House sparrow

Name and taxonomy

Carl Linnaeus named the house sparrow in 1758, in the tenth edition of Systema Naturae. He called it Fringilla domestica, from a specimen collected in Sweden. The genus Fringilla later became the home of the chaffinches alone. Mathurin Jacques Brisson set up the genus Passer in 1760, and the sparrow moved into it.

The Latin passer means a small quick bird, and it shares that sense with the English word sparrow. The species name domesticus means belonging to the house. North Americans often call the bird the English sparrow, and readers in India say Indian sparrow. English dialects add spadger and spadgick in the south, spug and spuggy in the north, and spur in Scotland. German speakers who settled in North America brought spatzie, from Spatz.

Evolution and relatives

The genus Passer holds about 25 or 26 species, depending on the authority. They are dull birds with square tails and thick conical beaks, and they run 11 to 18 centimetres long. The house sparrow belongs to the Palaearctic group with black bibs. Studies of mitochondrial DNA place most of the splitting in the Pleistocene or earlier.

Its closest relatives are the willow sparrows of the Mediterranean. The Spanish sparrow is the main one, and the two species hybridise widely in North Africa. Mixed populations there run all the way from pure house sparrow to pure Spanish sparrow. The Italian sparrow of Italy looks like a bird halfway between the two. It may be a species that arose from hybrids long ago, and the argument is not settled.

Appearance

The house sparrow is compact, with a full chest and a large round head. A typical bird is 16 centimetres long, with a wingspan of 19 to 25 cm. Weight runs from 24 to 39.5 grams, and the European median is about 30 g. Southern subspecies are lighter, at around 26 grams. The bill is stout and conical, and its ridge measures 1.1 to 1.5 centimetres.

The male has a dark grey crown, chestnut sides to the head and a black bib on the throat and chest. His back is warm brown with heavy black streaks, and his underparts are pale grey. Fresh autumn feathers have pale tips that hide the pattern, and wear brings it out again by spring. The female has no black and no grey cap, only brown upperparts, dark streaks and a pale stripe over the eye. The size of a male's bib is thought to signal his status, though the studies agree only that it grows with age.

Habitat and range

The house sparrow started in the Middle East and spread across Eurasia with farming. Since the middle of the nineteenth century it has reached nearly every part of the world. Settlers released English birds in New York in 1852 to control a moth that stripped lime trees. Melbourne received sparrows in 1863, New Zealand in 1859 and Buenos Aires around 1870. Where the bird is new it can push its range forward by more than 230 kilometres in a year.

Dense forest and tundra are the only land habitats it does not use. It nests indoors in factories, warehouses and zoos without any trouble. One pair bred in an English coal mine 640 metres below the surface. Another bird fed at night on the observation deck of the Empire State Building. Densities peak in city centres, but more chicks survive in suburbs, where insects are easier to find.

The sparrow prefers dry conditions and copes with salt in its food. It can go without drinking water by eating berries instead. Most of eastern Asia has no house sparrows, because the Eurasian tree sparrow fills the same place there. GBIF holds records from 222 countries and territories, which is a measure of how far people have carried it.

Diet and feeding

Seeds of cereals and weeds make up most of the adult diet. Studies in temperate farmland put the seed share at about 90%. Given a choice the bird takes oats, wheat or maize first. Country sparrows pick waste grain out of dung and stubble, while town sparrows take bird seed and crumbs. The bird also eats buds, berries, grapes and cherries, and it tears yellow flowers apart in spring.

Insects matter most in the breeding season, especially beetles, caterpillars, flies and aphids. Parents feed the chicks on insects alone for roughly their first 15 days out of the egg. Grasshoppers and crickets are the commonest food that parents bring in. Sparrows swallow grit, either stone or broken shell, to grind hard food in the gizzard. They also steal food from other birds, including the American robin.

The species solves problems to reach a meal. Sparrows have triggered automatic supermarket doors and clung to hotel walls to watch food on balconies. In New Zealand they rob nectar from kowhai flowers. That flexibility probably explains why the bird settles so easily in a new country.

Behaviour and social life

The house sparrow is social in every season and feeds in flocks. It often joins other seed-eating birds at a food source. Nests sit in loose clumps rather than in defended territories. Birds bathe in dust and in water, and they sing together in a bush for no obvious reason. Females dominate males at feeders and at the nest, although they are the smaller sex.

Outside the breeding season the birds roost together in trees and shrubs. They chirp loudly before they settle at dusk and again before they leave at dawn. A sleeping sparrow tucks its bill under the shoulder feathers. Flight is direct rather than bouncing, at about 45.5 kilometres per hour and around 15 wingbeats a second. On the ground the bird hops, and it can swim if a predator forces it into water.

Sparrows learn from each other about strange objects and new food. Some individuals approach anything new, and others keep well away. Captive birds changed their behaviour after watching another bird, and even after hearing recorded calls. Most house sparrows move only a few kilometres in a whole lifetime. Two Central Asian subspecies are the exception, because they migrate and put on fat first.

