Head Color Variations in White-throated Sparrows

With a solid covering of snow on the ground it is not surprising that so many birds coming to backyard feeding stations at the moment. White-throated Sparrows are a common sight in winter hopping about the ground below our feeders helping themselves to small round pale millet seeds. Some of them are very striking with a bright yellow lore (area between the eyes and the base of the bill), and crisp white throat and supercilium (or eye-brow) outlined with a black crown stripe and eye-line (above). Others are duller, the white throat is not as bright and well defined and the supercilium is more of a tan coloration with a browner crown stripe and eye-line (below).

While this does not occur in every species we are programed to expect that the males are the bright ones and females have a duller plumage. When there is a noticeable variation between the two sexes this is known as sexual dimorphism. Polymorphism means that a species comes in more than one plumage color, which is retained throughout its lifetime. Each plumage is known as a morph. In the case of the White-throated Sparrow these two colorations are not due to age or different sexes but because there are indeed two different morphs. When they do pair up to breed they often select a mate of the ‘other’ morph.

all photos © adrian and jane binns