I've just received some more information from Nial Moore about some interesting behaviour notice in South Korea these past weeks, again, I copy his email below with his permission :
"It appears that the movement of Varied Tit probably started in the ROK in the last week/ten days of August. Personally, on August 26th and again on 29th, saw several small groups of Varied Tit spiralling up and dropping back down again into cover on Heuksan Island, a Yellow Sea offshore island about 40km west of other large islands, and some 500km east of Shanghai. This is an island with a breeding population of the species - but this type of behaviour was notably unusual. Back on the mainland on August 31st in Mokpo City (where Varied Tit is also common), >50 were watched moving west in only 15 minutes, with some birds probably >200m up and climbing (as typical for tits during "proper movements"). A small westward movement of Varied Tit (several groups of 4-5 birds) was also seen 150km further north the same day and on Sep 1st. Of major interest, Chris Cook reported to the Kantori Listserver on Sep 1st that in the Japanese Alps (on Honshu) the previous day "in a matter of a few hours, there were probably 100 birds or more in small groups -- 5, 10 or even 20 -- passing west".
Through until at least September 25th, 10s of Varied Tit also seemed to be showing irruptive behaviour in the SE of the ROK (Busan and Gimhae) - joined by an increasing number of Coal Tit - with small groups of birds flying out south to sea most days, and then moving off southwest. Even as I write this now, I can hear Varied Tit calling from trees in front of our office here in Busan.
Although the species can be quite numerous some years and we do get Varied Tit turning up most years on Korean Yellow Sea offshore islands (including on islands where they do not usually breed, confirming some movement), the number of birds involved and these locations suggests that this year has already been quite exceptional for the species.
With westward movement in at least one place in Japan and at several locations in the ROK during the past month, it is fascinating (and perhaps predictable?) that the species is now being found to the west (and southwest) of its usual range...Congratulations to the finders!
Best wishes and birding,
Nial"
