I’m sorry to have to report that we have lost another of this year’s satellite tagged hen harrier chicks.
Brian, named after the very experienced raptor worker Brian Etheridge, was one of our non-public-facing birds. With the permission of the landowner and help of local Scottish Raptor Study Group members, he was tagged as part of the Hen Harrier LIFE Project on 4th July on an estate in Perthshire within the Cairngorms National Park. He fledged from the nest and stayed close to the nest site until the beginning of August when he moved north into southern Inverness-shire. Brian then spent the next few weeks over various areas of managed grouse moor, within the National Park with frequent strong, clear transmissions from his tag providing detailed information about his daily travels.
Brian having just received his satellite tag (photo: Jenny Weston)
Suddenly and without warning, these transmissions stopped on 22nd August. There was no indication of battery failure or other technical problems. His last recorded position was a few miles from Kingussie, though he may have travelled some distance before his satellite tag stopped. Despite a thorough search of the area with landowner cooperation, his body could not be found.
Brian is the fourth satellite-tagged hen harrier to suddenly disappear off radar this year, after our 2014 birds Highlander and Chance vanished in County Durham and South Lanarkshire respectively this Spring, and 2016 bird Elwood disappeared in the Monadhliaths last month.
The Scottish Government has ordered a review of satellite tracking data, following reports of the disappearance of a number of golden eagles in the Monadhliath mountains. Roseanna Cunningham, Cabinet Secretary for Environment, Climate Change and Land Reform, said:
“The latest reports of satellite-tagged golden eagles disappearing on or near grouse moors are very disturbing and disappointing.
“That is why I have instructed officials to analyse the evidence from around 90 surviving and missing satellite-tagged eagles, to discover if there is a pattern of suspicious activity.
“Grouse moor management does help species such as curlew and golden plover as well as generating much needed rural employment and income but this cannot be at any price.
“The public rightly expects all businesses in Scotland to obey the law. Let me be clear: grouse shooting is no exception.
“As previously stated, the Scottish Government is prepared to introduce further regulation of shooting businesses if necessary. It will be unfortunate if the activities of a few bring further regulation on the whole sector, but that is the risk those who defy the law and defy public opinion are running.”
This review has recently been expanded to include data from hen harriers and red kites. We welcome this review and look forward to the report on its findings.
It's now a case of all fingers and toes crossed for our remaining young satellite-tagged hen harriers. You can follow the fortunes of 10 of these birds online at www.rspb.org.uk/henharrierlife or @RSPB_Skydancer.
Since the publication of this blog, we've received an unprecedented number of requests to reveal Brian’s last known location. In publicising the disappearance, in suspicious circumstances, of any satellite-tagged birds, we have always been careful to avoid naming specific land holdings as it would be unfair to implicate individuals when, as already acknowledged, the birds are likely to have moved some distance from where they were last recorded.
We'll make an exception in this particular case because the bird roosted the night before on our Insh Marshes reserve whilst in the daytime ranging out on surrounding moorland, before he disappeared. But as stated in the original blog, the last received location is only an indication of the broad general area in which Brian was spending time. This was true of our hen harriers, Highlander, Chance, and Elwood, all of whom disappeared earlier this year, and why we haven’t previously named estates or specified last known locations.
The key point is that in all cases, satellite tags that were transmitting loud and clear and showing no sign of technical problems suddenly ceased transmitting, in circumstances strongly indicating that the tags had been destroyed. As in previous cases, a search was made of the last location where “Brian” was recorded, with no sign of the bird found.
Raymond Klaassen is one of the lead researchers at the Dutch Montagu's Harrier Foundation. Here he tells us about his work using satellite tracking to study the migration and mortality of Montagu's harriers on the continent.
