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Birdwing

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Template:Taxobox begin Template:Taxobox image Template:Taxobox begin placement Template:Taxobox regnum entry Template:Taxobox phylum entry Template:Taxobox classis entry Template:Taxobox ordo entry Template:Taxobox subordo entry Template:Taxobox superfamilia entry Template:Taxobox familia entry Template:Taxobox subfamilia entry Template:Taxobox tribus entry Template:Taxobox genus entry
Hübner, 1819 Template:Taxobox end placement Template:Taxobox section subdivision Many; see article Template:Taxobox end Birdwings are large, tropical papilionid butterflies native to mainland and archipelagic Southeast Asia and Australasia (with one Indian species), and are usually regarded as belonging to three genera: Ornithoptera, Trogonoptera and Troides. Other genera are recognised by some authorities, with a species count ranging from ca. 10–30. Birdwings are named for their exceptional size, angular wings, and birdlike flight.

Included among the birdwings are the largest and some of the rarest butterflies in the world: the largest, Queen Alexandra's Birdwing (Ornithoptera alexandrae); the second largest, the Goliath Birdwing (O. goliath); and the largest Australian butterfly, the Cairns Birdwing (O. euphorion). Another well-known species is Rajah Brooke's Birdwing (Trogonoptera brookiana), a particularly attractive species named after Sir James Brooke, the first White Rajah of 19th century Sarawak.

High demand from collectors, logging, and plantation expansions, have led to sharp population declines of most birdwing species. With one exception, all birdwings are listed in Appendix II of CITES as either vulnerable or rare, and accordingly their trade is restricted in countries party to the CITES convention. Exceptions are made for captive-bred specimens which are marketed via the Insect Farming and Trading Agency of New Guinea [1]. However, O. alexandrae is totally protected (Appendix I: endangered) and cannot legally be sold. This species is now known to be more common than previously thought and therefore it may, one day, be relegated to Appendix II and farmed commercially.

Adult physical description

Birdwings are typified by large size (up to a maximum body length of 7.6 cm [3 inches] and a wingspan of 28 cm [>11 inches] in O. alexandrae), showy coloration (in contrasting shades of green, yellow, black, white, and sometimes blue or orange), and slender, lanceolate forewings. With few exceptions (i.e., the New Guinean O. meridionalis and O. paradisea), the hindwings lack tails. Sexual dimorphism is strong in Ornithoptera species only, with females appreciably larger and less colourful than males.

A male Rajah Brooke's Birdwing at a Kuala Lumpur butterfly conservatory.

Males and females of most Troides birdwings are similar and have jet black to brown dorsal forewings, often with the veins bordered in grey to creamy-white. At least one of these darkly-coloured species (T. rhadamathus) possesses thermoreceptors on the anal veins (A2 and A3) of the wings and on the antennal clubs. The antennal receptors of the clubs—which also possess hygroreceptors that measure atmospheric humidity—are known as sensilla basiconica. The thermoreceptors are sensitive to sudden increases in temperature; they are thought to help the butterfly thermoregulate and avoid overheating while basking.

The colours of most species are pigmentary (via papiliochrome); but two species, Troides magellanus and the much rarer T. prattorum, are noted for their use of limited-view iridescence: the yellow of the dorsal hindwings is modified by bright blue-green iridescence which is only seen when the butterfly is viewed at a narrow, oblique angle. This "grazing iridescence" is brought about through diffraction of light (after back-reflection) by the wings' extremely steeply-set, multilayered rib-like scales (rather than the ridge-lamellae of most other iridescent butterflies, such as Morpho species). Such limited-view iridescence was previously only known from one other species, the lycaenid Ancyluris meliboeus. In A. meliboeus, however, the iridescence is produced by ridge-lamellar scales and features a wider range of colours.

Life history

File:Troides euphorion.jpg
Australia's largest butterfly, this Cairns Birdwing was photographed in Kuranda, Queensland.

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.

Breeding behaviour varies little between species: the female's role is relatively passive, slowly fluttering from perch to perch while the male performs an elaborate, quivering yet stationary dance 20–50 cm above her. 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. Some species have tubercles of contrasting colours, 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 chrysalides 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 ca. four months to get from egg to adult. Barring predation, this species can also survive up to three months as an adult.

List of species

Trogonoptera trojana male in a Kuala Lumpur butterfly conservatory.

Trogonoptera brookiana
Trogonoptera trojana
Troides aeacus
Troides amphrysus
Troides andromache
Troides criton
Troides cuneifera
Troides darsius
Troides dohertyi
Troides haliphron
Troides helena
Troides hypolitus
Troides magellanus
Troides minos
Troides miranda
Troides oblongomaculatus
Troides plato
Troides prattorum
Troides rhadamantus
Troides riedeli
Troides staudingeri
Troides vandepolli
Ornithoptera aesacus
Ornithoptera alexandrae
Ornithoptera croesus
Ornithoptera chimaera
Ornithoptera euphorion - There is a spectacular rare genetic mutation of this butterfly (less than 40 known examples - all from a single aberrant female) where the males are gold instead of green.
Ornithoptera richmondia - The smallest Ornithoptera species. Occasionally (and wrongly) regarded as a subspecies of O. priamus.
Ornithoptera goliath
Ornithoptera meridionalis
Ornithoptera paradisea
Ornithoptera priamus - Occurs as a number of subspecies, some of which are often regarded as full species e.g. O. (priamus) urvilleanus.
Ornithoptera rothschildi
Ornithoptera tithonus
Ornithoptera victoriae

Two other Ornithoptera 'species' are now regarded as hybrids:
Ornithoptera akakeae (hybrid of O. rothschildi x O. priamus poseidon)
Known from a single female specimen. Ornithoptera allotei (hybrid of O. victoriae x O. priamus urvilleanus) - This butterfly is, because of it's rarity, one of the World's most valuable, with male specimens typically selling for more than £4000.00 (US$7000.00). It would be an ideal candidate for commercial exploitation because its parents are not rare on Bougainville Island and can (apparently) be easily induced to mate with one another. ([2]).

References

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