Mallards make the most of the urban lifestyle

The Great British pastime of feeding the birds has been responsible for a trebling of the number of mallards during the past 25 years.

The Great British pastime of feeding the birds has been responsible for a trebling of the number of mallards during the past 25 years.

Mallards have for some time been the most abundant duck in Britain but a new survey by the British Trust for Ornithology has found them to be the fastest-breeding wetland bird in the country.

Much of the rise has been among domesticated mallards, the kind that feast on bread crusts offered to them in urban parks up and down the country. The increase has surprised experts at the trust because the winter population of mallards has been falling, possibly because global warming is encouraging more birds to stay year-round in the Baltic, Scandinavia and Russia.

Despite the drop in the winter population of about one third, the estimated number of mallards in the country as a whole is about 500,000, an increase of 190 per cent from 1975 to 1999.

Much of that was accounted for by the strength of the tame mallard population often found in urban areas, said John Marchant, a team leader in the trust's census unit.

"We are finding that there are more breeding birds along waterways and it is the tame birds that are accounting for much of the large population and the increase.

"We don't really know for sure why it is happening but it could be that there is more food and less predators and the birds are more prepared to nest close to human habitation," he said.

Other birds flourishing, according to the survey, included the mute swan, which is also tame and well fed in public parks. Its numbers have grown by 76 per cent since 1975, marking a remarkable recovery from the 1960s, when the population fell drastically. The drop was blamed on lead poisoning caused by the swans eating lead shot used by anglers. The swan picked it up when gathering grit to grind their food.

"There was a reduction in the population because large numbers were being poisoned by picking up lead weights, which made them ill and unable to eat properly. But lead has now been banned for 10 years and we are seeing a return in the mute swan population," Mr Marchant said.

The Waterways Bird Survey included birds that were not picked up by other surveys. Species it found to be thriving included the oystercatcher, whose numbers have risen by 110 per cent, the coot, which has gone up by 61 per cent, the curlew, up 72 per cent, and the reed warbler, up 79 per cent.

Others were not faring so well. Numbers of the reed bunting had fallen by 68 per cent, the little grebe by 57 per cent, the pied wagtail by 48 per cent, the grey wagtail by 42 per cent and the common sandpiper by 18 per cent.

The survey found a slight increase in the number of lapwings, a bird that has been under pressure because the growth of intensive farming is depriving it of its ideal habitats.

Mr Marchant said, however, that the survey results were not good news for the species, because although there might have been an increase over 25 years, the decline of the lapwing over the past five or 10 years had been "disastrous".