Marvelous Spatuletail

The male has only four tail feathers, whereas nearly all other birds have ten or twelve, and two of those four have been transformed into long, thin, largely bare shafts, each ending in a broad, rounded, iridescent violet-blue disc or racket. These two streamers can be several times the length of the bird's body, and crucially the male can move each one independently, crossing them over his back, swinging them out to the sides, and waving them in front of a female. No other hummingbird, and few other birds of any kind, has a tail structure quite like it, which is the source of both the common name and the scientific name, mirabilis, meaning wonderful or astonishing.

A courting male selects a display perch and, when a female arrives nearby, launches into an intense aerial performance in which he hovers directly in front of her, sometimes for less than a second at a time before repositioning, and rapidly flourishes the two racket-tipped tail feathers around and over his body, moving them separately so the blue discs flash and swing through the air. He also puffs out his brilliant turquoise throat patch. The display is so physically demanding that males have been filmed landing to rest and catch their breath between bouts, and only the fittest males can sustain a display impressive enough to win a mate.

The species is restricted to the montane forests and scrub of a single river valley on the eastern Andean slopes of northern Peru, an unusually tiny distribution even by hummingbird standards. It is thought to be adapted to a specific narrow band of elevation, climate, and vegetation found in that valley, and to be limited by the availability of the particular flowering plants it feeds on and the forest-edge and thicket habitat it favours. Its restricted range is a major part of why it is considered Endangered, since a species confined to one small area is highly vulnerable to habitat loss, disease, or other localised threats affecting that single place.

The main threat is loss of its already limited habitat, as forest and scrub in the Utcubamba valley are cleared for small-scale agriculture, cattle pasture, and firewood collection, fragmenting the areas where the birds can live and feed. Historically, males were also killed so that their hearts could be eaten as a purported aphrodisiac. Conservation responses have included establishing protected reserves within the valley, planting native nectar-producing shrubs and trees favoured by the birds, and running education programmes with local communities, and the marvelous spatuletail has become something of a flagship species for conservation of the region's cloud forest.