Oxwich Marsh Late July 2021: a foreign control and a poisonous visitor

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A couple of weekends of pretty good weather for ringing at the marsh.

The combined total for two mornings (31 July and 25 July) was as follows:

Avian highlights were:

  • Our first fledgling Cetti’s warblers of the year.
  • A garden warbler. This is a relatively scarce species in Gower that is predominantly captured at Oxwich on autumn passage. The last few days of July are typically when the first bird is caught. In a very good year we might capture 20 birds, but a more typical one will see around half that number. The bird was a youngster.
  • A steady trickle of goldfinch and siskin. The latter included a very recently fledged bird on 31 July. Unfortunately, due to the lack of ringing in spring resulting from Covid-19, we cannot really take a view on the number of broods local siskins have had this year. In some years we have recorded three distinct cohorts of young.
  • Excellent numbers of reed warbler, which included a day total of 63 on 31 July, and a French (Paris) ringed bird on 25 July.
  • Good numbers of sedge warbler. By 25 July some birds had built up significant fat deposits (score of 6: filling the tracheal pit and overlapping the breast muscle by several millimetres) indicating preparation for migration.
  • A surge in wren numbers as a result of juvenile dispersal.

The non-avian highlight was finding a young adder under one of our reptile mats – sadly we didn’t get a photo. Although there is an adder population very close to the ringing field (associated with the dunes and woodland to the landward side of Oxwich Bay), we hadn’t recorded the species close to the ringing station over the past few years, so this was a very welcome addition – albeit one that may lead to greater caution when monitoring in future due to the potential for a bite. Grass snakes occur commonly and common lizard frequently under our mats, and there is a supporting cast of voles, shrews and invertebrates that make monitoring them an interesting sideline to ringing. Also noted on site was a fox moth caterpillar on 25 July.

Totals ringed for the year to date remain modest due to the late start. A breakdown (this excludes recaptured and controlled birds) is as follows:

As can be seen from the table above, finches lead the way in terms of total numbers ringed in 2021. There is also a very healthy total of reed warblers considering we would expect to continue to catch them until early September, and 200 birds would normally constitute a good year at Oxwich. Conversely, the number of tits (particularly blue tit), reed bunting and blackcap appears quite low suggesting poor productivity locally. It is also disappointing that we have caught no young grasshopper warblers this year, despite reeling birds being present on the marsh throughout the spring and summer. Unexpected birds in 2021 to date have been hawfinch (our first and a very scarce bird in the recording area), marsh tit, mistle thrush and woodpigeon (these latter three species all occur relatively commonly locally but are not typically captured at the marsh).

Thanks to the team of Heather Coats, Wayne Morris, Val Wilson, Jo Conway, Alex McCubbin, Bethan Dalton, Richard Dann, Dionne Jenkins, Lucy Rowley, Tom Wright. Kate Hammond, Gareth Bowen-Llewelyn and Ezra Sherwell for company and assistance over the sessions, and to Tom and Richard for photos.

Owain Gabb



A fresh young willow warbler
The French ringed reed warbler. The scruffy appearance is due to body moult, which typically takes place prior to migration (in adults).
A fox moth caterpillar
The first garden warbler of the autumn
A young wren. The bird has warmer brown plumage tones and a less distinct supercilium than an adult
Male siskin. We continue to capture small numbers of new siskins at each session.
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