Friday, 21 November 2014

Blue and White Flycatcher - presumed intermedia

Blue and White Flycatcher Cyanoptila cyanomelana is a common breeding bird around Kyoto and males singing from prominent tree-top perches are a major element of the local birding scene in spring. They are also a common migrant and can often be seen in city parks.

Looking through my collection of photographs I find there are far more of females, I suppose partly because the vocal and more frequently seen males are so often way up high and also that there's at least a slight identification interest where females are concerned. After all, what possible identification challenge could there be with a male Blue and White? Or so I used to think.

I found an arresting male on Mishima (Yamaguchi) on 1 May 2010, well before Leader and Carey's Forktail (Aug 2012) paper on the Cyanoptila flycatchers, and wondered if this bird might have been cumatilis for which there was very little available information. Nial Moores was very helpful with information and steered me away from cumatilis and suggested the disputed form intermedia might be more likely to explain the appearance of this bird.

With Zappey's Flycatcher split from cyanomelana, taking the name cumatilis with it, the door opened for increased interest in the east Asian population. Though intermedia may not be universally recognised as a valid subspecies it seems to be gaining ground. It's breeding range on the neighbouring Asian mainland might suggest it could be regular on passage in Japan but like a some other taxa it shares a roughly similar breeding range with (Manchurian Reed Warbler, Daurian Starling, White-throated Rock Thrush to name but three), records seem very few. Its hitherto lack of recognition and perhaps resultant lack of interest or even awareness could be responsible for under recording but the Blue and Whites I see always look just that, with the noteable exception of the bird that prompts this post.

The Leader and Carey paper has a series of plates showing skins of cumatilis, cyanomelana and intermedia but while the former stands out as different the quality isn't good enough to show any tangible differences between the other two. However when I'd earlier seen the bird on Mishima, it had looked quite eye-catching compared to the many cyanomelana passing through at the time.

Unfortunately I was never able to get good views of the back and rump because it was on the edge of woodland on the uphill slope from the road cutting across the hillside. After a few minutes it retreated into the trees and I never saw it again. The following images show the view I did get plus a range of angles of cyanomelana, mostly in similarly bright conditions.

Above are two shots of a cyanomelana showing the distinctive black face, throat and upper breast with white through to the tail. The forehead and crown frequently look a much lighter silvery blue compared to the rest of the upperparts, the brightness and extent can depend on lighting and angle but there's usually a bluer border between the black face and silvery crown giving a capped appearance.
Below are two shots of my presumed intermedia which even at a glance looks quite different. The forehead looks silver rather than silvery blue and the crown as a whole is distinctly paler becoming light blue, rather than deep blue on the nape. The face of cyanomelana normally looks matt black but it can have bluish tips to some feathers if the light catches it. This bird on the other hand is more blue than black and the border between face and hind neck is far less distinct, unlike the lores to forehead division which is sharp from all angles.

Two shots of cyanomelana above (top in shade, bottom in direct light) that show the beautiful deep blue upperparts set off with subtle black detail on the inner webs of the tertials and on the inner webs and outer web bases to the greater coverts. The flight feathers and greater primary coverts are broadly fringed blue giving the overall impression of blue wings, concolourous with the mantle. The forehead and crown have a silvery sheen but as is often the case but this can all but disappear depending on the angle.
Below are more shots showing the general deep blue nape to tail uniformity.

The following shots of the Mishima bird show quite different upperparts colour. Compared to cyanomelana the crown is not only much lighter but also more extensively so and is obvious from any angle. The hind neck is blue but not as dark as that of cyanomelana and the upperparts are uniformly turquoise, the back isn't visible in these shots but the uniformity is hinted at by the visible sides of the rump and uppertail coverts. The tertials, greater coverts, flight feathers and greater primary coverts share the cyanomelana pattern but the turquoise fringes are less conspicuous and the wings look blacker and contrast more with the upperparts. The median and lesser coverts are blue and therefore also contrast with the turquoise upperparts. The greyish wash along the flanks isn't a typical feature of cyanomelana but some do show it to a degree.

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