Overview

The Eurasian tree sparrow (Passer montanus) is a passerine bird in the sparrow family with a rich chestnut crown and nape and a black patch on each pure white cheek. The sexes are similarly plumaged, and young birds are a duller version of the adult. This sparrow breeds over most of temperate Eurasia and Southeast Asia, where it is known as the tree sparrow.

The Eurasian tree sparrow's untidy nest is built in a natural cavity, a hole in a building, or the disused nest of a European magpie or white stork. As with other small birds, infection by parasites and diseases, and predation by birds of prey take their toll, and the typical life span is about two years.

Description

The Eurasian tree sparrow is 12.5–14 cm long, with a wingspan of about 21 cm and a weight of 24 grams, making it roughly 10% smaller than the house sparrow. The adult's crown and nape are rich chestnut, and there is a kidney-shaped black ear patch on each pure white cheek. The chin, throat, and the area between the bill and throat are black.

The upperparts are light brown, streaked with black, and the brown wings have two distinct narrow white bars. The legs are pale brown, and the bill is lead-blue in summer, becoming almost black in winter.

Distribution and Habitat

The Eurasian tree sparrow's natural breeding range comprises most of temperate Europe and Asia south of about latitude 68°N and through Southeast Asia to Java and Bali. It is sedentary over most of its extensive range, but northernmost breeding populations migrate south for the winter, and small numbers leave southern Europe for North Africa and the Middle East.

In Europe, the Eurasian tree sparrow shows a strong preference for nest-sites near wetland habitats and avoids breeding on intensively managed mixed farmland. When the Eurasian tree sparrow and the larger house sparrow occur in the same area, the house sparrow generally breeds in urban areas while the smaller Eurasian tree sparrow nests in the countryside.

In eastern Asia, however, it is an urban bird. In southern and central Asia, both Passer species may be found around towns and villages. In Australia, the Eurasian tree sparrow is largely an urban bird.

Behaviour and Ecology

Breeding

The Eurasian tree sparrow reaches breeding maturity within a year from hatching, and typically builds its nest in a cavity in an old tree or rock face. Some nests are built among roots of overhanging gorse or similar bush. Roof cavities in houses may be used, and in the tropics, the crown of a palm tree or the ceiling of a verandah can serve as a nest site.

Pairs may breed in isolation or loose colonies, and will readily use nest boxes. The male calls from near the nest site in spring to proclaim ownership and attract a mate. The untidy nest is composed of hay, grass, wool or other material and lined with feathers. The typical clutch is five or six eggs which hatch in 12–13 days, and the altricial chicks fledge after 15–18 days. Two or three broods may be raised each year.

Feeding

The Eurasian tree sparrow is a predominantly seed and grain-eating bird which feeds on the ground in flocks, often with house sparrows, finches, or buntings. It eats weed seeds, such as chickweeds and goosefoot, spilled grain, and it may also visit feeding stations, especially for peanuts.

It will also feed on invertebrates, especially during the breeding season when the young are fed mainly on animal food. It takes insects, woodlice, millipedes, centipedes, spiders and harvestmen. Adults use a variety of wetlands when foraging for invertebrate prey to feed nestlings.

Conservation Status

The Eurasian tree sparrow has a large range estimated as 98.3 million square kilometres and a population of 190–310 million individuals. Although the population is declining, the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List. For these reasons, the species' conservation status is evaluated at the global level as being of Least Concern.

Although the Eurasian tree sparrow has been expanding its range in Fennoscandia and eastern Europe, populations have been declining in much of western Europe. The collapse in populations seems to have been particularly severe in Great Britain, where there was a 95% decline between 1970 and 1998.

Relationship with Humans

The Eurasian tree sparrow is seen as a pest in some areas. In Australia, it damages many cereal and fruit crops and spoils cereal crops, animal feed and stored grain with its droppings.

In China, Mao Zedong attempted in April 1958 to reduce crop damage by Eurasian tree sparrows through the "Four Pests Campaign," mobilising millions of people to drive the birds to death by exhaustion. Although successful at reducing the sparrow population, the campaign overlooked the numbers of locusts and other insect pests consumed by the birds. Crop yields collapsed, exacerbating a famine that led to the deaths of millions of people between 1959 and 1961.

Cultural Significance

The Eurasian tree sparrow has long been depicted in Chinese and Japanese art, often on a plant spray or in a flying flock. The fluttering of the bird gave rise to a traditional Japanese dance, the Suzume Odori, developed in Sendai.

In the Philippines, where it is one of several species referred to as maya, the Eurasian tree sparrow is the most common bird in the cities. Many urban Filipinos confuse it with the former national bird of the Philippines, the black-headed munia.