Abstract
Phylloscopus tenellipes and Ph. borealis xanthodryas breed in high altitudes in Norikura range, Honshiu. They arrive foot zone in early May, but final snow fall on the peak was noticed as late as 27 May. In the foot-zone study area, the Bansho highland, these species were in full song in late May, but were apparently waitng for advance of season before leaving to high range for breeding. They were thus in the stage of pair formation assembly at lower level forest.
