Birds
Sparrow
Passeridae and Passerellidae · also called sparrows
The sparrow is the small brown bird everyone knows and nobody looks at twice — hopping under a cafe table, chirping from a hedge, bathing in a dust patch. It is also two different things. The house sparrow that followed farming across the world and the streaky sparrows of an American meadow belong to separate, only distantly related families that happen to share a name.
Overview
“Sparrow” covers two families. The Old World sparrows (Passeridae) — the house sparrow, tree sparrow, and their African and Asian relatives — are close to the weavers. The New World sparrows (Passerellidae) — song, white-throated, and chipping sparrows, plus juncos and towhees — sit near the buntings. Both are small, streaky, seed-eating songbirds that switch to insects to feed their chicks.
The house sparrow’s world tour
Tied to people and farming for about 10,000 years, the house sparrow spread across Eurasia with agriculture and was then introduced to the Americas, Australia, and southern Africa, becoming one of the most widespread wild birds on Earth. In male house sparrows, the black throat bib is an honest badge of rank — bigger bib, more fights won.
A quiet crisis
The house sparrow has fallen sharply across western Europe since the 1980s — down about 70 per cent in the UK and nearly gone from some city centres — from lost nest cavities in modern buildings, fewer insects for chicks, and less weedy green space. Several North American grassland sparrows are among the continent’s fastest-declining birds as prairie disappears.
Status
Sparrows as a whole are Not Evaluated, trend decreasing. Many species are still abundant, but the most familiar ones are in long-term decline, and a few, such as the Cape Sable seaside sparrow of Florida, are Endangered.
Sparrow: common questions
Are all sparrows related?
No. The word sparrow is used for two separate groups of small brown seed-eating birds that are not close relatives. The Old World sparrows, family Passeridae, are the house sparrow, tree sparrow, and their African and Asian kin, and their nearest relatives are the weavers. The New World sparrows, family Passerellidae, include the song sparrow, white-throated sparrow, junco, and towhee, and they sit near the buntings and the New World blackbirds. European settlers in the Americas simply applied the familiar name sparrow to the small brown local birds they saw, even though those birds are on a different branch of the songbird tree. The hedge sparrow, or dunnock, of Europe is a third case, being in yet another family, the accentors.
Why are house sparrows disappearing from cities?
The decline is real and has several likely causes acting together. Modern buildings have few of the nooks, holes, and gaps under eaves that house sparrows nest in, and renovation seals up old ones. Tidier streets and gardens, more paving, and heavy pesticide and herbicide use have reduced the insects that adult sparrows must catch to feed their chicks in the first days of life, so fewer young survive. Loss of weedy ground and seed sources cuts winter food. Increased predation by cats and sparrowhawks, air pollution, and disease have also been suggested. The pattern is strongest in western European cities, while rural and some other populations are more stable.
What is the difference between a sparrow and a finch?
They overlap in appearance and diet, being small seed-eating songbirds, but they are different families. True finches, family Fringillidae, tend to have stouter, more sharply conical bills, often brighter or bolder plumage, and a bounding flight, and they include the chaffinch, goldfinch, canary, and crossbills. Old World sparrows are plainer and streakier with slightly less specialised bills. New World sparrows are also streaky and brown. In North America, several birds called sparrows and several called finches are only loosely named, so the safest guide is the family rather than the common name.
Do sparrows mate for life?
House sparrows form pair bonds that usually last for a breeding season and often continue year after year while both birds survive, since the pair defends a nest site together and raises two or three broods a year. It is not strict lifelong monogamy, though. Genetic studies show that a proportion of chicks in a typical nest are fathered by a male other than the female's partner, and birds will re-pair quickly if a mate dies. New World sparrows show a wide range of systems, from seasonal monogamy in many species to polygyny in some marsh-nesting ones where a single male holds a territory covering several females.