New golden eagle satellite tags being tested in Cairngorms National Park, an eagle-killing hotspot

Press release from Cairngorms National Park Authority (3rd August 2021). My commentary is below that.

High tech tags to give insight into lives of golden eagles in Cairngorms National Park

Three golden eagle chicks in the Cairngorms National Park have been successfully tagged using the latest innovative technology. Three estates in the Cairngorms National Park – including two in Strathspey – are part of this latest raptor tagging initiative, a partnership project that has been developed and funded by the Cairngorms National Park Authority and NatureScot.

The ‘Celltrack’ tags being used have come from the USA and are among the leading technology in raptor tagging. They will provide a better understanding of the species’ movements, habitat preferences and mortality.

The birds’ movements are tracked in real-time by CNPA staff and partners with transmissions coming in daily, providing a multitude of data that can help better understand the life of juvenile golden eagles, with an inbuilt alert system should mortality occur, whether through natural causes, persecution or other anthropogenic influences. The tags have the ability to detect unusual behaviour and send alerts with accurate locations.

‘Celltrack’ tags make use of an innovative dual communication system with data being sent over the mobile phone network as well as through a network of (ARGOS) satellites. By using this hybrid communication system, the large quantity of location fixes acquired each day can be transmitted over the mobile phone network, with the additional security of satellite communications when birds are out of signal.

Dr Ewan Weston, an independent research ecologist, has been in charge of tagging the golden eagle chicks under licence. He commented: “Having been involved in fitting tags to eagles for 14 years, the technological advances in the tags we use now bring data that was previously unimaginable. The data we receive, feeds into wider research on the species and covers aspects of golden eagle biology and environment, providing an insight into aspects of their lives in incredible detail. This work has included aspects of their dispersal behaviour, interaction with the landscape and developments such as wind farms.”

Dr Pete Mayhew, Director of Nature and Climate Change at the CNPA said: “The more we know about golden eagles in the Cairngorms National Park – from fledging through to acquiring their own territories – the better we can conserve and enhance their populations for the future. This is another excellent conservation partnership project involving government bodies and private estates who all wish to see a healthy future for our raptor species.”

The CNPA set out plans for a golden eagle tagging project in 2019, which included the use of British Trust for Ornithology-provided tags; however, delays in production, technical issues and the impact of the Covid-19 pandemic has seen the project switch to using ‘Celltrack’ tags. However, partners will continue to work closely with BTO over the coming months, including sharing data from the three recently tagged golden eagle chicks.

Seafield & Strathspey Estates are a partner in the project – their Chief Executive Will Anderson said: “We are very proud of our raptor populations here and as a result we are involved in several tagging projects. We are particularly pleased to be partnering with the Park Authority in this initiative as the type and volume of data collected is likely to be incredibly beneficial to be able to plan for the future with the birds needs in mind.”

The RSPB Scotland has also had one of their young golden eagles tagged as part of this project. Fraser Cormack, RSPB Scotland Abernethy Warden said “With raptors still being persecuted in Scotland the data that these tags provide could be crucial in helping to stop such crimes. Also with this potentially being a new territory it will be great to see the chicks movements after fledgling and where it disperses to in the future.”

Andy Turner, NatureScot Wildlife Crime officer, added: “NatureScot are providing strong support to the CNPA on this project. This innovative technological development will strengthen our understanding of golden eagle movements, aiding both research and hopefully acting as a deterrent to illegal persecution. The ability for instant alerts and complex motion data will provide welcome new insights into the movements of these special birds.  If this is successful, I hope we can deploy this technology more widely.”

Licenses to tag Golden Eagles are granted on behalf of NatureScot by the British Trust for Ornithology who look at various criteria, especially animal welfare. Tag data will be managed by a small, dedicated team at the CNPA and Dr Ewan Weston, NatureScot, and Police Scotland’s Wildlife Crime Unit.


Hmmm. In principle, I am fully supportive of the continued satellite-tagging of golden eagles in Scotland because of the incredible insight they have provided in to the lives of this often elusive species.

Researchers have been able to provide tag data to influence conservation policy, based on new information about these birds that would previously have been almost impossible to find out (e.g. see here for a fantastic piece of modelling, based on satellite tag data, to predict how young dispersing golden eagles in Scotland will use specific landscape features, and here for the most recent scientific paper, again based on satellite tag data showing how young golden eagles in Scotland are actively avoiding wind turbines).

This sort of research is fundamental to our ability to conserve golden eagles and the quality of the research undertaken in Scotland is held in high regard by fellow scientists in Europe and North America.

