The flight and general appearance of the swifts have already been described. The common Indian swift (Cypselus affinis) is perhaps the bird most frequently seen in the Himalayas. A small dark sooty brown bird with a broad white bar across the back, a living monoplane that dashes through the air at the rate of 100 miles an hour, continually giving vent to what Jerdon has so well described as a "shivering scream," can be none other than this species. It nests under the eaves of houses or in verandahs. Hundreds of these swifts nest in the Landour bazar, and there is scarcely a dak bungalow or a deserted building in the whole of Kumaun which does not afford nesting sites for at least a dozen pairs of swifts. About sunset these birds indulge in riotous exercise, dashing with loud screams in and out among the pillars that support the roof of the verandah in which their nests are placed. The nest is composed of mud and feathers and straw. The saliva of the swift is sticky and makes excellent cement.
The other swift commonly seen in the Himalayas is the Alpine swift (Cypselus melba). This is distinguishable from the Indian species by its white abdomen and dark rump. It is perhaps the swiftest flier among birds. Like the species already described, it utters a shrill cry when on the wing.