Asian House Martin

The Asian house martin (Delichon dasypus) is a migratory passerine bird belonging to the swallow family Hirundinidae. Exhibiting mainly blue-black upperparts, this avian marvel is distinguished by its white rump, while its underparts are a pale grey. The species is characterized by a slightly forked tail, and it displays a remarkable adaptation for flight with its streamlined body.

Identification Tips

Adults of the nominate subspecies measure approximately 12 cm in length, with dark steel blue upperparts and a contrasting white rump. Their underparts are grey-washed white, and the tail and upperwings are brownish-black, while the underwings are grey-brown. Legs and feet are brownish-pink, covered with white feathers, and the bill is black. Males may appear whiter below than females, particularly in fresh plumage, and juveniles are less glossy with darker upperparts and grey-white underparts.

Habitat

The Asian house martin is fond of valleys and gorges within mountainous regions or coastal cliffs, where natural caves or crevices are utilized for nesting. It also adapts to large man-made structures for breeding, such as temples and hotels.

Distribution

This species' three subspecies are distributed across the Himalayas and central and eastern Asia, with wintering grounds lower in the mountains or in Southeast Asia. The range extends from the southeast of Russia to Japan and occasionally Korea, with winter migrations to areas including the Malay Peninsula and the Philippines.

Behaviour

Breeding colonies are established under overhangs on vertical cliffs or walls of buildings, where mud nests are constructed. Both sexes are involved in nest building, incubation of the white eggs, and feeding the chicks. The Asian house martin is known for its aerial feeding habits, often catching insects high in the air.

Song & Calls

The song of the Asian house martin is a metallic trill or sibilant twitter, while its call is a dry, metallic cheep, often with multiple syllables. Its vocalizations are similar to those of the common house martin but possess a more rasping quality.

Breeding

Nests are deep mud cones lined with grass or feathers, sometimes left open like a deeper version of a barn swallow nest. Clutches typically consist of three to four white eggs, with both parents sharing responsibilities for incubation and chick rearing.

Similar Species

The Asian house martin can be differentiated from the Nepal house martin by the latter's black chin and squarer tail. It also bears resemblance to the common house martin but is distinguishable by its darker underparts and less deeply forked tail.

Diet and Feeding

A diet of small insects such as flies, aphids, and Hymenoptera is typical, with occasional ground foraging indicated by the presence of terrestrial springtails and Lepidoptera larvae in the diet.

Predators and Parasites

While specific predators are not well-documented, they likely include fast-flying falcons capable of aerial pursuit. Parasites may include external lice and fleas, as well as internal blood parasites like avian malaria.

Conservation Status

The Asian house martin is classified as Least Concern by the IUCN, with a large and stable range, no significant decline in population, and a local abundance that suggests a northward expansion in Siberia.