On May 8th Kathy and I set out for a walk around St Davids Head. As we set off down the Cabin Track a Yellow Wagtail called and flew into the scrubby field where we've had a couple of Woodchat Shrikes in the last few springs. Given that the call was pretty typical Yellow Wagtail, it was a surprise and a delight that the bird on the ground displayed a black head. This also posed a few problems of course, in order to decide what race was here we needed to get good views of the extent of the black head, colour of throat, whether the pattern was consistent on both sides of the head etc.
First impressions were good, both sides of the head were the same and, excitingly, the head was uniformly glossy black with no difference to the ear coverts or the nape.
The upperparts generally were as for a bright male Yellow Wagtail. I don't see enough of them in this part of the world to say anything further. The underparts were entirely bright yellow, including the throat which showed no contrast.
There were no signs of dusky marking below and only the only slightest trace of a tiny white moustachial mark. When I've seen Black-headed Wagtails before and I've seen many, they were just like this bird. However the calls were always distinctly of the more rasping 'eastern-type'. This individual called just like a normal 'western-type'. I put out appeals on the Pembs Blog and Twitter for any information relevant to this and had several responses from people with experience of Black-headed Wagtails in Egypt, Cyprus etc saying that many did give 'western-type' calls and some did almost exclusively. This was a comfort. I also looked up images and accounts of Grey-headed Wagtails looking very like Black-headed. There were two particular individuals, one in Norfolk and one on St Agnes. The first did show some dusky markings on the breast at least and the second a particularly strong white moustachial stripe. I can see nothing in the plumage to indicate the St Davids bird can be anything but a good Black-headed Wagtail.
Unfortunately it didn't hang around for very long, maybe half an hour, following the horses around the field so nobody else got to see what was an amazing looking bird, one of the highlights of the spring.