Purple-throated Mountain-gem

The purple-throated mountaingem is 10 to 11.5 cm (3.9 to 4.5 in) long and weighs 4.5 to 6 g (0.16 to 0.21 oz). Both sexes of all subspecies have a medium-length straight black bill, a white to pale buff stripe behind the eye, and a fairly long tail. Adult males of the nominate subspecies L. c. calolaemus have a glittering emerald green to bluish green forehead and crown. The rest of their upperparts are metallic bronze-green that shades to bluish or grass green on the uppertail coverts. Much of the face is dusky bronze green and the gorget is metallic violet or purple. The breast is bright metallic green with duller flanks and belly that tend to bronzy green or gray. The undertail coverts are deep bronzy gray with paler gray margins. The tail is dull blue-black. Adult females of the nominate subspecies have bright metallic green upperparts that are somewhat bluish on the uppertail coverts and a bit bronzish elsewhere. The face is mostly blackish. The throat, breast, and belly are tawny yellow and the undertail coverts dull white to tawny buff. The central tail feathers and the upper half of the others are dull metallic green or bronze green. …

Subspecies L. c. pectoralis of purple-throated mountaingem is found from far southwestern Nicaragua to the Cordillera de Guanacaste in northwestern Costa Rica. The nominate L. c. calolaemus is found in the Cordillera Central and northern part of the Cordillera de Talamanca of northern and central Costa Rica. L. c. homogenes is found in western Panama from Chiriquí Province to Coclé Province and probably also in southern Costa Rica. The species inhabits humid montane evergreen forest and cloudforest, where it favors steep slopes and broken terrain. In central Costa Rica it ranges in elevation from 1,200 to 2,500 m (3,900 to 8,200 ft) and is found as low as 800 m (2,600 ft) in northern Costa Rica.

The purple-throated mountaingem feeds mostly on nectar. Males defend patches of flowers from other hummingbird species, from males of its own species, and also from females after courtship. Females are less territorial and often feed by trap-lining. The species takes nectar from a wide variety of flowers. It is the primary pollinator of Psychotria elata and Palicourea lasiorrachis (Rubiaceae). Females have slightly longer bills than males. There is some degree of niche differentiation between the sexes. Though both prefer flowers with a corolla 14 to 21 mm (0.55 to 0.83 in) long by 3.5 to 8 mm (0.14 to 0.31 in) wide, females far more often than males utilize plants with longer and thinner corollas. Like most hummingbirds, the purple-throated mountaingem also feeds on insectes. Males capture them by hawking from a perch. Females hover-glean, often beating their wings against foliage which apparently flushes prey.