Every year a proportion of the Scottsh golden eagle population is surveyed by licensed experts from the Scottish Raptor Study Group. This phenomenal voluntary effort (currently 373 home ranges [approx 53% of known ranges] monitored by 150 eagle experts) provides invaluable data that are submitted to the Scottish Raptor Monitoring Scheme and are used to inform conservation policy at local, regional and national level.
In addition to this annual monitoring, a national survey is periodically undertaken with both paid and voluntary experts in an effort to visit every known home range throughout Scotland.
Photo by Mark Hamblin
The latest national golden eagle survey took place in 2015 and the interim results were announced in November 2016. The main headline was that overall, the national population had increased by 15%, rising from 442 pairs recorded during the last national survey in 2003, to 508 territorial pairs in 2015, and the species was now considered to be in favourable conservation status.
This was excellent and welcome news, but as we pointed out at the time, the headline masked a more sinister situation. Although the national population had surpassed 500 territorial pairs, the magic number needed to upgrade the species’ national conservation status from ‘unfavourable’ to ‘favouable’, it was still well below the estimated capacity of 700 pairs. This meant that approx 200 pairs of golden eagles were still ‘missing’.
Unsurprisingly, the national survey revealed that golden eagle populations in the driven grouse moor areas of eastern and southern Scotland were still being suppressed and had not shown any significant sign of recovery since the previous national survey in 2003. Illegal persecution has been identified time and time again as the main constraint on population growth in these regions.
The formal scientific peer-reviewed results of the 2015 national survey were published last week in the journal Bird Study [Hayhow, D., Benn, S., Stevenson, A., Stirling-Aird, P. and Eaton, M. (2017). Status of golden eagle Aquila chrysaetos in Britain in 2015. Bird Study].
Unfortunately publishing restrictions do not permit us to upload the full paper (you’ll have to subscribe to Bird Study for full access) but here is the abstract:
[UPDATE: This paper is now fully available online, free access, thanks to the BTO. Click here]
In additon to details about the continued low occupancy on grouse moors in the eastern Highlands, the paper also provides information that dispels a couple of myths that are frequently claimed as ‘facts’ by the SGA and co.
You might remember the SGA giving evidence to a parliamentary committee earlier this year where they claimed that “the Cairngorms National Park held the highest density of eagles in the world“. They might want to have a look at this map. This is the distribution of pairs of golden eagles in 2015 and shows the densities of occupied home ranges by 10 x 10 km squares. As you can see, the highest densities of golden eagles were recorded in the Outer Hebrides and on Mull (no grouse moors in these areas):
Another commonly-heard myth, usually trotted out to support calls for the ‘control’ of white-tailed eagles, is that re-introduced white-tailed eagles are displacing golden eagles and taking over their territories/nest sites, even though recent research has demonstrated that these two species partition their habitat and prey preferences in western Scotland. In this latest paper, the authors comment:
“Although we have not assessed this in the current study, we report increases in golden eagles numbers in regions such as the Hebridean Islands in which there has been a rapid increase in white-tailed eagles (Holling 2016), which suggests that, at least at current population levels, there has been no major impact“.
The authors do acknowledge that the white-tailed eagle population is predicted to continue its expansion and this may, potentially, create competition between the two species in the future but right now, based on the currently available data, there is no evidence to suggest this is a population-level concern.
The main current threat to Scottish golden eagles is the same as it was following the previous national survey, fourteen years ago. And that is illegal persecution on some driven grouse moors in the eastern Highlands and south Scotland. The grouse-shooting representatives can continue to deny it, but this latest paper is yet another nail in the coffin of this filthy industry.