The decline in numbers of the house sparrow is of such great concern, that this bird has been 'upgraded' to the Birds of Conservation Concern Red List. The British Trust for Ornithology (BTO) is currently running a house sparrow appeal, in order to raise funds to carry out research and monitoring of the species in order to understand the pattern of decline (8). House sparrow numbers have more than halved over the past 25 years. To help find out why, the RSPB asked for volunteers across the country to take part in a survey of house sparrows. The survey, which ran from the 3-11 May 2003, saw a quarter of a million participants and just over 1 million house sparrows seen. A UK city league table for house sparrows was produced from the results collected. Lincoln came top with an average of 9.41 sparrows seen per home. London came last with an average of only 4.53 sparrows per home (9).