Vaux's swifts have tiny 4-1/2 inch bodies. Swifts have long wings that gently curve to a point. They are dark-colored birds, with a shade lighter on the throat and upper breast. As long as the birds are not too high above your head, you may be able to distinguish the slightly forked tail of the black swift from the short, rounded tail of the Vaux's.

Swifts have very high metabolisms and often fly several hundred miles a day in search of insects to fuel their bodies.

Adult swifts can attain a state of "torpor" when insects are scarce. Young, nest-bound swifts can go into torpor while their parents are away hunting.

Torpor "is a condition of deep sleep, with very slow breathing (one per minute) and heartbeat (four to eight per minute) at body temperatures close to the ambient temperature, down to a limit of a few degrees above freezing. Its basic purpose is to conserve calories at times when they are hard to come by" (Matthews, Dan. Cascade Olympic Natural History. 1988. InterPacific Printing Corporation. p.308).

Vaux's swifts are closely associated with unmanaged old-growth Douglas-fir forests. The nests of twigs are cemented together with the bird's saliva and built inside the hollows of trees. (Matthews, Dan. Cascade Olympic Natural History. 1988. InterPacific Printing Corporation. p.395).