Urban sparrow under severe threat from new housing

"A small bird will drop frozen dead from a bough, without ever having felt sorry for itself," wrote DH Lawrence. Not so today's suburban sparrow, which is in trouble as towns and cities expand and green spaces grow smaller and scarcer.

According to new research, house sparrows are in a sorry state, with their numbers reduced dramatically by too many houses. Researchers found that numbers of the birds, including the chirpy males, decline rapidly when gardens and green spaces in towns and cities are converted to housing.

In the new study, the researchers, who say little is known about the birds and their habitat in urban areas, looked at sparrow densities in 1,223 randomly selected urban areas in the UK measuring 500sq m and where there was a relatively high human population.

The numbers of chirping male house sparrows and of all house sparrows were analysed separately, and the results show that residential areas, allotments and farm buildings were key predictors of sparrow density and chirping male density.

Researchers found a threefold increase in the numbers of the birds in areas where there were gardens, and they say green spaces need to preserved to protect the bird.

"Allotments and residential areas with gardens are likely to be under pressure due to increased demand for housing, specifically from the infilling of green space within urban areas,'' say the researchers who report their findings in the Journal of Ornithology.

"It would seem to be imperative that any action plan to protect urban house sparrow populations should include specific protection of such key habitats.''

The house sparrow (Passer domesticus) is declining in many parts of Europe, with recent severe declines in urban areas. According to the Royal Society for the Protection of Birds, around 60 per cent of sparrows have been lost since the mid-1970s. Declines have been greatest in the south-east of England and in the centres of large cities, including London, Edinburgh and Glasgow. There are now thought to be between six and seven million breeding pairs.

The decline has been seen as particularly concerning because the house sparrow is one of very few species that thrives in close proximity to people, even in city centres.

It is also perplexing because, according to a government report, the number of birds in Wales and Scotland seems to be increasing, and rural houses and their gardens also support high densities of house sparrows: "Declines have been greatest in suburban and urban gardens. Rural gardens may be the most favoured habitat for the species,'' says the report.

Just why there has been such a dramatic drop in urban numbers is not clear, although there have been a number of theories, including predation by domestic cats and sparrowhawks, loss of sources of weed seeds as a result of the development of brownfield sites, pollution and disease.