Tuesday 2 May 2017

Interesting warblers at the lake

North Noaukchott Lake has thrown up many surprises in the past few months. For example I have seen both a dwarf bittern and an Allen's gallinule on separate occasions during the winter. Both are vagrants outside the Senegal River valley.

A week ago last Saturday I was walking round the lake specifically looking for warblers as now is the peak passage season for some of them.

I found two sedge warbler in two different places as well as a willow warbler out in the open. However there was one small corner of the lake where the warblers got very interesting. It was right next to the biggest pile of trash with one large bush adjacent to the side of a reed bed.

One warbler darted between that bush and the front of the reeds. It looks suspiciously like a marsh warbler. It behaved like one too.

The problem is only four have been proven in west Africa.

potential marsh warbler

It did not show the more ruddy overall impression of many reed warblers. Indeed the rump is in no way rusty and there is a hint of olive in the overall colouration. The primary tips are pale and there are eight of them. The wings look short too. The bill is at a difficult angle but it is consistant with the relatively shorter bill of a marsh warbler rather than a European reed warbler.

I believe the balance of probability is that it is a marsh warbler. I saw it well and observed its behaviour. I have asked three experts. I can understand why none will commit on the basis of one photo. However they all also say there is nothing inconsistant with a marsh warbler

I wish someone could recognise the ring. Circumstantially a high proportion of western Europe's marsh warbler are ringed.

When the bird moved to the front of the reed bed on a couple of occasions it would not tolerate another warbler near-by but which was dwelling more fulsomely in the reeds. It chased this European reed warbler when the two came close.

European reed warbler 1

It was good to contrast the two birds. The European reed warbler is browner and the bill is clearly long. The behaviour appeared different too.

European reed warbler 2

I had seen no reed warblers at the lake since early December. This is some strong evidence that none wintered there.

European reed warbler 3

In the large bush which the "marsh warbler" moved back and forth from, there was another warbler.

sedge warbler 1

It proved to be a third sedge warbler on the site.

sedge warbler 2

A close up of the crown show no middle stripe. This would have indicated an aquatic warbler.

Most of the world's population of aquatic warbler are believed to winter in the Senegal River delta area. Many must fly through Nouakchott. So far though none have been seen at the lake.

some barn swallow

I travelled to the far side of the lake to view some hirundines which were hawking around one corner. There were no rarieites this time. All were identified as barn swallow.

barn swallow

yellow wagtail

Yellow wagtail were still passing through.

little stint

Wader numbers were well down on those in winter and even earlier in spring though there were still a few little stint and wood sandpiper easily seen.

common moorhen

I scanned all of the water fowl for rarities but found none.

African collared dove

Though not rare, African collared dove is uncommon in the city. It is vastly out numbered by laughing dove and namaqua dove and considerably out numbered even by European collared dove. However this was the first time I had seen any at the lake.

African swamphen

African swamphen are difficult to miss on any visit.

the lake

A day later, I went out birding again. The "marsh warbler" is a probable vagrant but a day later a definite one was observed. I will blog about that next.

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