Question

List the possible reason for the decline in the sparrow population

Answer 1

NGO, factors leading to their decline are; rapidly changing cities that are inhabitable for the bird species, modern infrastructure that does not account for space for the sparrow to nest, and the sharp rise in pollution levels, caused by microwave towers and pesticides.

Answer 2

The House Sparrow Passer domesticus population in Britain suffered a major decline in the 1920s, particularly in built-up areas, which coincided with the replacement of the horse by the internal combustion engine. The mixed fortunes of House Sparrows since then are examined, emphasising that factors operating on farmland populations differ from those in towns and cities. Farmland sparrows decreased by about 60% between 1979 and 1995, but then stabilised at a new, lower level; this decline is attributed to changes in agricultural practices. The situation with sparrows in built-up areas is much more complex, with a gradual decline until about 1990. Since then, a massive decrease has led to almost complete extinction in some urban centres, while in the suburbs and small rural towns, sparrows have decreased little, if at all. Some speculative ideas are put forward to account for the situation in built-up areas.

... It has been reported that large scale declines in house sparrow (Passer domesticus) population in many European towns and cities. In urban sub-urban Britain, decline is started in mid-1980s and continued upto the 1990s (Summers-Smith, 2003;Robinson et al., 2005). Moreover, in South East England, urban birds population appeared to be declining more rapidly than sub-urban or rural populations (Crick et al., 2002); there have been dramatic reductions, almost to the point of extinction, in Hamburg, Edinburg, Glasgow and Ghent, although the species has increased in Wales and Scotland (Summers-Smith, 2003). ...
... In urban sub-urban Britain, decline is started in mid-1980s and continued upto the 1990s (Summers-Smith, 2003;Robinson et al., 2005). Moreover, in South East England, urban birds population appeared to be declining more rapidly than sub-urban or rural populations (Crick et al., 2002); there have been dramatic reductions, almost to the point of extinction, in Hamburg, Edinburg, Glasgow and Ghent, although the species has increased in Wales and Scotland (Summers-Smith, 2003). ...
... The best-documented changes have occurred in London where 60% decline was recorded in the numbers of breeding Passer domesticus between 1994 and 2004 (Raven et al., 2005). According to a study, decrease in colony size below some critical (captious) value may enfeeble breeding behavior to the extent that breeding declines, resulting in the disappearance of the colony as a breeding unit (Summers-Smith, 2003). Another possibility about the urban decline of common house sparrow is possible link with electromagnetic radiations (Balmori and Hallberg, 2007). ...
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