When is a Blue-headed Wagtail not a Blue-headed Wagtail? When it's a Channel Wagtail!

Above: Male Channel Wagtail, Covenham Reservoir, Lincolnshire, 13.04.09 by Nick Clayton

Firstly and very importantly, this short and admittedly brief article doesn't pretend nor intend to be a definitive treatment of the subject for I'm not entirely sure one could exist, yet! Moreover it's intention is simply to raise the awareness of county birders to the existence of so-called male 'Channel Wagtails' and to their identification and potential separation from true Blue-headed Wagtails. As always the key is caution plus a careful, thorough and honest approach should you encounter one of either. Leaving more contentious birds as 'showing characteristics of' will always be the safest and most accurate identification.

THE COMPLICATED BIT

Blue-headed Wagtail (Motacilla flava flava) is the continental counterpart of our own Yellow Wagtail (Motacilla flava flavissima) and in males of the races they are easily separable from each other by the colouration of the head. However, Blue-headed x Yellow Wagtail (M.f.flava x flavissima) intergrades are not a new concept by any means but more detailed study in the past decade or so has proven that in northern France in particular there is a zone of hybridisation between the two aforementioned races. These hybrid offspring birds have more recently been labelled as 'Channel Wagtails'. They are similar in appearance to true flava and have increasingly been recorded in the UK no doubt due in no small part to our increased awareness to their existence. One wonders how many have been passed off as Blue-headed Wagtails before now?

There is also more confusion when we consider that the Yellow Wagtail races of Blue-headed and Spanish Wagtail (M.f.iberae) hybridise producing the so-called 'Middlewest' Wagtail intergrade. Not to mention the race Ashy-headed Wagtail (M.f.cinereocapilla) breeding with another couple more races producing yet more hybrids! More often than not it all gets confusing and the features apparently useful in separating them get more and more subtle and open for mis-interpretation/identification. For the purposes of this article we largely avoid these other hybrids and races as for the majority of county birders, Blue-headed Wagtail is a barely annual county rarity and so our experience of this race alone is limited enough as it is.

Either way, the presence of a male Channel Wagtail at 'just out-of-county' Haughton Green Pool in Cheshire (Mike Baron pers comm.) provoked the necessity for raising their profile in Greater Manchester. It is likely that male Blue-headed Wagtails may have bred with female Yellow Wagtails (M.f.flavissima) on atleast a few occasions in Greater Manchester and the table below charts possible or proven occurrences. Not only do we potentially have to contend with hybrids between the two races but surely also those same hybrids breeding and producing 'watered down hybrids'!

So, now we know they are likely to occur, what do we look out for?

THE OTHER COMPLICATED BIT

Intentionally trying to keep this simple, male Blue-headed Wagtails are a handsome bird, similar to male Yellow Wagtail other than having an ashy-grey forehead, crown, nape and ear coverts and an obvious white supercilium which reaches to the rear of the ear coverts. There are other races of Yellow Wagtail that exhibit similar features and their separation is often subtle, necessitating field experience and a solid appreciation of both ageing and moult and it's potential effect on their appearance. I don't necessarily intend to delve into this murky world here despite being quite personally fond and experienced with them all, although we cannot broach the subject without crossing paths with one or two of them at some point. We really are just dipping our toe into the water here! Your reference really should be the excellent but still not entirely comprehensive (as hybrid issues are still evolving) 'Pipits & Wagtails of Europe, Asia and North America' by Per Alstrom and Krister Mild, Helm 2003. Don't expect to grasp it all or in fact much of anything, but an appreciation of the subject will go a long way. 

Above: A classic male Blue-headed Wagtail (M.f.flava) on the Great Orme, May 2008 by Marc Hughes. Note the hue of the ashy-grey head and ear coverts, the latter of which has a typically small sub-ocular patch (the pale area immediately under the eye). The supercilium is very slightly narrower than most but it's length is fairly typical.

Above: The same Great Orme, May 2008 male Blue-headed Wagtail (M.f.flava) by Marc Hughes. The ear coverts of male flava are often concolourous with the crown in hue but can sometimes be very slightly darker. This individual's white chin and yellow throat are classic flava features.

Above: Male Blue-headed Wagtail (M.f.flava), Chew Valley Lake, Somerset, spring 2003 by Simon Mackie. This male flava again shows the typical ashy-grey head of the race but the paleness on the forehead is due to the effect of strong sunlight in this particular image and highlights the need for careful study and appreciation of external factors which may affect your judgement. The supercilium is pure white, long and prominent without being excessively flared at it's rear. There is a small pale sub-ocular patch and this bird also exhibits a slight pale 'hollow' on the ear coverts which is perhaps slightly more than 'classic' but within the range of variation for flava. Again the chin is typically white and the throat yellow. 

