The Purple-throated Mountain-gem (Lampornis calolaemus) is a hummingbird which breeds in the mountains of southern Nicaragua, northern Costa Rica and western Panama. This bird inhabits forested areas in hilly terrain, and is found at altitudes from 800 m to 2500 m.
It is replaced in southern Costa Rica by its close relatives, the White-throated and Gray-tailed Mountain-gems, with which it is sometimes considered conspecific. These three species form a closely-related group that evolved some 3.5 million years ago and has diversified since.
It is 10.5 cm long. The male weighs 6.0 g and the female 4.8 g. The shortish black bill is slightly curved.
The adult male has bronze-green upperparts and underparts except for a brilliant green crown, purple throat and dark grey tail. The female lacks the bright crown and throat, and has rich cinnamon underparts. Young birds resemble the female but have buff fringes to the upperparts plumage.
The call of this species is a sharp buzzy zeet.
The food of this species is mainly nectar, taken from a variety of flowers. For the Rubiaceae Psychotria elata and Palicourea lasiorrachis, it is the default pollinator. Like other hummingbirds it also takes small insects as an essential source of protein. Male Purple-throated Mountain-gems defend flowers and scrubs in their feeding territories, and are dominant over most other hummingbirds.
Females have slightly longer bills than males. There is some degree of niche differentiation between the sexes. Though both prefer flowers with a corolla 14-21 mm long by 3.5-8 mm wide, females far more often than males utilize plants with longer and thinner corollas.
The female Purple-throated Mountain-gem is entirely responsible for nest building and incubation. She lays two white eggs in a deep plant-fibre cup nest 0.7-3.5 m high in a scrub, small tree or vine. Incubation takes 15-19 days, and fledging another 20-26.