The Life of S1(15)

The Life of S1(15)

Peter Cairns/2020VISION

We received some sad news recently about one of our satellite tracked males S1(15). Read on to find out what happened.

Five year old male, S1(15) fledged from Manton Bay in 2015 and was one of the first chicks Maya and 33(11) successfully raised as a breeding pair. S1(15) first returned to the UK two years later in 2017, where he was first spotted in Poole Harbour then later back in Rutland. In 2018, he was fitted with one of two available satellite transmitters, which would enable us to gain an exciting and valuable insight into his movements throughout the year.

Thanks to the satellite transmitter we have learned that S1(15) spends the winter months on a group of islands in an area of rich mangrove swamps, just off the coast of Guinea-Bissau.

S1(15)'s wintering grounds

The islands off the coast of Guinea-Bissau that S1(15) spent the winter months.

We have also been able to learn more about the route S1(15) takes on his migrations, which shows him follow, more-or-less, the same routes each time. This year he left Guinea-Bissau on 15th March and, after travelling over 4000 miles (over 6000 km) over the course of 19 days, he eventually arrived in Rutland on 4th April.

S1's full spring migratory route 2020

S1(15)'s full spring migratory route 2020.

S1(15) has held a territory in the local area, but has never successfully paired up with a female. The data we have received over the past few months from his satellite transmitter has astonished us! He has been making some vast and long journeys, crossing county borders. Over the Easter weekend he travelled into Suffolk, back towards Peterborough and went south via Northamptonshire into Bedfordshire. That weekend he covered almost 200 miles! It’s not the only ‘adventure’ that S1(15) has made this season. Another notable trip he made was to North Wales at the end of June – it’s pretty incredible how far these birds can travel!

S1's Easter weekend trip

S1(15)'s Easter weekend trip.

On 5th July, S1(15) again left Rutland, this time flying west, passing over Norfolk. His journey continued and he left the UK, crossed the North Sea, finally reaching land in Germany, just to the west of Hamburg. We do not know what made him leave the UK - it was far too early for him to have started his migration, plus he went west not south. Was it to try and find a mate? Or was it purely exploratory?

On 7th July S1(15), crossed the border into the Netherlands where he spent the next four days, before he left, heading in a north-westerly direction. Unfortunately, in the evening of 11th July, we stopped receiving data from his transmitter. S1(15)’s last data point was in the middle of the North Sea - between the UK and Denmark - and by looking at this and the projected direction of travel, this strongly indicates that S1(15) has very sadly died. He must have got into difficulty whilst crossing the North Sea - whether he got caught by some strong winds, had struggled to fish or as a result of something else unknown we don’t know.

S1's final route

S1(15)’s final journey into Germany then the Netherlands


There is still so much we don’t understand about the migration of ospreys, but S1(15) has taught us a lot over the past couple of years and has even surprised us with some of his movements and travels, especially this year. Hopefully, we will continue to learn more through the data we receive from male 4K(13)’s satellite transmitter, who now is the only individual with one fitted.