(Sakhalin, Arctic and Eastern Crowned), However its colour seemes to be
variously and the differences in upperpart coloration are hardly to the
colour-weaker (as me). Many of Japanese field guides describe that note
the colour of upperparts, but I think it is rather unuseful.
Arctic Warbler has no contrast of colours between the top of the head and
the mantle. Primary projection is slightly shorter than Arctic Warbler.
Distinguish from Eastern Crowned Warbler by whitish under tail coverts
, the dark spot on the lower mandible and the lack of median crown stripe.
However, the median crown stripe of Eastern Crowned Warbler is sometimes
rather indistictively in a front view.
2. 21th May 1996
Wajima-shi, Isikawa Prefecture
This birds might be moulting. Some of primaries(or/and secondaries) looks
to be lacked. Some of the outer primaries was renewed and may be growing.
The underparts is more whitish (especially on the under tail coverts) than Arctic and Eastern Crowned Warbler.
I think that the first impression can most similar with Arctic Warbler in Japan. But the supercilium is usually thiner in front of eye and never
cut sharply. And the supercilium is rather whitish (usually buffish in
Arctic).
