The Flights of Osprey S10 1999-2001

S10 was a breeding male and was eleven years old when caught by Roy Dennis at the fish farm on the Rothiemurchus Estate, near Aviemore on 24th August 1999. BTO ring number G8220. Orange ring, with black letters SO on right leg. Wing 485 mm, tail 215 mm, weight 1430 gms.

This bird was ringed as a chick at nest 6 (see bird S01) on 3rd July 1988 and was caught at Rothiemurchus on 18th May 1995. It had been a regular breeder in Strathspey since that time.

The orange lines indicate the autumn southerly migration routes, and the red lines the routes taken in the spring.

Maps produced using DMAP software

Autumn 1999

Regular transmissions show this bird stayed close to the area in which it was caught in and around Strath Spey. Its last chick was waiting for food at the nest on 3/9/99 which presumably explains S10's continued presence and pattern of foraging flights. S10 may have roosted overnight 17-18/9 near Blacktoft Sands RSPB reserve. On 19th he moved south towards Rutland Water, then 150km west and 90km south to a 3-day stop-over on Salisbury Plain.

The bird's speed increased while crossing the Channel (note SE direction and c.f . bird S10) but he returned to a leisurely pace once in France, travelling an average of just over 70km per day for 5 days. Then came a sudden acceleration as on 4/10 it moved 487km, flying over the Pyrenees into Central Spain. There were two good locations on the evening of 13/10 as S10 crossed to North Africa, well west of Gibraltar, probably flying across 420km of ocean. He then averaged about 320km per day before reaching the Atlantic coast

S10 remained near Nouadhibou (formally called Port Etienne) on the Mauritania coast throughout the winter. It is very interesting to zoom close in on the interactive map.

Spring and Autumn of 2000

In the spring of 2000, S10's transmitter switched on every 2-3 days as the bird returned northwards. On 24/3 it was only 23km from the position of 18/10. However, it then took a much more easterly route over north-west Africa and southern Spain before returning close to the route used on the southward migration last autumn on 1/4. The final parts of the journey were further west and there was a possible sighting in Guernsey on 4 April.

S10 had returned to Speyside on 8 April having flown a distance of 4547km in 18 days (253km per day.) Transmissions were received every 10 days from then on and these showed that S10 remained in Scotland until at least 27/8. On 7/9 it was at 46.41N+0.13W, about 40km W of Poitier in western France. In had reached the same latitude three weeks earlier than in 1999, and was about 65km further west. The Western Sahara location on 18/09 was120km east and 4 weeks earlier than last year. It had arrived back in its same wintering grounds by 29/09 at least three weeks earlier than the previous year.

During the winter transmissions were received every 10-11 days, showing that, once again, it was very static during the winter months. S10 had begun to move north again by 27 March 2001.