WSJournal. How to Impress a Bird

Even their names are vivid: Magnificent Riflebird. Splendid Astrapia. Superb Bird-of-Paradise.

Found in the New Guinea region and in parts of Australia, birds of paradise are a study in evolution and sexual selection. Males often have extravagant, colorful plumage to attract potential mates, made possible by a shortage of predators (there's less danger their appearance will attract unwanted attention). And in most species, the males perform complicated courtship dances. The exhibit "Birds of Paradise" at the National Geographic Museum in Washington, along with a book by Tim Laman and Edwin Scholes, offers research, photographs and video of the 39 species of the bird—which, naturalist Alfred Russel Wallace wrote in 1869, "must be ranked as one of the most beautiful and most wonderful of living things." Here is a look at some photos from the book; the exhibit runs until May 12.

GREATER BIRD OF PARADISE. Nearly every morning, the adult males of this species gather on branches and display their yellow feathers. In one courtship pose, the male turns away from the female on a downward-sloping branch so his plumes cascade over his back.

VICTORIA'S RIFLEBIRD. Sexual selection at work: This male riflebird shows how female mating preferences have altered the aerodynamically optimal wing shape in favor of blunttipped feathers that make an attractive ovoid display.

WILSON'S BIRD OF PARADISE. Evolving in isolation on New Guinea's mainland, both males and females of this species have an unusual skullcap of bare blue skin subdivided by a narrow web of tiny feathers.

SPLENDID ASTRAPIA. Because iridescence works subtly, this male looks black from most human vantage points. But when the angle and light are right, its colors are astonishing.