The Glow-throated Hummingbird (Selasphorus ardens) is a small hummingbird species found in Costa Rica and western Panama. With an average body length of 9-10 cm and weight of 2-3 grams, it is a tiny bird identifiable by its vibrant emerald green upperparts and white underparts. The male has a brilliant metallic emerald green throat that appears to “glow” in certain lighting.
The glow-throated hummingbird gets its name from the male’s vibrant, metallic emerald green throat. The throat has a scaled, feathered appearance that seems to glow when hit by sunlight. The rest of the upperparts are also a brilliant emerald green. The underparts are white from the chin down to the tail. The bill is long, straight and black. The legs and feet are gray-black. Females lack the vibrant emerald throat, instead having a pale white throat and belly with green upperparts. The tail is black in both sexes with white tips on the outer tail feathers.
Habitat and Distribution
The glow-throated hummingbird is endemic to lower mountain forest edges and second growth of Costa Rica and western Panama. Its elevational range is from 500 to 1500 m. It can be found along forest borders, forest gaps, gardens and plantations. This species has a small geographic range, being found mainly on the Caribbean slopes of Costa Rica’s Cordillera Central and Cordillera de Talamanca. Recently it has also been found in Veraguas Province, Panama.
Food and Feeding
Like all hummingbirds, the glow-throated hummingbird feeds on nectar from colorful tubular flowers. It uses its long, specialized tongue to dart in and out of flowers to lap up nectar. It also catches small insects such as gnats and fruit flies, feeding opportunistically as it flies and hovers. Favorite nectar sources include flowers from the Heliconia, Costus, Erythrina, Spathodea and Inga plant genera. The long bill allows it to access nectar from long, curved flowers that other shorter-billed hummingbirds cannot.
Breeding and Nesting
The glow-throated hummingbird breeds in the wet season between May to August. Males perform elaborate courtship displays, flying back and forth in rapid u-shaped patterns to impress watching females. Once paired, the female builds a small cup-shaped nest out of plant fibers, lichens and moss on a low horizontal branch or tree fern. She lines the nest with soft plant down. The female lays 2 tiny white eggs. She incubates them alone for 15-19 days. Once hatched, both parents feed the chicks with regurgitated insects and nectar. The young fledge at around 20-26 days old.
Threats and Conservation
The glow-throated hummingbird’s small geographic distribution makes it vulnerable to habitat loss and fragmentation. Deforestation for farming, timber and development has reduced its forest habitat. It may also be threatened by climate change impacting nectar availability. However, its presence inshade-grown coffee plantations and gardens has likely helped buffer some habitat loss. The species is currently classified as Least Concern by the IUCN Red List. Ongoing habitat conservation and further population surveys are needed to ensure this colorful species does not become threatened. Raising awareness and leaving natural areas on farms and plantations can help provide habitat. Providing sugar-water feeders and planting tubular flowers attractive to hummingbirds can also support populations on degraded lands.
– The glow-throated hummingbird has the second smallest known distribution of any hummingbird species in Costa Rica.
– Males make an insect-like buzzing sound with their wings during courtship displays, up to 100 dives per minute.
– Iridescent emerald throat feathers get their color from microscopic light-reflecting structures that refract greens and blues.
– A glow-throated hummingbird’s heart rate can reach over 500 beats per minute while hovering.
– Relative to their weight, hummingbirds have the largest brain of all birds, allowing excellent memory and spatial mapping.
– Hummingbirds can see ultraviolet light, helping them find nectar guides on flowers.
In summary, the aptly named glow-throated hummingbird is a exquisite and range-restricted Central American hummingbird species. Conserving lower mountain forest habitats will help protect the future of this tiny, sparkling-throated hummer and its specialized plant relationships. With an endangered forest home and threats from climate change, there are conservation challenges ahead for ensuring the species persists far into the future.