Hummingbirds are birds native to the Americas and comprise the biological family Trochilidae. With approximately 375 species and 113 genera, they occur from Alaska to Tierra del Fuego, but most species are found in Central and South America. As of 2026, 21 hummingbird species are listed as endangered or critically endangered, with about 255 species declining in population. Hummingbirds have varied specialized characteristics to enable rapid, maneuverable flight: exceptional metabolic capacity, adaptations to high altitude, sensitive visual and communication abilities, and long-distance migration in some species. Among all birds, male hummingbirds have the widest diversity of plumage color, particularly in blues, greens, and purples. Hummingbirds are the smallest mature birds, measuring 7.5–13 cm (3–5 in) in length. The smallest is the 5 cm (2.0 in) bee hummingbird, which weighs less than 2.0 g (0.07 oz), and the largest is the 23 cm (9 in) giant hummingbird, weighing 17–31 grams (0.60–1.09 oz). Noted for long beaks, hummingbirds are specialized for feeding on flower nectar, but all species also consume small insects. Hummingbirds are known by that name because of the humming sound created by their beating wings, which flap at high frequencies audible to other birds and humans. They hover at rapid wing-flapping rates, which vary from around 12 beats per second in the largest species to 99 per second in small hummingbirds. Hummingbirds have the highest mass-specific metabolic rate of any homeothermic animal. To conserve energy when food is scarce and at night when not foraging, they can enter torpor, a state similar to hibernation, and slow their metabolic rate to 1⁄15 of its normal rate. While most hummingbirds do not migrate, the rufous hummingbird has one of the longest migrations among birds, traveling twice per year between Alaska and Mexico, a distance of about 3,900 miles (6,300 km). Hummingbirds split from their sister group, the swifts and treeswifts, around 42 million years ago. The oldest known fossil hummingbird is Eurotrochilus, from the Rupelian Stage of Early Oligocene Europe.
Description
Hummingbirds are the smallest known and smallest living avian theropod dinosaurs. The iridescent colors and highly specialized feathers of many species (mainly in males) give some hummingbirds exotic common names, such as sun gem, fairy, woodstar, sapphire or sylph.
Morphology Across the estimated 375 species, hummingbird weights range from as small as 2.0 grams (0.071 oz) to as large as 20 grams (0.71 oz). They have characteristic long, narrow beaks (bills) which may be straight (of varying lengths) or highly curved. The bee hummingbird – only 6 centimetres (2.4 in) long and weighing about 2 grams (0.071 oz) – is the world's smallest bird and smallest warm-blooded vertebrate. The giant hummingbird is the largest, having a mass of 17–31 g (0.60–1.09 oz) – approximately twice as heavy as the next largest hummingbird – with a wingspan of 21.5 cm (8.5 in) and body length of 23 cm (9.1 in). Hummingbirds have compact bodies with relatively long, bladelike wings having anatomical structure enabling helicopter-like flight in any direction, including the ability to hover. Particularly while hovering, the wing beats produce the humming sounds, which function to alert other birds. In some species, the tail feathers produce sounds used by males during courtship flying. One species of hummingbird – the little woodstar (Chaetocercus bombus) – has a wing-beat frequency of 99 per second during hovering. Such extreme flight demands are supported by a high metabolic rate dependent on foraging for sugars from flower nectar.
Hummingbird legs are short with feet having three toes pointing forward and one backward – the hallux. The toes of hummingbirds are formed as claws with ridged inner surfaces to aid gripping onto flower stems or petals. Hummingbirds do not walk on the ground or hop like most birds, but rather shuffle laterally and use their feet to grip while perching, preening feathers, or nest-building (by females), and during fights to grab feathers of opponents. Hummingbirds apply their legs as pistons for generating thrust upon taking flight, although the shortness of their legs provides about 20% less propulsion than assessed in other birds. During flight, hummingbird feet are tucked up under the body, enabling optimal aerodynamics and maneuverability. Of those species that have been measured during flight, the top flight speeds of hummingbirds exceed 15 m/s (54 km/h; 34 mph). During courtship, some male species dive from 30 metres (100 ft) of height above a female at speeds around 23 m/s (83 km/h; 51 mph). The sexes differ in feather coloration, with males having distinct brilliance and ornamentation of head, neck, wing, and breast feathers. The most typical feather ornament in males is the gorget – a bib-like iridescent neck-feather patch that changes brilliance with the viewing angle to attract females and warn male competitors away from territory.
Life cycle Hummingbirds begin mating when they are a year old. Sex occurs over 3–5 seconds when the male joins its cloaca with the female's, passing sperm to fertilize the female's eggs. Hummingbird females build a nest resembling a small cup about 1.5 inches (3.8 cm) in diameter, commonly attached to a tree branch using spider webs, lichens, moss, and loose strings of plant fibers (image). Typically, two pea-sized white eggs (image) – the smallest of any bird – are incubated over 2–3 weeks in breeding season. Fed by regurgitation only from the mother, the chicks fledge about 3 weeks after hatching. As the nestlings develop juvenile plumage, they do more and more wing flapping as they develop their ability to fly. The nestlings finally leave the nest (fledge), but are initially awkward fliers still fed by their mother. Nectar-feeding hummingbirds ingest large volumes of liquid which must be eliminated. Nestlings elevate their cloaca ejecting a stream of dilute liquid containing suspended fecal material beyond the rim of the nest. The average lifespan of a ruby-throated hummingbird is estimated to be 3–5 years, with most deaths occurring in yearlings, although one banded ruby-throated hummingbird lived for 9 years and 2 months. Bee hummingbirds live 7–10 years.
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