In late June 2015 a female Pallid Harrier Circus macrourus (named ‘Potku ‘) breeding in Utajärvi, Northern Ostrobothnia, Finland, was fitted with GPS/GSM transmitter. The main breeding area of the Pallid Harrier covers the steppes of Russia and Kazakhstan and it is quite a mystery how and why the species has begun to breed in Finland.
In recent years a growing number of Pallid Harriers have been observed in France and Spain between September and April. This leads one to guess whether some of the pallids breeding in Finland might opt for this migration route instead of the well-known route through the Middle East.
This female took a western route through France, Spain and Morocco. She spent eight days in the Eure-et-Loir department southwest of Paris after which, on the morning of September 19, she started to fly resolutely towards Africa. The first night was spent East of the city of Poitiers in Western France. The next night remains a slight mystery since Potku was still flying around midnight local time somewhere near Zaragoza in northern Spain. A few hours earlier she had crossed the Pyrenees near the Bay of Biscay between Biarritz and Pamplona. The highest mountains on her route were about 1 000 metres high – flying this way she avoided having to climb over the highest peaks of the Pyrenees.
Potku didn’t spend a lot of time in Spain. She spent the second night in the country on a field 70 km inland of Alicante, the third already close to the Alboran Sea east of the port town of Almeria. On Wednesday morning September 23 the Pallid Harrier headed to the western end of the Mediterranean and made the 200 km sea flight in seven hours. In Morocco she flew another 150 km inland and settled for the night on a hill that, in satellite image, looks quite dry and barren.
She entered the Moroccan Atlantic Sahara in the evening of September 27. After this, two locations were received until the transmitter fell quiet east of Smara. Potku had flown into the desert.
The GPS relocated Potku in the morning of September 29 when she got up from her roost in the middle of perfect emptiness 130 km southeast of Bir Moghrein. The next data point is from the western part of Mauritania from Sunday morning October 4 when Potku was flying towards the capital city of Nouakchott some 200 kilometres the the Northeast.
The way Potku crossed Morocco is interesting. Whereas she flew around the Pyrenees along a route that allowed her to avoid all the highest peaks, she did just the opposite with the Atlas Mountains. She crossed the highest mountain range of Northern Africa at its highest point. She flew over 3 600 metre high terrain just a couple of kilometres off Jbel Toubkal, the highest peak of the Atlas Mountains, at 4 167 metres (http://www.luomus.fi/en/female-pallid-harrier-potku)