The White-throated Mountaingem Hummingbird (Lampornis castaneoventris) is a small hummingbird native to the mountainous regions of Central America. With its glittering emerald green upperparts, clean white underparts, and signature white-edged throat, this species is one of the most striking hummingbirds in its range.
The White-throated Mountaingem Hummingbird is a mid-sized hummingbird, measuring about 4 inches long with a wingspan of 5 inches. As its name suggests, this species is most commonly found in mountainous areas between 1500-3200 meters in elevation. Its breeding range extends from southern Mexico through Guatemala, El Salvador, Honduras and Nicaragua.
Some key identifying features of the White-throated Mountaingem include its brilliant metallic green upperparts and crown, clean white underparts, and the distinctive white margins on the sides of its black throat. The long bill of the male is reddish in color with a black tip. Females are similar in appearance, but lack the red bill and have white margins on the throat instead of black. Juveniles resemble adult females.
Taxonomy and genetics
The White-throated Mountaingem is classified in the family Trochilidae and the genus Lampornis. Within the genus, its closest relative is the endemic Amethyst-throated Mountaingem of Costa Rica and western Panama. Genetic analyses reveal these sister species diverged approximately 1 million years ago.
There are three recognized subspecies of the White-throated Mountaingem:
L. c. castaneoventris – The nominate subspecies found in Guatemala, El Salvador and Honduras. Males have extensive purple-blue on uppertail coverts.
L. c. lampropygius – Found in southern Mexico. Males lack extensive purple-blue in tail and have more white behind the eyes.
L. c. mexicanus – Occurs in northern Nicaragua. Intermediate in appearance between the other two subspecies.
Habitat and range
The White-throated Mountaingem frequents cloud forests and pine-oak woodlands in mountain ranges and high valleys. Its elevational range extends from around 1500 meters up to 3200 meters. Typically it forages in areas with plenty of flowering plants and larger trees for perching.
This species ranges from Chiapas state in southern Mexico, south through Guatemala, El Salvador, Honduras, and into north-central Nicaragua. The largest populations occur in protected mountainous areas like Sierra de las Minas Biosphere Reserve in Guatemala. Fragmentation of forest habitat in some parts of its range has caused local declines.
Like all hummingbirds, the White-throated Mountaingem feeds on nectar from flowers using its specialized long bill. Some favorite food plants include species in the genera Fuchsia,Drymonia, Centropogon and others with long, pendulous flowers adapted for pollination by hummingbirds. This species prefers flowers with higher sucrose concentrations. It also supplements its diet with small insects like gnats, aphids, and spiders.
The White-throated Mountaingem uses its bill to stab at flowers multiple times in quick succession to extract nectar. Its long, specialized tongue allows it to lap up nectar at a rate of over 10 licks per second! The rapid licking is accompanied by buzzing sounds from the beating of its wings.
Several unique evolutionary adaptations allow the White-throated Mountaingem to thrive in its mountainous habitat:
– High metabolisic rate – Hummingbirds have among the highest metabolic rates of any animals. The Mountaingem’s high metabolism allows it to sustain hover-feeding and endurance flight in the thin mountain air.
– Rapid heat loss – Dilated blood vessels in its skin allow the Mountaingem to quickly dissipate excess body heat generated during exertion. This prevents overheating in warm valleys.
– Cold torpor – To conserve energy overnight, the Mountaingem enters a deep torpor lowering its body temperature and metabolic rate. This adaptation is essential for surviving frigid high-elevation nights.
– Short wings – The wings of White-throated Mountaingem are comparatively short for a hummingbird. This improves agility and lift generation in confined mountain spaces.
Courtship and breeding
The breeding season for the White-throated Mountaingem runs from March to June. During this time, courting males perform elaborate aerial displays to impress females. Dives, loops and sudden U-turns are incorporated into the aerial dances.
Females build a compact cup nest out of soft plant fibers, spider webs, and lichen on a protected horizontal branch or in a tree fork. The female takes sole responsibility for constructing the nest over a period of 10-12 days. She incubates the 2 pea-sized white eggs for 15-19 days before they hatch.
The chicks are born helpless, with closed eyes and few feathers. Both parents share duty feeding the chicks with regurgitated insects and nectar. After fledging at 20-26 days old, the young hummingbirds reach independence. In captivity, White-throated Mountaingems have been known to live up to 12 years.
Status and conservation
The White-throated Mountaingem is evaluated as Least Concern on the IUCN Red List of Threatened Species. Its extensive range and populations are relatively stable currently. Local declines have been observed where mountain forests have been logged or converted to pine plantations.
This species occurs in a number of protected areas across its range. Some key reserves include El Impossible National Park in El Salvador, La Muralla National Park in Honduras, and Tajumulco Wildlife Sanctuary in Guatemala. Continued protection of higher elevation cloud forests and pine-oak habitats will benefit the long-term outlook for the Mountaingem.
The dazzling White-throated Mountaingem is a specialized hummingbird exquisitely adapted to a mountain existence. Traversing pine-oak and cloud forest habitats from southern Mexico to Nicaragua, this species exhibits unique evolutionary adaptations for life at high elevations including energetic flight, heat dissipation abilities, cold torpor, and short wings. While currently stable in population, habitat protections in its mountainous realm will continue to be needed into the future to ensure the persistence of this jewel of the highlands.