What happened to Mark and Madge, the Montagu's harriers we were tracking on their migration from the UK to Africa? Ben Koks and Almut Schlaich, from the Dutch Montagu's Harrier Foundation, have exciting news...
Tracking birds with satellite transmitters is still bringing us new insights in wildlife ecology. In 2014, the RSPB and the Dutch Montagu's Harrier Foundation organised the tagging of three adult Montagu's harriers in the UK.
The main objective of this particular part of our work is not only to find out more about the migration of Montagu's harriers, but to gain a better understanding of where they 'stopover' and spend winter. For this reason, we started doing fieldwork in countries like Niger, Mali, Burkina Faso and Senegal in 2006. We also visited eastern Morocco, an important stopover site, four times in 2010 and 2011.
We wanted to see with our own eyes what happened to 'our' birds. Rather than waiting for the satellite coordinates, we went and found the birds! This combination of high-tech and old-fashioned fieldwork is necessary to understand Montagu's harriers in greater detail. Another major objective was to find out where deaths occur. Without satellite tagging, this would have been impossible.
When we received an enthusiastic invitation from Mark Thomas of the RSPB to be part of an exciting workshop about the conservation of Montagu's harriers in the UK, we replied in a split second with a thrilled 'Yes'. Later in 2014, together with Mark and some of the other dedicated British Monty's fieldworkers, we caught and tagged three adult birds. One male ('Mark') and two females ('Mo' and 'Madge'), all funded by Mark Constantine at Lush.
We know that Mo did not even start her migration because in August she died in circumstances that sadly suggest illegal persecution. We knew about the killing of hen harriers in the UK but we were not aware that Montagu's are under pressure because of illegal persecution here, too!
After their departure from the UK, Mark and Madge started their autumn migration in the last week of August, and on the RSPB website people can follow their journeys.
It's always exciting to see how they do it. Madge reached Senegal on 23 October. Mark arrived in his first wintering area in Mali on 4 October, then headed to Senegal on 7 November and finally reached his second wintering area on 10 December. So far so good.
Both birds seemed to stay in their wintering areas, but just before Christmas we saw that though Madge's transmitter was still sending data, she was not moving anymore. In other words, Madge died at that time.
During our fieldwork in Senegal we visited the wintering areas of Mark and Madge. We arrived in Madge's area, near the village of Ndiaouara, on 29 January. Not far away from the Gambian border, at Madge's last-known location, we found a small roost of six Montagu's and six marsh harriers. This is a typical type of wintering habitat of many Monty's in western Africa.
We saw during our regular grasshopper counts that there was plenty of food in this area, so this could not be the cause of Madge's death. It's possible she was killed by a jackal or Verreaux's eagle-owl - these are both predators of Montagu's harriers and were present in the area where Madge died.
Madge was already an 'old lady' during her last breeding. We spent almost a day trying to find Madge and her satellite tag with the help of local boys, but we were unsuccessful. The vegetation was too high and too dense to find a tiny, 12g device in an area of one squarekilometre. We left our contact details in the hope the transmitter will be found by someone in the future. Fingers crossed we get some news when we return to Senegal again in March.
Looking for Mark was totally different. First of all, we knew that this male was still alive but we had to tackle at least one problem. We knew that he was roosting on a small island called Gaye, but we had to organise a safe trip there. Using our contacts we made our way to a small village called Ndiol and found a fisherman with a good motor on his pirogue (fishing boat) to take us to the place where we thought our British hero was roosting regularly!
We found a roost of at least six harriers there on the evening of 5 February and planned a trip the next day. On the 6th we had enough time to visit the rich and beautiful island, collect more than 70 regurgitated pellets (with an average of 10 prey items per pellet). And, best of all, we counted a total of 26 Montagu's harriers at Mark's roost! Unfortunately, we didn't see him, but we were still very satisfied with our work - with the bonus of five magnificent short-eared owls hiding under a small tree.
Going back to our own roost, after eating dinner we checked our photos and discovered to our great joy that we had photographed Mark! He had been too far away for us to see his tag's antenna, but the camera caught this most important evidence. We had found Mark in his main wintering site, he was safely surrounded by water and we once again had a new piece of the puzzle of harrier ecology on two continents.
We have just arrived back home in Holland: we collected information about at least 7,000 prey items from 12 roosts, counted the biggest harrier roost ever (4,000+ Montagu's harriers), proved again that wintering short-eared owls are quite regular in the Sahel, met a lot of people, kept our four-wheel drive running. And we learned a lot about 'our' migrant birds and their place in rapidly-changing landscapes in this part of the world.
Satellite transmitters connect these worlds to each other and we hope to report more results from further fieldwork in this stunning region of our globe very soon.
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