Generally, sparrows tend to be small, plump brown-grey birds with short tails and stubby, powerful beaks. The differences between sparrow species can be subtle. They are primarily seed-eaters, though they also consume small insects. A few species scavenge for food around cities and, like gulls or pigeons, will happily eat virtually anything in small quantities. Members of this family range in size from the Chestnut Sparrow (Passer eminibey), at 11.4 cm (4.5 inches) and 13.4 g, to the Parrot-billed Sparrow (Passer gongonensis), at 18 cm (7 inches) and 42 g (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.