mbill

Long Valley
One of the Crested Bulbul Club member Mr. Yip have taken a photo of this wagtail, is it a Citrine Wagtail/黃頭鶺鴒?
Thanks experts to identify.

HFCheung

I think this is a very good candidate, but not conclusive to me.  
The ring around the ear, and the slightly paler area in the centre of the ring are very good features.  However, there are also doubts to me.  For example, the ring around the year can depend on angle of view, and many Citrine Wagtails would have a thicker wingbar.

I hope there are more photographs.

HF Cheung

kkoel

I would say this is a Yellow Wagtail, due to the dark lores, and thin wing-bar as Fai Gor mentioned. The "ear-ring" is definitely shown by Citrine, but it tends to be thick and conspicuous; some Yellows do show ear-rings, but is thin like this individual. =)

mbill

Thanks fai Gor and Koel. It only seems to be.

lpaul

I am not sure it is possible to identify based on this photo alone.  However, there are many pro Citrine features including the pale surround to the ear-coverts, the paler centre to the ear-coverts, the apparently pale lores and the longish looking bill.  However, all of these can change with posture and may be more or less obvious in other postures and photos.  Regarding the wing bars; as it is not possible to see all of the greater coverts in the photo I don't see how an assessment of the wing bar size can be made, plus this also diminishes with wear.