Over the past few weeks we’ve been wondering when our satellite-tagged osprey, Jules, would set-off from his wintering site in the Casamance region of southern Senegal. Ospreys with established nests usually leave in mid-March, but younger birds often depart later. Jules was unringed when we tagged him at Rothiemurchus Fishery last September, and he then set-off on migration the very next morning; meaning we do not know how old he is, or if he has an established nest site. It also made predicting his spring departure more tricky.
Jules finally left his wintering site on Saturday 14th April; a relatively late departure that indicates he is probably a young bird without a nest to reclaim. Nevertheless he has made excellent progress and last night he roosted just south of the Atlas Mountains in Morocco having flown 2336 km during his first six days of migration, and successfully crossed the Sahara. Here’s a day-by-day summary of his journey so far.
Saturday 14 April
Jules set-off from his wintering site in the Casamance region of southern Senegal at approximately 11:00 GMT. He flew 191 km ENE at a maximum altitude of 1316 m before stopping to roost a few kilometres south of the River Gambia.
Sunday 15th April
Jules left his overnight roost at around 09:30 and headed across the River Gambia soon afterwards. By 12:47 he had flown 81 km due north, and at this point he changed his heading to north-east. He maintained the same bearing for the rest of the afternoon before settling to roost close to the border of Senegal and Mauritania after a day’s flight of 340 km.
Monday 16th April
After a couple of short local movements Jules resumed his migration at 09:30 and crossed into Mauritania soon afterwards, with the vast and desolate Sahara ahead. The wind must have been in his favour because he maintained a perfect north-easterly heading during the course of the day, flying a total of 349 km across the desert at a maximum altitude of 1464 m.
Jules’ first three days of spring migration
Tuesday 17th April
Having roosted on the desert floor, Jules began migrating again at approximately 09:00 GMT. Unlike the previous day he set-off on a northerly heading, and then maintained it for the rest of the day, crossing the Akchâr Desert region of central Mauritania. He made particularly fast progress during the middle part of the day when thermals would have been strongest, covering 208 km in four hours after midday. When he finally settled to roost at around 19:15 he had flown an impressive 503 km during the day and was now close to the border with Western Sahara.
Wednesday 18th April
Jules left his roost site just before 09:00 GMT and headed north. By 14:00 he had flown 237 km and at this point he turned more to the north-east, appearing to follow ridges in the desert below. He maintained this heading for the rest of the afternoon, flying at altitudes of up to 2000 m. He eventually settled to roost in northern Western Sahara shortly after 19:00 after a day’s flight of 437 km.
Jules appeared to be following ridges than run north-east across the northern part of the Sahara during the afternoon of the 18th April
Thursday 19th April
Jules was now nearing the end of his crossing of the Sahara and he left his roost site in the desert at 09:15. As the previous afternoon he maintained an almost perfect north-easterly bearing as he crossed the northern reaches of the Sahara into southern Morocco, flying at a maximum altitude of 2500 m. He passed well to the east of Tiznit and continued across the Anti-Atlas Mountains until after dark. When he finally settled to roost at 20:30 he had flown 516 km during the course of the day and was approximately 100 km east of Agadir.
Jules has made fast progress across the Sahara over the past four days
All being well Jules will have crossed the Atlas Mountains today, and will reach Spain over the weekend. We’ll have another update on his progress early next week. In the meantime you can check out Jules’ flight so far on our interactive map.
