The stripe-breasted starthroat hummingbird is a small, colorful hummingbird found in Mexico, Central America, and parts of South America. With its iridescent green back, white breast with black stripes, and long decurved bill, this species is unmistakable. The stripe-breasted starthroat inhabits a variety of habitats and feeds on nectar from flowering plants and small insects. While not currently threatened, habitat loss puts pressure on some populations. This article will provide an overview of the stripe-breasted starthroat, including its classification, physical description, habitat, diet, behavior, reproduction, conservation status, and unique adaptations.
Classification and Phylogeny
The stripe-breasted starthroat belongs to the hummingbird family Trochilidae and the genus Heliomaster. The Trochilidae family contains all hummingbirds and is diverse, with over 300 described species. Heliomaster is a genus of mid-sized hummingbirds restricted to the Americas. Within this genus, the stripe-breasted starthroat is one of seven similar starthroat species, all possessing elongated decurved bills adapted for accessing nectar from long tubular flowers. Its closest relatives are thought to be the plain-capped starthroat of Mexico and the blue-throated starthroat of Costa Rica.
Physical Description
The stripe-breasted starthroat is a relatively large hummingbird, measuring 11-12 cm (4.5 in) in length with a wingspan of 5.7 cm (2.25 in) and a weight of 5-7 grams (0.2 oz). As its name suggests, it has bright iridescent green upperparts from forehead to tail. Its underparts are snowy white with distinct thick black stripes running vertically down its breast and belly. The male has an iridescent purple-blue crown and throat, while the female’s crown and throat are gray. Both sexes have a long black bill with a slight downward curve and a black mask through the eye. The tail is dark green with white outer tail feathers. Juveniles resemble adult females but with buffy stripes and fringed throat feathers.
Habitat
The stripe-breasted starthroat occupies a range of tropical and subtropical habitats at elevations up to 2500 m. It is found in forest and woodland, second growth, plantations, parks, and gardens. This adaptability allows it to thrive across its range, from southeastern Mexico south to Panama and in disjunct populations in Venezuela, Colombia, Ecuador and Peru. Ideal habitat provides a mix of feeding, nesting, and roosting resources. Key habitat features include flowering plants as nectar sources, sheltered areas for nesting, and high perches for roosting and scanning for food sources and predators.
Diet
Like all hummingbirds, the stripe-breasted starthroat meets its high metabolic demands through a liquid diet of floral nectar and small insects and spiders. It favors flowers with long tubular corollas, using its specialized long bill to access the nectar at the base. Some favorite nectar sources include Heliconia, Drymonia, and Episcia flowers. The starthroat supplements this diet by hawking small insects like flies, wasps, and aphids out of webs and foliage. Its long bill allows the bird to capture insects on the wing with great precision. Foraging occurs from low vegetation up to the high canopy.
Behavior
The stripe-breasted starthroat is solitary and territorial. Males establish breeding territories with plentiful nectar sources which they aggressively defend from intrusions by other males or predators. Their iridescent throats are thought to serve as signals to proclaim territory ownership and threaten rivals. Females, meanwhile, have their own smaller feeding territories distinct from the males’ breeding territories. Outside the breeding season, these solitary birds may congregate in “leks” at favored nectar sources. The starthroat’s small size and rapid flight allow it to energetically defend territories and escape threats. It engages in aerial dogfights with intruders and dives swiftly away from hawks or other predators.
Reproduction
The breeding season of the stripe-breasted starthroat varies across its range, aligning with peak flower availability. In Central America, breeding occurs from November to June. Courtship consists of aerial displays where the male flies in repeated vertical u-shaped or circular patterns to impress females. Once paired, the female builds a small cup nest out of plant fibers and spider webs on a horizontal branch or tree fork 2-15 m above ground. She incubates the two tiny white eggs for 15-19 days. The altricial hatchlings are fed regurgitated food by the female and leave the nest at 22-26 days old. Males play no role in parental care. Females may raise up to two broods per season.
Conservation Status
The stripe-breasted starthroat is evaluated as a species of Least Concern by the IUCN Red List. It has a large range and population, with stable numbers in most regions. However, habitat loss and degradation pose localized threats, especially in parts of Central America. Conversion of natural habitats to agricultural use reduces available nesting sites and nectar supplies. Climate change may also impact flowering cycles and food availability. Protecting areas of natural forest habitat and shade coffee or cacao plantations will benefit stripe-breasted starthroat populations into the future. More research is needed on potential declines in fragmented habitats.
Unique Adaptations
The stripe-breasted starthroat possesses several key anatomical and behavioral adaptations for its lifestyle and feeding strategy:
– Long decurved bill adapted for obtaining nectar from long tubular flowers – this distinct bill shape sets it and other starthroats apart from other hummingbirds
– Small size and rapid metabolic rate necessary for sustaining its energetic hovering flight using wings that can beat up to 70 times per second
– Color vision and excellent eyesight to find flowers and breeding plumage to attract mates
– Breeding territorial behavior using aerial displays and vocalizations to signal ownership of prime habitat
– Highly effective hovering ability allows it to precisely extract nectar and capture small insects on the wing
– Short legs and feet used primarily for perching rather than walking or hopping
– Long slender tongue with forked tip for nectar lapping while hovering at flowers
Conclusion
With its striking plumage and specialized adaptations, the stripe-breasted starthroat hummingbird is a remarkable example of convergent evolution in nectar-feeding tropical birds. As habitat loss accelerates across Mesoamerica, the flexibility and resilience of this charismatic species may be tested. Ongoing conservation efforts aimed at protecting critical breeding and feeding habitat will give the stripe-breasted starthroat the best chance to thrive for many generations. Though small, this beautiful bird fills an important ecological role as a pollinator and controller of insect populations. Learning more about its natural history and developing an appreciation for its unique traits and behaviors can inspire increased conservation attention. The stripe-breasted starthroat provides a window into the amazing diversity of form and function seen across the tropics.