Ospreys became extinct in England 150 years ago, but last year a number of wildlife groups took steps to encourage the birds to breed in England, after their successful reintroduction in Scotland.
Ospreys usually spend several months near their nests before migrating to West Africa.
They remain there for about three years, before returning to their birthplace to breed. Information relayed to a Website will help researchers establish whether the birds fly across areas where they are threatened by hunters' guns, particularly in France, Spain and Africa. A Website, launched on Sunday by the Anglian Water Osprey Project in partnership with the Leicestershire and Rutland Wildlife Trust, features maps linked to individual birds. In July last year, chicks were taken from broods in Scotland and put into huge pens overlooking a 3,000-acre lake in Leicestershire. The area, Rutland Water, is used by ospreys as a stopover point on their way back to Scotland from North Africa.