Il mondo degli animali: i nostri coabitanti

The Secrets to Birds' Vibrant Plumage Coloration, Part 2 of 2



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Much research shows that male birds with brighter plumage colors have a better chance of pairing, as females recognize bright plumage colors as an indicator of good health and strength. In order to tell subtle color differences between individual males, females produce more opsins or specialized light sensitive proteins in their retinas over time. This causes the male’s plumage to become more and more colorful, in order to be competitive and distinctive.

After molting in the fall, the European Starlings’ new head and body feathers display cream-colored tips, from which their non-breeding plumage emerges. During winter and spring, these gradually wear off. By the time breeding season begins, their dark and iridescent breeding plumage with shades of green and violet is revealed. So these birds produce their breeding and non-breeding plumages through only one molting.

Interestingly, scientists have found that in many species in which the females have less bright plumage than males, the level of carotenoid pigmentation is actually the same in both genders. However, females increase the expression of a special gene that generates carotenoid-destroying enzymes to make their plumage duller.

Certainly. Greater Painted-Snipes are famous for their gender role reversal – females do the courting and defend the territory while males incubate the eggs and look after the chicks. Role reversal is very rare – perhaps less than 50 species of birds show such behavior. In these species, there are more adult males than adult females, so their social roles shift accordingly!

On the other hand, the female never leaves her nest which she makes in a tree hollow, and because suitable homes are scarce in the birds’ rainforest habitat, she defends it at all costs. Therefore, females develop bright scarlet plumage to attract males and warn potential competitors that her tree hollow is already taken.

Some birds even use their vibrant plumage to warn off potential threats. The hooded pitohuis, which reside in New Guinea, use the contrast between their black and red plumage to repel anyone seeking to harm them. This adaptation was so successful that other Pitohui species opted to acquire the same color pattern!

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