New research has underlined the importance of gardens for the declining House Sparrow. By looking at the location of House Sparrow colonies in towns and cities across Britain, BTO researchers have discovered that houses with gardens are preferred over other forms of urban green space (e.g. parks). This knowledge can be used to help urban planners in the decision-making process and gives hope that House Sparrow decline can be reversed.
Urban House Sparrow populations have been in decline across much of Europe since the late 1970s and the humble sparrow is now listed as a species of conservation concern. It is thought that urban sparrow populations may be influenced by several factors, including pollution levels, insect abundance, nest site availability and the presence of predators.
The importance within urban areas of houses with gardens has just been established by researchers working on the BTO House Sparrow Survey dataset. Residential areas with gardens are, it seems, preferred over all other forms of urban green space. As Mike Toms, BTO Head of Garden Ecology, explains:
"Our research suggests that much of the green space in our towns and cities is unsuitable for breeding sparrows. When you think about it this makes a lot of sense. Urban parks, for example, tend to be rather open habitats, with little in the way of the dense scrubby cover that sparrows favour and few nesting opportunities. Large urban gardens, or groups of smaller gardens that back onto one another, usually have some thick bushes in which the sparrows can gather and, importantly, they have nesting opportunities in nest boxes and the cavities under roof tiles."
He continued: "Understanding the importance of urban gardens for House Sparrows means that we can advise planners and developers on how to retain and encourage House Sparrow populations within our changing urban landscape. Our research suggests, for example, that urban infilling through ‘garden grabbing’ is likely to be highly detrimental to House Sparrows."
Individual homeowners can encourage House Sparrows by planting Cotoneaster, Berberis and other suitable shrubs, and by offering nesting opportunities in the form of nest boxes with a 32mm diameter entrance hole.
More information is available at http://www.bto.org/volunteer-surveys/gbw/about/background/projects/sparrows/field-survey
Notes for Editors
- The results of this study have just been published: Shaw, L.M., Chamberlain, D., Conway, G.J. & Toms, M.P. (2011). Spatial distribution and habitat preferences of the House Sparrow, Passer domesticus, in urbanised landscapes. BTO Research Report No. 599. This report is free to download from http://www.bto.org/volunteer-surveys/gbw/publications/papers/btorr599
- Mike Toms added: "While the results of our earlier work showed the importance of urban green space (including gardens and allotments) to individual House Sparrows, this new work is more important because it relates to breeding colonies. If we lose the breeding colonies then we lose the House Sparrows." This earlier work appeared in: Chamberlain, D.E., Toms, M.P., Cleary-McHarg, R. & Banks, A.N. (2007). House Sparrow (Passer domesticus) habitat use in urbanized landscapes. Journal of Ornithology 148: 453-462.
- The BTO House Sparrow Survey examined the ways in which House Sparrows use urbanised landscapes. Volunteer birdwatchers visited a series of randomly selected survey squares over two breeding seasons and mapped the locations of House Sparrows and House Sparrow colonies in relation to habitat type. The relationship between House Sparrow locations and habitat type were then examined statistically, testing for any associations that might be present. Habitat use around House Sparrow nest sites was found to be significantly non-random, with the birds consistently selecting residential areas with gardens over every other habitat type.
- The BTO is the UK’s leading bird research organisation. Over thirty thousand birdwatchers contribute to the BTO’s surveys. They collect information that forms the basis of conservation action in the UK. The BTO maintains a staff of 100 at its offices in Norfolk and Stirling, who analyse and publicise the results of project work. The BTO’s investigations are funded by government, industry and conservation organisations. Visit www.bto.org
Head of Garden Ecology
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Email: gbw [at] bto.org
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