The importance of stop-overs for migrating ospreys

Once we started to satellite track ospreys we found that individuals had favourite stop-over places on spring and autumn migrations where they could rest and catch fish. One of the earliest birds we tagged was a breeding female at nest B16 in Moray in July 2008, near where I live and we named her Beatrice. This year she will be 15 years old – she was ringed as a chick in her nest in Strathdon in 2000. She’s also are longest tracked osprey – her transmitter has well exceeded its lifetime expectancy at seven years.

Today, Beatrice is at her favourite stop-over on the River Adour, near Dax in south-west France, just north of the Pyrenees. Like in previous years she wintered at the same place on River Guadiaro in southern Spain, between Malaga and Gibraltar.  Some ospreys spend only a few days at the stop-over but in spring Beatrice is a long stayer. This year she reached the Adour on 4th March. Over the years, she has arrived at the River Ardour on the 3rd March, 4th (twice), 5th, 7th (twice) and 10th in 2009.

The duration of stop-over has ranged from 20 days to 26 days; being 20 days (twice), 24 days (three times) and 26 days (once). Dates for onward migration from the stop-over sites ranges from 26th to 30th March, so she should be settled there for another two weeks.  Over the years I’ve noted that her daily  ranging pattern (how far she is going to hunt for fish) has varied noticeably. In 2012 and 2013 her daily flights were all within 3 square km (so fishing must have been good and easy), In other springs she has ranged much more widely – 25 sq km in 2013, 49 sq km in 2011, 62 sq km in 2010 and a massive 112 sq km last spring (2014).

Today, I have had emails from Joanne Brambley and Jean-Valentin Dourthe, both of who have gone to find and photograph Beatrice and her habitat on the River Adour in previous years. They both said the river is very flooded this spring  and she might find fishing in her favourite area difficult – that’s already evident as she has already ranged over 82 sq km since she arrived on 4th March. Nevertheless they are hoping to see her before she heads north to Scotland. It’s a privilege to be able to follow an individual osprey for so many years and learn so much about her life.  I wonder how long she will stay this time.

Baetrice  Beatrice at Adour stop-over in 2012 J-V Dourthe

Beatrice at Adour stop-over in 2012 J-V Dourthe