I’m also very pleased to see the Cairngorms National Park Authority (CNPA) and NatureScot continue to recognise the importance and significance of golden eagle satellite-tagging, and be willing to put their money where their mouths are by funding this tagging sub-project, despite the best attempts of the grouse-shooting industry to derail this type of research. The shooters object because as well as ecological and biological insights, these tags are also providing illuminating information about the locations where golden eagles are still being illegally killed, almost 70 years after they became a protected species.

Significantly, the satellite tag data have allowed researchers to identify several geographical clusters where golden eagle persecution still takes place and more often than not, these are on or very close to moors being managed for driven grouse shooting. Unfortunately for the CNPA, some of those clusters are actually inside the Cairngorms National Park:

[This map shows the last known locations of satellite-tagged golden eagles that have either been found illegally killed or have disappeared in suspicious circumstances between 2004-2016. Data from the SNH report Analyses of the fates of satellite-tracked golden eagles in Scotland (2017) authored by Dr Alan Fielding & Dr Phil Whitfield]

It’s clear then, that the CNPA (and NatureScot) are in an embarrassing position and want/need to be seen to be doing something about the ongoing persecution. And ongoing it is, as we’ve seen with an illegally poisoned white-tailed eagle being found on a grouse moor inside the National Park last year (here) and yet another illegally poisoned golden eagle being discovered on another grouse moor inside the National Park earlier this year (see here). The subsequent bad press from these crimes is difficult for the CNPA to deal with (e.g. here).

And that leads me to be cynical about the timing of this latest press release. If you remember, back in 2019 the CNPA issued a similar press release (see here), stating that a new type of tag had been developed and would be fitted to golden eagles in the National Park over the forthcoming 18 months. The CNPA claimed this new tag would ‘provide an instant fix on any birds which die’.

The reality was somewhat different. The ‘new tag’ wasn’t developed to a sufficient standard that it could be trialled and thus was not fitted. That 2019 press release was considerably premature and I’m going to stick my neck out again and say this latest press release is similarly premature. Although this time a ‘new tag’ has actually been fitted and deployed on three young birds, it is far too soon to know whether the tag actually works as is being claimed, not least whether it will provide an ‘instant alert’ when an eagle dies. The ‘new tag’ being deployed this time is collecting the same type of data as the tags we currently deploy on golden eagles, and it has been used to track raptors in North America, but it is not the tag that we were told was being developed, with public funding, to specifically help detect illegal persecution of golden eagles in Scotland.

So why might the CNPA be keen to put out this press release prematurely? Well, if you’re a cynic like me, you might think that the CNPA has recently received a barrage of criticism for its inability to prevent the illegal killing of golden eagles (and other raptors) inside the National Park, sparked by the discovery of the poisoned golden eagle on Invercauld Estate earlier this spring, and so they’re keen to try and turn that around:

[The deliberately poisoned golden eagle, next to a poisoned mountain hare bait. Photo by RSPB Scotland]

The timing of the press release might also have a lot to do with the CNPA’s forthcoming five-year management plan, where it will have to report on its failures to meet the previous plan’s raptor conservation-based objectives. If the CNPA can chuck in a few ‘positives’ in to the new plan, such as the deployment of these new tags, it might act as a sweetener to those who will, quite rightly, be criticising the Park’s lack of progress on this issue.

Having said all that, I wouldn’t be alone in being delighted if this tag does function as is being claimed, and provides an ‘instant alert’ when an eagle dies, whether that be from natural causes or from illegal persecution. Any technological advance that would help the police to identify the criminals would be warmly welcomed by all (except for the criminals, obviously).

It’ll be interesting to see what happens with this new tag once the young eagles disperse during the autumn and travel into grouse moor areas where eagles are still not tolerated.

Incidentally, there will be short film about golden eagle persecution in Scotland being shown during this weekend’s live broadcast for Hen Harrier Day (Saturday 7th August 2021). If you want to hear more about this and what else is coming up, please sign up for Wild Justice’s event notification here.

16 thoughts on “New golden eagle satellite tags being tested in Cairngorms National Park, an eagle-killing hotspot”

  1. Three of them, that’s nice. About how many GE chicks would you expect to be raised in the Cairngorm Nat Pk in an average year?

    It’s a start.

  2. One thing that urgently needs doing here, and which I confidently expect that most of the readers of this blog will NOT do, is to assess what effect tags have on the animals to which they are attached.

