Eurasian Tree Sparrow

The Eurasian tree sparrow (Passer montanus) is a small, compact sparrow widespread across much of Eurasia. Adults are about 12.5–14 cm long and weigh roughly 20–25 g. Both sexes look alike, with a rich chestnut crown, white cheeks marked by a distinct black spot, a small black bib and brown, dark-streaked upperparts.

It is easily confused with the house sparrow (Passer domesticus), but the tree sparrow is smaller and neater, with a completely chestnut crown and the diagnostic black cheek spot. Male and female house sparrows also differ strongly in plumage, whereas adult tree sparrows are very similar between the sexes.

Eurasian tree sparrows thrive in farmland, villages, gardens, parks, woodland edges and other semi-open landscapes that combine feeding areas with cavities for nesting. Across much of Europe they are particularly associated with rural and small-scale settled landscapes, although in parts of Asia they can also be common in large cities.

Good habitat provides several resources close together: seed-rich ground and short vegetation for feeding, invertebrate-rich margins for raising young and cavities in trees or buildings for nesting. This helps explain why varied farmland can support the species better than highly uniform landscapes.

Seeds, grain, buds and other plant material form most of the adult diet outside the breeding season. Birds frequently forage on the ground in fields, farmyards and gardens and can gather quickly where grain or weed seeds are concentrated.

Insects and other small invertebrates become much more important in spring and summer because nestlings are fed a strongly animal-based diet. Suitable breeding habitat therefore needs not only seed sources but also places where adults can collect abundant small prey close to the nest.

Tree sparrows are strongly social outside the breeding season and commonly feed and roost in flocks. Group foraging allows birds to watch both food and one another, and individuals can switch between finding their own food and exploiting discoveries made by flock-mates.

A field study published in 2008 found that position within a feeding flock influenced which tactic a bird used. Individuals near the centre were more likely to exploit food found by others, while birds near the edge more often searched for new food themselves. A bird’s position in the flock can therefore shape how it finds food.

The species is resident or only partly migratory across much of its range. Many birds remain near their breeding areas throughout the year, while others make seasonal movements, especially in colder northern and eastern regions.

Movements outside breeding can still be substantial even in populations that are not regular long-distance migrants. Flocks shift among farmland, villages and other feeding areas as seed availability and weather change, and some breeding areas may be partly vacated in winter.

Tree sparrows are cavity nesters. Pairs use holes in trees, walls and buildings, as well as nest boxes and other sheltered spaces. Several pairs may breed close together where suitable holes are concentrated, and established sites can be reused between years.

A typical clutch contains 5–6 eggs. Both parents incubate for about 12–13 days and both feed the young after hatching. The chicks normally remain in the cavity for around 15–17 days before fledging. One or two broods are typical, depending on local conditions and the length of the breeding season.

The species has also established populations well outside its native range. About 20 birds from Germany were released in St. Louis, Missouri, in 1870 and founded the North American population, which remains concentrated in parts of the central United States rather than spreading across the continent like the introduced house sparrow. A separate introduction in Melbourne in 1863 involved about 30 birds of Chinese origin and founded the population now found mainly in parts of Victoria and southern New South Wales.

These populations provide an unusual contrast with the species’ enormous native Eurasian range: a sparrow that is highly adaptable across its natural distribution has nevertheless remained geographically restricted in some introduced regions.

The Eurasian tree sparrow is classified as least concern on the IUCN Red List. Its enormous Eurasian range and large global population mean that the species remains globally secure.

Across Europe, the population index fell by about 47% between 1980 and 2024. The decline has slowed considerably in recent years, with a decrease of about 4% in 2015–2024. Regional differences remain large, so this long-term European decline can coexist with stable or increasing populations in some countries.