Eurasian Skylark (Alauda arvensis) - HBW 9, p. 598

Taxonomy: Alauda arvensis Linnaeus, 1758, Europe = Sweden.
May form a superspecies with A. gulgula, and has been considered conspecific. Race japonica sometimes considered a race of that species owing to similarities in plumage and structure; alternatively, treated by many as a separate species on grounds of constant differences in plumage and apparent sympatric breeding with race lonnbergi of present species in Sakhalin, but limits of E taxa disputed by others; further study required. Large number of races described, but distributions and geographical boundaries poorly understood, obscured by considerable individual variation within populations, also by intergradation, and most taxa identifiable only by comparing series of specimens at same stage of plumage wear; validity of some generally accepted taxa remains questionable. Other proposed races sometimes recognized include ticehursti (NW Iberia), included in guillelmi; dementieva (SE of Caspian Sea), in dulcivox; alticola (SE Altai), in kiborti; nigrescens (Amur Basin), in intermedia; and buxtoni (NE coast of Sea of Okhotsk), in pekinensis. Thirteen subspecies tentatively recognized.