Different lengths of the 2nd and the 7th primary flight feathers in the Yellow-browed Warblers is one of the main distinguishing characteristics of their subspecies: Phylloscopus inornatus inornatus and Ph. i. humei. During the studies 1996—2000 and 2007 in different areas of central and southern parts of Russian Far East the individuals Ph. i. inornatus having the wing formula typical for Ph. i. humei were repeatedly captured. Therefore we consider use of this characteristic to be doubtful for identification subspecies of Yellow-browed Warblers. We explain similarity between the wing formulae of Ph. i. inornatus from the study area and those of Ph. i. humei by the Seebohm’s rule. South edge of the Ph. i. inornatus’ range as well as the northern part of the Ph. i. humei’s range lies in the same latitudes. And while having similar distances of their migration routes the birds of the same species will probably have the same wing formulae (consequence of the Seebohm’s rule).

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