Saturday, 25 October 2014

Oxwich Marsh 16 & 25 October 2014: crests and a yellow-browed warbler

A couple of quiet sessions in terms of numbers, predominantly due to the weather which has been unsettled for the past two weeks.  On both dates the wind has been an issue, and while we were able to put out most of our usual nets on 16 October, today we limited ourselves to two sixty-foot nets and a forty-foot net in an area of relatively sheltered scrub (and took these down before 11am).
 
On 16 October we trapped a range of typical species.  The breakdown was as follows:
 
Species New Re-trapped Total
Wren 2 1 3
Dunnock 0 1 1
Robin 1 1 2
Chiffchaff 1 0 1
Goldcrest 1 0 1
Long-tailed Tit 3 1 4
Blue Tit 3 1 4
Great Tit 2 0 2
Chaffinch 2 0 2
Goldfinch 5 14 19
Reed Bunting 7 1 8
Total: 27 20 47
 
The only real highlights were the good numbers of reed bunting and single chiffchaff.
 
Today was a little different, however.  Despite the limited net, the gusty north-westerly wind across the marsh and a catch of only 26, the quality was far better.  A breakdown is below:
 
Species New Re-trapped Total
Wren 1 0 1
Dunnock 0 1 1
Song Thrush 0 1 1
Yellow-browed Warbler 1 0 1
Goldcrest 3 0 3
Firecrest 2 0 2
Blue Tit 2 3 5
Great Tit 2 0 2
Chaffinch 8 0 8
Goldfinch 2 0 2
Total: 21 5 26
 
Over the course of the morning there was substantial overhead passage of chaffinch.  This was reflected in the catch.  However the large flocks of goldfinch typical of recent visits were less in evidence.
 
The first net round produced several goldcrest.  Not unusual, as birds have been regularly trapped in the marsh for the last month.  It was so quiet that we did a little bit of rush cutting to create some better foraging habitat for snipe (which we intend to target for ringing over coming weeks). 
 
The second round was similarly quiet.  The third was a bit different.  A foraging flock of birds had apparently moved through.  In addition to a couple of tits, a yellow-browed warbler and a firecrest were in the nets.  During the following round a second firecrest was trapped.  Both firecrests were first-winter females, and the yellow-browed warbler a male (and probably also a first winter bird).
 
Svensson (1992) indicates that yellow-browed warbler can be sexed on wing length, with male wings being between 55-60mm and females 51-56m (based on a sample size of 595 birds).  Our bird had a wing of 59mm, which is outside the zone of overlap.  The bird was carrying fat (score of 3) and weighed 7.1g.  The tail feathers of the bird were narrow and abraded, probably indicating it was a 1st winter.
 
The two firecrests were also sexed based on wing length (males have wing lengths of 52-56mm and females 48-53mm).  The head of adult male firecrests has a brilliant golden-orange patch, while first winter males and females can be similar, with only a tinge of orange in the crown: the wing lengths were therefore critical in establishing sex.  The tails of both birds were sharply pointed (adults are rounded) indicating first winter birds.  The firecrests both had wing lengths of 50mm and weights of 5g and 5.2g respectively. 
 
Over the course of the morning considerable movements of birds were also noted: a flock of 12 mistle thrushes, regular small parties of skylark and redwing, a few song thrush, and a steady movement of woodpigeon were all noted.  Over 25 snipe were estimated to be in the near part of the freshwater marsh.
 
An excellent morning.  A late decision to go proved the right one! 
 
Thanks to Cedwyn Davies, Charlie Sargent, Keith Vaughton and Darren Hicks for company and assistance, and to Charlie for the loan of his brushcutter.
 
Picture of one of the firecrests and the yellow-browed warbler are below.
 
Owain Gabb
25/10/14
 
Yellow-browed warbler (showing tail)

Yellow-browed warbler
Firecrest (1st winter female)
 

2 comments:

  1. Well deserved rarities at last. I'll never get Cedwyn and Charlie back into East Glamorgan now!

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  2. I could be open to a bribe Dave! Yes, they were nice birds and we hope there is still time for others to show.

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