Sea eagles are being blamed for the deaths of many lambs
Scottish farmers in the north-west Highlands claim sea eagles brought back to the area in the 1970s and 1980s have killed more than 200 lambs.
Crofters in Gairloch say the RSPB and Scottish Natural Heritage are not taking their concerns seriously enough.
The RSPB examined one nest but said it was unlikely the birds were responsible for all the deaths.
Although sea eagles have taken several lambs in the past, the farmers say this year's death toll is much worse.
The RSPB said the birds were reintroduced into the area in projects several decades ago, but that they are now self-sustaining.
William Fraser, chairman of Gairloch and Poolewe branch of the Crofting Foundation, believes it is this particular breed of bird that is directly to blame for the rise in lamb deaths.
Speaking to BBC Radio 4's Farming Today, he said: "This year has been particularly bad.
"The crofters know how many lambs they put out after lambing season and one woman has lost 50% of her animals.
"She actually saw a sea eagle lifting a lamb from her field and flying off with it.
"We've had lambs that have had their necks sliced, they then can't lift them and are found going round in circles".
Carcasses of lambs have reportedly been examined by vets and found to have talon damage and injuries caused by being dropped from a height.
Another crofter described going close to a sea eagle's nest and finding what he described as a sheep's graveyard.
The farmers want help to deal with the situation but say not much has been forthcoming.
Mr Fraser said: "We have been keeping lambs here for generations and if this is not sorted out, this could be the end.
"We feel they put the birds here without our consent and without asking our advice."
The RSPB examined one nest in the area which contained the remains of four lambs.
But it pointed out there are only three breeding pairs of sea eagle in the Gairloch area, and it would be highly unlikely the birds were responsible for the loss of all of the lambs.
An RSPB spokesman said the reintroduction of sea eagles into Scotland has been "one of the greatest conservation success stories of recent years".
Fifteen of the birds were released into the wild in Fife, in the east of Scotland, in August.
The spokesman said: "These surprising claims must be compared with a recent study conducted on the island of Mull - the most densely populated area of Scotland for breeding sea eagles with eight pairs - which concluded that between only 33 and 37 lambs were killed by the birds on the whole island each year.
"In the whole of Wester Ross, there are just three breeding pairs of sea eagles. Gairloch occupies less than a quarter of Mull's land area.
"We are therefore extremely surprised at the claims of the number of lambs alleged to have been killed by sea eagles.
"There was also evidence that many of those killed on Mull were what is termed 'non viable', meaning they would not have survived into adulthood anyway due to disease and illness.
"Sea eagle predation is not a major cause of lamb mortality."
A spokesman for Scottish Natural Heritage (SNH) told the Times it will investigate each case thoroughly and it will find solutions for those farmers affected.
An SNH spokesman told the Scotsman: "We are aware of these concerns and very surprised at the numbers being talked about.
"There is no doubt that they will take lambs, but usually dead or weak ones, and we've never heard of it being done on this scale."
A public meeting on the issue is due to take place on 29 September.
This story has been amended as an earlier version suggested that the birds responsible were the same ones released recently under an RSPB programme.