The white-throated greenback hummingbird is a small, vibrantly colored hummingbird that is native to the tropical forests of Central America. With its bright green back, white throat, and metallic blue crown, this species is one of the most striking members of the Trochilidae family.
Physical characteristics
The white-throated greenback hummingbird gets its name from the adult male’s brilliant emerald green back and bright white throat. The crown and forehead are an iridescent blue-green that appears metallic in bright light. The underside is mostly white with some gray on the flanks. Females lack the male’s striking colors, with a pale gray throat and breast, dull greenish upperparts, and white tips on the tail feathers. Both sexes have straight black bills and reddish feet.
These diminutive birds measure 7 to 8 cm long and weigh around 3 to 4 grams. Their wingspan reaches 10 to 11 cm. Relative to its body size, the white-throated greenback hummingbird has the largest wing area of any bird, allowing it to hover and maneuver with great agility.
Habitat and range
The white-throated greenback inhabits tropical lowland rainforests, forest borders, plantations, and gardens from sea level up to 1500 m elevation. Its range extends from southern Mexico through Guatemala, Belize, El Salvador and Honduras.
Within its Central American range, this species can be found in a variety of wooded habitats. It occurs in evergreen and semi-deciduous forest as well as second growth woodland and forest edges. The white-throated greenback readily visits gardens and agricultural areas with suitable nectar plants.
Diet and feeding
Like all hummingbirds, the white-throated greenback has a fast metabolism and relies on nectar as its main food source. It uses its specialized tubular tongue to lap up nectar from a variety of blooming plants such as heliconias, ginger flowers, and epiphytic bromeliads.
This species also consumes small insects and spiders to meet its nutritional needs for protein. The male will establish feeding territories, chasing other males or species away from preferred nectar sources.
Unique adaptations
The white-throated greenback possesses specialized anatomical and physiological adaptations that allow it to hover and thrive on its high-energy liquid diet. These include:
Wings
The hummingbird’s wings are uniquely adapted for sustained hovering flight. They beat approximately 70 times per second, allowing the bird to float in place while feeding. The bones are hollow to minimize weight.
Feet
The feet are small and weak, used only for perching rather than walking or hopping. The toes have special claws that clamp tightly onto branches.
Metabolism
Hummingbirds have extremely fast metabolic rates to power their wing muscles and process their nectar diet. Their heart rate can reach over 500 beats per minute and they take 250 breaths per minute while feeding.
Tongue
The tongue is long, extendable, and forked at the tip. This allows the bird to efficiently lap up liquid nectar while hovering close to the flower.
Vision
Excellent vision allows hummingbirds to see color wavelengths into the ultraviolet spectrum. This helps them detect nectar guides on flowers. They can also distinguish minute motion to find small insect prey.
Reproduction and breeding
The breeding season for the white-throated greenback runs from November to June, coinciding with peak flower and food availability. Though the species is socially monogamous, both males and females will seek additional mates throughout the breeding period.
Males establish breeding territories with suitable flowering plants that they aggressively defend from intruders. Their courtship display consists of aerial displays over the territory where the male flies in loops and dives to impress watching females.
Once paired, the female builds a small cup nest out of plant fibers, lichen, and moss on a low horizontal branch or tree fork 3 to 10 meters above ground. She will lay two tiny white eggs over 2 separate days. Incubation lasts 15 to 19 days and the hatchlings fledge in about 20 to 26 days. The female cares for and feeds the chicks without assistance from the male.
Migration
Most white-throated greenback hummingbird populations are non-migratory and remain in their resident range year-round. Those that breed at higher elevations may migrate altitudinally up and down mountain slopes to follow the blooming of nectar flowers. There is no long-distance migration to a separate wintering range.
Threats and conservation
Habitat loss is the primary threat facing the white-throated greenback hummingbird. Deforestation for agriculture, logging, and human settlement has reduced its nesting and feeding habitat across Central America. The species is currently classified as Least Concern by the IUCN Red List but population declines are suspected in several areas.
Maintaining protected reserves and shade-grown coffee plantations with adequate flowers provides important habitat for the species. Sugar-water feeding stations in gardens and parks can also supplement its food resources, especially during dry seasons when wild nectar is limited. Limiting pesticide use allows for healthy insect populations that the birds rely on.
Fun facts
Here are a few interesting facts about the dazzling white-throated greenback hummingbird:
- Hummingbirds are the only birds that can fly backwards and upside down
- Their wings beat on average 70 times per second, and up to 200 times per second during courtship displays
- They have the highest metabolism of any animal relative to their size
- Their feet are so weak they can barely walk – they spend nearly their entire lives in flight
- The Aztecs considered hummingbirds sacred creatures and symbols of vigor and energy
- Their range does not overlap with the very similar sparkling-tailed hummingbird
- Males perform aerial “dive displays” during courtship, plummeting over 50 feet before pulling up sharply
- They can lick up to 13 times per second while feeding on nectar
- Hummingbirds are the only birds that have knees that bend backwards (all other birds’ knees bend forwards)
Conclusion
With its vibrant colors, diminutive size, remarkable flight capabilities, and important ecological role in pollination, the white-throated greenback hummingbird is a fascinating and beautiful tropical species. Conserving the rainforest habitats these birds rely on through responsible land management and ecotourism practices can ensure healthy populations of these captivating creatures for future generations. Their uniqueness and charisma make them important ambassadors for the wildlife of Central America.
