The striking appearance of male hummingbirds, contrasting sharply with the more muted females, is known as sexual dimorphism. This difference evolved because males compete for mates and perform conspicuous courtship displays, requiring elaborate, showy features. Recognizing these visual traits is the most reliable way to distinguish an adult male from a female or a juvenile bird.
The Signature Feature: Iridescent Gorgets
The most distinctive feature of a male hummingbird is its gorget, a patch of specialized, brightly colored feathers covering the throat and sometimes extending to the head. This intense coloration is not caused by pigment but by structural color, which relies on the physics of light. The feathers contain microscopic structures that selectively reflect and refract light, creating the dazzling, metallic iridescence. The color’s appearance changes dramatically based on the angle of the light and the observer’s position, sometimes flashing brilliantly and other times appearing dark or black.
Distinctive Body Size and Structure
Female hummingbirds are generally slightly larger and heavier than males in many species, accommodating the biological demands of egg production and nesting. Conversely, the male’s slightly smaller size and lighter build favor the agility and speed required for aerial courtship displays. The male’s overall body plumage is typically a glossy metallic green on the back and crown, with a grayish or buffy underside. Some males also exhibit slight differences in bill structure, occasionally having a shorter or straighter bill related to the aggressive defense of feeding territories.
Tail and Wing Differentiation
The tail structure of male hummingbirds is a clear visual indicator, specialized for courtship and display flights. Unlike the female’s more rounded tail, the male’s tail feathers frequently have a distinct shape, such as a deep fork, a notched end, or elongated, tapered outer feathers, which are used during high-speed pendulum dives. The wings also have subtle structural differences. In some species, the shape of the outer primary feathers generates a distinct auditory effect—a unique buzzing, trilling, or whistling sound—that advertises the male’s presence.
Visual Identification of Common Male Hummingbirds
The combination of the gorget, crown color, and tail shape allows for practical identification of common North American male hummingbirds. The male Ruby-throated Hummingbird, found in eastern North America, is recognized by its brilliant, metallic ruby-red gorget and a distinctly forked, all-dark tail, contrasting sharply with his emerald green back. The male Anna’s Hummingbird, common along the Pacific Coast, displays a rose-red or fuchsia gorget that extends upward to cover the entire crown or forehead. The Rufous Hummingbird male is largely rusty-red or rufous over its back and flanks, with an iridescent copper-red or orange gorget. His tail is notably tapered with rufous and black feathers.