Oxwich Marsh 31 August 2020: summer wags its tail

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A weekend of light to moderate northerly winds and open skies. Northerly weather in autumn is typically associated with low numbers of migrants in the marsh, and the weekend seemed to bear this out. The working theory as to why this happens is that the ideal conditions for movement result in an exodus, and there is little incentive for birds moving from further north to pitch down at Oxwich as opposed to carrying on their journey south.

The catch was as follows:

The highlights were:

  • Excellent numbers of greenfinches and goldfinches ringed. These species, along with other residents, swelled our total considerably.
  • Our best ever day catching grey wagtails. Birds had been noted moving during the calmer mornings over the previous week or so, and recent heavy rain had resulted in one of our net rides resembling a long, marshy pool. The wagtails were all caught in this area. Twenty or thirty were probably present over the course of the morning, with the birds occurring in small groups. All of the ten birds captured were first winters.
  • A few (4) tree pipits. The numbers were slightly disappointing given the conditions, but assumedly a lot of birds may have been going through high. In previous Augusts, on days with light winds, parties of tree pipits have been obvious, and calling regular over the marsh. In 2020 we have only recorded ones and twos, and the overall catch has been modest. We don’t tend to catch the species beyond 10 September, and the peak in terms of movement is likely to have already passed.
  • A whinchat. A first winter bird. A less than annual bird at Oxwich (our fifth since 2014), and a lovely species to study in the hand. A few stonechats were a nice accompaniment, including a female that had been ringed around a month previously and had gone a long way through its main moult in the meantime. Normally our stonechats seem to move through quite quickly. We have ringed 90 birds on the marsh over the past few years, and any recaptures tend to be days as opposed to weeks later.

Other wildlife included grass snakes and common lizards under our reptile mats, a fox moth caterpillar, and a flyover green sandpiper.

Photos are below.

Owain Gabb


Grey wagtail (Richard Dann)
Grey wagtail (Richard Dann)
Grey wagtail. Some birds were provisionally sexed based on the amount of yellow on the underparts
Moult limit in the wing of a grey wagtail. The bird has retained six greater coverts. The inner greater covers, lesser and median coverts have been replaced during the partial post juvenile moult. In a number of the other wagtails the post juvenile moult was more limited, with only the lesser and some median coverts replaced.
Tree pipit (Richard Dann) Note the strong bill, facial pattern and short hind claw. These are all features that separate the species from the superficially similar meadow pipit.
Head of tree pipit. We take a bill depth measurement (on the proximal (body side) of the nostrils) as this, and hind claw length can be used to formally separate the species from meadow pipit. Very different birds to look at in the hand however, with the white belly of tree pipit being a very obvious feature.
Fox moth caterpillar. A common species in Gower
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