Hen harriers are an endangered species according to conservationists
Illegal shooting is threatening the survival of Britain's bird of prey population, the Royal Society for the Protection of Birds warns.
The RSPB believes some killings are being carried out by those who see birds of prey as a threat to the grouse shooting industry.
The RSPB says the shootings put the hen harrier population at particular risk.
The British Association for Shooting and Conservation (BASC) said it condemned persecution of birds of prey.
RSPB spokesman Andre Farrar said the solution to the problem would a cultural change among those who maintain a "Victorian" attitude to birds of prey.
He said birds of prey often ate grouse and small birds, prompting some gamekeepers to see them as a menace.
Mr Farrar added: "The shooting industry can help us solve this problem." He also said the problem could be tackled through effective enforcement of laws.
Its research suggests birds of prey such as golden eagles, hen harriers, goshawks, buzzards, red kites, and peregrine falcons are being killed.
Those found guilty of killing birds of prey can face penalties of up to £5,000 and a jail sentence for repeat offending.
The BASC said that it "has and will expel any member found guilty of killing them or related offences".
Last year, only 15 pairs of hen harriers nested successfully in Britain.
Illegal hunting also threatens the golden eagle, which conservationists have been attempting to reintroduce to Scotland and northern England.
The RSPB says the killings are happening in areas such as the north Pennines, the Yorkshire Dales, the North York Moors and the Peak District.
Dr Mark Avery, the RSPB's conservation director, said: "It is outrageous that birds of prey are still being killed illegally and that these fantastic birds are destroyed before they can cast their shadows on some of our most beautiful wild places.
"The skies are owned by no-one, but a callous few want to deprive the nation of some of our most charismatic wildlife."
BASC added that expelled members risked losing their jobs and shooting opportunity as well as their insurance.
It says it works closely with shooters and conservationists including the RSPB to research and advise on how to reduce possible conflict between birds of prey and game.
It said: "The success in lowland England is there for all to see where buzzards, sparrow hawks and red kites have increased in recent years.
"Shooters and conservationists must continue working together to see a similar improvement in the uplands."