Differences on the wing-formula of Eyebrowed Thrush, Brown-headed Thrush, Pale Thrush and Izu Thrush

Abstract

Components of wing-formula; the longest primary (s), the order of the p9, feather gaps on primaries and emarginations of outer webs of primaries were compared between the Eyebrowed Thrush (n=29), the Pale Thrush (n=39), the Brown Thrush(n=79) and the Izu Thrush (n=16). All the components were significantly different between four species, and species with longer migration had more pointed wings. Wing-formula was effective in the identification of the four species because the appearance of gaps on the primary was divided into two groups; Eyebrowed/Izu and Pale/Brown-headed, the gap of the Izu Thrush was composed different primaries from the others and emarginations might exist more proximal, and emarginations of the Eyebrowed Thrush existed more distal.