This nomadic species is a close relative of the hen harrier and so similar in appearance to the untrained eye, it can be difficult to tell them apart. Montagu's harriers currently breed on agricultural land in just three locations in the UK, and widely across Europe, from Spain to Belarus. The satellite tags used by the Dutch Montagu's Harrier Foundation are of the same make and model as those currently being used to track hen harriers in the UK. The tagging process is also subject to the same stringent licensing procedures to ensure the welfare of the birds always comes first.
The Montagu’s harrier is a rare breeding bird in the Netherlands with a breeding population of about 30-60 pairs. Conservation includes fencing all nests in agricultural fields in order to protect the young during harvest. In addition, efforts are made to improve the harriers’ foraging conditions via Agri-Environment Schemes. However, as Montagu’s harriers are long-distance migrants wintering in sub-Saharan Africa it is equally important to also conserve this elegant species during the non-breeding season. If for example a disaster would occur along the migration route or in the wintering area, all conservation efforts on the breeding grounds would be in vain.
A basic but essential step towards a year-round conservation is to determine migration routes and wintering areas and satellite tags are the perfect tool with which to do this. In 2006 we tagged the first two Dutch Montagu’s harriers using satellite transmitters, and it was thrilling to be able to follow the journeys of the birds via the daily updates. Since then, we have tracked more than 67 adult Montagu’s harriers from six different countries in Europe, in which the UK has been the latest addition.
Satellite transmitters are small technological wonders that allow tracking individual birds around the globe in almost real-time. This is vital, as it actually allows studying when and where the birds die. It is always sad to lose a bird that you have come to know quite well, but information about mortality is of course extremely important for conservation. After having accumulated seven years of tracking data, we decided to review the causes of death of all of our tracked birds to date. In order to boost the dataset we also included data from Swedish Marsh Harriers and Ospreys which had been satellite tracked by colleagues from Lund University in Sweden using the same technology.
One important question we had was whether migration is a dangerous behaviour in comparison to breeding and wintering. Indeed, we lost relatively many birds during time they were travelling, and thus the daily mortality rate was clearly raised for migration periods, especially for spring migration. The safest time of the year turned out to be the winter in Africa.
When a bird dies, the transmitter is designed to keep sending positions, providing a large number of data points from the final location. The satellite transmitter also has an activity sensor which indicates whether the bird is moving, and this sensor data can be used to confirm the death of the bird. Mortality is more difficult to prove when contact with the transmitter ceases abruptly (observed in 14% of all cases). Was it the bird that died or has there been a technical failure of the transmitter? Technical failures generally are rare. We have recorded a few throughout the years (6% of all cases), however failures have always been preceded by irregular transmission periods and, most importantly, a drop in battery voltage (another parameter monitored by the transmitter). This makes it relatively straightforward to distinguish between a likely mortality event and a likely transmitter failure. Indeed, we never saw a bird returning to the breeding area that we had deemed to have died based on the different sources of satellite telemetry data, but we have seen birds returning with non-functioning transmitters in cases where we had deemed technical failures.
A sad but instrumental example of how satellite telemetry could help to evaluate individual cases of mortality is the disappearance of Montagu’s harrier female “Mo” in East Anglia in 2014. This breeding bird was tracked successfully for several weeks after tagging, until suddenly no new locations were received after the 8th of August. Technical failure could readily be ruled out in this case as the transmitter had been working perfectly well up to the point contact ceased (and Mo was not observed in the field anymore despite extensive searches). Most likely the bird died but it is unlikely that a natural predator was involved given the fact that the signal stopped so abruptly. In the event of a natural death, we would expect the tag to continue transmitting and send out a new signal to indicate the bird had died. In fact, this information combined by the fact that the last positions were received from a hunting estate points towards illegal persecution.
In summary, satellite telemetry actually is a powerful tool to prove illegal persecution. For example, the repeated disappearance of tagged Hen Harriers and Golden Eagles in certain areas in the UK can only be explained by high levels of illegal persecution. The use of this technology opens exciting opportunities to not only study natural causes of mortality of raptors in the field in more detail but also to fight illegal persecution in a better way.
