Pale-legged (and Sakhalin) Leaf Warblers have uniform pale pink legs, feet and claws; a good example of this can be found at:
http://orientalbirdimages.org/se ... _ID=&pagesize=1
Note also the cleaner underparts compared to Arctic.
Regarding Arctic Warbler taxonomy; it seems likely that the 3-way split proposed in three recent papers will be adopted by the IOC (now the authority on such matters which the HKBWS Records Committee follows). This would result in borealis (northern Palearctic, Alaska) xanthrodryas (much of Japan) and examinandus (ne Hokkaido and Kamchatka) being treated as different species.
Given their distribution and wintering ranges, it seems likely that all three occur in HK. There is a record of xanthrodryas but that is being reviewed as examinandus was not included in the original assessment (it was not even a recognised subspecies at the time!).
The elevation to species level of these three taxa is based on differences in DNA, vocalizations, and morphology.
With the vocal differences in mind, I spent time on Sunday listening to the calls and song of Arctic Warblers on Po Toi. I heard five or six different individuals singing, and another five or six calling. The songs matched well recordings from Japan (i.e. xanthrodryas). The calls were interesting too, as in addition to the ‘typical’ dry dzick Arctic Warbler call, I also heard a distinctly di-syllabic gri-grik call, which is a call I had not noticed previously.
It seems likely that xanthrodryas (for which the English name Pacific Warbler has been proposed) is a common spring migrant through HK. Examinandus should also occur, and it may well be that borealis is the commonest form in autumn. In the meantime, much work is required to collect sound recordings of singing birds, plus careful measuring and analysis of DNA from trapped birds before we can determine whether all three (soon to be!) species do indeed occur in Hong Kong.
