David Wheeler tells a story about some orphaned cygnets. They were hand reared by a keeper, but instead of imprinting on him, they latched on to his footwear - after that they would happily follow any pair of green wellies, thinking it was their mum and dad.

As manager of Abbotsbury Swannery, David, who has responsibility for school visits, has many such tales for the children. The Swannery is home to the only managed colony of mute swans in the world, and from April onwards more than l00 nesting pairs congregate there to get down to the hazardous business of rearing their young. The swans are wild, but the Abbotsbury keepers help nature along by preparing nests, finding foster parents for lost cygnets, and feeding the breeding pairs.

David describes himself as a “swan social worker”. The management of the colony is necessary, he says, because large numbers of cygnets would otherwise die.

“The swans are not clipped or pinioned - they do exactly as they want. But we give them breakfast, lunch and dinner in bed to keep the families in the nest. It takes around two weeks before cygnets can recognise their mother’s call and they can get lost or taken by rats or mink or foxes. We try to keep them together,” he says.

Swans are believed to have been at Abbotsbury since the 11th century, when Benedictine monks kept them as a source of food. The site, at one end of the Fleet, an eight-mile stretch of lagoon behind Chesil Beach near Weymouth in Dorset, is a Grade 1 site of special scientific interest, and is an ideal feeding and nesting ground for swans and other birds.

Free of hazards such as power lines and fish-hooks, the Fleet attracts between 700 and 1,200 swans throughout the year, and although not all of them breed, the nesting period between May and June is the best time for schools to make a visit, as then the nests, eggs, cygnets and swans are literally everywhere.

Children are fascinated by the Swannery, says David, and never tire of asking questions. “It is something really special when they can sit right next to a swan and watch the eggs hatch, or see a cygnet close up, and realise that the birds are there of their own choice.

“About two to three days before hatching the pens (mothers) and chicks start chatting away to each other to start the imprinting process - children are thrilled to hear that noise coming out of an egg,” he says.

All school parties to the Swannery are guided, and in addition to providing an excellent and comprehensive teacher’s pack, staff try to involve children in the tagging, sexing and recording of the birds where possible. There is wheelchair access, and tours can be specially adapted for the visually impaired and other special needs groups.

David, a former teacher, also delights in introducing children to Abbotsbury’s characters, such as Thumper, an aggressive cob who has fathered more than l00 cygnets, and Ben, who as yet hasn’t had much luck with the ladies.

Abbotsbury Swannery,Abbotsbury, near Weymouth, Dorset, is open from March 24 to November 3 1996, seven days a week,l0am - 6pm. School parties is Pounds 2.25 per child; teachers Pounds 3.50 orfree with every l0 children. Tel: 0l305 871684