Tree Sparrow Project Update - taken from The Harrier No.156
Steve Piotrowski
“During the 1937 breeding season Tree Sparrows built in all my nine nest boxes. For the sake of the tits I repeatedly threw out their nests. Eight pairs refused to be dislodged: but at least a pair of Great Tits occupied one box and reared a brood. This box has since been taken over by Tree Sparrows like the other eight, most of which now contain second broods.” Bland, H. M. 1937. Trans. Suffolk Nat. Soc., 3:305.
In partnership with Suffolk Naturalists’ Society, Suffolk Ornithologists Group will be funding the research side of the Suffolk Tree Sparrow project.
Thirty years ago, the Tree Sparrow was a very familiar sight in the Suffolk country - side. By the turn of this Millennium it was on the verge of extinction, both as a breeding and wintering species. Nationally, Tree Sparrow populations crashed between the 1970s and the early 1990s with the current population now being about 3% of that of the 1970s. The plummet in population has occurred at the same time as decreases in the numbers and/or range of other farmland birds which share the Tree Sparrow’s diet of grass, wildflower seeds and some cereal grains. Com ponents of agricultural intensification, such as reductions in winter stubble availability, are likely to have contributed to the decline.
Tree Sparrows are fairly sedentary, so the magnitude of wintering flocks can be used as an indicator for the breeding population. Flocks of 100-150 were regularly recorded up to the mid-1980s and, occasionally, there were four-figure gatherings. Between 1985 and 2005 flocks of 30 or more were very rare indeed, but three-figure flocks have been noted during consecutive winters of 2006-2007 and 2007-2008, perhaps indicating a partial recovery. The current breeding population is likely to be in the region of 30-50 pairs.
Breeding performance has improved substantially as population sizes have decreased, suggesting that decreases in productivity were not responsible for the decline. Tree Sparrows nest in holes in trees, thatched buildings and old orchards, but readily take to nest boxes. They form loose local colonies and where these are supported with nest boxes and ample seed supplies local populations can be stable and increasing.
Suffolk’s remaining Tree Sparrow colonies are generally in mixed farming areas with access to small wetland patches and artificial nest sites or old/pollard trees. However, there are others which thrive in isolated gardens surviving solely on supple mentary feeding.
The project is being administered by the Suffolk Wildlife Trust and, in this first year, will be working with landowners to identify flocks. Since the critical limiting factors for Tree Sparrows are all year-round food supply and nest sites, SWT will be working with local people to provide Tree Sparrows with B&B. Nest boxes will be erected at suitable sites where breeding colonies are known to exist and seed mix provided as a reliable food source. I will head the project and am urging people to keep a look out for the birds around their homes. Their favoured environment is farmland, but cottage gardens are also relatively popular. Smaller than a House Sparrow and more active with its tail almost permanently cocked, Tree Sparrows have a chestnut brown crown and nape (rather than grey), and white cheeks and collar with a distinctive black cheek-spot. They are shyer than House Sparrows and both sexes are identical.
The research part of the project will involve monitoring winter flocks and determining local movements and to determine interchange between the coast and west. This work, which is already underway, will involve the capture of wintering birds and the ringing of pulli in nest boxes. Birds will be indentified by colour rings, so observers are urged to keep a close eye on the flocks in their area.
Acknowledgement
SWT’s Tree Sparrow work has been funded by Natural England’s Countdown 2010 with work in Dedham Vale being supported by the Dedham Vale Sustainable Development Fund. The Suffolk Ornithologists’ Group and Suffolk Naturalists’ Society have funded the research side of the project.
Please report all tree sparrow sightings to your relevant County Recorder.
Tree Sparrow (Photo:I.Goodall)