Oxwich Marsh 12 July: productivity in the reedbed

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Excellent conditions for ringing on the marsh this morning, with overhead cloud and no wind until persistent light rain stopped play around 11:00.
A total of 83 birds of 17 species were captured.  The breakdown of newly ringed and recaptured birds was as follows:

Species New Re-trapped Total
Great Spotted
0 2 2
Wren 3 0 3
Dunnock 5 3 8
Robin 1 1 2
Blackbird 2 0 2
2 0 2
Reed Warbler 8 1 9
Whitethroat 0 1 1
Blackcap 13 1 14
Chiffchaff 2 0 2
Willow Warbler 2 0 2
Blue Tit 11 5 16
Great Tit 3 3 6
Chaffinch 6 1 7
Greenfinch 4 0 4
Bullfinch 1 0 1
Reed Bunting 0 2 2
Total: 63 20 83

Features of the catch included welcome evidence of productivity in Cetti’s warbler, with two young birds (in entirely juvenile plumage) captured, and an increase in the number of reed warblers trapped, which was also largely due to captures of recently fledged birds.  Cetti’s warbler can be sexed on the basis of the marked difference in size between males (which are considerably heavier and have longer wings) and females.  There is a limited zone of overlap, but most birds can be sexed, and with experience you can often assess whether a bird is likely to be male or female while it is still in the net.

Willow warbler

Blackcap numbers were again relatively high, with the 13 new birds taking the 2014 total to 79.  The bullfinch, a second calendar year male, was only the fourth new bird of the year, and it was good to catch both fledgling chiffchaff and willow warbler.  If rain hadn’t intervened, it is likely that we would have (again) topped the 100 mark.

Pictures of the bullfinch are below.  The wing (bottom photo) showed three retained juvenile greater coverts, indicating the limit of post juvenile moult, and making ageing straightforward.

There was little evidence of overhead movement of birds other than large numbers of house martins foraging and commuting over the marsh.  A fly over lesser redpoll was noted, but there were no pipits or other passerines recorded.

Many thanks to Heather Coats, Cedwyn Davies, Charlie Sargent, Wayne Morris and Keith Vaughton for assistance and company this morning.

Owain Gabb

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