Anna’s Hummingbird

Overview

Anna’s Hummingbird (Calypte anna) is a dazzling, pugnacious, and remarkably hardy trochilid that ranks among the most familiar and beloved backyard birds of western North America. Resident year-round along the Pacific coastline, this stocky, medium-sized hummingbird defies typical migratory patterns by remaining in temperate northern zones throughout freezing winter storms. The male is world-renowned for his breathtaking, iridescent ruby-magenta ‘gorget’ and crown that blazes like incandescent gemstone fire when angled toward the sun, complemented by metallic bronze-green upperparts and pale gray breast feathers.

Beyond its radiant beauty, Calypte anna is an undisputed master of high-speed aerial acrobatics. During springtime courtship displays, territorial males perform dramatic high-altitude dives, plunging toward the earth from heights of over 100 feet (30 meters) before pulling out of the dive at speeds exceeding 60 miles per hour, producing an explosive, metallic chirp with their specialized outer tail feathers. Highly adaptable to human presence, the proliferation of urban exotic gardens and backyard nectar feeders has fueled a historic northward expansion of its breeding range over the past century.

Biology and Physical Characteristics

The physical mechanics of Anna’s hummingbird represent a pinnacle of physiological engineering. Flapping its wings between 40 and 55 beats per second, it can hover motionless in three-dimensional space, fly backward, and execute instantaneous direction reversals. Its metabolic rate is one of the highest in the vertebrate kingdom, requiring heart rates up to 1,260 beats per minute during flight. To survive cold winter nights when flower nectar is unavailable and temperatures plunge below freezing, Calypte anna enters a profound physiological state known as torpor, dropping its body temperature from 104°F (40°C) down to near-ambient temperatures (as low as 48°F / 9°C) to conserve critical energy.

Behavior and Ecology

Anna’s hummingbirds are fiercely territorial solitary birds. Males aggressively defend patches of nectar-rich flowers and artificial feeders from all intruders—including other hummingbirds, large bumblebees, and even passerines—perching prominently atop exposed branch tips and singing a scratchy, buzzing metallic song that is unusual for hummingbirds. Courtship involves the famous ‘shuttle dance’ and 130-foot vertical dive. Females build tiny, exquisite cup-shaped nests constructed from plant down and animal hair bound tightly with sticky spider silk and camouflaged with lichens, laying two tiny, bean-sized white eggs in early winter.

Conservation and Human Impact

Calypte anna is categorized as Least Concern on the IUCN Red List, with a thriving and rapidly expanding continental population estimated at over 8 million individuals. Unlike many migratory avian species threatened by urban expansion, Anna’s hummingbird has benefited immensely from residential landscaping, ornamental winter-flowering plants like eucalyptus, and widespread year-round supplementary feeding.

Interesting Factoid

Relative to its tiny body size, a male Anna’s hummingbird in its courtship dive travels faster than a fighter jet, reaching speeds of 385 body lengths per second—and at the bottom of the dive, it experiences gravitational forces approaching 10 Gs.