Passer montanus (2)
|The Tree Sparrow has a large range; the total size has not yet been quantified, but includes at least 48,000 km˛ in Africa alone. The total population is also unknown, but includes an estimated 52–96 million individuals in Europe. Although population trends have not been evaluated, the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (that is, declining more than 30 percent in ten years or three generations). For these reasons, the species is evaluated at the global level as "least concern".|
Although the Tree Sparrow has been expanding its range in Fennoscandia and eastern Europe, populations have been declining in much of western Europe, a trend reflected in other farmland birds farmland birds such as the Skylark, Corn Bunting and Northern Lapwing. From 1980 to 2003, common farmland bird numbers fell by 28%. The collapse in populations seems to have been particularly severe in Great Britain, where there was a 95% decline between 1970 and 1998, and Ireland, which retains only 1,000-1,500 pairs. Breeding performance has improved substantially as population sizes have decreased, suggesting that decreases in productivity were not responsible for the decline and that survival was the critical factor. The large decline in Tree Sparrow numbers is probably the result of agricultural intensification and specialisation, particularly the increased use of herbicides and a trend towards autumn-sown crops (at the expense of spring-sown crops that produce stubble fields in winter). The change from mixed to specialised farming and the increased use of insecticides has reduced the amount of insect food available for nestlings.