Soon after publishing yesterday’s post about UV settling back into his usual range – quite large in itself – new data arrived. UV flew 182 km on a round trip to the south! Interpreting behaviour can be a real challenge. Yesterday was a good example as Paul describes so effectively below:-
Ospreys. Gotta luvvem, right? Just when we thought that UV had settled down to a winter of comparative idleness at his winter quarters in north-west Senegal, he decides to prove us wrong.
Just before 7:00 UTC yesterday morning he left his roost site and headed off – not westwards towards his usual hunting grounds, but south-east into the rural interior. What was going on?
Joanna and I have been analysing osprey behaviour for a long time, and we have developed some standard methods and protocols to help us understand it. We check the weather for that location. We study the terrain features being traversed. We consult maps to see if there are rivers or lakes on the route which might attract one of our birds. We did all those things yesterday, and we were baffled.
Moving at a brisk clip, UV flew for almost 50km, down to an otherwise unremarkable area of farmland near the town of Gueoul. No lakes here. No irrigation canals, no flooded mine workings – nothing fish-related at all. As the morning breeze died away, UV began to circle. He gained almost 600 m of height before gliding down and away northwards over fields and Baobab trees new-greened after the seasonal rains.
Another 50 km, and the autumn sun began to generate rising air currents – “thermals” – above the flat landscape. UV flew. Using little or no excess energy, he soared in graceful arcs to the apex of these thermals. On my screen, his GPS track forms cathedral spires of altitude, and the glides between them are flying buttresses – an architecture of the air, made visible.
Technical analysis went out the window. There is only one interpretation that fits what we saw UV doing yesterday. He is a young, strong creature, back home in his adopted land. His flight back to the river was not merely a journey – it was a virtuoso performance by a master of the aeronautic art. UV had no destination in view, no special reason to make this trip…
He did it because he could. … Ospreys. Gotta love them.