A report has found 17 birds of prey were illegally killed or injured in the East of England last year.
The RSPB said birds such as peregrine falcons and red kites were being shot, poisoned and trapped.
They are calling on the Government to do more to protect raptors from persecution.
Jeff Knott, RSPB Director for Eastern England: “It’s terrible that illegal killing of birds of prey is still something we see happening all over the UK, and for me especially sad that so many magnificent birds, including peregrines and red kites, are being wantonly killed in Eastern England.
"The RSPB has worked for many years alongside landowners and shooting estates to manage habitat and save threatened species.
"Without the work of gamekeepers in The Brecks it is very likely stone-curlews would be extinct as UK breeding birds today. But the continuing spectre of raptor killing has undoubtedly cast a dark shadow on the positive contribution made by good game management to the conservation of these and other threatened species.
"It is encouraging then, that today there are shooting estates and gamekeepers putting their heads above the parapet to condemn the killing of birds of prey.
"I can only hope that one day we will see these crimes become a thing of the past.”
Stewart McIntrye, Estate Sporting and Conservation Manager in Cambridgeshire, said: “There is no justifiable reason for persecuting birds of prey.
"As a gamekeeper and conservation manager it is my role and responsibility to ensure that all wildlife can successfully cohabit alongside the estate’s farming operations and organised game shoots.
"Raptors are top predators and of course they take some game birds when they are hunting, but they are part of a healthy countryside with well managed habitats for the wildlife that lives there.”