Breeds with certainty around Cherrapunji and Lilancote, in Khasi Hills (north-eastern India); also thought to breed in Lushai Hills, in Mizoram (extreme southern Assam), where series of specimens collected in May. Recently recorded in Bhutan; may occur in Myanmar and (1 specimen) Nepal. In Thailand, to date only known by winter records from north-west.
Population
Estimated population is 250 - 999 (2010).
Dark-rumped Swift (Apus acuticauda) [XC37532]
by id from Deothang, Bhutan (song)
Subspecies
Forms superspecies with Fork-tailed Swift (Apus pacificus), of which in past occasionally considered a subspecies. Population from Blue Mts, in Lushai Hills of southern Assam, described as subspecies rupchandi, but claimed differences in plumage do not hold good. It is also suggested that, if a series of specimens were available from Thailand, they might show that population to represent a separate form.
No subspecies.
Similar Species
Fork-tailed Swift (Apus pacificus) which has a white rump-band, less sharply forked tail and paler throat, Common Swift (Apus apus) which lacks scaling to underparts and has shorter, less deeply forked tail.
References
See References.
BirdLife International Species Factsheet