Birds of prey including the peregrine falcon, red kite, goshawk and hen harrier are being poisoned or shot in the North York Moors and Yorkshire Dales at a rate unknown in any other region, according to the RSPB.
North Yorkshire has been named the UK's "black spot", with more crimes against birds of prey and owls reported in the last year than in north Scotland and Wales and all the counties of the south of England combined, found the charity's Bird Crime 2010 report, to be published on Thursday.
Almost 10 per cent of the 117 incidents against 11 species last year took place in the county, which has consistently recorded high rates of such crime, according to the RSPB.
Conservationists claim the majority of these crimes can be blamed on those working on shooting estates, especially gamekeepers wanting to illegally rid grouse moors of all potential predators.
The number of reported incidents in North Yorkshire doubled between 2009 and 2010, from 27 to 54, with 10 confirmed cases of bird of prey persecutions. These include the poisoning of four red kites and three buzzards and the shooting of a goshawk. Two-week old chicks were also found laced with a banned pesticide and left as bait in the Yorkshire Dales.
Confirmed incidents of birds of prey crime across the UK remained constant between 2009 and 2010, but the RSPB said the recorded numbers were just the "tip of the iceberg".
Species policy officer Jeff Knott told The IoS that persecution was still a "major problem" for several UK birds, including government-listed "priority" birds such the golden eagle and the hen harrier, which has seen a 20 per cent reduction in its population since 2004.
He said: "Over the past 50 years, we have seen progress in lowland areas, where there now isn't much persecution. This has allowed species like buzzards and red kites to recover.
"Unfortunately, on very intensive upland grouse moors, there has been no change in attitudes since Victorian times. It is thought anything with hooked beaks should be got rid of."
According to the RSPB figures, almost 75 per cent of those convicted for bird of prey crime over the past 20 years have had ties to game hunting, but only around 4 per cent of confirmed cases make it to court each year. A spokesman for the British Association of Shooting and Conservation said the group "absolutely condemn" illegal persecution of raptors, but denied the problem was as widespread as claimed. "The gamekeeper is a convenient scapegoat but not all the blame can be laid at his door," he added.
PC Gareth Jones, who has worked for the North Yorkshire police wildlife crime unit for six years, said it is "worrying" that birds of prey are not present in the numbers they should be in his county. "Most gamekeepers out there are honest, but there will always be the rogues who will do anything in their power to kill birds of prey," he said.
He added that Scotland was "enlightened" when it came to protecting birds of prey and suggested that the Westminster government should adopt the new "vicarious liability" offence for those who turn a blind eye to bird persecution, adopted in Scotland earlier this year.
A spokesman for the Department for Environment, Food and Rural Affairs said: "We will look closely at how the new legislation in Scotland works and will consider this when shaping wildlife crime policy in England."