Saturday, 31 August 2013

An influx of reedbed warblers ............

A pleasant morning with Keith Vaughton and Cedwyn Davies during which we caught a total of 58 birds at Oxwich Marsh.

The day started damp and cool, but the north-westerly wind remained light until mid morning, and the sun came out by around 07:00.

The catch was made up of: reed warbler (19), sedge warbler (8), chiffchaff (7), willow warbler (2), blackcap (1), reed bunting (1), blue tit (11), bullfinch (3), wren (3), robin (2) and treecreeper (1).  Therefore a nice mix of migrant warblers and resident species.


The catch of migrant warblers was dominated by juvenile birds, and there was no evidence (from fat deposits) that these were ready to make a long distance movement.  However, the sedge warbler, pictured to the left and below, was an adult and carrying significant fat.  This can be seen in the picture to the left.  The tracheal pit is full (in fact slightly convex and overlapping the breast muscle by several mm).  Fat is assessed using standard scoring system, and can be used to help understand the timing of migratory movements.  The feathers are gently blown to expose the skin. A more typical (!) photo of the sedge warbler is to the right.

Owain Gabb 31/08/2013

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