Wednesday, 5 October 2016

Oxwich Marsh: the first 10,000 birds

A quiet couple of sessions with few birds in the marsh of late. Hopefully better is to come over the rest of October. Since our last blog post (on 17 September) we have had one evening session, to try and mop up some late swallows, and one weekend session, on Sunday 2 October. 

The combined results were as follows:

Table 1. Birds Captured 18/09-02/10/2016
Species
Ringed
Recaptured
Total
Swallow
10
0
10
Meadow Pipit
1
0
1
Pied/White Wagtail
14
0
14
Wren
2
1
3
Dunnock
0
1
1
Robin
1
1
2
Sedge Warbler
1
0
1
Reed Warbler
2
0
2
Blackcap
6
0
6
Chiffchaff
3
0
3
Willow Warbler
1
0
1
Blue Tit
2
3
5
Great Tit
0
1
1
Chaffinch
0
2
2
Greenfinch
4
1
5
Goldfinch
11
1
12
Reed Bunting
3
2
5
Total:
61
13
74

There was little unexpected about the combined catch: a couple of the adult male wagtails could be confirmed as 'alba' based on their plumage characteristics, but most were juveniles; we had our usual stragglers in terms of sedge and reed warblers, all young of the year carrying very little fat; the swallow attempt was close to being a complete failure; and, the meadow pipits didn't respond as well to a tape as usual due (assumedly) to open skies lighting up the nets. The willow warbler was the latest we have captured on the site by nine days.

Time then to reflect: we have now ringed over 10,000 birds on the marsh, recapturing a further 4,700 - albeit with a few controls thrown in. 2013 was a reconnaissance year, so these have largely been ringed between 2014 and the current date. Our activities have developed as the Ringing Group has grown and we have got to know the site, but have there been many surprises?

Table 2. Totals of Birds Ringed at Oxwich (Feb 2013 to 5 Oct 2016)
Species
Ringed
Species
Ringed
Swallow
1398
Grasshopper Warbler
38
Goldfinch
1193
Song Thrush
33
Greenfinch
1018
Stonechat
31
Blue Tit
991
Snipe
24
Chaffinch
626
Treecreeper
17
Reed Warbler
617
Kingfisher
12
Blackcap
597
Coal Tit
12
Sedge Warbler
487
Lesser Redpoll
9
Chiffchaff
376
Jack Snipe
8
Reed Bunting
368
Firecrest
7
Willow Warbler
344
House Martin
6
Great Tit
329
Lesser Whitethroat
5
Goldcrest
274
Sparrowhawk
4
Siskin
250
Skylark
4
Wren
222
Nuthatch
3
Robin
207
Magpie
3
Meadow Pipit
127
Green Woodpecker
2
Dunnock
126
Redstart
2
Whitethroat
125
Whinchat
2
Redwing
107
Marsh Tit
2
Blackbird
89
Starling
2
Long-tailed Tit
69
Brambling
2
Cetti's Warbler
63
Water Rail
1
Sand Martin
55
Woodpigeon
1
Tree Pipit
53
Wheatear
1
Pied/White Wagtail
51
Mistle Thrush
1
Great Spotted Woodpecker
44
Yellow-browed Warbler
1
Bullfinch
43
Wood Warbler
1
Garden Warbler
41
Willow Tit
1
Total
10516

The twenty most commonly ringed species are perhaps unsurprising in retrospect. We have put a fair bit of effort into capturing swallows coming in to roost, we feed the site year round (hence capture tits and finches when we target them during the winter and early spring in particular), ring moderate numbers (in comparison with many groups / sites) of reed bed warblers and reed bunting, and see a variable passage of chiffchaff, blackcap and goldcrest that peaks in the mid to late autumn. Captures of redwing and meadow pipit result from using tape lures, and will vary annually based on weather at critical times, and the degree of influx from the continent (in the case of the former). 

As we get further down the list, however, the results could maybe have been foreseen less easily. We didn't know the site was used as a roost by passage wagtails, garden warbler is a relatively scarcely recorded migrant on Gower, and the numbers of grasshopper warbler and tree pipit caught have been pleasing given the modest totals of these species typically ringed in Wales. Conversely, we have captured very few lesser whitethroat, which does breed on Gower, albeit not in large numbers, which has been a little disappointing given the interesting migratory ecology of the species. 

We have seen some species fluctuate considerably in terms of numbers captured between years. We caught 300 of our blackcaps in 2014 - the past two years combined will probably not exceed this number (51 of the total were captured in 2013), while bullfinch are locally scarce this year (2 ringed), and although long-tailed tits appear common, with many large flocks noted, none have found their way into the nets (also only 2 ringed this year).

Some of the scarcer / less frequently seen species have been nice to see and to attempt to age (in some cases), particularly the snipe species, the firecrests, marsh and willow tit, wood warbler and redstarts. To date we have not really caught a rarity, with yellow-browed warbler maybe being the scarcest of the species captured. There is still time in 2016, but that is not the driver.

It is also not all about numbers of course - but a more detailed analysis of recapture data, evidence for and timing of breeding, and a summary of controls can wait until the year end report.

Limited photos this week. The below shows a chiffchaff (foreground) and what is almost certainly the last willow warbler of the year (background). The birds were similar in terms of feather colour tones and leg colour, with the supercilium (eye stripe) of the willow warbler being far more prominent. They were definitively separated be examining differences in emargination and wing formula. 

Chiffchaff (foreground) and willow warbler (background)

Thanks to Ben Rees, Sammy-Jo Pengelly, Darren Hicks, Val Wilson, Emma Cole, Wayne Morris and Heather Coats for their company and assistance over the last couple of sessions, and to all who have ringed or assisted on site since February 2013.

As always the support of Natural Resources Wales and the grant funding supplied by the Gower Society are much appreciated.

Owain Gabb
05/10/2016
Knot grass Acronicta rumicis caterpillar on nodding thistle

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