HERITAGE OF THE WILD: RSPB takes lead in drive to preserve bird's habitat

The bittern is one of the rarest British birds, with a breeding population totalling less than 50. A handsome, reclusive relative of the slightly larger and more common grey heron, it lives in reed marshes in Norfolk, Suffolk and Lancashire preying on fish, especially eels, frogs and occasionally on small mammals and birds.

The golden-brown bitterns are hardly ever seen because they stay among the tall, dense reeds and are well camouflaged. The only way to estimate their breeding population is to listen for the strange, booming calls of the males trying to attract a mate from January to May. It is thought to be the deepest sound produced by any bird, a brief, fog-horn like tone which can be heard up to a mile away.

Last summer, 20 booming males were heard in Britain, up on the 16 detected in 1994. But 40 years ago there were more than four times as many and they had a much wider range.

The bittern is endangered in Britain and across Europe mainly due to destruction of its habitat. Large areas of reedbed have been drained and gone under the plough this century. The bird is one of the 116 declining or endangered British animal and plant species or one of the 14 types of dwindling habitat covered by new rescue plans drawn up by a steering group of government scientists and wildlife conservation groups. The Government has promised to respond in the spring.

Poisoning by pesticides, harsh winters, sewage pollution lowering fish populations and disturbance by pleasure boating are also likely factors in the bittern's decline. What remains of their habitat in Britain has to be managed to preserve it. Trees and shrubs invade neglected reedbeds and they turn into boggy forests. So the reeds have to be cut back and allowed to regrow, and the water table kept high to bring in the bitterns.

Those that breed here already depend on nature reserves run by the Royal Society for the Protection of Birds and other organisations for their habitat.

The steering group proposes that by 2000 the population should be growing and expanding its range, reaching at least 100 booming males over the next quarter-century. This can be done by preserving the 22 remaining large reedbeds where bittern once occurred and creating 1,200 hectares of new habitat - about four and a half square miles.

The RSPB has made a start, purchasing a carrot field in Lakenheath, Suffolk, which will be turned into marshy reedbed. The steering group estimates the cost of the bittern recovery programme at pounds 10,000 a year.