Police are appealing for information after a protected red kite was found dead in a wood.
A walker discovered the carcass of the bird of prey in woodland near Aboyne in Aberdeenshire on 6 April.
A post-mortem examination showed that the bird did not die of natural causes.
PC Mike Whyte, Police Scotland’s local wildlife crime liaison officer, said inquiries had so far failed to identify a suspect. An appeal is now being made to the public for information.
The three-year-old female, known as Red/Blue 44 because of its colour combination and the number on its wing tags, was fledged from a nest in Perthshire in 2010. She bred successfully last year and raised three chicks not far from where her carcass was discovered.
Ian Thomson, RSPB Scotland’s head of investigations, said: “It is unforgiveable that someone could deliberately target such a fantastic bird, and I ask anyone who may be able to assist in bringing the perpetrator to justice to contact the police.”
Since 1989, 401 red kites have been released in Scotland in an attempt to re-establish the species after it became extinct as a breeding bird here in 1917. Last year, 214 breeding pairs were identified.
“Despite a Scottish reintroduction programme that has been going for 24 years, the red kite is still a rare breeding bird here,” said Mr Thomson. “It is one of our most spectacular and unmistakable birds of prey, with its main diet being carrion, insects or small mammals.”
RSPB Scotland’s red kite project officer for north-east Scotland, Jenny Lennon, said: “The whole Aberdeen red kite team of staff, partners and volunteers are deeply saddened by the death of Red/Blue 44 – our first known case of illegal killing in Aberdeenshire since the project began six years ago.
“The female was of great importance to our young population, with only a handful of our 20 or so breeding pairs on Deeside itself. We hope the three 2012 offspring of Red/Blue 44 will thrive in Aberdeenshire and contribute further to the Scottish red kite population.”
The news comes just two days after a petition was presented to the Scottish Parliament calling for environment minister Paul Wheelhouse to ensure that no licences are issued in Scotland that would allow the culling of buzzards to protect game
The petition, which has attracted more than 23,000 signatures, was started by birdwatcher Lewis Davies from Rosyth after revelations that England’s nature conservation agency had allowed the secret destruction of buzzard eggs and nests to protect a pheasant shoot.
Mr Davies hopes to ensure that the same does not happen in Scotland. He said: “I remember growing up in a time when the sight of a buzzard or any bird of prey was a rarity. I don’t want that to be the case for my children.”
Earlier this year, there were calls for a crackdown on pesticides to control vermin after a Scottish Government study found evidence of widespread poisoning of birds of prey.
Experts from Science and Advice for Scottish Agriculture studied the use of rodenticides on arable farms between 2000 and 2010 and the presence of residues in raptor carcasses.
It was found that red kites, which feed on rodents, were “particularly vulnerable”, and traces of rodenticides had been discovered in the liver tissue of more than two-thirds of the birds examined. A tenth of birds died from ingesting poison.