Staff from the charity undertook covert surveillance of the grouse moor, which they have chosen not to name, during which they filmed a live eagle owl being used as 'bait' to lure in a pair of buzzards which were then shot by a man concealed nearby.
They saw the suspect leaving a gamekeeper's cottage in an ATV and he was even intercepted arriving back at his home with the bird in the back of his vehicle.
Yet police were unable to prosecute him because he could not be conclusively identified from the footage taken on the moor last spring.
Frustrated officers have instead contacted the estate's management to address the ongoing issues around wildlife persecution.
Details of the complex investigation, which took place throughout 2019 and 2020, have only now been publicly revealed by the RSPB now that the case has been closed with no criminal charges brought.
The estate came under scrutiny following an anonymous tip-off about the use of a tethered eagle owl as a 'decoy' in 2019. As eagle owls are 'apex' predators, other species such as buzzards will attempt to drive them away from their territory - meaning that they can be effectively used to lure raptors to an area where they can be illegally shot.
As well as the concerns over the purpose of the decoys, the RSPB also fears that many of these captive owls are not well cared-for.
What happened on the Dales grouse moor?
The incident captured on film happened on April 27 last year, following an earlier encounter in May 2019.
The RSPB account of events, written by investigations officer Howard Jones, reads: "After many hours of watching and waiting, on 21 May 2019 we had a breakthrough. We saw an ATV (all-terrain vehicle), with a large distinctive wooden box on the rear, being driven to a spot on the moor nearly two kilometres from where we were watching. The driver took out a live eagle owl from the rear box and tethered it to a small stone cairn. He then sat nearby with his gun, but no birds of prey appeared on this occasion, and so they left. This confirmed our original information was accurate. Whilst confident this was the local underkeeper, we needed to secure the crucial identification of the suspect.
"We continued our surveillance effort, however despite seeing the distinctive ATV on numerous occasions we had no further luck, so we decided to try again the following spring in 2020.
"On 27 April 2020, we decided to walk in from a different direction. En route, we spotted an ATV about five kilometres away going up to a different part of the moor. We settled down and through a telescope Jack could make out an ‘object’ on a post near a grouse butt with the ATV driver sat nearby. The ‘object’ then flapped, and it seemed the eagle owl was back in use. I set the video camera into record mode, and left Jack to look for a better observation position.
"A few moments later Jack called out that a buzzard had been shot. I rushed back and watched intently through the camcorder screen. Minutes later, a second buzzard was shot: I could just make out the bird dropping out the sky and landing near the decoy owl. Two buzzards gunned down in the space of 10 minutes tells you just how horrifically effective this eagle owl decoy technique can be. A third buzzard appeared, but narrowly got away. The offender collected the body of the second buzzard and started to leave the scene on his ATV with the owl back in the box on the back. Our luck was out as we could not be confident on the final disposal location of the buzzard they had picked up.
"These moments are very intense, and my mind was racing as to the best approach and also aware of the standard of evidence required in court from years of experience. I have been through this situation before and contemplated it many times more in my head. I was present with two colleagues in 2017 when two short-eared owls were shot on a grouse moor in Cumbria. On that occasion we were closer, had filmed where both bodies were hidden and there was only one way that the gamekeeper’s pick-up could leave the moor. North Yorkshire Police arrested the suspect on the moor, the owls were recovered and a conviction followed. None of those conditions were in our favour this time unfortunately. The chances of a police interception here were remote and, with no bodies and the identification evidence not quite there, the best decision was to keep watching and hoping to film better evidence.
"Once again, from a new observation position, we played the waiting game to prove the identity of the suspect. On numerous occasions we saw the same distinctive ATV on the moor, and in the distance saw it coming and going from the local gamekeeper’s home and could now tie the vehicle to a person and address. We decided to draw a line confident in the identification of the suspect and passed our evidence to North Yorkshire Police. We are grateful for the support from PC Mark Wood and his colleagues.
"North Yorkshire Police visited the gamekeeper’s home and undertook a search of the locations on the moor identified in 2019 and 2020. This was the fourth known raid on a grouse moor estate in North Yorkshire in 2020. During the search, the suspect arrived home with the eagle owl in the rear box on his ATV. Despite the highly incriminating evidence we had gathered, ultimately with no admission, the identification of the male in question did not cross the evidential threshold needed by the CPS. Unfortunately, that is the harsh reality of trying to investigate these cases: justice is rarely done."
Inspector Matt Hagen from North Yorkshire Police, said: “We conducted a search warrant and interviewed an individual in relation to this incident. Ultimately, however, the identity of the suspect on the film could not be proved, and it was not possible to bring about a prosecution. However this does not mean the event didn’t happen. We know that a gamekeeper on a grouse moor has been shooting buzzards, using a live eagle owl decoy to bring those buzzards into a position where they could be shot. We urge the public to report incidents like this to the police, and to come forward if they have information about this or any other incident involving the illegal killing of birds of prey.”