The White-throated Mountaingem, known scientifically as Lampornis castaneoventris, is a hummingbird of striking beauty, endemic to the highlands of Costa Rica and Panama. This avian jewel measures approximately 12 cm in length and tips the scales at a delicate 5 to 6 grams.
Males of the species boast dark bronzy green upperparts with an emerald green crown, while their tail is a contrasting black to bluish black. A distinctive white chin and throat are complemented by bright green sides of the neck and upper breast, with the lower breast and vent area cloaked in dark gray. Females, on the other hand, are adorned with bright green upperparts throughout. Their central tail feathers shimmer with dark metallic to bronze green, and the outer feathers are a paler shade. A dark rufous throat and belly, along with gray undertail coverts edged in white or buff, complete their plumage.
The White-throated Mountaingem is a denizen of the oak forests' interior, edges, and shrubby clearings, as well as gardens nestled close to these wooded areas. It flourishes at elevations from 1,500 meters up to the timberline.
This species is a jewel confined to the mountains of western Panama's Chiriquí Province, where it flits and hovers in its montane realm.
As year-round residents, males of the species are known to be territorial, vigorously defending their floral domains. They exhibit dominance over smaller hummingbirds and show deference to larger species such as the Fiery-throated Hummingbird. Both sexes partake in the pursuit of small arthropods, which they deftly glean from foliage.
The White-throated Mountaingem communicates with high-pitched "ziit" or "ziip" calls and serenades the forest with a 'sputtery, bubbly' song that adds to the rich tapestry of sounds in its habitat.
The breeding season for this species stretches from October to April. The female constructs a delicate cup-shaped nest from fine fibers, adorned with moss and lichen on the exterior. Details on incubation and fledging periods remain a mystery to ornithologists.
The IUCN has classified the White-throated Mountaingem as Least Concern, though it is noted that the species could face threats from human activities such as deforestation for timber and agriculture. Despite its limited range, it is currently considered common within its habitat.