Male birds are often more brightly coloured than females of the very same species.

The longer version

Brightness comes from two sources. Pigments such as carotenoids have to be taken from food, while structural colour is made by microscopic layers in the feather that reflect particular wavelengths. Males compete for mates and display, so brighter plumage pays off for them, whereas a female sitting on a nest gains more from being inconspicuous.

The difference is strongest where males do not help incubate and weakest where both parents share the work. The cost is real, since bright birds attract predators as well as mates. Hormones drive the change, so a male often wears bright colours only in the breeding season and moults into a plainer version afterward.

Where this entry sits

Here you will find feathered trivia about flight, migration, nests, eggs, and the songs birds sing. Expect short surprising facts on penguins, owls, hummingbirds, and other familiar birds from gardens, forests, wetlands, and distant coastlines. The full list sits on the Birds page, where every entry is listed in order.