The initiative was set up in April and involves Grampian Police, Scottish Natural Heritage, the North East Raptor Study Group (NERSG) and five local estates.

We certainly cannot afford to see numbers continue to go down

Jon Hardey, NERSG

It aims to protect hen harriers and peregrine falcons by monitoring sites and sharing information with concerned groups.

Paul Timms, of Scottish Natural Heritage, attempted to explain the bird number reductions: "It seems that a number of older birds have died out naturally.

"Normally younger harriers would move in and take over nest sites and territories, but the population is so low that there are few new birds to take over from the old."

'Essential work'

Jon Hardey, from NERSG, said the findings showed that the work of Falcon 2000 was essential.

He added: "It is critical to protect the birds we have at the moment so that the population can bounce back over the next few years.

"We certainly cannot afford to see numbers continue to go down."

Falcon 2000 relies heavily on the work of its member groups including Grampian Police.

Sergeant Roddy Macinnes is the force's wildlife liaison co-ordinator, who along with three of his colleagues, investigates reports of wildlife crime.

He said he was happy to be involved with the initiative but he called on members of the public to "do their bit" by keeping their eyes and ears open.