Some female hummingbirds have evolved to look like males

MALE BIRDS are often colourful and ornate. These embellishments demonstrate the wearer is a suitable candidate for fatherhood and is not to be trifled with by other males. Why females are sometimes colourful too is more of a mystery.One idea is that if the sexes co-operate to raise their young—which birds often do—males as well as females must be choosy about their mates. But Jay Falk of the University of Washington has another explanation. In a paper in he suggests it is a way for females to avoid being harassed when they are feeding.