The corncrake - the only globally threatened bird to breed regularly in the UK - started to disappear from the English countryside more than a century ago.
Corncrakes are migratory birds that travel from Africa to breed in the UK. They live on land, but are rarely seen in the wild as they live in thick vegetation, grassland and field corners, camouflaged by their brown feathers.
Modern farming techniques, the spread of fast efficient mowers that kill chicks and adults, and now the reduction in cattle numbers, which in turn reduces the need for hay and silage thus drastically reducing potential nesting areas, has hit the corncrake population very hard.
Today this relative of the more familiar coot and moorhen only breeds in the northwest of Scotland, where conservationists have been working intensively with local crofters and landowners to ensure the bird's continual survival.
As a result of this collaboration, farmers do not cut the fields until later in the season, giving the corncrake female enough time to nest and rear her first brood and in many cases her second as well. They also always cut their fields from the centre out in a circle or large strips meaning any adults and chicks left should have enough time to escape to the edges which are always left to grow wild.
This development has led to increasing numbers in Scotland, but without suitable habitat protection and restoration these birds will find it very difficult to gain a foothold in England again.
In 2002, ZSL, RSPB and Natural England created a partnership for the captive breeding and release of corncrakes. The birds are bred and hand reared by ZSL at ZSL Whipsnade Zoo and then released at the RSPB's Nene Washes nature reserve in Cambridgeshire.
At the beginning of June 2005 a wild male corncrake was heard calling at the nature reserve in Cambridgeshire. It was established that this bird had been bred at Whipsnade in 2004 and is excellent evidence that a captive bred and released, hand-reared bird had migrated to Africa and back (around 3000 miles), ending up less 2-3 km from its original release site.