Summer visitor come to Kanto region center Japan. About 1week earlier than usual year. I watched Asian brown flycatcher, Blue-and-white flycatcher, Asian stubtail, Ashy minivet, Japanese thrush, Eastern crowned warbler in last weekend. But Narucissus flycatcher was not watched. This article is written about eastern crowned warbler.
Eurasian crested warbler is the most popular warbler in Japan. Separate from Iijima's reed warbler is not difficult. IIjima's reed warbler's face is paler than Eurasian crested's. The song "tyo-tyo- biiin" is heard not only breeding area but also stoppover range. I saw IIjima's reed warblers in fall, They moved and searched some feed on deciduous trees. I think Eurasian crested spend like Iijima's reed warbler in witering area. Other popular warbler in Japan is Sakhalin leaf warbler, Kamchatka reef warbler and Japanese reef warbler. In my guess, Sakhalin leaf spend in winter like Japanese bush warbler or Dusky warbler. Japanese reef warbler maybe resemble to Arctic warbler that I saw in Yonaguni-island Southern Ryukyu. I think Japanese reef has wide habitat preference, too.
Eastern crested flue to above branch. I cannnot guess how they migrate, alone? or with flock members? In case of island of sea of Japan, A lot of Eastern crested were observed in morning but only few this species were observed. I think Narucissus flycatcher migrate with flock and they sometimes close each individuals in a sea island. Otherwise in Eastern crested, the distance between individual is not short in many time. It is needed to consider their body size are very small and they can use huge areas in a forest. Migrate with flock over sea is likely to do, but I think they are not maintaining the flock in mainland. Then, why some case the some individual of Eastern crested are observed in same time same place? They migrate adjust the temperature that some insects operating? or migrate alone but recognizing each other with vocal.