It has a fast and direct flight and can take nectar by hovering like a hummingbird but often perches at the base of flowers.

The males can appear all black in harsh sunlight but the purple iridescence is visible on closer observation or under good light conditions.

Less than 10 cm (3.9 in) long they have a down-curved bill with brush-tipped tubular tongues that aid in nectar feeding.

The male is glossy metallic bluish to purplish[2] black on the upper parts with the wings appearing dark brown.

In the breeding plumage, the male can be confused with the syntopic Loten's sunbird which has a long bill and a distinctive broad maroon band on the breast.

[3] Local movements are, however, noted especially in the drier parts of northwestern India and Pakistan where they are said to arrive in large numbers before summer.

[4] The race intermedius extends from the border of Orissa and Andhra Pradesh[12] northwards into Bangladesh, Myanmar and Indochina.

A male ringed in Bharatpur was recovered in Dehra Dun about 350 km (220 mi) to the north.

They are important pollinators of some plant species such as Butea monosperma,[14] Acacia,[15] Woodfordia[16][17] and Dendrophthoe.

[22] In courtship displays the male raises his head, fans his tail and flutters with partly open wings that expose the pectoral tufts and sings before the female.

[23] In Sri Lanka and in southern India, it sometimes builds its nest by modifying and lining the cobweb structures formed by colonial or 'social' spiders, Stegodyphus sarasinorum (Eresidae).

[13][9] The nest is usually suspended from a low branch, often of thorny plants[26] but are sometimes built close to human habitations, attached to wires or other man-made objects[27][28] and even indoors in an unused toilet.