The king bird-of-paradise, this so-called "living gem", is the smallest and the most vividly colored of the birds-of-paradise. Males are recognizable by their brilliant red coloring and their two long, ornamental wire-like tail feather shafts, and the circular swirl of feathers of bright green on the ends. The underside is white, and there is a green stripe across the chest. A male also features a black spot above each eye. The legs and feet of both males and females are blue; the color of the female is much less bright, with her back, head, and throat being olive-brown and her chest a variegated buff. The lifespan of this species is unknown. Generally a bird-of-paradise lives 5-8 years in the wild and up to 30 years in captivity.
These birds are polygynous, and after mating they go on to attract the next female. A female will incubate the eggs and feed the chicks by herself. Males will display on their own at exploded leks or at traditional arboreal courts in groups. Displays are from October to January. The male displays by perching upright on a branch, vibrating his wings and then holding his body parallel to the branch, spreading his pectoral feathers and raising his tail over his head while dancing. He then swings his tail and then his body side to side and finally hangs upside down on the branch with his wings folded, swinging like a pendulum. Males that do not succeed in impressing the females through their displays may possibly never mate at all. March to October is the breeding season. The females will build and attend their nests alone in the cavities of lower trees. The incubation period is about 17 days and the nestling period is for about 14 days.
King birds-of-paradise are abundant and are not considered as threatened. However the skins and bright feathers of the male are sometimes sought by the native men of New Guinea.
According to IUCN, the King bird-of-paradise is common and widespread throughout its range but no overall population estimate is available. Currently this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today remain stable.