Tree sparrow  (Passer montanus)

Similar to the house sparrow (Passer domesticus), the tree sparrow was not recognised as a separate species until 1713 (4). Both sexes are similar (5), with a rich chestnut-brown head and nape, a clear black spot on white cheeks, and a white collar. The voice consists of various chirps and cheeps, which are of a higher pitch than those of the house sparrow (5).

The tree sparrow has a broad geographical range, and is generally found throughout western, central and southern Europe, east into Asia to the Pacific coast of Russia and south to Indonesia (2). The UK population of the tree sparrow underwent a drastic decline of 95% between 1970 and 1998 (7); the species is now scarce in the uplands, the far north and west, and is almost absent from the south west, Wales and the north west. Some populations persist in the Midlands, southern and eastern England (6).

The tree sparrow inhabits open farmland with plenty of hedgerows, trees or small woodland patches (2). It can also be found in large gardens and disused quarries and on the edges of wetlands and open water such as reservoirs and gravel pits. In Scotland flocks may form on stubble and turnip fields in winter (2).

Tree sparrows feed mainly on plant matter, including seeds, buds, shoots, berries and flowers, they also take invertebrates such as grasshoppers, beetles and spiders when available. The young are fed entirely on invertebrates in their first week (2). The breeding season is between mid April and early August. The nest is built in holes, dense conifers or occasionally in old nests of larger birds. Two to three broods can be produced a year, each containing 2-7 eggs. The incubation duties are shared by both parents; after 11-14 days the chicks hatch and fledging occurs after a further 15-20 days. (2).

Although the reasons for the decline of the tree sparrow are not fully known, it has coincided with severe declines in many other farmland bird species (6). The decline is highly likely to be due to changes in agricultural practices such as the switch to autumn sown rather than spring sown crops which results in a reduction of winter stubble fields, valuable sources of food for these species. The use of herbicides and pesticides may also have an impact on the food supply. Availability of nesting sites may also be causing problems for the tree sparrow. In the 1970s and 80s many large elms were lost as a result of Dutch elm disease, removing a large number of nesting sites from the landscape (6).

In a number of areas, nest box schemes have been started to provide the tree sparrow with suitable nesting sites. Agri-environment schemes such as the new Arable Stewardship Scheme encourage the retention of winter stubble fields and other measures that should benefit the species. The tree sparrow is a priority species under the UK Biodiversity Action Plan, the plan aims to halt or reverse the decline by 2003 and promote a sustained recovery of the species (6).

For more on British birds see the RSPB website:
http://www.rspb.org.uk

Information authenticated by the RSPB:
http://www.rspb.org.uk/