By environment correspondent Alex Kirby

A leading UK conservation charity, the Royal Society for the Protection of Birds (RSPB), is to pay at least a million pounds to find out how to help endangered birds.

It is buying a 180-hectare farm in eastern England to develop methods of agriculture that will encourage wildlife.

The farm, 10 km west of Cambridge, is being sold for an undisclosed sum, and the RSPB is launching an appeal to raise �750,000 towards the cost from its members and supporters.

The charity's conservation director, Mark Avery, said: "The decline of farmland birds is now a top priority for the RSPB.

Help for farmers

"Buying this farm is a long-term move which will allow us to develop new wildlife-friendly ways to farm, and enable us to communicate advice and best practice to farmers and decision makers against a background of real farm economics.

"In the future, when subsidies are no longer linked to production, the knowledge that we gain from the farm will allow us to put forward fully-costed farming alternatives with clear benefits for farmers and wildlife."

The RSPB says that skylarks, yellowhammers and corn buntings have all declined by more than 60% over the past 25 years, along with many mammals, insects and wild plants.

It says other species have also suffered from the intensification and specialisation of agriculture.

The main driver of this process continues to be the European Union's common agricultural policy and its system of subsidies for production.

The charity says the farm will allow it to carry out a detailed research programme to devise and test new cropping techniques, which farmers elsewhere in the UK will then be able to use.

Fewer chemicals

These may include encouraging skylarks by leaving some areas that will be sown more thinly than usual, providing bare patches for the birds to nest on.

Other less intensive cultivation methods aimed at leaving seeds in the fields for finches during the winter could include reductions in pesticide use, and conservation headlands - areas left completely unsprayed.

The land is "a typical intensively-run lowland arable farm", growing mostly autumn-sown cereals and oilseed rape.

Three-quarters of it will be managed for the RSPB as a viable farm business, with the other quarter used for the experimental work.

Grahame Madge of the RSPB told BBC News Online: "We are buying the farm outright, rather than working with a friendly farmer on his land, because we need to have total control over the management.

"We have to be able to be adventurous in the techniques we'll be trialling. Some may not be commercially viable in the short run.

"Our long term aim, though, is to prove that you can farm economically while at the same time taking wildlife into account.

"It's a delicate balance between proving that the new methods are viable, and doing something that farmers will regard as simply idealistic."

All photographs by Chris Gomersall/RSPB