Rare bird of prey poisoned by 'Nidderdale cocktail', RSPB says
At least one hen harrier in the past year has been poisoned by a lethal mix dubbed ‘the Nidderdale Cocktail,’ the RSPB has revealed.
The charity said it suspects that a total of seven RSPB satellite-tagged Hen Harriers were illegally killed on or near grouse moors in northern England in 2025, with one Hen Harrier confirmed poisoned and six more disappearing in suspicious circumstances – all sending their final transmission on or near land managed for grouse shooting.
Hen harriers have been monitored by satellite tags by the RSPB for some 15 years, following prolonged concerns that they were being illegally killed - with the charity describing the bird as the “most intensely persecuted” of all birds of prey.
The tags still work after a bird has died - but in cases where they have stopped transmitting with explanation, the RSPB suspects they have been deliberately removed.
In England, in the last 10 years (2016-2025), 72 satellite tagged Hen Harriers – monitored by the RSPB and Natural England – have suddenly and suspiciously disappeared, with some 85 per cent of these vanishing on or near land managed for grouse shooting.
One hen harrier named Ataksak, was confirmed poisoned after its body was recovered close to a grouse moor in North Yorkshire in early January 2025.
Toxicological testing revealed that it had died after being exposed to a lethal pesticide mixture, known as the ‘Nidderdale Cocktail’. Since 2011 this poison has been connected to the deaths of 15 birds of prey and one dog, all in North Yorkshire.
Mark Thomas, RSPB UK head of investigations said: "Although the suspected persecution of six of our satellite tagged Hen Harriers in one year is extremely concerning, these birds are sadly just the latest in a long trend.
“Since 2010 over one hundred satellite tagged Hen Harriers are suspected to have been illegally killed in the UK, with the majority disappearing on or near land managed for grouse shooting.
“As satellite tagged hen harriers represent a small proportion of the UK’s total hen harrier population the true number of Hen Harriers that are being illegally killed across the uplands of the UK is likely to be significantly greater. What we’re seeing is just the tip of the iceberg.”
The RSPB is calling for the introduction of a robust licensing system for all gamebird shooting in the UK, which would penalise shooting estates where crimes are being committed.
James Robinson, RSPB Chief Operating Officer said: “These latest incidents paint a desperate picture for hen harrier recovery in England. To prevent this pattern of killing, and give this vulnerable species a realistic hope of recovery, we urgently need licensing of all gamebird shooting to be introduced in England.
“Under this proportionate legislation if a crime is suspected to have taken place, based on a civil burden of proof, the shooting estate can have their licence to shoot revoked - creating a meaningful deterrent against this type of wildlife crime.
"Scotland took this welcome step in 2024 when it introduced licensing for grouse shooting. We need to follow their lead and give hen harriers in England the safety they desperately need.”