One of the key things we have learnt from our satellite tracking studies in recent years is that adult Ospreys are able to refine their migration route over successive journeys. By using prominent geographical features such as mountains, rivers and coastlines, they make the most direct flight possible without taking unnecessary risks. They are superb navigators and there is no clearer example of this than 30(05)’s first four days of migration this year.
When 30 wasn’t at her nest site on Thursday evening, we thought she had departed on migration, but it wasn’t until this morning – when we were able to download the latest full batch of satellite data – that we could confirm just that. And what a start she has made – non-GPS signals showed that by yesterday evening she had reached Cadiz in the south of Spain.
30 first bred at a nest close to Rutland Water in 2009 and has continued to do so each year since. Sadly this year her mate, 08(01), failed to return and she has spent much of the summer alone. Having failed to rear a family for the first time in five summers, we wondered how long 30 would linger at her nest site this autumn. She clearly felt the time was right to depart on Thursday morning because by midday she was flying south over Wellingborough, some 36km south of Rutland Water at an altitude of 600m. Over the course of the next four hours she made steady progress south at an average altitude of 750m, passing over Milton Keynes and then to the west of London.
By 4:30pm she had the south coast in her sights, and with conditions good for migration, she continued onwards, passing over Worthing and then out to sea. Her 168mk crossing of the English Channel took almost exactly 3 hours, and she made landfall just to the South-west of the busy shipping port of Le Havre, at 8pm. An hour later as darkness fell she was perched another 48km to the South-west, close to a farm in a typically rural part of Normandy. Under normal circumstances 30 would have roosted there for the night, but evidently still feeling strong, she continued south. We do not know exactly how long she was flying for during the night, but by 2:30am GMT she had covered another 119km and by 6am was another 41km further on, perched in an arable field 16km North of the Loire river. She may well have caught a breakfast fish because two hours later, at 8am, she was perched beside a small farm lake. She certainly deserved a meal because she had covered more than 540km since leaving Rutland Water. An incredible first day of migration.
If 30 did have some breakfast she didn’t eat for long because by 9am she had crossed the Loire and was flying powerfully south. Over the course of the next four hours she flew 145 kilometres and by midday was at an altitude of 1500m just to the east of La Rochelle. The French coast would now have been clearly in her sights and for the rest of the day she followed it south, passing to the west of Bordeaux and then onwards towards the Spanish border at an average altitude of around 500m. This is 30’s eight autumn migration and she will have learnt over the course of her seven previous journeys that following the coastline aids her navigation. And she’s not the only one, when John Wright and I spent time on the French coast in September 2009 and 2010 we saw numerous Ospreys heading south.
Having followed the coast south, 30 eventually arrived in Spanish airspace just before 7pm. She passed over Donosita San-Sebastian and then continued flying for another hour before settling in a wooded valley in the Basque Country. In 12 hours of flying she had covered a remarkable 547km.
30’s Basque Country roost site was just 50km from the Urdaibai Estuary where we have two schools who are participating in our Osprey Flyways Project. With the help of their music teacher they have composed and recorded a great song about Osprey migration. It describes an Ospreys journey from the UK to Africa, via the Basque Country so it seems fitting to include it here.
Next morning 30 set off at first light. At 6am she was flying South-west at 54km/h at an altitude of 450km and she maintained this heading for the rest of the morning and into the early afternoon. By 2pm she was approaching Madrid at an altitude of 2620m – by far the highest altitude of her migration thus far. Interestingly, this corresponds with the journeys of our other GPS satellite-tagged birds – 09(98) and AW(06) – both of whom migrated at similar altitudes over central Spain. After passing Madrid she continued South-west and settled for the night close to the village of Santa Eufemia in the very northern part of Andalucia after day’s flight of 546km.
In her first three days of migration 30 had covered 540km, 547km and 546km respectively. Such consistent flying demonstrates what an incredible navigator she has become.
At 6am next morning (Sunday) 30 had flown another 14km further south and was close to the shores of Embalse de la Colado, a large reservoir, typical of Andalucia. There is every chance that she visited the reservoir to go fishing, but by 9am she was on the wing again, heading South-west at an altitude of 790 metres. She clearly knew exactly where she was going because, whilst we are yet to receive any further GPS positions for yesterday, accurate non-GPS locations showed that she had reached Cadiz by 4:20pm; a flight of some 240km. The fact that this is less than half the distance of her previous three days’ flying suggests that she will either stop-over at Cadiz for a few days, or perhaps even spend the winter there. Numerous Ospreys spend the winter fishing in Cadiz harbour and when I visited with Lloyd Park and Paul Stammers from Rutland Water in 2008 we saw at least five different Ospreys simultaneously. Who knows, maybe one of them was 30?
It will be very interesting to see where 30 is when the next batch of GPS data comes in. Will she still be at Cadiz, or will she be in Morocco? We’ll update you as soon as we know.