Thursday, 31 August 2017

Oxwich Marsh 30 August 2017: an unexpected roost visitor

A variable forecast, depending on the websites visited, made for a slightly uneasy build up to our weekly attempt to catch roosting swallows and wagtails. In the end, all was well, and the west / north-westerly wind dropped markedly during the hour and a half before dusk, as is often the case at the site.

We capture swallows using a line of nets crossing a bund through the marsh. In 2015 and 2016 wagtails were roosting in the reed bed at the end of this bund, and we were also able to target them. The last few sessions had drawn a blank on wagtails however, and observations suggested the roost had moved nearer to the South Pond (a few hundred metres distant). We therefore trialled nets close to the pond, using audio to concentrate the birds.

The results were as follows:

Species
Ringed
Recaptured
Total
Sand Martin
2
0
2
Swallow
57
1
58
Yellow Wagtail
1
0
1
Pied/White Wagtail
20
0
20
Robin
0
1
1
Reed Warbler
2
1
3
Reed Bunting
0
1
1
Total:
82
4
86

While the swallow catch was disappointing, the wagtail catch was very good. The capture of a yellow wagtail amongst the whites / pieds was particularly notable.

This was the first yellow wagtail to be captured at the site, and is a species not regularly processed by ringers in Wales. Totals for the past five years for which data are available indicate Welsh totals of 2 (2015), 7 (2014), 5 (2013), 0 (2012) and 15 (2011) birds. This reflects the fact that the species has a restricted breeding range in Wales and only occurs in Gower as a relatively uncommon passage migrant.

The yellow wagtail was a first year bird that had finished its post juvenile moult. It had largely retained its greater coverts and all of its tertials, with a single moulted greater covert and moulted median and lesser coverts providing a useful contrast in colour tone for ageing purposes. It was considered likely to be a male, based on the extent of yellow on the underparts.

Record shots are below.

Thanks to Heather Coats, Keith Vaughton, Cedwyn Davies, Jo Conway, Chris Jones, Jez Smith, Kirsty Franklin and Stephen Vickers for company and assistance.

Owain Gabb
31/08/2017

Yellow wagtail (1st winter male)

Yellow wagtail


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