White Wagtail (lugens x ocularis?), Taiwan (1 Viewer)

[modrawnu]

There is a strange white wagtail found by my friend in nothern Taiwan today. Could it be a cross individual between ocularis and lugens ?

Location: Taoyuan, northern Taiwan
Date: 20-March-2019

 

[johnallcock]

I suspect it's just a lugens. I think the grey feathers on the back are retained first-winter feathers - young lugens are often paler on the back than adults, and are very easily confused with ocularis.

What is interesting on this bird is the head pattern. The eyestripe on lugens is typically noticeably wider behind the eye, but it is uniform width on this bird, which is more like ocularis. I'm not sure whether this pattern is within the range of individual variation in lugens or whether it does perhaps support your suggestion that it is an intergrade.

 

[modrawnu]

I suspect it's just a lugens. I think the grey feathers on the back are retained first-winter feathers - young lugens are often paler on the back than adults, and are very easily confused with ocularis.

What is interesting on this bird is the head pattern. The eyestripe on lugens is typically noticeably wider behind the eye, but it is uniform width on this bird, which is more like ocularis. I'm not sure whether this pattern is within the range of individual variation in lugens or whether it does perhaps support your suggestion that it is an intergrade.

Thanks, John.

In my opinion, the head pattern is compatible with the breeding plumage of ocularis by the thin eye stripe behind the eye and the black patch on throat reaching to bill base that lugens usually not. Otherwise, the back and wing pattern are good for lugens.

 

[johnallcock]

I didn't realise that lugens had a white chin, but looking at pictures I see that you're right, and that the black bib doesn't usually reach the bill. This pattern as well as the eyestripe do look better for ocularis.

According to Alstrom & Mild 'Pipits and Wagtails', lugens and ocularis do interbreed, so this seems like a feasible explanation.

 

[Nutcracker]

I didn't realise that lugens had a white chin, ...

Difference between non-breeding and breeding plumage? Applies like that to a lot of the subspecies.

 

[johnallcock]

Difference between non-breeding and breeding plumage? Applies like that to a lot of the subspecies.

Yes, the extent of black on the bib varies seasonally in all subspecies. But my point (and the point made by modrawnu in post #3) is that lugens seems to have a white chin even in breeding plumage: http://orientalbirdimages.org/search.php?Bird_ID=2086&Bird_Image_ID=168365&Location=japan