Compared to the male, the female (left) is usually more drab, as seen in this pair of Sparrows.
Sexual dimorphism refers to physical differences between the male and the female of the same species.
Many bird species display differences in plumage and colouration. The male usually has a flashier plumage because of his role in the courting display. The plumage of the female is generally more cryptic, helping her hide from predators when nesting. One notable exception is the Eclectus Parrot, in which the two sexes have different but equally flashy colours.
In many species, there is also a size difference between the sexes, with the male usually being larger than the female. In most diurnal birds of prey, however, the opposite is true.