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Birdwings are spectacular butterflies with birdlike flight. The group contains some of the largest butterflies in the world such as the stunning Queen Alexandra's birdwing and the Goliath birdwing, which has such large wings that it takes over 15 minutes for it to crawl out of the chrysalis. The bright males and the large size may be the first thing you notice, but these species have made some interesting adaptations to life in the tropics.
Birdwings are tropical or subtropical butterflies that often live in restricted areas. The Queen Alexandra's birdwing, or Ornithoptera alexandrae, is found in a small strip of lowland coastal rainforest in northern Papua New Guinea. There are between 30 to 40 different species, and wings are often shades of green, yellow, black and white. Some species have orange and blue wings. The males are often sparkling, while the females tend to be brown or black.
Cairns butterfly, or Ornithoptera priamus, can be found in Northern Queensland, Australia. It has adapted to the conditions in the rainforest by laying eggs on poisonous leaves of Aristolochia vines. The caterpillar is not only able to eat the leaves, but the leaves protect them from predators such as birds. The toxins are stored in red spines on the back of the caterpillar, and the colourful spines scare away predators which often are afraid of bright colours. Chemical receptors in the forelegs help the female butterfly to find the right kinds of leaves. She "tastes" various leaves until she find the poisonous ones on which to lay her eggs.
Troides birdwings are found in India and Sri Lanka; they have stunning black or brown dorsal forewings. Some of these species, such as the Sri Lanka national butterfly, Troides rhadamathu, have thermoreceptors. These receptors help the butterfly to measure sudden changes in temperature. Butterflies like to bask in the sun, and in the tropics the temperature can sudden increase; the receptors may help the butterfly to regulate its body temperature. The caterpillar larva has also adapted to the climate by evolving antennal clubs with hygroreceptors, which help the larva to measure the humidity.
Many birdwing female species lay one egg on the underside of the leaf. Often species of butterflies lay several eggs in a cluster. The caterpillars are voracious eaters and they will turn into cannibalism if there is a food shortage. Thus, birdwing butterflies make sure that there is enough food for their caterpillars. The caterpillars tend to not move around; instead they spend their lives in the same place.
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