Sunday, March 18, 2001		Nature

These legendary birds of paradise are exotic
By Nutan Shukla

BIRDS of paradise are known for their extraordinary colourful plumage, and their bizarre and exotic appearance. Females are dull in colour, but males are brilliantly hued with iridescent plumage. Why these birds have been given this heavenly name has a very interesting story behind it. In 1522, the surviving ship of Magellan’s round-the-world expedition returned to Spain, loaded with gifts for King Charles V from a ruler of the Molucca Islands. The presents included feathers with exotic shapes and brilliant colours. When the people of Spain saw these feathers they could not believe that such beautiful things came from forests in south-east Asia, they thought the feathers must have come from paradise. Hence these birds were given the name birds of paradise.

Found in Papua New Guinea, north-eastern Australia and Maluku (formerly the Moluccan Islands), some species of birds of paradise perform courtship displays on special branches, while others on carefully prepared courts on the floor of the forests. In both cases a great deal of preparation is done by the males. In the case of magnificent bird of paradise the male spends most of his time trimming away the twigs and branches of the tree to enable light to penetrate. He continues doing it until a bright shaft of sunlight pierces through the darkness of the forest and illuminates his display patch like the spotlight does on the stage. After the ‘light-arrangements’ are made, the male performs his displays with his beautiful, iridescent plumage shimmering with dazzling highlights. This helps the female spot him.

There are 20 genera with 43 species of these birds. The brilliant orange plumes of the male raggianas, or Count Raggi’s birds of paradise, are seen at their best during the birds’ spectacular courtship dances.

Males gather in groups at traditional courting sites in trees, each defending its own perch. When the brown females arrive, the males begin a frenzied bout of songs and dance, hopping about, flapping their wings and shaking their orange tail feathers. They then freeze in a head-down posture that shows off their tail feathers and allows their female visitors to inspect them.

If a female does not find a male she likes, she moves to another display area. But if she does find one, she perches beside him. The male then performs a brief precopulatory dance, almost inverted and throwing his feathers over his head and into her face, while she plucks at his feathers. Once mated, the female flies off to lay her eggs and to raise her young on her own. The male birds, meanwhile, await the next female visitor, and then begin the whole procedure again.

When a magnificent blue bird of paradise, another member of the family, wants to find a mate, he hangs upside-down high on a prominent branch in the New Guinea rain forest and stages a brilliant show. His iridescent blue tail plumes are spread out in a shimmering mass above his velvety black head and breast, and his two extra-long black tail straps rise skywards in graceful curves. Once in this position, he swings to and fro, making strange, grating calls.

When he has caught a female’s eye, the jay-sized bird relies on his spectacular plumage to encourage her to choose him to be her mate.

A courting Emperor of Germany bird of paradise uses his long white flank feathers to catch a hen’s eye — he raises his wings to display them.

After the Europeans discovered these birds, trade in their skin started which continued for a few centuries. The highest quantum of export was from Papua New Guinea and the neighbouring islands. Skins of these birds were prepared by removing not only the flesh but also the legs and feet. With this fairy-tale-like stories started floating about these birds saying that they needed no feet since they never landed on the earth but flew always in the sunlight.

It was in the year 1824 that the real story about these birds came to light when a French naturalist Rene Lesson visited north-western Papua New Guinea. The celebrated British naturalist Alfred Russel Wallace came to the country 26 years after Rene Lesson in 1950s. Visits of these people had both positive and negative impact on the future of these birds. While on the one hand, the world came to know about the reality of these creatures, on the other, it also set off disastrous trade in bird plumes. There was a time when the skin of these birds became the most-sought-after item throughout the world.

It is believed that brilliant colours, extraordinary shapes of feathers and the courtship behaviour of males have evolved through sexual selection. However, it has not been proved, but scientists believe that the females choose the most colourful and attractive male as their mate. In this way it is the success of the showiest, rather than the survival of the fittest.

The theory of sexual selection, first given by Charles Darwin, tries to explain why females prefer strong, sturdy, healthy or colourful males.

There are two ways in which males compete to win over females. In one, males may fight over females. Among the various animal species where fight and victory is the decisive factor, females opt for males which are the largest, strongest or have the most effective weapons, as in the case of antlers of stags. The other form is less direct. In such cases mating success depends on how effective a male is in attracting and stimulating females. Here elaborate displays by males and those physical characteristics that are associated with these displays such as bright and vibrant colours and elaborate plumage play an important role. The brilliantly coloured plumage and courtship displays of birds of paradise are believed to have evolved through this form of sexual selection based on female preference.

In fact sexual selection is a powerful force in the evolutionary process that arises when some males are more successful than others in obtaining mating partners which tend to pass on whatever characteristics enabled them to do so to their offsprings. Consequently, the characteristics (in the form of genes) that enable males to find mates will spread rapidly through a population, and will become more and more pronounced.