In March the satellite-tag fitted to the young sea eagle known as Blue X suddenly stopped transmitting in the Glen Quaich area of Highland Perthshire, an area dominated by land managed for driven grouse shooting. Her disappearance is described by RSPB Scotland as ‘highly suspicious’. It is important to understand what we mean by this, as we’re often accused of ‘trial by media’ without corroborating evidence in cases like this one.

Image; Blue X shortly after fledging. Image credit Dennis Gentles

There is a very small chance, less than 2%, that the tag had a mechanical failure – these tags are widely used in studies of birds of prey throughout the world, and they have a proven reliability. Had the bird naturally, or had the tag become detached and fallen to the ground, we would expect it to continue to transmit, at least for a few days, even if the solar panel through which the tag’s battery remains charged had become obscured.

We don’t know the exact location where the tag failed, basically because we can't say for certain how far after the last known location fix Blue X travelled. That is why we don’t publish the data showing the last location or lay the blame with any individual estate as we cannot know for sure. However, studying her patterns of behaviour in the days and hours leading up to the tag failure strongly suggests that she was fairly settled in Glen Quaich.

Sadly, there is a very high likelihood, that Blue X was deliberately killed somewhere close to the location of her last transmission and the tag destroyed to hide the evidence. That this happened in the same area that three satellite-tagged golden eagles have also disappeared and a raven and red kite were poisoned in recent years, adds to a picture of local intolerance towards protected birds of prey and undoubtedly makes this latest case highly suspicious, if not conclusive.

The loss of Blue X is particularly hard to bear. She was a unique individual; already weighing 6kg at eight weeks old when the tag was fitted she was likely one of the biggest eagles ever to grace the skies of Scotland. She had a unique upbringing, when her father, Turquoise 1, also fledged another chick, Blue X’s half sister Blue V, from a different nest 28 miles away in Angus.

Image; Blue X (centre) with her parents near the nest in Fife. Image credit Richard Tough.

At the Fife nest she was watched over by a dedicated team of volunteers who put in a commendable 815 hours during the 2017 breeding season. Staff from RSPB Scotland and Forest Enterprise Scotland have put in a great deal of effort to make this a success. Whilst Blue X was still an embryo in an egg, a photographer attempting to get closer shots of the mother, Turquoise 1, flushed her from the nest leaving the eggs exposed to the elements. The timely intervention of two of the nest watch volunteers allowed Turquoise 1 to return to incubating the eggs and undoubtedly saved the life of Blue X before she’d even hatched.

Image:; Satellite-tag data from Blue X during her visit to Mull

Blue X was one of four young sea eagles to flee to the west coast of Scotland at the end of February when the ‘beast from the east’ weather front drove high winds and heavy snow into the eastern highlands. She visited Mull before finally returning east to Perthshire in mid-March where she would live for only a few more days. Her half sister blue V has recently made the same trip out to Mull and is still on the west coast. We can only hope that if she returns she finds a safer route back to East Scotland.