Sunday, 31 August 2014

Oxwich Marsh 31 August 2014: a boom in blackcaps

A gentle westerly breeze, and a damp morning that rapidly became warm and sunny.  Due to limited personnel, we only put up nets in two of our normal trapping areas; the reed bed and the 'fen meadow.' 
 
In total 81 birds were trapped.  The breakdown was as follows:
 
Species New Re-trapped Total
Tree Pipit 1 0 1
Wren 1 0 1
Dunnock 1 1 2
Robin 3 0 3
Cetti's Warbler 2 0 2
Sedge Warbler 10 1 11
Reed Warbler 10 0 10
Whitethroat 2 1 3
Garden Warbler 1 0 1
Blackcap 27 0 27
Chiffchaff 8 1 9
Willow Warbler 4 0 4
Goldcrest 1 0 1
Blue Tit 1 1 2
Great Tit 1 0 1
Greenfinch 1 0 1
Bullfinch 1 0 1
Reed Bunting 1 0 1
Total: 76 5 81
 
The highlights of the catch were the sixth tree pipit of the year, an excellent catch of blackcaps, another garden warbler, and an influx of chiffchaffs.  In recent weeks very few chiffchaffs have been caught, with willow warblers far more obvious around the marsh (and in the catch), so this signals a slight changing of the guard.
 
Tree pipit
The tree pipit was a young bird, and showed two generations of feathers in the wing.  The hind claw measured 8mm and the depth of the bill behind the nasal cavity was 4.1mm (the similar meadow pipit has a longer hind claw and narrower bill - and there are various plumage differences).
 
The blackcaps were all juveniles.  However they were in very different stages in terms of moult, with one bird being in entirely juvenile plumage (with a bare belly), many showing some post juvenile moult, and some having finished moulting for the year.  Some of the blackcaps and the garden warbler were carrying significant fat, and were clearly feeding up in preparation for / staging in the reed bed during migration. 
 
We are now rapidly approaching 2,000 new birds for the year at the marsh.  This reflects both increased effort in 2014 and, it would seem, a good breeding season for many migrant species.  Hopefully this will be confirmed when the stats come out for Constant Effort Sites around the UK.
 
Many thanks to Wayne Morris for company and assistance this morning.
 
Owain Gabb
31/08/2014

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