POLICE are investigating after one of England's rarest birds of vanished - presumed dead - from North-East moorland.

Hen harriers are endangered in England, with only a handful of nesting pairs remaining, the vast majority in the Forest of Bowland, near Preston.

This year, there has only been one report of a nesting pair in the North-East, on a stretch of moorland at a secret location in County Durham.

Had the Durham pair bred, it would have been the first time the birds had produced chicks in the county for eight years.

Now, police working for Operation Artemis, the nationwide operation set up to protect harriers from persecution, have been called in after the male vanished.

Conservationists say the overwhelming reason for their decline nationally is persecution by gamekeepers, although the shooting lobby blames factors including the theft of eggs by collectors and poor weather conditions.

English Nature is running a Hen Harrier Recovery Project to monitor the fortunes of the birds across the country, and its staff monitoring the Durham nest had hoped the birds would come to no harm.

It is now assumed that the male has died, with persecution a strong possibility.

John Olley, English Nature's project officer, said: "Male hen harriers do not desert a nest when paired with a single female and, unfortunately, it must be assumed this male hen harrier is dead.

"We have checked with colleagues in Scotland and their experience from many decades of monitoring work, involving well over a thousand nests, has shown that the only recorded cause for the disappearance of a fit, healthy adult male in the middle of the breeding season is illegal persecution.

"Not only is the loss of this male a blow to the conservation of the hen harrier in England, it is also a huge disappointment to the volunteers and members of the Durham Bird Club, who gave up their time to help monitor this beautiful but, sadly, endangered bird."

A North-East naturalist connected to the project, who asked not to be named, said: "The sight of the male hen harrier gliding over the moorland back to the nest with prey and the female rising from the nest was astonishing and breathtaking.

"If this bird has been killed, it has been a mindless act. It is a shocking incident.