UV: at second stopover still!

Before covering what we know of UV’s activity since the last post, here is an image provided by Paul showing UV using the flying technique known as ‘crosswind tacking’ as he pushed across to the coast last Thursday. You can read about other techniques in recent articles on Paul’s blog, some of which include data from the Kielder tracked juveniles.

UV 'crosswind tacking' in the Sahara Courtesy Paul Wildlifewriter

UV ‘crosswind tacking’ in the Sahara
Courtesy Paul Wildlifewriter

A further image from Paul illustrates a probable fish catch during UV’s Friday afternoon on Bajo Tortugo. High tide that day was at 17.40 UTC. (UTC is the same as GMT.)

Probably a successful catch Courtesy Paul Wildlifewriter

Probably a successful catch
Courtesy Paul Wildlifewriter

Moving forward in time, we left UV still at Bajo Tortugo early on Saturday. In the aerial photo of the Gulf of Cintra here; you can see the lagoon area on the left of the shot. UV stayed in that general area all day. His lack of activity reduced the number of fixes so at best they were around every 15 minutes, but he can’t have gone much further than the limits shown on the image below.

UV on 13 Dec

UV on 13 Dec

He left the western edge of Bajo Tortugo by about 16.00 GMT as soon after he was on the 12 December overnight roost. He moved further north by 18.11, shortly before sunset, but this was not his final roost. By 19.09 he was another 500m NE, his final journey of the day and made in nautical twilight.

On 14 December he appeared to remain at the roost site until well after 09.00; the first activity was a fix where he was crossing the Gulf of Cintra. This was at 09.54 and the next fix was 10.33 when he was stationary on the SW side of the Gulf a little way inland. He was in the same general area until just after noon when he moved slightly further inland for over an hour before going to the shore line and possibly fished as his speed was under 2 kph in consecutive fixes just offshore. Below is an image of his activity near the sea in the afternoon, which lasted less than 20 minutes. His longer roosts inland are the darker fixes, more obvious if you click to enlarge the image.

Catching lunch? Less than 20 mins at the shore

Catching lunch? Less than 20 mins at the shore

UV roosted near a track in the desert (the bottom point in the image above) until just after 16.00 when he flew initially in a SSE direction then adjusted to SSW as he reached 507m altitude before descending. Paul identified a frontal system passing over at sunset, which was at 18.20; just at that time UV moved a very short distance, maybe to a more sheltered spot in the dunes which probably have changed since the Google Earth image was captured. Here are the two roosts.

UV moves from one dune to another at sunset

UV moves from one dune to another at sunset

Did UV move over the Gulf because he was intending to head away from the stopover? The data on 15 December came in very early and he hadn’t left the roost. As this post was nearly finished it wasn’t clear if there would be data today – if he had continued his migration yesterday he could well be out of cell tower range.

But then an e-mail arrived, showing him exploring the SW corner of the Gulf over the past couple of days. Fish will be relatively easy to spot in the sheltered water near the headland. His behaviour both days has been similar with his journey to the water punctuated by long stops; the longest for each day have pins. On both days he arrived at the sea around 15.00. Yesterday he was only there for about 30 minutes before heading inland; today he was still there at the last fix at 15.16. Here is an image showing UV’s travel yesterday and today until soon after 15.00.

UV activity 15 and 16 Dec

UV activity 15 and 16 Dec

He doesn’t seem to be getting ready to move on. But there weren’t any signs of that in Portugal either!



This entry was posted in Blue UV, Migration, Osprey updates and tagged , . Bookmark the permalink.

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