The Salim Ali's Swift (Apus salimali), is a small bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

, superficially similar to a House Martin

House Martin

The Common House Martin , sometimes called the Northern House Martin or, particularly in Europe, just House Martin, is a migratory passerine bird of the swallow family which breeds in Europe, north Africa and temperate Asia; and winters in sub-Saharan Africa and tropical Asia...

. It is, however, completely unrelated to those passerine

Passerine

A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...

 species, since swift

Swift

The swifts are a family, Apodidae, of highly aerial birds. They are superficially similar to swallows, but are actually not closely related to passerine species at all; swifts are in the separate order Apodiformes, which they share with hummingbirds...

s are in the order Apodiformes. The resemblances between the groups are due to convergent evolution

Convergent evolution

Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...

 reflecting similar life styles.

These birds have very short legs which they use only for clinging to vertical surfaces. The scientific name comes from the Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 απους, apous, meaning "without feet". They never settle voluntarily on the ground. Salim Ali's Swifts spend most of their lives in the air, living on the insects they catch in their beaks.

Salim Ali's Swifts breeds from the eastern Tibet

Tibet

Tibet is a plateau region in Asia, north-east of the Himalayas. It is the traditional homeland of the Tibetan people as well as some other ethnic groups such as Monpas, Qiang, and Lhobas, and is now also inhabited by considerable numbers of Han and Hui people...

an Plateau eastwards through western Sichuan

Sichuan

' , known formerly in the West by its postal map spellings of Szechwan or Szechuan is a province in Southwest China with its capital in Chengdu...

 province. This species is migratory

Bird migration

Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...

, however its wintering range is unknown. This swift is longer tailed and a narrower white rump compared to other species in the complex. A 2011 study has many taxonomists splitting this species from the Fork-tailed Swift

Fork-tailed Swift

Fork-tailed Swift is the historic name of a kind of bird which has since been divided taxonomically into four species. It could refer to any of four different species of swifts:*Pacific Swift, Apus pacificus*Salim Ali's Swift, Apus salimali...

 complex.

These swifts build their nests on cliffs, laying 2-3 eggs. A swift will return to the same site year after year, rebuilding its nest when necessary.

Salim Ali's Swifts are similar in size to Common Swift

Common Swift

The Common Swift is a small bird, superficially similar to the Barn Swallow or House Martin. It is, however, completely unrelated to those passerine species, since swifts are in the separate order Apodiformes...

, and they are black except for a white rump. They can be distinguished from a partially leucistic

Leucistic

Leucism is a condition characterized by reduced pigmentation in animals and humans. Unlike albinism, it is caused by a reduction in all types of skin pigment, not just melanin.- Details :...

 Common Swift by the deeper tail fork, longer wings, bigger head and larger white throat patch.

It was previously mis-categorized as an alternative name for Apus pacificus kanoi.