True sparrows carry stubby beaks from the Old World
Passeridae—the Old World or true sparrows—are compact brown-and-grey songbirds with short tails and strong seed-cracking bills. Field marks between species can be maddeningly fine. Constantine Rafinesque coined the family in 1815; house sparrows later colonized cities almost everywhere humans sailed.
The family holds 43 species in eight genera, from the chestnut sparrow at 11.4 cm and about 13 grams to the parrot-billed sparrow at 18 cm and 42 grams. Beyond the core genus Passer it includes snowfinches and rock sparrows, and molecular and skeletal work by Jon Fjeldså's team moved the cinnamon ibon of the Philippines, once thought a white-eye, into its own subfamily here; it lives in cloud-forest canopy, unusual for a group that mostly prefers grassland, desert and scrub. Compared with finches, sparrows keep a tiny outer primary feather and an extra tongue bone, the preglossale, that stiffens the tongue to grip seeds.
Classification has wandered. From the 1920s some ornithologists folded sparrows into the weaver family, others into the finches, and estrildid finches were long lumped in until a 2008 scheme gave them their own family. American sparrows belong to Passerellidae, related to Old World buntings and split from them only in 2017. The dunnock, or hedge sparrow, and the Java sparrow are sparrows in name only.
Native to Europe, Africa and Asia, some species were carried abroad by settlers and naturalised quickly. House sparrows now live across North America, in every Australian state but Western Australia, and in the crowded parts of South America. Of the 26 species recognised in one major handbook, 17 nest on or feed around buildings.
Most are sociable, nesting in loose colonies and gathering in single-species winter roosts; one Egyptian roost held about 10,000 house sparrows. The great sparrow is the exception, keeping to pairs and small family parties. They are among the few songbirds that dust-bathe, scraping a hollow and flicking earth over themselves, sometimes a hundred at once. Grain eaters can be pests, yet China's Great Sparrow Campaign of the 1950s was followed by surging insect damage.
Source: Old World sparrow
