A natural death on Mull

Skydancer

Skydancer
Get the latest news on our hen harrier conservation work, including the five-year Hen Harrier Life+ project.

Skydancer - the UK's hen harriers

Follow the efforts of RSPB staff during the breeding season, as they attempt to monitor and protect one of England's rarest breeding birds of prey - the hen harrier.

A natural death on Mull

  • Comments 5
  • Likes

When satellite tagged hen harriers suddenly vanish, as has happened four times already this year with Chance, Highlander, Elwood, and Brian, the questions left unanswered are almost as painful as the disappearance itself. However, sometimes - just sometimes - a body is recovered and the mind can rest easy.

Hermione was one of four young to fledge from a nest on an estate owned and managed by the charity, Highland Renewal, on the Hebridean Isle of Mull in 2016. She was satellite-tagged by the Hen Harrier LIFE Project on 29th July 2016, and her name was chosen as the winner of an online poll run by the University of Central Lancashire (UCLan), who sponsored the tag. 

Female hen harrier, Hermione, on the Isle of Mull, shortly after having her satellite tag fitted. (Image: Paul Haworth)

After fledging a few days later, Hermione spent all her time close to her nest area on Mull, with her tag sending out clear and consistent signals. On 28th September, however, it became clear from the data received that she had stopped moving. RSPB Scotland Investigations staff attended within a few days and quickly located her body and the transmitter, only a few kilometres from her nest – it was clear that she had died naturally, and her remains had been partially eaten. Sad though this is, many young harriers do not survive their first winter, with starvation or predation a regular cause of death.

It is interesting to contrast the death of Hermione with the disappearances of the four satellite tagged hen harriers mentioned above. The locating of Hermione’s body was straightforward, because, as we’d expect with birds dying of natural causes, her transmitter continued to provide us with good location data, directing our search efforts. In the cases of Highlander, Chance, Brian and Elwood, transmitters that were functioning similarly well, suddenly and unexpectedly stopped. While we will never definitively be able to say what happened to them without recovering their bodies, the weight of evidence is strongly suggestive of human interference and it is highly likely that these birds were killed, and the transmitters destroyed. 

Arati Iyengar from UCLan offered this comment: "It is very sad to hear about Hermione’s death. However, there is some consolation in that her death was due to natural circumstances unlike in so many previous cases where human interference has been the most likely explanation."

Hermione's satellite data, along with that of all of our previously tagged hen harriers, will now be included in the Scottish Government review of satellite tracking data from golden eagles, hen harriers and red kites. We await their findings with interest. 

In the meantime, we can only hope for a more positive future for our 9 remaining satellite-tagged hen harriers. Join us in following their fortunes on the Hen Harrier LIFE Project website at www.rspb.org.uk/henharrierlife or @RSPB_Skydancer.

---

Hermione’s satellite tag was sponsored by the University of Central Lancashire (UCLan), whose researchers have recently developed a forensic DNA identification kit specific to hen harriers, which allows individual birds to be identified from tiny samples of genetic material such as blood or feathers. Find out more about this exciting research here.

  

 

Comments
  • Thanks Blanaid, will do likewise.

  • Keith,

    As far as we’re aware, the Scottish Government’s satellite-tagging review is already collecting a significant amount of data and information on the fitting, operation and reliability of transmitters. To quote from their website:

    “The review will investigate a massive data set on satellite tagged raptors, much of it funded and held by RSPB, Highland Foundation for Wildlife and Natural Research. The review will report on the fate of tagged birds, the distribution of losses and known and adjudged causes of loss. It will attempt to determine the significance of these losses nationally and regionally, and factors associated with these. Drawing on international research, the review will comment on the reliability of tags, any effects of tags on raptors, and any inferences on the value of the techniques employed in Scotland.”

    The Scottish Government review is rightly an independent process and as such, we will not be commenting on its methods other than to say that we have, and will continue to, submit information to the Review as and when we are asked to do so.

  • Blanaid,

    For information, and to reinforce my earlier point below, more evidence of inadequately fitted satellite transmitters, or premature failure of the satellite transmitter harness system, see here - http://tinyurl.com/jgu324t  

    This issue is clearly more widespread than is publicly acknowledged, and should be given the same media airing as the earlier unhelpful speculation of conflating every loss of satellite signal with human persecution.  

    Clearly the system failure rate of satellite tagging for golden eagles in eastern Scotland is much higher than the rosy picture that is painted by many.

    On your point below about the avocet radio tags, none appear to have been found by tracking them with a radio receiver, 2 were found below a buzzard plucking post, and the other aerial found embedded in a buzzard casting/pellet.  The radio system, like a satellite system, will not operate when any one element of the system - aerial, electronics pack or battery - is detached from any other element.

    Finally, how does one go about inputting into the Scottish Government review of satellite-tagged raptors.  Roseanna Cunningham needs to be made aware of the apparent prevalence of these fitting / harness failures.

  • Keith – thanks for your message.

    Several birds of prey, fitted with satellite-transmitters, that have died, have been located in recent years. For example, I’m sure you will be aware of “Alma” & “Fearnan”, golden eagles both found poisoned on grouse moors in Angus, and “Annie”, a hen harrier found shot in SW Scotland. We have also recovered a number of birds that have died of natural causes – through predation or starvation, as well as transmitters that have become detached, as designed, from their hosts. It's also interesting to note that in the wader study you link to, despite three of the tagged chicks being predated, all three tags were recovered.

    As you may have seen in our recent guest blog by the Dutch Montagu’s harrier project, the transmitters are highly reliable, and numerous recent studies, notably one on Black Kites in Spain, have demonstrated that, if fitted correctly, such transmitters do not adversely impact on the birds survival, breeding performance or behaviour.

    With regards to your specific request to publish photos of Hermione, while we will of course notify the public through this blog if anything happens to one of our tagged birds (they are after all, public-facing already and one of the aims of the Hen Harrier LIFE Project is to tell their stories), we feel that while the Scottish Government review of satellite-tagged raptors is ongoing, it would be inappropriate to comment more widely on specific cases. We will be contributing comprehensive information regarding all of our dead or missing birds, including Hermione, to this review and await their findings with interest.

  • Blanaid,

    Good to hear that the body was recovered this time and that no evidence of foul play was found.  This bears out Donald Watson’s finding that HHs have a high mortality rate in their 1st year (D. Watson 1977, The Hen Harrier).

    What would be interesting for all, would be a photograph of the dead bird, as discovered in situ, showing the relative position of the satellite tag and aerial.  We know for example that radio and satellite transmitters do not continue to function when they have been munched by a predator, see here - http://tinyurl.com/zdakpzj or when they have either been inadequately fitted, or when the harness system has failed, see here – http://tinyurl.com/h3atx4s  

    So, it would be illuminating to see a photo of a transmitter that continues to function after the host bird has died, as originally found and before the body has been disturbed for examination, and of the orientation of aerial and solar-powered battery pack in such a case.