Lecture 31

Listen to part of a university lecture by a professor of Natural History

Professor: Now, as a part of our study of biological evolution and evolutionary processes, let’s look for a few minutes at an extraordinary group of bird species, the Birds of Paradise. You may’ve seen pictures of some of these fantastic birds– I think there’s one in the next chapter of our textbook. The male Birds of Paradise are incredibly beautiful creatures. They have extremely elongated and very elaborate sets of many-coloured feathers arising from their head and tail and wings, and when the males display for the females during courtship, they can erect and manipulate these feather tracts, waving or shaking or twirling or wiggling these feathers. And at the same time they often assume very odd postures or do acrobatics- so they put on quite incredible performances to attract females.

In fact, the male plumage is so gorgeous that Bird of Paradise skins have been highly valued trade items for hundreds, if not thousands, of years. The Birds of Paradise are restricted almost entirely to the tropical jungles of the New Guinea archipelago, to the large island of Papua-New Guinea and its surrounding islands. Not only have the Papuan men traditionally adorned themselves with Bird of Paradise feathers since before history, but these feathers appeared as rare and valuable trade goods in other parts of Asia as long as two thousand years ago.

However, they weren’t discovered by the Western world until the sixteenth century. In 1520, the famous Portuguese explorer, Ferdinand Magellan, was given several Bird of Paradise skins by the Sultan of Batchian- in the Moluccan Islands- and they created quite a sensation back in Europe. As exploration expanded, more and more skins were sent to the United States and Europe, and the beauty of the feathers resulted, of course, in their becoming fashionable decorations for ladies’ hats. By the end of the nineteenth century, thousands of trade skins had been exported from New Guinea. Through London alone, between the years 1904 and 1908, 155,000 skins were imported.

Luckily, it was about this time that groups like the Audubon Society and the Royal Society for the Protection of Birds were becoming active defenders of wildlife, and from 1908, laws banning the import of bird feathers were beginning to be passed in many countries. In 1955, the government of Nepal was having difficulty getting new Bird of Paradise plumes for the Royal Nepali crown for the coronation of their new King, Mahendra, until they finally arranged for replacements from an illegal shipment of skins that had earlier been confiscated by the US Customs Service.

At last, in 1990, Indonesia itself passed a law banning the trade in Bird of Paradise skins. Incredibly, none of the Birds of Paradise are Endangered species today, although several are on the Vulnerable list and on the Near Threatened list. Today, only sustainable hunting for ceremonial purposes is permitted to the local native tribes.

There’s about forty species of Birds of Paradise, and they’re really outstanding examples of the evolutionary phenomenon of species radiation from a single ancestor, because each isolated mountain range in the New Guinea archipelago has its own unique, endemic species- species that’re found nowhere else in the world. The Birds of Paradise are all very closely related-actually, they’re all closely related to our common crows!- but each species has evolved in isolation into something that looks and behaves very different from its relatives on the next mountain or in the next valley. In fact, elevation is probably the single most important ecological sorting mechanism for the adaptive radiation of these birds into so many different, unique forms.

On top of their extraordinary plumage, these birds’ve also developed a whole range of breeding strategies. A few species are monogamous- which means that one male and one female mate and raise young. But most species are polygamous, where the males try to attract and mate with as many females as possible, and the females raise the young birds alone. Some of these polygamous males perform single, non-territorial displays when they find a female. In other cases, the single male frequents some sort of regular display ground, called a ‘court’, where he may clear a space and perform for passing females. And in yet other species, the males gather at distinctive, traditional, communal display grounds called ‘leks’. Here, many males will compete for female attention and perform as energetically as they can, because the females choose the ones who put on the best show. The native Papuans call these performances ‘sakaleli’ or ‘dancing parties’, and they are truly amazing exhibitions. Just picture a dazzling gold-white-and-green Greater Bird of Paradise, who leans forward and downward, and lowers his open wings to display his large, lacy, golden flank feathers raised above his back and over his head like Japanese fans. Or the immaculate black-and-turquoise Blue Bird of Paradise, who hangs completely upside-down and flexes his legs slowly and rhythmically to vibrate his long, thin tail feathers for the ladies.

This big, sequential radiation of behaviours and plumages- as well as similar sequential variations in morphology and feeding habits- is a really rich source of research opportunities for graduate students, and I hope that some of you will have the chance to participate in Bird of Paradise research during your careers, because they are amazingly beautiful birds with fascinating habits.