By Paul Rincon
Science reporter, BBC News
Golden eagles are gravely threatened by a £200m wind farm scheme proposed for the Hebridean island of Lewis, campaigners have warned.
The Pairc peninsula is a good habitat for golden eagles
Three of the predatory birds a year could be killed in collisions with turbine blades - the highest mortality from any wind power project in the UK.
The figures come from the developer's own environmental statement.
The planned 205 megawatt Pairc wind farm in south-eastern Lewis would comprise 57 turbines.
Campaigners are also alarmed at the possibility of peat slides in some areas where the 145 metre (475ft) structures are to stand.
Developer Scottish and Southern Energy (SSE) found 10 infrastructure sites on the Pairc peninsula were at a high risk of peat slides, a further 16 were considered to be at moderate risk.
"The eagle kill is pretty horrific, as is the threat of peat slide," said Catriona Campbell, of anti-wind farm group Moorland Without Turbines (MWT).
Golden eagles are on the Amber list of birds of conservation concern and are afforded the highest level of protection under UK law. There are about 60 pairs in total on Lewis.
Extrapolating the figure of three deaths per year over the project's 25-year lifetime arrives at a figure of 76 golden eagles killed in collisions over the course of the scheme. This already assumes that birds strongly avoid the turbines.
"[Pairc] is a significant site, not only for golden eagles but also for sea eagles," said Martin Scott, the Royal Society for the Protection of Birds (RSPB) Western Isles conservation officer.
The site has a high density of eagles in a relatively small area. There are three to four golden eagle pairs in the vicinity of the wind farm, with one pair nesting at the heart of the site.
Proponents of the wind farm say the actual number of eagle deaths would be much lower than 76. They argue that once the pair whose territory is centred on the new farm is lost, a void will exist, causing the eagle mortality to drop off after the first few years.
Eagles on the periphery of the scheme may move elsewhere - with few moving in to claim the territory.
Even if this was assumed to be true, Mr Scott said, it could cause other problems.
"Our concern is that the void caused by the loss of the pair would act as a sump to draw other [bird species] into the turbine area, because there are no eagles to chase them away," he explained.
"On Lewis - where there are now three big schemes - when people talk about displacing birds from one area to another, they are simply moving them on to another wind farm."
The developer's peat assessment has also generated consternation.
The destructive potential of peat slides was amply illustrated when, in 2003, nearly 0.1 sq mile (0.5 sq km) of bog slid 1.5 miles (2.5km) down a hillside at Derrybrien, western Ireland.
An investigation concluded that construction on a 71-turbine wind farm contributed to the landslip.
The 13,837-acre (5,600-hectare) Pairc site varies in altitude between 20 metres (65ft) and 180 metre (590ft), with topography generally sloping upwards from west to east.
SSE said that after mitigation - such as specialist monitoring of construction and careful placement of turbines - the peat slide risk is reduced to "low" for 20 infrastructure sites and "moderate/low" for the remaining six.
But MWT said residents on the Pairc peninsula should be concerned.
The wind farms have split opinion on Lewis. Council leaders said renewable energy schemes will help safeguard the island's economic future, but critics insist they threaten the island's natural beauty, its ecology and wildlife.
Ms Campbell said that, taken together, the three schemes comprised 40 miles (64km) of turbines. She said the cumulative impact of all three schemes needed urgent assessment.
The Comhairle nan Eilean Siar (Western Isles Council) has not yet adopted a position on the Pairc scheme.
Calum Ian McIver, the Comhairle's head of economic development, said several hearings would be held as part of its evaluation process, allowing interested parties to submit their views.
Council members will decide whether or not to approve the scheme later this year. The final verdict rests with the Scottish Executive.
SSE declined to comment for this report.