Severn Beach, May 2004: © John Martin.

Circumstances:

On May 2nd 2004, having checked out the foreshore at Severn Beach on the 06:45 high tide (too foggy to see all but a few close Arctic Terns going upstream and the roosting waders), I had been to New Passage where quite a few passerines had evidently arrived overnight. These included Whinchat's, Wheatears, Garden and Sedge Warblers. RFR rang at about 09.00 with news of a Wood Warbler, quite a scarce bird here, singing in the bushes on the old tip at Severn Beach, so I made my way back there. The early morning mist had lifted and while crossing the old tip, an area with much Bramble and Hawthorn scrub, I noticed a lot of warblers including many Whitethroats in the bushes. While checking these out I saw a warbler facing away in a nearby bush - a Sylvia with pale grey upperparts and browner wings. It looked more like a Subalpine than a Lesser Whitethroat but I assumed I was just seeing it badly and misjudging it. It moved into a fairly isolated Hawthorn and I saw the same features again, along with strong buffy flanks. I was surprised to see that it really was a female Subalpine Warbler when it came into full view!

It was only 10 metres away and showed well long enough for me to note most of the salient features. I rang PDB who was only 100 metres or so away with the Wood Warbler. The excitement had got to me and I managed just a few slightly shaky views of the bird by the time PDB arrived along with RFR and another birder. PDB saw it briefly in the bush but it was then chased by a territorial male Whitethroat and flew across the track in front of us into an extensive thicket of Blackthorn and Hawthorn. I put the news out and tried to relocate it for the next two hours but without success. In the evening we returned and a tape of Subalpine Warbler song was played in the same area, but to no avail. It was not seen again.

Description:

I made notes and a sketch in the field immediately after the observation. The following is based on these field notes:

Size, shape and behaviour:

Clearly a small warbler with typical Sylvia shape, it was obviously smaller than Whitethroat (several seen nearby and one chased it off giving direct comparison) and estimated to be about Lesser Whitethroat size or possibly a bit smaller. In flight it was noticeably shorter tailed than Whitethroat.

Plumage:

Upperparts - Mantle and head pale cold ashy grey. It was greyer and paler here than Lesser Whitethroat and lacked any darker ear coverts but had a faint white eye-ring. The wings were contrastingly neutral brown and appeared somewhat worn and possibly faded. The darker tertial centres were looked for and noted. In flight the shortish (for a Sylvia) tail had obvious contrasting white outer feathers that appeared rather broad and even in width.

Underparts - There was a strong and extensive colour wash on the flanks that I noted as buff. The colour was distinctive, hard to put in words although with warm orange rather than yellow tones. This wash was present but paler on the breast and throat.

The throat sides had a patch with stronger orange tones that bordered and emphasised the quite broad white sub-moustachial stripe.

Bare parts - The legs were orangey flesh. The bill colour was not noted although the bill was fairly small. The eye and orbital ring colours were not seen.

No call was heard.

Discussion:

Although the bird was seen rather briefly the views were close, the species is distinctive and this was a well-marked female with quite bright underparts. The combination of small size and shortish tail with white outer tail feathers, uniform pale grey upperparts and head with contrastingly brown wings, the white sub-moustachial contrasting with the warm orangey buff of the throat sides with a paler wash on much of the underparts, and the orangey flesh legs are diagnostic.

I am familiar with the species having previously seen nine in Britain since 1982 and many others of the nominate race cantillans and eastern albistriata in the Mediterranean and West Africa. I have also seen the race moltonii which has a restricted range, in Mallorca.

It was disappointing not to see the bird for longer or to hear it call as I would have liked to have been able to age it and attempt to identify it to subspecies. The worn looking or faded wings, however, made me think it might be a second calendar year bird but better views would have been necessary to be sure.

With sub specific identification in mind I had a look at some skins of females in the Natural History Museum at Tring a few days later. I found examples of both cantillans and albistriata, the two forms that have been recorded in Britain, looking very similar to the Severn Beach bird. Sub specific identification of female Subalpine Warblers is problematic on current knowledge and even birds in the hand are tricky.

In April at least five Subalpine Warblers were reported arriving in the Southwest, from Dorset to Scilly, on April 16th and 17th. At least some of these were cantillans - the expected form early in the season overshooting from the western Mediterranean. On April 30th a first summer male albistriata was trapped at Portland Bird Observatory.

A further seven Subalpine Warblers arrived in Britain in the first week of May from Scilly to Shetland, three of them reported as albistriata. Thus the date and location give little clue as to which race the Severn Beach bird is most likely to have been.

This is the first record for the S. Gloucestershire recording area and has been accepted by BBRC.

John Martin - May 2004.