White-throated sparrow

Appearance

The white-throated sparrow is a passerine bird of the American sparrow family Passerellidae. It measures 15 to 19 cm in length with a wingspan of 23 cm. Typical weight is 22 to 32 g, with an average of 26 g. Among standard measurements, the wing chord is 6.3 to 7.9 cm, the tail is 6.8 to 7.7 cm, the bill is 1 to 1.2 cm and the tarsus is 2.2 to 2.4 cm. They are similar in appearance to the white-crowned sparrow, but with white throat markings and yellow lores.

There are two adult plumage variations known as the tan-striped and white-striped forms. On the white-striped form the crown is black with a white central stripe. The supercilium is white as well. The auriculars are gray with the upper edge forming a black eye line.

On the tan form, the crown is dark brown with a tan central stripe. The supercilium is tan as well. The auriculars are gray/light brown with the upper edge forming a brown eye line. Both variations feature dark eyes, a white throat, yellow lores and gray bill. There is variation and some individuals may show dark lateral stripes of each side of the throat.

They almost always pair with the opposite color morph for breeding. The two color morphs occur in approximately equal numbers. Both male and female white-striped birds are more aggressive than tan-striped birds during the breeding season.

The breast has gray/tan streaks and the streaks continue down the flanks but the belly is generally light gray. The wings are rufous with two distinct white wing bars. Sexes are morphologically similar.

Naming

The genus name "Zonotrichia" is from Ancient Greek "zone", "band", and "thrix, trikhos", "hair". The specific "albicollis" is from Latin "albus", white, and "collum", "neck".

Reproduction

White-throated sparrows breed in central Canada and New England. They nest either on the ground under shrubs or low in trees in deciduous or mixed forest areas and lay three to five brown-marked blue or green-white eggs.

Food

These birds forage on the ground under or near thickets or in low vegetation. They mainly eat seeds, insects and berries, and are attracted to bird feeders.

Migration

In winter, this species migrates to the southern and eastern United States. It stays year round in the Atlantic provinces of Canada. This bird is a rare vagrant to western Europe. Alongside some other species such as the cardinal, dark-eyed junco, song sparrow and chickadees, this species ranks among the most abundant native birds during winter in eastern North America.

Despite a high level of con-specific rivalry within white-throated sparrows, this species is often dominated by other seed-eating winter residents, even those that are no larger than itself like the song sparrow, and thus may endure high levels of predation while foraging since restricted to sub-optimal sites at times by competition. Not to mention numerous mammalian carnivores, at least ten avian predators often hunt them and they are among the most regular prey species for some smaller raptors, i.e. the sharp-shinned hawk and eastern screech-owl.