Press Releases - July/August 2007
Item 6

No. 2007/08/64
August 2007

Building more houses – yet another threat to
House Sparrows

In a paper published this week in the Journal of Ornithology (note 1), BTO scientists report on a survey of chirping sparrows that involved over one thousand volunteer birdwatchers, concluding that further loss of urban green space could be very bad news for House Sparrows.

Over one thousand volunteers walked the streets of British towns and villages to count chirping House Sparrows, as part of the BTO’s House Sparrow Survey. Most of these people take part in the BTO/CJ Garden BirdWatch Scheme; they left the comfort of their armchairs to count chirping sparrows in a total of 1,223 randomly selected areas nearby (each survey square being 500m by 500m). Observers were asked to walk along pavements within built up areas and to visit parks and allotments. They counted and mapped all of the sparrows that they saw and heard, with particular attention being paid to chirping male sparrows, declaring ownership of territories.

The funding for survey organisation and data analysis was provided by the BTO’s House Sparrow Appeal (note 2).

Summary of findings

When traditional suburban housing starts being replaced with continuous development (i.e. without gardens), House Sparrow density falls rapidly. For example, when the area of flats exceeds that of houses with gardens, the House Sparrow density drops to a very low level and sparrows will probably disappear from the locale. Even a relatively small loss of private gardens has large effects on sparrow abundance, and continued loss of private gardens within urban landscapes could have serious consequences for the House Sparrow population. Gardens are likely to be important foraging habitats and also provide the habitat structure, in particular low bushes, favoured by sparrows.

Allotments were also key habitats, holding some of the highest sparrow densities. The evidence suggested that this habitat is more important for feeding than for breeding. Allotments may provide good foraging opportunities due to the diversity of the habitat, not just in the sense of what is cultivated but also more generally, with abandoned allotments likely to provide rich sources of both invertebrates and weed seeds.

Allotments and residential areas with gardens are likely to be under pressure due to increased demand for housing, specifically from infilling of green space within urban areas, e.g. gardens of large private houses and Victorian terraces sold off for building flats, local authorities selling allotments and other amenity green space for property development.

Dr Dan Chamberlain of the BTO (lead author)
"These results suggest that how we plan our urban housing could be crucial for the fortunes of species such as the House Sparrow. Given that it is planned that three million homes should be built in Britain by 2020, it would seem imperative that biodiversity considerations are included in the planning process. Provision of adequate green space is a key priority; it can enhance biodiversity within new developments and improve the quality of life of the residents – whether they are people or sparrows."

Please see over for notes for editors

Notes for Editors

1. House Sparrow (Passer domesticus) habitat use in urbanized landscapes appeared in the Journal of Ornithology. The authors are Dan E Chamberlain, Mike P Toms, Rosie Cleary-McHarg and Alex N Banks (all of BTO). The article was published in the Online First edition of the journal (DOI 10.1007/s10336-007-0165-x) in July 2007.
2. The work was funded through the BTO House Sparrow Appeal; an appeal to BTO supporters and, in particular, the John Spedan Lewis Charitable Trust, Leslie Mary Carter Charitable Trust, Salter Charitable Trust and Elsie Mary Elkes Charitable Trust.
3. House Sparrow is Red listed as in need of direct conservation action. The population is in long-term decline with a loss of over 50% of the population in the UK between 1977 and 2004.
4. The BTO/CJ Garden BirdWatch is the only nationwide survey of garden birds to run weekly throughout the year, providing important information on how birds use gardens, and how this use changes over time. Currently, some 16,500 people take part in the project. The BTO/CJ Garden BirdWatch is funded by participants’ contributions and supported by CJ WildBird Foods Ltd and is the largest year round survey of garden birds anywhere in the world. For more information see www.bto.org/gbw
5. Images of garden birds are freely available for use in association with this press release. Please contact to request an electronic version. Please quote reference number 2007/08/64

For further information please contact:

Dan Chamberlain on 01842 750050 or e-mail: (during office hours)
Paul Stancliffe on 01842 750050 or e-mail: (during office hours)