There are three things found only in the Americas that I really enjoy - cactuses, monkeys with prehensile tails and hummingbirds. In the Old World, that is, Africa, Europe and Asia, there are ecological equivalents of hummingbirds called sunbirds. They, too, are small with iridescent colors and are flower pollinators. But they can't hold a biological candle to our hummers.
The Cuban hummingbird is the world's smallest bird, the size of a bumblebee. Hummers are the only birds that can fly backwards and even upside down. They beat their wings at an astonishing 150 times per second. Some in temperate climes hibernate nightly in a state of torpor to save energy. They have the fastest heartbeat of any animal, 1,000 per minute. You get the idea. Amazing birds.
Two species of hummingbirds are easily seen in the Bay Area. Anna's hummingbird is now a year-long resident, perhaps due to planted ornamental flowers. They weigh no more than a nickel and appear mostly green. The males display for the females by ascending to 130 feet and then plummeting to the ground with a burst of noise produced through their tail feathers. They orient this dive so that their iridescent throat feathers flash in the sun, hopefully impressing that female.
Allen's hummingbirds migrate here from southern Mexico where they have wintered. They arrive early in January and males perform a pendulum breeding display, cruising back and forth in a wide arc in front of the female. They are slightly smaller than the Anna's and are coppery orange with a little green on the back.
Less common is the Rufous Hummingbird. These smaller hummers migrate from Central America all the way up into Alaska and, boy, are they feisty. Often fighting off birds twice their size for access to nectar. We only see these brilliant birds in the springtime. As their name indicates they are coppery brown.