The Pacific swift (Apus pacificus) is a species of bird that is part of the Swift family. It breeds in eastern Asia. It is strongly migratory, spending the northern hemisphere's winter in Southeast Asia and Australia. The general shape and blackish plumage recall its relative, the common swift, from which it is distinguished by a white rump band and heavily marked underparts. The sexes are identical in appearance, although young birds can be identified by pale fringes to the wing feathers that are absent in adults. This swift's main call is a screech typical of its family. It is one of a group of closely related Asian swifts formerly regarded as one species. The Pacific swift is found in a wide range of climatic zones and habitats. It breeds in sheltered locations such as caves, natural rock crevices or under the roofs of houses. The nest is a half-cup of dry grass and other fine material that is gathered in flight, cemented with saliva and attached to a vertical surface. The two or three white eggs are incubated for about seventeen days to hatching. Subsequently, the chicks have a long but variable period in the nest before they are fully fledged. When the parents cannot find sufficient food in bad weather, the young can survive for days without being fed by metabolising body fat. Like all members of its family, the Pacific swift feeds exclusively on insects caught in flight. It tends to hunt higher than most of its relatives other than the white-throated needletail. The Pacific swift has a large population and extensive breeding area, and faces few threats from predators or human activities. It is classed as being of least concern by the International Union for Conservation of Nature. It has occurred as far afield as the US and New Zealand, and it is a very rare vagrant in Europe.