Old
World sparrows are a family of
small passerine birds. They are also known as true sparrows,
names also used for a particular genus of the family, Passer. They are distinct from
both the American sparrows, in the family Passerellidae, and from a
few other birds sharing their name, such as the Java sparrow of the
family Estrildidae. Many species nest on buildings and the house and Eurasian
tree sparrows, in particular, inhabit cities in large numbers, so sparrows are
among the most familiar of all wild birds. They are primarily seed eaters,
though they also consume small insects.
Generally, Old World sparrows are small, plump,
brown and grey birds with short tails and stubby, powerful beaks. The
differences between sparrow species can be subtle. Members of this family range
in size from the chestnut sparrow , at 11.4 centimetres (4.5 in)
and 13.4 grams (0.47 oz), to the parrot billed sparrow, at 18 centimetres (7.1 in) and 42 grams (1.5 oz).
Sparrows are physically similar to other seed eating birds, such as finches,
but have a vestigial dorsal outer primary feather and an extra bone
in the tongue. This bone, the preglossale, helps stiffen the tongue when
holding seeds.