Alauda, Linn., Syst. Nat., 10th ed. i, p. 165 (1758). Type, Alauda arvensis Linn.
The genus Alauda contains the true Sky-Larks, of which but one species is recognized by Hartert in his latest revision of the group, though this is divided into a great number of races which vary from one another not only in size and colour but also in the comparative length of their different primaries.
In Alauda the bill is slender and feeble and the nostrils are covered by plumelets. The wing has ten primaries of which the first is minute, though differing a little according to the geographical position of the subspecies; the length of the second, third and fourth also vary but the wing is always short, not reaching beyond the middle of the tail; the tarsus is long and fairly stout and the hind claw very long and nearly straight.
The sexes are alike and the young are barred above with blackish and white.
There has been considerable discussion and great difference of opinion expressed as to the names some of the races of Sky-Larks should bear. Ticehurst (' Ibis,' 1922, p. 149) resuscitates Brooks's name dulcivox for the "Western large form of Indian Sky-Lark and I think he does so rightly. Brooks (in loc, cit. infra) gives an extraordinarily good diagnosis of this Lark and not only shows how it differs from typical arvensis but also how it differs from the smaller local breeding races and from the Eastern form, which more nearly approaches true arvensis than any of these. His " cold grey tone of the upper plumage with strongly contrasting central streaks " not only at once separates it from either inopinata or japonica which are found in Winter within the limits of this work, but equally well shows the character in which it differs from intermedia with which Hartert has incorporated it. The true intermedia is a little darker and more rufescent above and also, generally, more fulvous below.
As regards the number of species which should be recognized, it seems more convenient to recognize two, a larger, arvensis group and a smaller, gulgula, group, for in two cases the breeding ranges of two forms seem to overlap. Kinnear keeps inopinata as a full species on account of its long fourth primary, but as this character is not quite constant I prefer for the present to keep it as a race of the larger arvensis group.
Key to Species.
A. Fifth primary falls short of tip of wing by more than 5 mm…………….A. arvensis, p. 315.
B. Fifth primary falls short of tip of wing by less than 5 mm…………….A. gulgula, p. 318.