Birdwing

Birdwings are butterflies in the swallowtail family, that belong to the genera Trogonoptera, Troides, and Ornithoptera. Most recent authorities recognise 36 species, however, this is debated, and some authorities include additional genera. Birdwings are named for their exceptional size, angular wings, and birdlike flight. They are native to the Indian subcontinent, mainland and archipelagic Southeast Asia, and Australasia. Included among the birdwings are some of the largest butterflies in the world: the largest, Queen Alexandra's birdwing; the second largest, the Goliath birdwing; the largest butterfly endemic to Australia, the Cairns birdwing; and the largest butterfly in India, the southern birdwing. Another well-known species is Rajah Brooke's birdwing, a particularly attractive species named after Sir James Brooke, the first White Rajah of 19th-century Sarawak. Due to their size and brightly coloured males, they are popular among collectors of butterflies, but all birdwings are now listed by CITES, thereby limiting (and in the case of O. alexandrae completely banning) international trade. After mating, females immediately begin to seek appropriate host plants; climbing vines of the genera Aristolochia and Pararistolochia (both in the family Aristolochiaceae) are sought exclusively. The female lays her spherical eggs under the tips of the vine's leaves, one egg per leaf. The caterpillars are voracious eaters but move very little; a small group will defoliate an entire vine. If starved due to overcrowding, the caterpillars may resort to cannibalism. Fleshy spine-like tubercles line the caterpillars' backs, and their bodies are dark red to brown and velvety black. Some species have tubercles of contrasting colours, often red, or pale 'saddle' markings. Like other members of their family, birdwing caterpillars possess a retractable organ behind their heads called an osmeterium. Shaped like the forked tongue of a snake, the osmeterium excretes a fetid terpene-based compound and is deployed when the caterpillar is provoked. The caterpillars are also unappealing to most predators due to their toxicity: the vines which the caterpillars feed upon contain aristolochic acid, a poisonous compound known to be carcinogenic in rats. The feeding caterpillars incorporate and concentrate the aristolochic acid into their tissues, where the poison will persist through metamorphosis and into adulthood. Birdwing chrysalids are camouflaged to look like a dead leaf or twig. Before pupating, the caterpillars may wander considerable distances from their host plants. In O. alexandrae, it takes about four months to get from egg to adult. Barring predation, this species can also survive up to three months as an adult. Birdwings inhabit rainforests and adults are usually glimpsed along the forest periphery. They feed upon—and are important long-range pollinators of—nectar-bearing flowers of the forest canopy, as well as terrestrial flowers, such as lantana. They are strong flyers and seek sunlit spots in which to bask.