Communication and senses

Almost every sparrow sound is a version of the short chirp. Writers transcribe it as chirrup, tschilp or philip. A resting flock uses it to keep contact, and a male uses it to claim a nest hole and call for a mate. In the breeding season he repeats it fast and hard, which counts as his song. Young birds, especially in captivity, produce a real warbling song like a greenfinch's.

An angry male trills the call, and a female uses the same trill to push a male off the nest. A nasal quer serves as the alarm, and a shrill chree marks real distress. A soft quee between paired birds calms an argument. None of these sounds is unique, because every sparrow in the family uses much the same set. Sight rules the bird's world, as it probably does for most small seed eaters.

Reproduction and life cycle

House sparrows pair for life and defend a nest site rather than a territory. An unmated male starts a nest and calls beside it until a female comes. He displays by drooping and shivering his wings, raising his tail and showing off the bib. Pairs are faithful in name only, and about 15% of fledglings are not the mate's young. Birds that find no nest may help a pair instead, which puts them first in line for a vacancy.

Cavities are the favourite nest site, above all a gap in the eaves of a house. Holes in cliffs and banks, tree hollows, street lights and old swallow nests all serve. The nest is a domed mass of stems and roots, lined with dead grass, leaves, feathers and paper. It measures roughly 20 by 30 centimetres on the outside, though the size varies a lot. In cold weather the birds build extra roost nests to hold in heat.

A clutch usually holds four or five eggs, and counts from one to 10 are on record. The eggs are white to greenish white with brown or grey spots, and each weighs about 2.9 grams. Incubation lasts 11 to 14 days and falls mostly to the female, who alone has a brood patch. Chicks stay in the nest 14 to 16 days as a rule, and both parents feed them. Two clutches a year are normal, four are possible in temperate country and seven in the tropics.

Predators and threats

Cats and birds of prey kill the most house sparrows. Sparrowhawks and merlins are the sharpest bird hunters, but cats probably take the greater toll. Crows, magpies and squirrels rob nests, and people have eaten sparrows in many countries. On European roads the house sparrow is the bird most often found dead.

Only about 20 to 25% of hatched sparrows live to their first breeding season. An adult has a 45 to 65% chance of surviving each year. A ringed bird in Denmark was found dead 19 years and 9 months after it was marked. The oldest captive bird reached 23 years. Nests carry a heavy load of parasites, including blowflies and more than 1,400 kinds of beetle.

Population and conservation

The IUCN rates the house sparrow as Least Concern and puts the world total near 1.4 billion birds. Only the red-billed quelea may be more numerous among wild birds. Naturalists have logged 560542 house sparrow observations on iNaturalist. The global figure hides a steep decline close to the bird's Eurasian home.

A 21-year citizen science study found European numbers down by nearly 60% by 2021. British numbers peaked in the early 1970s and have since fallen 68%, and about 90% in some regions. The RSPB puts the house sparrow on its red list for the United Kingdom. Dutch numbers halved after the 1980s, and North American numbers are down 84% since 1966. The bird has largely gone from central London and from several large South Asian cities.

A shortage of insect food for the chicks looks like the main cause. Monoculture crops, heavy pesticide use and paved gardens all cut the insect supply. Modern buildings offer fewer holes, so conservation groups now push sparrow nest boxes. Sparrowhawk predation, avian malaria and traffic fumes have all been proposed as extra causes. Delhi named the house sparrow its state bird in 2012 to help the campaign.

Relationship with humans

Sparrows have lived with people for about 10,000 years. Most of the world treats the bird as a pest, because it takes grain and shares diseases with livestock. In most countries no law protects it. Control has meant traps, poison, shooting, blocked holes and destroyed nests. Every large campaign has failed, and the sparrow eats crop pests as well as crops.

The bird has also been food for a very long time. From about 1560 people in northern Europe hung earthenware sparrow pots under the eaves to farm the young. Sparrow pie was a country dish, and eaters believed it worked as an aphrodisiac. Sparrow clubs in early twentieth-century England killed millions of birds and eggs to little effect. Germany persecuted the species from at least 1650 until 1970.

In culture and myth

In ancient Greek tradition the sparrow belonged to Aphrodite, the goddess of love. The birds seemed lustful to Greek observers, and Chaucer and Shakespeare kept that idea alive. In the Gospel of Matthew the sparrow stands for the care that God takes of small things. That line reached Hamlet, and later the hymn His Eye Is on the Sparrow. For most people the house sparrow stands for the ordinary and the common.

China ran the Four Pests campaign against sparrows from 1958, though it mainly hit the Eurasian tree sparrow. Whole towns turned out with gongs, poles and slingshots, and reported kills reached nearly 2 billion in one year. Insects then multiplied without the birds, which helped bring on the famine that followed. World Sparrow Day has been held on 20 March since 2010, and the Nature Forever Society of India started it. Its founder, Mohammed Dilawar, meant it to draw attention to the birds that people stop noticing.