Saturday, 27 September 2014

Oxwich Marsh 27 Sept: Chiffchaffs and Goldcrests

A still cloudy morning.  In total we erected just over 600 feet of net.  The wind didn't really pick up, but bird numbers declined rapidly, and by 10:30 we started to take the nets down.

The (modest) catch of 60 was made up as follows:

Species New Re-trapped Total
Great Spotted Woodpecker 1 0 1
Meadow Pipit 7 0 7
Wren 1 1 2
Dunnock 1 2 3
Robin 3 4 7
Cetti's Warbler 1 0 1
Reed Warbler 1 0 1
Blackcap 3 0 3
Chiffchaff 13 0 13
Goldcrest 9 0 9
Blue Tit 1 1 2
Chaffinch 2 0 2
Goldfinch 1 0 1
Reed Bunting 8 0 8
Total: 52 8 60

The better elements of the morning were the good numbers of reed bunting, goldcrest and chiffchaff, a late reed warbler, the 22nd new Cetti's warbler of the year and an un-ringed great spotted woodpecker (the vast majority of woodpeckers trapped in recent months have been ringed birds).  The haul of chiffchaffs took us over 100 new birds of that species in 2014. However, this was not a classic session!
A picture of one of the goldcrests is below. 


Goldcrest (pic: Charlie Sargent)

The settled weather and relatively low number of birds allowed a little more time for studying plumage characteristics in detail.  A number of the species we captured are not straightforward to age, and this was a good learning / revision / consolidation exercise.  Goldcrests can be aged based on tail characteristics, with juveniles typically having very pointed and adults more rounded tail feathers, but many birds are intermediate and some cannot be aged reliably.  First winter robins often show a break in the greater coverts: frequently the inner (moulted) greater coverts are olive-toned and the outer coverts are browner, while the inside of the upper mandible of young birds is often yellowish (as opposed to dark).  Other useful features can be growth bars in the tail (indicating feathers were grown at the same time and are therefore juvenile) and the shape of the tips.  It is also very useful to look at autumn reed buntings : the tail shape and degree of feather wear in young birds is really obvious at this time of year in comparison to adults.  The latter becomes less of a useful feature as the winter goes on.

Many thanks to Cedwyn Davies, Heather Coates, Charlie Sargent, Wayne Morris, Hannah Meinertzhagen, Emma Cole, Gail Cobbold, Chris and Rhys Stevens for their company and assistance this morning.  Thanks in particular to Cedwyn for the lift and to Gail for acting as scribe again.

Owain Gabb
27/09/14

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