In August UV faced the challenge of hunting in murky waters resulting from the sedimentary outflow from the mouth of the Senegal River during the rainy season. Although he left the Langue de Barbarie for one day he returned to his wintering grounds and adjusted his behaviour by foraging further afield and/or further offshore and by avoiding the tidal lagoon completely.
During September he has gradually returned to his ‘old’ foraging areas at sea even though silt will still be affecting water clarity to some extent for some distance offshore. He still hasn’t hunted in the tidal lagoon and isn’t perching near it. This animation by Paul shows UV’s activity day by day and the absence from the lagoon is very clear.
The animation shows us much more. Other changes in UV’s behaviour are apparent. He has travelled to the mainland more frequently – on 14 of 30 days. The rains create temporary wetlands and UV has been visiting a couple of such areas. Mostly he has been a few km ESE of his base and for only an hour or so with perhaps 15 or 20 minutes perched. Here is a close up of a typical visit on 9 September.
Could he be catching anything? The water will be shallow so he could scoop a fish up (the tracker temperature does not help determine whether he hunted in this situation) and eat some of it (or a whole small one!) before returning to the Langue. Recently he has been a bit further north. This image shows the overview of a trip on 28 September.
And next a close up of the area in which UV stopped twice for a total of about 30 minutes.
On current Google Earth imagery (April 2015) there doesn’t seem to be much water where UV flew low then perched but historic imagery for October 2013 reveals there will be plenty.
Migrating birds including ospreys will have been passing along the coast and some will have stopped at the Langue, a known area for overwintering. UV’s behaviour could have reflected this with some chasing, perhaps, or disturbance from favoured perches. There is no evidence from the data, just a few small changes in his activity. This image of 25 September shows him moving around the beach, using five perches over the day rather than the main one where the orange tracks converge.
But he sat for long periods and as you can see from the image was quite settled. The Lounge de Barbarie (credit: Pip) rather the Langue is apt! On this image there are a cluster of fixes on the right end of the trees. UV has started sitting there recently and has roosted there, but he still uses his normal roost most of the time.
There’ll be an update on 7H in September in the next couple of days.
Many thanks to Paul for the UV animation.