Soaring sparrowhawk population 'leads to shock decline in humble sparrow'

Sparrowhawks, left, have increased dramatically in numbers, but scientists have blamed the birds of prey for the 65 per cent drop in sparrow populations


Their alarming decline has been blamed on everything from gardeners' pesticides to mobile phone masts.

But it seems one of the sparrow's oldest enemies could be the real culprit behind its shocking fall in numbers.

Soaring numbers of sparrowhawks have been killing the sparrows off, say scientists.

A report claims to show the strongest evidence yet that the birds of prey are to blame for the 65 per cent fall in Britain's sparrows since the 1970s.

But the finding has angered other bird experts, who say it will lead to the unfair persecution of sparrowhawks.

The hawks themselves were wiped out over much of Britain in the 1950s because of organochlorine pesticides such as DDT.

These weakened the birds' eggshells, causing the chicks inside to die - which led to populations plummeting.

But since the chemicals were banned in the 1970s, their numbers have quadrupled.
Dr Christopher Bell, anr Bell, an
ecologist who led the research with colleagues from Cambridge University and the British Trust for Ornithology, said the research overturned previous assumptions that sparrowhawks had no effect on sparrow populations.

He said urban sparrows were easily picked off because of their bold behaviour. The study, published in The Auk, the journal of the American Ornithologists Union, also explains why urban sparrows have disappeared from richer parts of cities - while continuing to thrive in poorer areas.

Dr Bell said: 'This is because the affluent parts of cities provide safe nesting places for sparrowhawks in the large gardens of grand houses, and in private grounds and restricted areas of parkland, whereas no such nesting opportunities occur in poorer districts.'

Sparrowhawks started to move into urban areas in the late 1980s and 1990s, which coincides with urban sparrow declines. However,
bird charities such as the RSPB say there is no evidence they are to blame for songbird populations falling.

Instead, they blame changes in farming - such as the switch from spring to autumn sowing crops, the loss of stubble over winter and the increased use of selective pesticides.


source: dailymail