Hummingbirds belong to the avian family Trochilidae and their closest relatives are the equally fascinating swifts. Hummingbirds are small (2-20 grams), with long narrow bills, and small saber-like wings.
Males (and occasionally females) often have a colorful gorget: small, stiff, highly reflective, colored feathers on the throat and upper chest. These shiny feathers and others around the head may look sooty black until a hummer turns its head to catch the sun and display the intense metallic spectral color.
Hummingbirds and swifts are able to stroke with power both on the down- and up-beat of a wing flap. Their power and small size allow tremendous agility in flight. In fact, hummingbirds are the only vertebrates capable of sustained hovering—staying in one place during flight—and they can fly backwards and upside down as well.
To their maneuverability, hummingbirds add speed and stamina. Hummingbirds have been clocked at close to 30 mph indirect flight and more than 45 mph during courtship dives. Migratory ruby-throated hummingbirds have no problem flying 18 to 20 straight hours to cross the Gulf of Mexico, powered by their fat stores and given a bit of help from winds.
Hummingbirds are one of the few groups of birds that are known to go into torpor. Torpor is a very deep sleep-like state in which metabolic functions are slowed to a minimum and a very low body temperature is maintained. If torpor lasted for long periods, we would call it hibernation, but hummingbirds can go into torpor any night of the year when temperature and food conditions demand it.
Hummingbirds are the masters of torpor because they have to be. Their feathers offer poor insulation and they have incredibly high metabolic demands. Torpor allows them to check-out physiologically when they can’t maintain their normal 105° body temperature.
The almost 340 species of hummingbirds are entirely restricted to the New World, where they can be found from Tierra Del Fuego to southern Alaska and from below sea level deserts to steamy tropical forests up to 16,000 feet in the Andes of South America.
Most species live in the tropics, and while 17 species regularly nest in the United States, many of these are found close to the Mexican border. Most areas in the U.S. have one or two breeding species, and only the ruby-throated hummingbird nests east of the Mississippi.