The WHITE-THROATED PRICKLY-TAILED SWIFT (_Acanthylis caudacuta_) is about
eight inches and a half long, and twenty broad; the wing measures eight
and the tail two inches. The head, upper tail-covers, sides of the wings,
quills, and tail are pale black, with a metallic greenish blue gloss; the
back and shoulder-feathers are whitish brown, the breast and nape white.
The under side is blackish brown, the lower wing-covers and a streak on
the side of the head are white, more or less intermixed with glossy,
blackish blue feathers. The inner web of the secondary quills is also
white; the beak is black, the foot lead-colour, and the eye deep brown.
We learn from Jerdon that this species is found in the south-eastern
provinces of the Himalaya, Nepaul, Sikkim, and Bhotan, and that its
flight is extraordinarily light and rapid. The breeding settlements are
generally at a considerable height in the mountains, but always below the
snow boundary. The strange prickly tail appears to be employed to assist
the bird while climbing. Further particulars as to its habits and mode of
life are entirely wanting.