The bird with metal in its feathers

Livingstone's turaco Tauraco livingstonii

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 red pigments in turaco feathers are wholly unique. And the secret ingredient is... copper.

Turacos are a family of pigeon-sized birds from African forests that adore fruit - 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.

Turacos have another claim to fame. They're the world's only truly green birds. Parrots and many other species may appear green but aren't really. The green in their feathers is structural, so is a sort of optical illusion, unlike the chemical, turacoverdinbased pigment in turacos.

The bird that asks us for help

Greater honeyguide Indicator indicator

PET PARROTS HAVE BEEN KNOWN to ask their owners for things. Alex, the African grey parrot who lived with the scientist Irene Pepperberg and contributed much to our understanding of avian intelligence, would request cuddles. In the wild such interactions are extremely rare. In fact, only one wild bird actively solicits our help the greater honeyguide.