Klaassen, R. H., Hake, M., Strandberg, R., Koks, B. J., Trierweiler, C., Exo, K. M., ... & Alerstam, T. (2014). When and where does mortality occur in migratory birds? Direct evidence from long‐term satellite tracking of raptors.Journal of Animal Ecology, 83(1), 176-184.
Koks, B. J., Trierweiler, C., Visser, E. G., Dijkstra, C., & Komdeur, J. (2007). Do voles make agricultural habitat attractive to Montagu's Harrier Circus pygargus?. Ibis, 149(3), 575-586.
Trierweiler, C., Koks, B. J., Drent, R. H., Exo, K. M., Komdeur, J., Dijkstra, C., & Bairlein, F. (2007). Satellite tracking of two Montagu’s Harriers (Circus pygargus): dual pathways during autumn migration. Journal of Ornithology,148(4), 513-516.
Trierweiler, C., & Koks, B. J. (2009). Montagu’s harrier Circus pygargus.Living on the edge: Wetlands and birds in a changing Sahel, 312-327.
Trierweiler, C., Mullie, W. C., Drent, R. H., Exo, K. M., Komdeur, J., Bairlein, F., ... & Koks, B. J. (2013). A Palaearctic migratory raptor species tracks shifting prey availability within its wintering range in the Sahel. Journal of animal ecology, 82(1), 107-120.
Trierweiler, C., Klaassen, R. H., Drent, R. H., Exo, K. M., Komdeur, J., Bairlein, F., & Koks, B. J. (2014). Migratory connectivity and population-specific migration routes in a long-distance migratory bird. Proceedings of the Royal Society of London B: Biological Sciences, 281(1778), 20132897.
Schlaich, A. E., Klaassen, R. H., Bouten, W., Both, C., & Koks, B. J. (2015). Testing a novel agri‐environment scheme based on the ecology of the target species, Montagu's Harrier Circus pygargus. Ibis, 157(4), 713-721.
Vansteelant, W. M. G., Bouten, W., Klaassen, R. H. G., Koks, B. J., Schlaich, A. E., van Diermen, J., ... & Shamoun‐Baranes, J. (2015). Regional and seasonal flight speeds of soaring migrants and the role of weather conditions at hourly and daily scales. Journal of Avian Biology,46(1), 25-39.
Guest blog from Katy Saulite, one of our two Community Engagement Officers for the Hen Harrier LIFE Project.
Hello everyone. I feel like it is long overdue that I introduce myself as one of two community engagement officers working as part of the Hen Harrier LIFE Project. As part of this introduction I would like to include a delightfully kind drawing I received from a pupil of Muirkirk Primary School in May, during my first outreach session to a school as part of the project.
My name’s Katy and I'm working predominantly in Scotland, delivering exciting community engagement work through the LIFE project across our target project Special Protection Areas (SPAs). As I am now getting stuck into my role I hope to give regular updates of my work with schools, agricultural colleges, community groups and the wider public.
I am happy to report that this summer saw me getting out and about to five different primary schools, in and around the Forest of Clunie and Muirkirk and North Lowther Uplands SPAs. These visits included assemblies, active workshops and, in one case, a very blustery trip onto the moorland around Muirkirk. Feedback in the form of poetry, drawing, rap and interpretive dance has certainly been entertaining but more importantly extremely encouraging and heartening that these children have been inspired by the story of the hen harrier, and have shown concern for its future. I am very much looking forward to my future work with the Hen Harrier LIFE Project but for now will leave you with a lovely little poem from a pupil in the P6/7 class of Kirkmichael Primary. Enjoy!
Kirkmichael Primary 6/7 class posing with their hen harrier poems.
The hen harrier swoops so gracefully.
To find a girl, he needs to twirl!
Dips and dives through the skies,
To find the mate to be his date!
Kirkmichael Primary pupil May 2016