The Rufous-shafted Woodstar (Chaetocercus jourdanii) is a small hummingbird that is found in parts of western North America. With its glittering green and red plumage and long, slender bill, this species is a beautiful addition to the diverse hummingbird family.
The Rufous-shafted Woodstar belongs to the hummingbird family Trochilidae. There are over 300 different species of hummingbirds, all located in the Americas. Hummingbirds are the smallest birds in the world, with most species only reaching 3-5 inches in length. Despite their tiny size, hummingbirds have incredibly high metabolisms and fast heart rates needed to support their rapid wing beats and hovering flight. Their diet consists mainly of nectar, and they serve as important pollinators for many plants. The Rufous-shafted Woodstar is medium-sized for a hummingbird and exhibits marked sexual dimorphism. The males have vibrant iridescent green crowns and throats with a reddish-pink belly, while the relatively drab females have greenish upperparts and whitish underparts with cinnamon flanks. This species breeds in pine-oak forests in mountainous regions of the western US and Mexico before migrating south to wintering grounds in Mexico. In this article, we will explore the identification, range, habitat, diet, behavior, breeding, conservation status, and unique adaptations of this dazzling hummingbird.
The Rufous-shafted Woodstar averages 3.5-4 inches in length and weighs around .1 ounce. The adult males are unmistakable with their glittering emerald green cap and gorget (throat patch) sharply contrasted against a whitish collar. The back appears olive green while the underparts are vivid reddish-pink fading to a buffy hue on the belly. The outer tail feathers have bold white tips. The long slender bill is mostly black but reddish at the base. Females lack the bold colors of the male and instead have greenish upperparts and a whitish underside with cinnamon flanks. The tail is rounded with white corners. Immature birds resemble adult females but with buffy edges to the feathers. In poor lighting, this species could potentially be confused with other small hummingbirds, but at close range their distinctive plumage makes identification straightforward.
The breeding range of the Rufous-shafted Woodstar extends from southeastern Alaska south through western Canada to the western United States including California, Oregon, Washington, Idaho, western Montana, and Wyoming. Isolated breeding populations also occur in parts of Colorado, New Mexico, and Arizona. After the breeding season, this species migrates through Mexico to wintering grounds located primarily in central Mexico. Vagrant individuals sometimes stray east of the typical range, with a few records as far as Florida and Louisiana. The range overlaps and intergrades with the similar Calliope Hummingbird in certain areas.
This hummingbird inhabites mountain meadows, pine-oak forests, canyon streamsides, and other relatively arid to semi-arid environments at elevations between 4,000-8,000 feet. Breeding occurs at lower elevations within this range, while wintering takes place predominantly at middle elevations. Typical habitat includes open woodlands near meadows, lakes, and streams. Available natural food sources and presence of adequate nesting sites help determine suitable habitat. During the winter, they expand into adjacent scrublands and can even be found in citrus groves and gardens.
Like all hummingbirds, the Rufous-shafted Woodstar feeds mainly on nectar from colorful tubular flowers. Some favorite natural food plants include Indian paintbrush, columbine, larkspur, trumpet vine, monkeyflower, and penstemon. The long, slender bill allows access to nectar of even the deepest blooms. The tongue is forked to aid in lapping up liquid. To obtain protein, these birds capture small insects such as gnats, aphids, and spiders while hovering. Sap from wells created by sapsuckers is another dietary component. Feeders stocked with sugar water are readily visited by this species, especially during migration and winter when natural food sources become scarce.
The Rufous-shafted Woodstar exhibits typical hummingbird behaviors. Males are highly territorial, using aerial displays to chase intruders from their feeding areas. Fast dives and rapid wingbeats make for dynamic chases. Females also defend their nesting areas against other females. Both sexes are solitary outside of the breeding season, not associating with each other except when mating. Despite their small size, hummingbirds are relatively aggressive, and even consume insects for the protein boost needed to maintain their turbo-charged lifestyle. This species can be observed perching more often than other hummingbirds. Unique traits include a butterfly-like flight display and singing from exposed perches. Males have courtship dives up to 100 feet. The wings beat an estimated 25-80 times per second depending on activity. This rapid beating creates the signature humming noise.
The breeding season for this species runs from May to July. The males arrive first to claim the best nesting areas with plentiful flowers. After the females return from migration, mating occurs. The male will perform courtship displays to entice the female, diving through the air in looping patterns while vocalizing with buzzing songs. Once paired, the female builds a delicate cup-shaped nest out of soft plant down and spider webs on the upward-slanting branch of a coniferous tree. Lichens and moss adorn the exterior for camouflage. The eggs are tiny white ovals, usually just two in number. Only the female cares for the nest, incubating the eggs for about 16-17 days. The chicks hatch unable to see and with minimal down. The female feeds the chicks with regurgitated insects and nectar, and they fledge in around 20-26 days. More than one brood may be raised per season.
The Rufous-shafted Woodstar is evaluated as a species of Least Concern on the IUCN Red List. Partners in Flight estimates the global breeding population at 1.5 million, with 67% spending part of the year in the U.S. Numbers seem to be stable overall, though local declines have occurred in areas of southern California. Threats include habitat loss and degradation, climate change affecting food sources, and competition with other bird species for nest cavities. Providing artificial feeders with sugar water may help supplement food availability. Maintaining native plant communities that offer critical nectar resources through responsible land management practices can also benefit the species. Limiting insecticide use reduces prey availability impacts. Careful monitoring of populations across the range is recommended to detect any emerging trends. With appropriate conservation measures, this dazzling pollinator and aerial acrobat can continue lighting up the skies across western North America.
The Rufous-shafted Woodstar possesses many exquisite and specialized adaptations to facilitate its nectar-feeding lifestyle:
– Bill: The long, slender bill is a key adaptation for accessing nectar at the base of long tubular flowers. The bill’s precise fit allows the bird to efficiently extract more nectar.
– Tongue: The extensible tongue tips are forked to lap up liquid nectar. When retracted, it coils up in a unique shape to fit around the skull.
– Flight: Aerodynamic body with articulated shoulder joints permits precise maneuverability in flight, including the ability to hover and fly backwards. This allows efficient nectar feeding while on the wing.
-Vision: High resolution vision adapted for discerning colorful flowers and identifying nutritious nectar sources.
– Metabolism: Extremely high metabolic rate enables the rapid energy demands of flight. Heart rate reaches over 1,200 beats per minute during flight.
– Digestion: Rapid digestion allows processing of huge amounts of nectar for energy. Kidneys efficiently eliminate excess water from all the nectar.
– Thermoregulation: High body temperature around 104-105 F maintained even at night by entering periodic torpor. This aids survival in cold alpine environments.
– Feathers: Lightweight, intricate feathers minimize drag. Some feathers utilize iridescence to attract mates.
– Feet: Tiny feet used mainly just for perching, not walking or hopping.
– Migration: Some populations migrate enormous distances up to 2,000 miles between breeding and wintering grounds. Navigation skills orient the bird on these long journeys.
– Reproduction: High-energy demands of courtship displays and the fact that the female alone cares for the needs of her offspring requires numerous behavioral and physiological adaptations in the breeding season.
The characteristic features of the Rufous-shafted Woodstar reveal the many specialized traits that enable its success in accessing nutritious floral nectar while navigating the dynamic and demanding lifestyle of a tiny hummingbird. Continued research helps provide an even deeper appreciation of this species’ unique evolutionary adaptations.