2010 Volume 22 Issue 1_2 Pages 37-49
Taxonomy, morphological traits and migration patterns of subspecies of the Arctic Warbler Phylloscopus borealis in Eastern Asia, including Japan, are still poorly known. International cooperative research is required to resolve these issues. In this research, field work surveys, including banding, were conducted at the Niigata Coast, Japan and in central Kamchatka, Russia. The focus was on morphological traits and migrating habits of a subspecies of P. borealis. Analysis of previous unpublished data indicated than in Niigata, a clear and regular northward migration occurs in early summer, from late May to middle June. Also, no clear differences in diagnostic morphological traits (wing length, tail length, primary wing formula, the difference between the length of the outermost primary and the maximum length of the primary coverts (P10 - PCmax), and the number of buff patches on the greater secondary coverts, etc.) were observed between birds obtained in Niigata and Kamchatka. This data thus supports the view that migrants in Niigata and migrants and/or summer visitors in Kamchatka belong to the same population comprising a subspecies (most probably P. b. examinandus; not P. b. xanthodryas or P. b. borealis).
