no particular preference. “It’s hard to say if the mating advantage of female-looking females really matters to them. We’ve seen in our experiments that although they have an advantage in attracting mates, females with male colors are courted as well,” explains Jay Falk, of the Department of Neurobiology and behavior at the mentioned university and one of the study authors. The full conclusions have been published in the journal current biology.

I mean, this outfit They do not offer advantages when it comes to breeding, but they do offer advantages for accessing food or hiding from potential predators, supporting the researchers’ idea that these colors favor social selection. This theory states that animals’ decorative and defense systems evolve as a function of competition for food, friends, or parental attention. According to Falk, until now sexual selection has been the main driver of these changes, but this work could open up new horizons: “The study really shows that you have to think broadly outside sexual selection to get a full understanding of why certain birds are colorful and some are not. “. He continues, “We have studied a species that likely has sexual selection in males, but nevertheless, this does not provide a complete history of ornamentation, especially when it comes to females.”

This “disguise” does not offer advantages when it comes to reproduction, but rather offers advantages for accessing food or hiding from potential predators.

This type of hummingbird is not the only species in which this change in appearance occurs. In this species of birds, it is a relatively common phenomenon, both in young individuals and in adults. But it also happens outside of the bird world. Science has reported cases of female fish, dragonflies, butterflies, or lizards adopting a male appearance. In the case of this type, this phenomenon was discovered in 1950. “It is possible that there is a kind of equilibrium that keeps things stable. We still don’t understand why most females do not resemble males, and why both species can exist simultaneously,” Falk says.

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The expert believes that the study can broaden the horizons and better appreciate the life of animals. “I think it helps people in a way to know that there is still a lot of mystery in a bird that you can find in your garden, and that you don’t have to go very far to find them,” he concludes.

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