Sparrow numbers fall by 25 per cent in a year

The astonishing decline of the house sparrow in London goes on and on, new figures reveal today.

The astonishing decline of the house sparrow in London goes on and on, new figures reveal today.

The 59 per cent decrease in numbers between 1994 and 2000, when many Londoners saw sparrows disappear from their gardens, was followed by a further 25 per cent drop between 2000 and 2001, according to the British Trust for Ornithology.

The new figures, announced in the trust's magazine, come from its 2001 breeding bird survey, which covers large tracts of Britain, and last year covered 54 sq km (21 sq miles) in London. It is based on observation of singing male birds, which are holding territory and thus likely to be breeding.

There are now hardly any sparrows left in central London. There have been two declines in "cockneys sparrers" from the huge numbers present around 1900. The first, which took place between the wars, followed the replacement of the horse by motor vehicles in London. Grain spilt from nosebags or undigested in dung fed tens of thousands of sparrows.

In 1925, 2,603 birds were counted in Kensington Gardens; in 1948, there were 885. But the recent decline has been far steeper. In 1975, there were 544 birds in Kensington Gardens but in 1995 just 46, and in 2000 only eight were counted.

The results of a sparrow survey organised by the London Biodiversity Partnership, involving 11,000 people, are now being processed as part of a substantial research effort to explain the recent decline. One expert, Denis Summers-Smith, believes a chemical additive in lead-free petrol might be linked. Other theories include predation by pet cats, magpies and sparrowhawks, the loss of nesting places because of tidier gardens, and the possibility of a "suicidal tendency" leading birds to abandon colonies when numbers are critically low.

The house sparrow's decline has been so alarming that this year it was placed on Britain's official "Red List" of endangered birds, joining rarities such as the bittern, the stone curlew and the white-tailed eagle.