Many birds have fabulous plumage to attract mates or send warning messages. Some of the colours in their feathers are produced by microscopic structures on the feather surface that absorb and reflect light in a certain way. These are known as structural colours. Other colours are produced by pigments, dye-like substances that occur widely in nature. Birds may make their own pigments or obtain them from their food. But the green and\u00a0red pigments\u00a0in turaco feathers are wholly unique. And the secret ingredient is\u2026 copper.<\/p>\n Turacos are a family of pigeon-sized birds from African forests that adore fruit \u2013 a diet that happens to be rich in copper. The metal is taken up by their bodies and helps to form two dazzling pigments not found in any other bird, or indeed any other animal. Turacoverdin creates vivid green feathers, while turacin turns them red. It was once estimated that an adult turaco would take around three months to eat enough fruit to produce its gorgeous coloration. The more it eats, the brighter its plumage.<\/p>\n Turacos have another claim to fame. They\u2019re the world\u2019s only truly green birds. Parrots and many other species may appear green but aren\u2019t really. The green in their feathers is structural, so is a sort of optical illusion, unlike the chemical, turacoverdin-based pigment in turacos.<\/p>\n The bird that asks us for help<\/strong><\/p>\n Pet\u00a0parrots have been known to ask their owners for things but in the wild, such interactions are extremely rare. In fact, only one wild bird actively solicits our help \u2013 the greater honeyguide.<\/p>\n The behaviour does not occur throughout the honeyguide\u2019s African range. But in parts of Kenya, Tanzania and Mozambique, it\u00a0forms a partnership with humans\u00a0in which both parties benefit. The little brown bird feeds on wild\u00a0honeybee\u00a0nests \u2013 in particular, the larvae and waxy structure. The problem is, bees\u2019 nests are sturdy and well defended. So the honeyguide asks for assistance. Having found a nest in a tree, it uses a squeaky call to attract the attention of people nearby, then repeatedly flies a short way and calls again, guiding its helpers to the nest like a feathery satnav. The human honey hunters climb the tree and soon are sharing the spoils with their guide.<\/p>\n The bird that sings upside-down<\/strong><\/p>\n One of the most bizarre\u00a0bird songs on the planet rings out through the forests and fruit plantations of Central America. It belongs to the male Montezuma oropendola, which produces a torrent of rattles and gurgles with a strangely metallic quality. But that\u2019s not the only remarkable thing about it. The oropendola also likes to sing upside-down, while swinging energetically under his perch like an avian trapeze artist, which no doubt enhances the impact of his singing and helps him attract a mate.<\/p>\n There are other birds that hang upside-down to display to would-be partners, including several\u00a0birds of paradise. But their songs are mostly croaks and can\u2019t compete with the oropendola\u2019s virtuoso vocals.<\/p>\nGreater honeyguide<\/h3>\n
Montezuma oropendola<\/h3>\n