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Twelve species of sunbirds, the small perching birds, which are the counterparts of America’s hummingbirds and Australia’s honeyeaters, are found in India, writes
Rajiv Kalsi SUNBIRDS are small perching birds, which feed largely on nectar from flowers, although they also take insects, especially when feeding young ones. They belong to the family nectariniidae, which is spread over Africa, south Asia and parts of north Australia. Sunbirds have counterparts in two distantly related groups: the hummingbirds of America and the honeyeaters of Australia. The resemblances are largely due to convergent evolution on account of their similar nectar-feeding habit. Some sunbird species can take nectar by hovering like a hummingbird, but usually perch to feed.
There are 12 species of sunbirds in India. The smallest sunbird is the crimson-backed sunbird (nectarinia minima), which is only 8-cm-long and weighs as little as 4g. The sunbirds occupy a wide range of habitats, with a majority of species being found in primary rainforest, but other habitats used by the family include disturbed secondary forest, open woodland, open scrub or bush land and alpine forest. Some species have readily adapted to human landscapes such as plantations, gardens and agricultural land. Sunbirds have also adapted to life in high altitudes; Mrs Gould’s sunbird (aethopyga gouldiae), green-tailed sunbird (aethopyga nipalensis) and fire-tailed sunbird (aethopyga ignicauda), for instance, can be found at altitudes of 3000m to 4000 m high. To cope with the freezing conditions, they encounter on high mountains, sunbirds have the ability to lower their body temperatures while roosting. Purple sunbird (nectarinia asiatica) is an abundant, resident breeder widely distributed in India. Purple sunbirds are tiny, only 10 cm long and the adult male is mainly glossy purple. The eclipse male has yellow-grey upper parts and a yellow breast with a blue central streak extending to the belly. The female has yellow-grey upper parts and yellowish under parts, and a faint supercilium. The call is a humming zit-zit. This species is found in a variety of habitats with some trees, including forest and cultivation. Sunbirds are strongly sexually dimorphic, with the males usually brilliantly plumaged in iridescent metallic colours. The colour of the iridescence changes with the angle of incident light such that a blue may suddenly appear green or black. Many have marked contrasts in their colours, especially among the genus nectarinia, who have broad red bands across their chests. Brightly coloured pectoral tufts, usually yellow or red, are a feature of many species, particularly among males that use them in courtship and aggressive displays. As an adaptation to their feeding on nectar, the predominantly black bills of sunbirds are nearly all down-curved. The birds’ tongues are long and may be extruded far beyond the tip of the bill. The tongues vary in size and shape, with tubular structures and serrations at the tips being most common. To reach the nectar in flowers with long petals, the sunbirds pierce a hole at the base of the flower. Tails may be short and square-ended, or graduated and elongated, with males of the genus nectarinia, and aethopyga having extended central tail feathers. The legs are long and thin and usually black, with feet having curved claws. Sunbirds are diurnal and active from dawn to dusk. Their high metabolic rate and small size necessitate almost constant searches for food, but they sometimes rest on exposed perches to preen, wipe their bills, or sing. Characteristically, they draw attention to themselves by their high-pitched calls as they flit from one flower to another, but they also catch insects on the wing and may hover in front of flowers as they probe them for nectar. Pugnacious and aggressive to intruders of their own species, they also attack other species of sunbirds, especially at feeding areas. Sunbirds are mostly found solitary, in pairs, or in family groups, but they are also social, coming together to feed at abundant sources of nectar or joining in mixed-species groups in forest canopies. Although not renowned for their singing, the vocalisations of sunbirds include complex and occasionally melodious songs. These are chattering warbles, interspersed with whistles and wheezes, uttered from prominent perches such as dead trees. The songs of sunbirds are used to advertise their territories, which they defend vigorously around nests and feeding zones. Courtship displays involve exposure of pectoral tufts by males of those species that possess them, and elaborate bowing rituals, with wings partly open and quivering, and tails cocked or fanned. They are generally monogamous and often territorial. Up to three eggs are laid in a purse-shaped suspended nest. The female builds the nest and incubates the eggs alone, although the male assists in rearing the young after hatching. The nests of sunbirds are often targeted by brood parasites such as cuckoos.
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