    Putting a tag on a bird of prey exacts a cost from the animal, and that cost is not from the weight of the tag, but from the extent to which it interferes with the aerodynamics of the animal. Raptors are primarily gliding animals which rely on having as efficient a flight profile as possible; fairly small changes to such an animal’s wings and body will make subtle changes to the flight characteristics such as changing laminar flow to turbulent flow, or changing the attack angle at which these effects occur.

    See here for real-world measurements:

    The best option here is to compare mortality of tagged and untagged individuals based on how many of each survive to breed, using standard metal leg rings to track the birds. Based on other research on terns, I rather think you’re in for an extremely unpleasant shock when the results come in.

    1. Dan,

      How on earth can you ‘confidently expect that most readers of this blog will not…..’ etc etc?? You can’t possibly know that, let alone ‘confidently expect’ it!

      And besides, your assumption is way off the mark…..

      Can I suggest you read the report referred to in the blog, Analyses of the fates of satellite tagged golden eagles in Scotland, and pay particular attention to chapter 7, where this very issue was assessed at great length.

      Quote from the authors in their summary:

      ‘On available information, we have found no substantive evidence that the satellite tagging of golden eagles in Scotland has caused any substantial ‘harm’ to the tagged birds, either physically, behaviourally or demographically’.

      Click to access analyses-of-the-fates-of-satellite-tracked-golden-eagles-in-scotland.pdf

    2. Sat tags are being the world over. BTO are more than able to make this decision in the interests of birds.

      Monitoring birds has risks and impacts which are weighed up with the benefits to science, conservation etc.

      What undoubtedly has a huge impact on many species of raptor is persecution and sat tags are proving this.

      Shooting, trapping, poisoning, removal of prey, destruction of nest sites definately have significant impact and needs to be addressed.

    3. I think this is the original paper. It’s beyond my fogged brain, but I believe it’s mostly about wing tags. Flicking thru I didn’t see a comparison of leg bands against SatNav.

        1. That paper is wing tags; others are for body tags of various sorts. The interesting thing is that there are very few studies of what the actual effect of tagging a bird actually is; one of the more amusing ones was tagging zebra finches with coloured leg tags (for identification at range) which demonstrated that a male zebra finch with red leg bands was actually seen as sexier than a normal male by females!

          The points I am trying to make are these:

          1) Tags on birds have effects; the effect of tagging needs to be studied and quantified independent of any information received from the tags themselves.

          2) Birds have habitat preferences, and shooting estate management heavily alters the general habitat in ways which are known to strongly alter the geographical distribution of said raptors.

          I would finally note that most animals really do not like humans one little bit. Even big raptors do not like the presence of humans, and thus all tend to avoid areas where human disturbance is commonplace. Managed estates suffer less disturbance than other areas do, hence may be viewed preferentially for just this reason.

          1. Ok if we accept your point, and these tags have an averse effect on the bird carrying it, then since the tag will still be working, a stationary signal will enable the field worker to retrieve the carcass. Once this has happened, if the evidence collected, shows a high mortality on birds tagged (from exhaustion, starvation etc, but not lead poisoning) then the science will change.

            But this isn’t what is happening the carcass and tag disappear. What other factors could be causing the disappearance of the bird and tag? Without the evidence of the tag and the carcass nothing can be concluded regarding the effect of the tag.

            Indeed other studies where tagged birds aren’t subject to persecution have shown that the tags don’t adversely affect the mortality of the carriers.

            Perhaps the birds remove the tags themselves and wrap them in lead before chucking it into the burn.

          2. “The points I am trying to make are these:”

            Plant as much obfuscation as possible.

            The field work on the efficacy of satellite tags has already been done.

            “Managed estates suffer less disturbance than other areas do, hence may be viewed preferentially for just this reason.”

            Possibly. And they may also provide more prey. But the indisputable fact is that satellite tagged birds mysteriously disappear on or near such estates, and that can only be explained by management interference.

    4. I think “the extremely unpleasant shock” was the experience of those involved in driven grouse shooting, who were no longer able to dismiss the high mortality rates of golden eagles on and around driven grouse moors due criminal activity!!
      If the claims that driven grouse shooting requires the continual illegal persecution of raptors in order to produce the artificially high grouse densities required to make make most driven grouse moors a viable business concerns, then the benefit of fitting satellite tags to birds such as golden eagles to help ensure their survival and improve their conservation status will far outweigh any potential disadvantages these devices may have.

