A male Blue-headed Wagtail has been present in fields adjacent to Summer Leys LNR since its discovery on 12th April. Being a scarce migrant in Northants and the UK in general, it has attracted a lot of attention from local birders and scrutiny of the accompanying Yellow Wagtails has also thrown up some interesting plumage variants, sparking much debate on origins and racial identity.
Fortunately, the site routinely attracts a wealth of photographers, who have been on hand to capture a range of images, allowing subsequent at length plumage examination.
So, here they are …
Blue-headed Wagtail
A straightforward, classic individual featuring all the diagnostic characteristics of a male nominate race flava, i.e. sharply demarcated bright blue head with ear coverts and lores darker than the crown, a striking white, long supercilium extending from the base of the bill and over the ear coverts, obvious broken white eye-ring and white flecks in the ear coverts. It also has a yellow throat with a thin white side border.
Blue-headed/‘Channel’-type variant
A not so easy to analyse individual. This bird has a much more diffuse head pattern, with green tones permeating the blue, which is paler than that of the male Blue-headed Wagtail, above. It has a largely white throat and remnants of a ‘necklace’ and the worn-looking outer greater coverts suggest it may be a first-summer bird. The overall appearance closely matches female Blue-headed Wagtail and it may indeed be just that. However, a degree of caution is normally urged when trying to assign females of the ‘yellow wagtail group’ to race …
Yellow-headed Wagtail-type variant
A very interesting bird, which appears to show characteristics of the race lutea., i.e. strikingly deep yellow underparts and head, the latter with only a hint of dusky lores and a ghosting of green on the crown, which is said to match lutea perfectly (Shirihai & Svensson 2019). However it lacks the broad yellow tips to the median and greater coverts normally exhibited by this race, the coverts in this case conforming to those of standard flavissima Yellow Wagtail.
This race breeds in the lower Volga, middle Ural region and possibly north-west Kirghiz Steppe. While birds resembling lutea have been recorded in the UK, the race is not on the British list and they are generally considered to be variant flavissima. Feathers or faecal samples allowing DNA analysis would be highly desirable in proving subspecific ID in this case.
Northants birds 
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