The tree sparrow is the house sparrow’s country cousin but its name is misleading: in Britain it prefers arable farmland and rural gardens to woodland.
Its Latin name, Passer montanus, is equally confusing for it isn’t a bird that favours mountains in Europe, though it breeds at up to 2,500m in the Himalayas.
Tree sparrows have a far greater natural distribution worldwide than the house sparrow: they are found throughout much of Europe and Asia, and east to Indonesia and Japan.
There are six recognised sub-species of tree sparrow but they differ little in appearance. The smallest individuals occur in the extreme south of the birds’ range.
In the west of its extensive range the tree sparrow prefers more rural areas to the house sparrow, but in the east (where the house sparrow is absent) it is often found in the centre of towns and villages.
This sparrow was introduced to St Louis, Missouri, USA, in 1870; the population still exists today, extending north to the towns of Virginia and Springfield.
An attempt to establish tree sparrows in New Zealand in 1868 eventually ended in failure.
In 1958 Mao Tse Tung’s Marxist government ordered the extinction of sparrows, which were regarded as pests. Millions were killed (all tree sparrows) before it was discovered that because the sparrows ate insects as well as grain they were in fact highly beneficial.
Tree sparrow populations in the British Isles fluctuate. However, the last 40 years have seen a huge decline, due largely to agricultural changes.
Britain’s tree sparrow population is thought to number just 10% of size of the population in the late 1960s.
Unlike house sparrows, both sexes of tree sparrows are identical in appearance, with no seasonal change in plumage.
Like their house sparrow cousin, tree sparrows are sociable birds and usually found in small flocks. They like to breed in small, loose colonies, too.
In areas where they occur they are readily attracted to bird feeders. Though reputedly keen on millet, they are also enthusiastic consumers of sunflowers, and especially sunflower hearts.
Though the adults are chiefly seed-eaters, the young depend on a diet of insects.
Unlike the stay-at-home house sparrow, tree sparrows wander far more, with many moving between breeding and wintering areas.
A number of British-ringed tree sparrows have been caught on the Continent, and birds ringed in the Netherlands, Belgium and France have been found in England.
They are hole-nesters and will readily use nest boxes. Colonies can be established by providing a number of suitable nest boxes in a small area.
Where conditions are favourable, breeding success can be high, with pairs rearing two or sometimes three broods a year.
The clutch size ranges from two to seven eggs. They take 11-14 days to hatch, with the young fledging in 15 to 20 days.
Once a pair bond has been established, the two birds remain in company for much of the time, feeding, bathing and preening together.
During the winter these sparrows like to roost in holes, and they will also use nest boxes for roosting.