      Where your argument completely fails is that it is impossible to know the exact mortality rate in non satellite tagged birds, as any bird illegally killed is disposed of by the criminals, so that there is no evidence of the crimes they have committed.
      At least satellite tagging does provide an opportunity to recover birds that die, and hopefully establish the cause of death. If the cause of death was down malnutrition caused by the satellite tag interfering with the birds ability to fly and hunt- do you not think this would be reported by the scientists?
      What is also very evident from many of the autopsies carried out on birds of prey , is just how many birds have suffered old injuries associated with criminal activity (ie the bird having been previously shot – but has managed to survive the injuries) . Satellite tagging has exposed to some degree- the sheer scale of criminal persecution suffered by raptors in places where they should be safe.

      What is also very evident, is that the only way driven grouse shooting can function, is for there to be an artificially high density of grouse on a moor to be driven towards the guns. This artificially high grouse population can only come about through the eradication of all predators to those grouse, and the man made creation of an environment/ecosystem which favours grouse over all other species. This is not conservation, and is something that those involved in DGS are desperately trying to hide from the public and politicians, and as such will commission any amount of dubious research which tries to hide the truth.
      It is very similar to how the agrochemical industry behaved, (and probably still does behave if we consider such things as the use of neonicotinoids) which was thankfully was so brilliantly exposed many years ago by Rachel Carson in her landmark book- Silent Spring.

      Hopefully one day- we will arrive at a point where the satellite tagging of raptors isn’t needed because the wildlife crimes will have stopped.
      I suspect the first step on that road, is most probably going to be when driven grouse shooting and all its associated ills is made unlawful, and the only hunting permitted, is a more sustainable form of “walk up shooting”.

      Many grouse moor owners could probably do this today, if they were motivated by true conservation, and had the vision to branch out into other forms of land use, rather than trying to cling on to a form of shooting that most people in the modern world find unethical and completely at odds with proper sustainable conservation which benefits all flora and fauna.

      The State of Nature reports in 2019 should also have been a “very unpleasant shock” for all those involved in countryside management, as these reports highlight our failure to manage the countryside in a proper and sustainable way.
      It may be that in the future even more species will have to be satellite tagged if we are to understand what is causing their demise and improve their conservation state. I just wonder what other despicable behaviour towards our wildlife further satellite tagging could reveal????

      So is you concern about the effects of satellite tagging based on wanting to obscure what is really happening to those creatures, rather than a genuine scientifically supported view that satellite tagging is so fundamentally detrimental to the health and well being of those creatures, that it should be stopped??

    5. Ruth’s right that report is superb, it’s amazing what you’ll find out from it. Sat tags are incredibly well designed from the biodegradable stitching that disintegrates after five years (so the bird will have survived for that length of time with a sat tag) on some models when the battery will have been drained so the then scientifically useless sat tag can drop off, to the built in weak points in the harness so that if it gets caught up in branch or cleft in a rock face the bird can break free. With the latter if that didn’t work then the signal would have led to the trapped bird being located dead or alive – which to my knowledge has never happened. No sat tags are bloody amazing. The only way they would be a danger to birds of prey was if somehow placing one on a bird predisposed it to develop suicidal tendencies such as seeking out poisoned bait, to keep flying in front of a shotgun or into ‘crow’ traps. If sat tags had shown that it wasn’t illegal persecution, but flying into windmills that was suppressing the golden eagle population over swathes of Scotland would the grouse shooters still be decrying them or would they be saying what a fantastic piece of kit they are for finding the real cause of low eagle numbers? They did find the real cause, but the problem for some is it isn’t windmills.

    6. Explain why satellite tags have not impaired the long-distance migration of cuckoos over many years (BTO tagging scheme) but affect the short-distance movements of eagles.

    7. Hi Dan, on the topic of leg rings – could you head up an appeal to keepers* past and present across the land to hand in their treasured little collections of these, in their jam jars and biscuit tins hidden on dusty shelves or buried behind the back sheds.
      * the (now) old keepers and their predecessors definetly do / did this out of some strange fetish and / or to boost their bragging rights amongst each other. The younger generation I don’t know about – they may deem it too risky. Either way Dan, it would add some interest to your proposed research.

  3. illegally killed bird of prey found, evidence points to game bird shooting industry ;

    ” oh yes you did ”
    ” oh no we didn’t ”

    and repeat !

  4. “This is another excellent conservation partnership project involving government bodies and private estates who all wish to see a healthy future for our raptor species.”

    Private estates like Invercauld? Is he having a laugh?

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s