Birds have several types of feathers of various shapes and sizes, which are specialized to serve different functions. Feathers enable birds to fly, help to regulate body temperature and provide camouflage from dangerous predators. They are also useful for identification and attracting mates.
Feathers come in a variety of colors, ranging from dull neutrals to bright and sometimes iridescent hues. There are two different sources from which feathers get their color. The colors yellow and red are caused by a pigment in the feather, much like pigments create different skin colors in humans. The brilliant iridescent blue and green colors of a peacock feather are not the result of pigment, but are caused by light refraction. The coloring displayed by some birds is the result of a combination of both of these methods.
Birds’ coloring did not develop at random, but has evolved through sexual selection. Male birds have adapted to help them better attract females of their species. The most obvious example of this is colorful plumage. Large, colorful crests and tails, such as the elaborate “tail of eyes” displayed by the male peacock are examples of feathers being used to attract the opposite sex.
While the males and females of some bird species are nearly identical in color, in most species it is typically the male who is more brightly colored than the female. Birds rely mainly on visual cues when selecting a mate and have extraordinary eyesight with which to discern colors. In the spring, during mating season, males will display brighter, more colorful plumage, sometimes referred to as breeding plumage. The saturated red breast of the robin that is often associated with spring is a good example of this adaptation.
The dull coloring of most females in no accident either. Female birds are most often brown or green, providing them camouflage while they care for their young in the nest. Thus, the bird world is the opposite of the human world, where females are more often “decorated” in an attempt to win the attraction of males. Brightly colored feathers are replaced with colorful clothing and makeup.
Interestingly, while colorful plumage serves to increase a male’s mating success, it actually decreases his chance of survival by making him more easily visible to predators. However, such traits still evolve because they increase mating and reproduction, even if they harm individual survival. A male bird with a small, dull colored tail would probably have a much better chance of survival, but if he did not find another way to attract females, his genes could not be passed down to the next generation.
A few species of birds do exist in which the females are larger and more colorful than than males. Interestingly, in these instances, mating roles are typically reversed. Females of these species rely on their appearance to attract mates while the dull colored males stay in the nest to incubate the eggs and care for the young.
