Several of my recent posts have bemoaned the lack of Sedge Warblers ( or 'sister sledges' as some of the team call them)--compared to Reed Warblers. We suspected that they had been washed out during their initial nesting attempts--but hoped they would bounce back with a second breeding attempt. This morning's session seemed to show that they have done just that.!
Some Sedge Warblers are early migrants so it is possible that the increased numbers were due to migration--but the presence of some young which had clearly only recently left the nest pointed to a more successful breeding attempt.
The picture below shows a rather dark plumaged, recently fledged sedge warbler with some very interesting marks on some of its feathers--most noticeable the tips of its primary flight feathers.
The most probable cause of such marks is a particular change/difference/deficit in the food provided by the parents as the nestling was growing its flight feathers. If the parents had say, been unable to provide sufficient good quality food, then this is reflected in the quality of the feathers and produces so called 'fault bars' such as in this bird. Generally the feather is weakened and it's not unusual to see feathers broken off at such weak points. This is of course not a good start if -as in this case- the bird is preparing for a long southward migration, with a sub-standard set of flight feathers.
So it was that we ringed 19 new sedge warblers which for the first time this season outnumbered reed warblers on 13. 10 blackcaps was more like the expected numbers with 9 chiffchaff completing the warbler contribution to an overall total of 59 new birds.
Migration is happening now--results from coastal ringing sites confirm this so over the coming weeks we should be catching an increasing number of passage birds using our site to re-fuel during their long migration effort. Watch this space.......
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