Friday, 31 October 2014

Oxwich Marsh 28 & 30 October 2014: 3,000 new birds for the year

We managed two sessions this week despite continued unsettled, albeit mild, weather.  These took us over 3,000 new birds for the site for the year.
The breakdown of species / numbers during the respective sessions can be seen in the tables below (28 October is above).

Species New Re-trapped Total
Skylark 2 0 2
Wren 2 3 5
Dunnock 1 2 3
Robin 1 1 2
Stonechat 0 1 1
Blackbird 2 0 2
Chiffchaff 3 0 3
Goldcrest 4 0 4
Long-tailed Tit 3 0 3
Blue Tit 11 3 14
Chaffinch 7 1 8
Greenfinch 16 2 18
Goldfinch 27 4 31
Reed Bunting 1 0 1
Total: 80 17 97
Species New Re-trapped Total
Wren 2 0 2
Dunnock 1 1 2
Robin 0 2 2
Blackbird 0 1 1
Blue Tit 8 5 13
Great Tit 1 1 2
Chaffinch 2 1 3
Greenfinch 5 4 9
Goldfinch 19 20 39
Reed Bunting 4 0 4
Total: 42 35 77

Despite higher wind speed on 28 October, the catch was larger, and there was better diversity.  There are foraging flocks of mixed tits and warblers (mainly chiffchaff and goldcrest) around the marsh and in Oxwich village at the moment, and during the session we managed to connect with a couple of these.  During the session on 30 October, the tits we trapped were mainly close to the feeders and not in mixed species flocks.  The breakdown during this latter session had a wintry feel to it.
The highlights of the (combined) catch were the two skylarks caught in the Natural Resources Wales compound (there was substantial overhead passage of the species on 28 October), the three chiffchaffs caught on 28 October, and the 46 new goldfinches caught over the two sessions.  There is a large flock of goldfinch on the marsh at the moment: 60-80 birds are often present in scrub close to the bird feeders, but the true number using them could be far higher as smaller parties are regularly noted commuting to and from the flock.
A picture of the two skylarks is below:
The two skylarks trapped on 28 October
Due to their moult strategy, skylarks cannot be aged on plumage characteristics in the autumn.  Both adults and juveniles undergo a full post-breeding / post-juvenile moult, so all feathers are replaced and plumage is identical.
Finches cause far more ageing problems, however, as indicated in the series of photographs of a male greenfinch below:
Greenfinch tail.  This has been moulted (more typical of an adult bird than a first winter in the UK but not so in northern Europe), and the feathers are broad and show very little wear.  The depth of the yellow on the outer tail feathers, and the fact that it reaches the shaft indicates a male.

The wing of the same bird.  The 'dirty' edge to the large alula feather and the lack of broad grey fringes to the primary coverts indicate a 1st winter.  There are no retained greater coverts. Typically in male birds the yellow on the outer webs of the 3rd-5th primaries is more extensive.

Wear on the primary tips of the greenfinch, indicating that these are retained juvenile feathers.

The features noted above are among those that are studied / evaluated when ageing many of the birds we catch.  Comments on the age etc. of the greenfinch are welcomed.
As noted above, the sessions also saw us move past 3,000 new birds for the year at the site.  This reflects the commitment of a small group of people who have made the effort to get to the site regularly, often at short notice due to changes in the weather forecast, in 2014.  It also reflects the support given to the work by Natural Resources Wales, who have allowed us to extend our trapping in to new areas of the marsh.  A breakdown of the catch to date is below:
Species New Re-trapped Total
Sparrowhawk 3 2 5
Woodpigeon 1 0 1
Kingfisher 6 1 7
Great Spotted Woodpecker 11 25 36
Skylark 2 0 2
Sand Martin 14 0 14
Swallow 382 0 382
House Martin 1 0 1
Tree Pipit 13 0 13
Meadow Pipit 41 1 42
Wren 58 42 100
Dunnock 52 69 121
Robin 92 57 149
Stonechat 5 1 6
Blackbird 24 18 42
Song Thrush 4 1 5
Cetti's Warbler 22 10 32
Grasshopper Warbler 6 0 6
Sedge Warbler 116 10 126
Reed Warbler 144 23 167
Lesser Whitethroat 2 0 2
Whitethroat 42 4 46
Garden Warbler 21 1 22
Blackcap 293 16 309
Yellow-browed Warbler 1 0 1
Wood Warbler 1 0 1
Chiffchaff 132 6 138
Willow Warbler 92 7 99
Goldcrest 60 1 61
Firecrest 2 0 2
Long-tailed Tit 22 7 29
Marsh Tit 2 5 7
Coal Tit 3 0 3
Blue Tit 271 245 516
Great Tit 102 141 243
Treecreeper 1 0 1
Magpie 1 0 1
Starling 2 0 2
Chaffinch 165 36 201
Greenfinch 313 76 389
Goldfinch 391 137 528
Siskin 60 55 115
Bullfinch 15 11 26
Reed Bunting 139 72 211
Total: 3130 1080 4210
Following the session on 30 October, a yellow-browed warbler was heard calling repeatedly from scrub close to the trapping area.  Results from previous sessions indicate that both yellow-browed warbler and firecrest are associated with some of the roving tit flocks in the area at present.
Thanks to Heather Coats, Charlie Sargent, Darren Hicks, Cedwyn Davies and Keith Vaughton for company and assistance over the two sessions. 

All pictures by Charlie Sargent.

Owain Gabb

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
Yellow-browed warbler (showing tail)

Yellow-browed warbler
Firecrest (1st winter female)