Above: Male Blue-headed Wagtail (M.f.flava), Cyprus, spring 2008 by Simon Mackie. This flava shows a slightly more flared supercilium behind the eye, though it is particularly well defined. The sub-ocular patch appears very slightly larger than is usual and is perhaps at the extreme edge of the variation for the race. The head colour is spot on however.

Above: Male Channel Wagtail (M.f.flava x flavissima), Covenham Reservoir, Lincolnshire, 13.04.09 by Nick Clayton. This excellent image of a frankly cracking bird shows the features of this hybrid beautifully. The hue of the head colour is clearly much paler than those of the flavas above appearing almost lavender in this image and is the primary feature of recognising Channel Wagtail. The supercilium is rather broad and flared behind the eye whilst the sub-ocular patch typically shows distinctly more extensive and solid white which extends well towards the rear of the ear coverts. Often, as in this instance, it is so extensive that it occupies much of the lower half of the ear coverts where it becomes a pitfall for Sykes's Wagtail (M.f.beema). The throat of this bird appears entirely white recalling the hybrid of Blue-headed and Spanish Wagtail (M.f.iberae) known as 'Middlewest Wagtail'. It is alleged however, that Middlewest Wagtail should also show the ear coverts as generally the darkest part of the head and a rather fine supercilium in front of the eye, not reaching the bill. I have no personal field experience of 'Middlewest Wagtail' (is that the best name we could come up with?) and leave this bird simply as Channel Wagtail thanks!

Above: Male Channel Wagtail (M.f.flava x flavissima), Startops Reservoir, Hertfordshire, 13.04.07 by Mike Collard. One again the exact hue of the head and ear coverts is clearly too pale for a true flava and the ear coverts appear to exhibit a reasonable sub-ocular patch though apparently within the range of variation for true flava. Clearly there is much variation and some overlap!

Above two images: Male Channel Wagtail (M.f.flava x flavissima), Haughton Green Pool, Cheshire, 01.05.09 by Mike Baron. These record shots clearly portray a Channel Wagtail although caution should always be borne in mind when assessing images in particular and the need to consider the lighting and it's potential effect on the appraisal of colour hues. Once again the head is too pale for a true flava being more 'powder blue' here and the supercilium broad and particularly flared behind the eye. The pale sub-ocular patch is very extensive and extends to occupy most of the lower ear coverts. This individual (as opposed to the Covenham Reservoir bird above) has an almost completely yellow throat and was at one point during it's stay paired to a female flavissima Yellow Wagtail.

Above: Yellow Wagtail ssp., spring 2008, Bahrain by Adrian Drummond-Hill. The hue of the bluish-grey forehead, crown and nape is akin to male Blue-headed Wagtail (M.f.flava) but whilst darker lores are also a feature of this race, these ear coverts are considerably too dark for a true Blue-headed Wagtail. This bird completely lacks any pale sub-ocular patch and the white supercilium appears reduced in width particularly above and behind the eye. It displays a striking similarity to Eastern Yellow Wagtail (M.f.tschutschensis) although that is said not to occur in Bahrain. It may well be a so called 'dombrowski' intergrade between Black-headed Wagtail and Blue-headed or Sykes's Wagtail (M.f.feldegg x flava/beema), a hybrid that can render it's recognition from a true tschutschensis impossible. Perhaps it may even be a hybrid offspring of Blue-headed and Grey-headed Wagtail (M.f.flava x thunbergi)? Some birds can defy conclusive identification which ever way you look.

Above: Sykes's Wagtail (M.f.beema), Bahrain by Adrian Drummond-Hill. Channel Wagtail can bear a striking and often almost inseparable similarity to Sykes's Wagtail and despite having good personal field experience of them I certainly wouldn't make such a call lightly in a UK context to say the least! This individual displays typical Sykes's features of a more bluish-grey head, long, bold and rather even width white supercilium and all yellow throat and chin. The ear coverts of Sykes's Wagtail show extensive white so that the whole lower half of them are white and only a broad bluish-grey eye-stripe remains. Such features can be matched to varying degrees by Channel Wagtail and any such bird in a vagrant context should be listened to just as carefully as the plumage studied. The call is different between it and flava or it's hybrids.

Acknowledgements

My most sincere thanks are to those photographers the length and breadth of the UK who very kindly answered my call and permitted me to use their marvellous images to illustrate this article. So many thanks to Adrian Drummond-Hill (also residing in Saudi Arabia), Mike Collard, Simon Mackie, Mike Baron, Marc Hughes and Nick Clayton.

References and essential further reading

Alstrom P. and Mild K. Pipits & Wagtails of Europe, Asia and North America. Helm 2003.

Dubois P. 2007. Yellow, Blue-headed, 'Channel' and extra-limital Wagtails: from myth to reality. Birding World 20 (3): 104-112.

Svensson L. 1992. Identification Guide to European Passerines.

Ian McKerchar, May 2009

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