Size and trends of the House Sparrow Passer domesticus population in Great Britain

摘要

House Sparrow Passer domesticus populations have declined throughout Europe over the last two to three decades; this is of particular concern in urban areas. We analysed data from extensive census schemes organized by the British Trust for Ornithology to determine the current population size of the House Sparrow in Britain, and to assess long-term patterns of change, both in the wider countryside and in urban environments. The national breeding population of House Sparrows was estimated at approximately 13 million individuals (95% confidence interval, 11.9-14.8 million), or about six million pairs. Most of these occur in southeast England and densities are greatest in suburban and rural garden habitats. Overall, populations in rural areas have declined by 47% since the mid 1970s, whereas those in urban and suburban areas have declined by about 60%. Changes in farming practices are likely to account for at least some of the decline in the wider countryside, probably related to changes in food resources, with a loss of grain in fields and more secure storage of harvested grain, though these changes are unquantified. In urban areas, there was an earlier period of decline in the first half of the 20th century due to the loss of horse-drawn transport and generally cleaner streets. The overall national decline since the 1970s masks much heterogeneity in trend among regional populations, and evidence suggests that population processes in the House Sparrow may be relatively fine-grained.