Police have searched an estate after the disappearance of the first white-tailed sea eagle to be raised in the east of Scotland in almost 200 years.
The male bird, which was raised in a nest in Fife last year, was fitted with a satellite tag before it could fly.
Police have made searches of Aberdeenshire's North Glenbuchat Estate where the eagle was last tracked to.
The owners of the North Glenbuchat estate are yet to respond to inquiries from BBC Scotland.
Police officers have spent the day searching property on the estate.
A Police Scotland spokesman said: "We are concerned for the welfare of a white tailed eagle and enquiries are ongoing to locate the bird.
"Around April 10, 2014, we became aware that the bird was missing from the Glenbuchat area of Strathdon as there were no further recordings from its transmitter.
"There is concern for the welfare of this very rare bird.
"As a result searches have been carried out in the area on both land and within premises."
In recent years, several satellite tagged golden eagles have also disappeared in the Strathdon area.
In 2011, the body of one of the birds was recovered at Glenbuchat. Tests showed it had been poisoned.
RSPB Scotland's Head of Investigations, Ian Thomson, said: "The disappearance of this white tailed eagle is very depressing, and particularly so since it joins a list of other satellite-tagged eagles that have vanished on the grouse moors of upper Donside in the last few years.
"It is significant that the only carcass found was that of an illegally poisoned golden eagle back in 2011.
"A police follow-up to that incident, on this same estate, found a poison bait, a poisoned buzzard and a shot short-eared owl.
"Four other satellite-tagged golden eagles have disappeared in the same area, without trace or further transmissions from the tag, in the last five years. This area has become a black hole for eagles".
In 2006, the then head gamekeeper on the North Glenbuchat Estate, Hector McNeil, was fined £850 at Aberdeen Sheriff Court after being convicted of poisoning wild birds and possessing an illegal pesticide.
In June last year, BBC Scotland revealed police were investigating the alleged destruction of a white tailed eagle nest in Angus.
It was thought to be the first nest to be built by white tailed eagles in the east of the country, following a reintroduction programme.
Police Scotland have asked anyone who was in the Glenbuchat area around 10 April and who may have any information to contact them by dialling 101.
The last British white-tailed eagle was shot in Shetland in 1918.
Since the 1970s, the species has been reintroduced to the west coast of Scotland.
Over the past six years, the focus has switched to bringing back the bird on Scotland's east coast.
More than 80 birds, taken from nests in Norway, have been released from a secret location in Fife.
The reintroduction project is run by RSPB Scotland, Scottish Natural Heritage and Forestry Commission Scotland.
It has cost £452,000 to date, with funding coming from the RSPB, SNH and the Heritage Lottery Fund.
- 13 June 2013
- 5 May 2011
- 12 July 2006