Thunder and … foraging!

In the previous post we described UV changing behaviour slightly and foraging along the shoreline of the northern part of the Langue de Barbarie. On 3 and 4 November data didn’t show UV foraging activity in any detail.  There were very few fixes on 4 November, a day of unseasonal thunderstorms.

courtesy Paul Wildlifewriter

courtesy Paul Wildlifewriter

UV sat tight inland most of the day although the showers could have missed his spot altogether. The daily recorded rainfall at Saint-Louis airport was 0.51mm. Podor airport (about 180 km upriver in a straight line) recorded 6.10mm.

NASA weather satellite imagery had been showing quite a small area of silt (carried downriver as a result of the earlier seasonal rains) around the Senegal River mouth although it looked dense. Today looks rather different.

courtesy Paul Wildlifewriter

courtesy Paul Wildlifewriter

The silt is extending about 20 km offshore, well past the 6 km distance UV has been foraging sometimes. The silt plume is heading south. This slideshow of graphics prepared by Paul shows the seasonal currents. Green is cooler water, the arrows show the direction of the currents.

This slideshow requires JavaScript.

Paul: “The prevailing direction is north-south – “The Canary Current”. This flow starts as an upwelling of cold water from the deep ocean, and gets warmer as it travels south near the surface. The cold source is nutrient-rich, which is why that whole region along the west African continental shelf is such a rich fishing area. (For ospreys and people.)”

Is it possible to discern a change in UV’s behaviour caused by the currents carrying the sediment south and out to sea? On 5 November UV flew further north along the shoreline than previously since his return. The data doesn’t show him heading out to the deeper ocean – blue – at all.

UV's foraging areas

UV’s foraging areas

The single offshore fix to the south was at 13.00 UTC when the frequency of fixes was 15-20 minutes apart, so he could have been further afield during that sortie. UV also foraged just off the SW of the spit, a popular place for him.

On 6 November there were many more fixes for much of the day. He had two foraging trips near land to the south of his usual areas. This image shows the longest.

Around 50 minutes of foraging

Around 50 minutes of foraging

An animation can bring alive so much better than an image how UV foraged. Many thanks to Paul for this one.




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

6 Responses to Thunder and … foraging!

  1. JW4926 says:

    Fascinating! Thank you both …… and the lad :-)

  2. Cirrus says:

    A terrific video of the foraging . Thank you Paul WLW. Thanks for another Blog Joanna

    • JW4926 says:

      Isn’t it just Cirrus? There was definitely method in UV’s foraging tactics when you see it animated.

      • joannadailey says:

        Thanks, Cirrus and JW for your comments. The animation was by far the best way to show UV’s foraging strategy – trying to show it in stills was ineffective. The animations do take time, Paul’s willingness to devote the hours on those and other analysis/graphics is much appreciated.

  3. Sandra Bainbridge says:

    Thank you Joanna and Paul for your amazing updates. You both have taking tracking to the top level and beyond. Love the foraging video amazing.

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