Predation by white-tailed eagles on lambs and sheep remains a major concern for sheep farmers, despite a study suggesting that seabirds and fish are now the most important food source for the birds.

The study - The breeding season diet of white-tailed eagles in Scotland - examined the species' diet from 1998 to 2017, and found the amount of lamb in the seabirds' diet has decreased over the years.

The research was conducted by a group of white-tailed eagle experts and was published in the Scottish Ornithologists' Club (SOC) journal, Scottish Birds.

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RSPB Scotland said it hopes the study will provide some reassurance to farmers and crofters concerned about their livestock being hunted.

However, David Colthart, a hill farmer from Appin near Oban said the 180 farmers and crofters currently signed up to the Sea Eagle Management Scheme (SEMS) continue to suffer losses of lambs to the birds and said the need for management will continue to grow as the species multiplies.

The paper shows the species has a diverse diet during breeding seasons, with 11,375 food items recorded across 293 samples taken from nest sites across 92 white-tailed eagle territories in Scotland.

It found that 121 species were recorded, including 70 species of bird, 17 species of mammals, and at least 30 species of fish.

When the study began in 1998 there were only 18 pairs of white-tailed eagles, also known as sea eagles, in Scotland, with the majority living in the Inner Hebrides.

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By 2017, there were at least 122 pairs across the country, and a total of 58 nests were sampled in that year.

The analysis found that as time went on, the proportion of lamb remains in nests decreased.

Between 1998 and 2002, 15 nests were sampled and lamb accounted for more than 30% of items in five of those nests.

The report found that by 2017, lamb accounted for the same percentage in just five of 58 nests sampled, demonstrating a stark decrease in how much the species relies on lamb as a food source.

White-tailed eagles are scavengers and generally rely on carrion for food. The study found lambs were occasionally killed, but were generally smaller in size, making them more vulnerable to predators.

The researchers said: "The previously widespread view that lambs are an important food for white-tailed eagles has been superseded; the prevailing evidence now is that marine items such as seabirds and fishes are the most important breeding season food in Scotland."

However, Mr Colthart countered: “Over the 20 years of the study period, the population density and range of WTEs has increased significantly and the impact on hill flocks in some locations has without doubt increased especially in areas where there is a lack of available natural prey.

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“Indeed, since the study stopped collecting its data six years ago, WTE numbers and their range will have increased significantly. Over the period of the study, in some areas, the number of livestock kept will have also declined.

“Unfortunately, the study fails to drill down on the local impact where specific farms and crofts have had their viability undermined by WTE predation and we hope RSPB Scotland will take the opportunity to address that in the future.

“That has a serious agricultural impact on the business but also on the health and wellbeing of those who are living with eagle predation on their flock on a regular basis.

“The study also focuses on breeding pairs and prey remains that are found in their nests and doesn’t consider the impact that the many juvenile birds may have, nor does it consider what is killed and eaten away from the nest and not taken back.

“Our focus at NFU Scotland continues to support the farmers and crofters that are experiencing serious issues with WTE predation and support the WTE action plan and the Sea Eagle Management Scheme (SEMS). Indeed, any future study could examine if the reduction of predation in some areas is down to the actions being undertaken as part of SEMS.”