
Photo: (c) Afsar Nayakkan, some rights reserved (CC BY) · CC-BY (May be cropped or resized)
Apus leuconyx
Also known as: Apus pacificus leuconyx
AviList (2026) treats this bird as a subspecies, Apus pacificus leuconyx, of the Fork-tailed Swift (Apus pacificus), which is also on this site. IOC lists it as a separate species.
Habitat
Nests on cliffs
Range
Breeds from the outer Himalayas through the Assam hills; winters in India and Sri Lanka
Clutch size
2–3 eggs
Blyth's swift is a small swift, superficially similar to a house martin but unrelated to it. It is similar in size to the common swift and black except for a white rump. It can be distinguished from a partly pale common swift by its deeper tail fork, longer wings, bigger head and larger white throat patch (Wikipedia, general species account).
It breeds from the outer Himalayas through the Assam hills, building its nests on cliffs and laying two or three eggs. It is migratory, wintering in India and Sri Lanka. A swift returns to the same site year after year, rebuilding its nest when necessary. The account opened does not name Bhutan.