Farmers and conservationists are now working together in a bid to find a solution. So-called distraction food and helium balloons are among counter-measures being trialled.
The sea eagle, or white-tailed eagle, is the UK’s largest bird of prey – with an average wingspan of more than 2m (6.5ft).
Stock under attack
There are now known to be about 130 breeding pairs of sea eagles in Scotland, from hotspots such as Skye and Mull across to the mainland.
It is estimated this could rise to at least 500 pairs by 2040.
In Appin, on the west coast of Loch Linnhe, in Argyll and Bute, David Colthart keeps 650 blackface sheep across 3,200 acres.
He said his stock had been under attack since sea eagles started nesting in the area.
Describing one incident, he said: “This is a typical example of a plucking, it’s basically where the bird has lifted one of the lambs and it’s taken it to a certain point and it’s plucked some of the wool and skin off, eaten some of it, and maybe taken the rest back to its nest.”
He added: “It’s very frustrating when you see that, and some members of the public aren’t taking it seriously, they think we’re just making it up.
“It’s not sustainable for any kind of farm business here in the west. We’re in a very marginal farming area, and its difficult enough to raise the lambs you’ve got and the sea eagle is the one that starts unpicking the ability for that flock to sustain itself.
“Round this area, the wider area, there’s at least half a dozen pairs, between here and round about Oban.
“And you’ve got Mull as well, so that’s not too far away. Mull’s only 16 miles as the eagle flies, so to speak.”
Trials in conjunction with Scottish Natural Heritage (SNH) are being held to see how the birds can be distracted from killing lambs.
SNH’s Rae McKenzie, who is overseeing the project, said: “We’re trying a whole load of different scaring techniques and management.
“You’re seeing helium balloons, they float about in the air and they deter the sea eagles from coming near the lambing areas.
“We’re struggling a bit with those because they’re not staying in the air the way they should, because of the weather or maybe just because they’re maybe too light to do this kind of job in this kind of terrain.”
Luring the birds away from livestock with alternative food is another option being assessed.
Mr McKenzie added: “We’re considering trialling things like lasers, but we’re not there yet with that, we need to think about the practicalities of that.
“There’s all sorts of other noise-based, light-based type scaring devices on the market we might take a look at.
“We want a toolbox of things, not every eagle will respond to every scaring device, so hopefully if we’ve got things that work in some places and don’t work in others we can mix and match.
“I think the best chance we’ve got of doing that is working together, and hopefully getting a better understanding of what the birds will respond to, and how we might apply different measures in different places.”
You can see this story on Landward on BBC One Scotland on Friday at 20:30.