Is this a first for tracking analysis? And more on UV

UV is still at the southern end of the Gulf of Cintra. Paul identified him almost certainly ‘plunge-diving’ to catch an early supper on Monday. In Paul’s words.

It’s very seldom that we can spot the moment when an osprey plunge-dives to take a fish, just by looking at the satellite tracking. In fact, it may never have been done before.

This is that exact moment.

On the afternoon of 15.12.14, UV is on the south side of Gulf of Cintra,
flying along the beach at around 25 metres height. At 15:38 he spots
something, turns back towards it, drops down at 15:40 and then climbs back
to the same height. We know he went into the water because the temperature
telemetry from his tracker – which has been steady at around 24 DegC,
suddenly falls by five degrees.

But how do we know he actually caught one?

As soon as this hunting pass is completed, UV flies 900m inland, where he
stops for over an hour at ground level. Having presumably finished his
dinner, he then flies direct to his roost site (which is 12 km to the
southeast, among high dunes) arriving there at 18:35. He does nothing else
that evening.

UV fishing Courtesy Paul Wildlifewriter

UV fishing
Courtesy Paul Wildlifewriter

Many thanks to Paul for this great insight, and for more weather research today.

Since Wednesday’s post UV has remained on the SW side of the Gulf of Cintra and today is even further SW. But before discussing that, a couple of interesting points about his behaviour. On 17 December he was at the coast by 09.00 and spent most of the time around the shore, with one excursion about a km out to sea. Heading back inland he had a short roost then a long one for about 4 hours until just after 17.30. The image below shows both points.

Moving to keep in the shade?

Moving to keep in the shade?

You can see that during the longer stop UV is on the NE side of a large dune. He moved gradually along in a mainly E/SE direction – was he keeping in the shade?

From 14 to 16 December he used the same dune further inland for his overnight roost, but after starting off on it yesterday he moved in twilight to a new spot. From the image below it seems no better than his ‘usual’ one, although the landscape may not be quite the same now as when the image was captured.

Overnight roosts

Overnight roosts

Today he started moving towards the coast sometime after 09.30 but did not reach it before the data downloaded at 13.40. He was south of the headland, so outside the Gulf of Cintra, on the west side of a large dune. Although he sometimes doesn’t hunt until the afternoon he may have moved to this new spot because of the weather. The wind is from the east, and there were several large sandstorms inland south and east of UV. It is possible that more minor dust streams  have reached UV’s area in the airflow. So he may need to keep hunkered down for a few hours.

The unpredictable sandstorms at this time of year are a good reason why UV may be well advised to head south, but then again he could encounter them en route. Worry, worry!

Here is an image from early afternoon on 16 December until about the same time today. The yellow bull’s eye is the last fix before the download.

UV's range pm 16 Dec to pm 18 Dec

UV’s range pm 16 Dec to pm 18 Dec

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

5 Responses to Is this a first for tracking analysis? And more on UV

  1. Joanna’s point about the dune landscape not being the same now as portrayed in Google earth is important. The aerial photography at the location shown is dated November 2003. Given the nature of the terrain and the prevailing winds, it is very probable that the dune distribution has been changing constantly over the intervening period.

  2. KEITH ROGERS says:

    Many Thanks – Joanna and Paul.
    I do not suppose there is much shelter in the area UV is. I would like to see him safely move to Mauritania and The National Park – Banc D’Arguin and settle there until he returns home. The Sahara can be hostile – I know as I have spent many trips and weeks deep into it on oil and gas business.
    Great to hear that 7H is still settled in Morroco and one wonders if she will move on.

  3. joannadailey says:

    Minimal shelter as far as the Google Earth and panoramio images show, Keith, just the tall dunes. But despite no experience of the conditions there UV seems to have adapted to ‘no trees, sea not lake fishing’ and is happy to stay for now.

  4. Ems says:

    Great analysis.

  5. Sandra Bainbridge says:

    Fascinating Paul and Joanna, Thank you and stay safe UV

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