National Geographic : 2007 Jul
All birds of paradise descend from crow like ancestors, but only manucodes still look the part. Males and females are nearly identical and likely monogamous, unlike their flashy, flirtatious kin. MANUCODIA COMRII under their rule, and the Dutch followed suit in 1931. Today no birds of paradise leave the island legally except for scientific use. The indigenous people of New Guinea revered the birds long before outsiders paid heed. The finest plumes were used as bride price, and the birds figure prominently in local myths as an cestors and clan totems. They are revered still. "We love these birds," says a lowland tribesman. "The people of my family arebirds of paradise." Anthropologist Gillian Gillison of the Uni versity of Toronto lived among New Guinea tribes for more than a decade. She points to a myth in which a girl places her brother's lifeless body in a hollow tree. She strikes the tree, and birds of paradise explode upward like smoke and downward like fire. The smoke represents dark, highland birds, the fire vivid, lowland species. "To local people, the feathers are relat ed to the spirit flying," she says. "They also sym bolize a birth. They're the origin of the world." With their glam attire and sexual theatrics, birds of paradise also embody a biological mystery: Why would evolution, with its pitiless account ing of cost and benefit, tolerate such ostentation, much less give rise to it? After all, exhibitionism is expensive, in biological terms, and a red flag to predators. 94 NATIONAL GEOGRAPHIC * JULY 2007 "Here in New Guinea it isn't nature tooth and claw, but nature with painted skirt and crowned brow-a bird drag show," says biologist Ed Scholes of New York's Museum of Natural His tory. "Life here is pretty comfortable for birds of paradise. The island's unique environment has allowed them to go to extremes unheard of elsewhere." Under harsher conditions, he says, "evolution simply wouldn't have come up with these birds." Fruit and insects abound all year in the forests of New Guinea, the largest tropical island in the world, and natural threats are few. Linked to Australia until about 8,000 years ago, the 1,500 mile-long island shared much of its neighbor's fauna. Marsupials and birds were plentiful, but placental mammals were entirely absent, mean ing no monkeys and squirrels to compete with birds for food, and no cats to prey on them. The result: an avian paradise that today is home to more than 700 species of birds. Freed of other pressures, birds of paradise began to specialize for sexual competition. Traits that made one bird more attractive than another were passed on and enhanced over time. Known as sexual selection, this process "is to birds of paradise what natural selection is to Darwin's finches-the prime mover," says Scholes. "The usual rules of survival aren't as important here as the rules of successful mating."