Southern Bird Wing is the largest among butterflies of southern India and has a wingspan of 140 - 190 mm. The upper surface of its fore wings is deep black and that of its hind wings is golden - yellow with black wing - borders. The female is similar to the male, but less shiny and has a row of large triangular spots on the yellow areas of the hind wings. In both the sexes the undersides are similar to the uppersides.
Status, Distribution and Habitat
It is restricted to southern India and is very common in many areas of the southern and central Western Ghats. It is also found in Southern Maharashtra and northern Goa where, however, it is uncomen. It inhabits diverse habitats from lowland evergreen forests near the coast to mixed deciduous forests, dry scrub and agricultural fields. It is common in the monsoon and post - monsoon months but uncommon in summer.
Southern Bird Wing usually flies very high, among or above tree-tops in the forests, but sometimes descends to the ground. It flies in a leisurely manner, circling and sailing over the plants. This flight, coupled with its bright colours, advertises the fact that the species is unpalatable to birds and other large insectivorous predators. This unpalatability is due to the presence of aristolochic acids, which the caterpillar ingests while feeding on the leaves of its host plant which contain them. the fluttering of its wings sometimes gives the impression that the butterfly would not be able to fly afr but it is indded a very determined flier and covers long distances in a single flight. Even while flying in the canopy, it attracts attention because of its extremely large size, the wingspan being larger thatn those of small birds, hence the name: "birdwing".
The only food source of the Southern Bird Wing butterfly is flower nectar. Like many other large forest butterfly species that also inhabit gardens and orchards, it has taken to feeding on Lantana, Ixora and Mussaenda, which are common ornamental garden plants. The butterfly keeps fluttering its wings while feeding but closes them over its back when it rests.
Most of the diurnal butterflies become active in the morning only after the sun-rays raise the ambient temperature. The Birdwing, however, is remarkable in that it starts flying very early in the morning, much before other butterflies and thus may be found feeding earlier than them. the species does not exhibit any special basking behavious, but its jet-black scales are very efficient in capturing heat.
Reproduction of Southern Birdwing Butterfly
The habitually high-flying Birdwing female flies close to the ground and shrubs in search of the larval host plants, all of which are aristolochiaceous creepers and climbers. the female hovers about the host plant, and lays spherical eggs singly on the edges of the undersides of young leaves and shoots. the little caterpillar lives on the underside of leaves but as it grows fatter and larger, it rests on the underside of stalks and stems. As with the Roses, the caterpillar is extremely slow and uninterested in moving. the caterpillar and pupa, in general appearance , are similar to those of Common Rose. The caterpillar is velvety maroon-red with a shiny black head. It has four rows of long, fleshy and bright red tubercles - two subdorsal and two spiracular. the dorsal surface of the segments is shiny. the back has grey markings and there is a broad, oblique, pinkinsh - white band on the 7th and 8 th segments. The abdominal segments bear flattened outgrowths. The pupa is pale brown or green, marked with fine brown striations and minute markings. It is found on the underside of leaves, twigs, etc. If touched, it makes hissing sounds by rubbing together the 8th, 9th and 10th abdominal segments and swaying from side to side.
The caterpillars are heavily parasitized by tiny Braconid wasps. Dozens of Braconid larvae, after eating the Birdwing caterpillar from inside, puncture the skin, wriggle out and make whitish cottony cocoons on the body of the caterpilar. After the Braconids pupate the caterpilar does not feed, but remains alive and motionless for a few hours or even days.
Larval Host Plants of Southern Bird Wing Butterfly
The host plants are small climbers and creepers of the family Aristolochiaceae, which grow in openings in the forests and on fallow lands: Aristolochia indica, Aristolochia tagala and Thottea siliquosa.