Due to their size and brightly coloured males, they are popular among collectors of butterflies, but all birdwings are now listed by CITES,[1] 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.

Fleshy spine-like tubercles line the caterpillars' backs, and their bodies are dark red to brown and velvety black.

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 feeding caterpillars incorporate and concentrate the aristolochic acid into their tissues, where the poison will persist through metamorphosis and into adulthood.

Birdwings are typified by large size (up to a maximum body length of 7.6 cm or 3 inches and a wingspan of 28 cm or 11 inches in O. alexandrae), showy colouration (in contrasting shades of green, yellow, black, white, and sometimes blue or orange), and slender, lanceolate forewings.

Sexual dimorphism is strong in Ornithoptera species only, where males are black combined with bright iridescent green, blue, orange, or yellow while the larger and less colourful females are overall black or dark brownish with white, pale brown, or yellow markings.

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.

The thermoreceptors are sensitive to sudden increases in temperature; they are thought to help the butterfly thermoregulate and avoid overheating while basking.

The close evolutionary relationship between Troides and Ornithoptera butterflies is well demonstrated by the fact that commercial breeders have produced numerous hybrids between the two.

All Ornithoptera species are found in the northern portion of the Australasian realm, east of Weber's line; the Moluccas, New Guinea, the Solomon Islands, and northeastern Australia.

At the 2006 meeting of the CITES Animals Committee some suggested O. alexandrae should be moved to Appendix II, as the conservation benefits of sustainable management perhaps are higher than those of the trade ban.

[7] Three Troides and eight Ornithoptera species have been given assessments by the IUCN Red List, with classifications ranging from "least concern" to "endangered".

After consideration, the male may choose to hover twenty to thirty centimeters above the female, displaying the bright yellow marking on its hindwings.

Following insemination, it is common for the male Ornithoptera to produce a mating plug, which will seal the ostium bursae and prevent remating by the female, as new sperm is unable to enter the opening.

Due to the protected nature of Ornithoptera it has been difficult to study the spectral sensitivities of the sexes although this difference in coloration alludes to the idea of sensory exploitation of the female's photoreceptors.

Gynandromorphs are suspected to be due to genetic errors associated with cell division such as nondisjunction, as well as fertilization of binucleate ova and fertilisation of multiple sperm that may fuse and act as a second nucleus.