A Packet of Energy: Hummingbirds may be small, but they pack a lot energy in those tiny bodies. They come in a variety of dazzling colors, and due to the structure of their wings, they are the only birds with the ability to fly backward and upside down. They beat their wings rapidly; smaller species can flap their wings up to 80 times a second.

Nose for Nectar: The ruby-throated hummingbird migrates from Central America to Canada yearly, a trip that is nearly 2,000 miles long. All that acrobatic flying needs energy, which they get from sipping nectar through their small beaks. The bill size and shape often matches the shape of their favorite flowers. Hummingbirds will also feed on insects and tree sap.

Tiny to Very Tiny: The largest hummingbird, aptly named the giant hummingbird, is still tiny, weighing in at no more than .8 ounces (approximately 23 grams). The smallest species — and smallest bird in the world — is the bee hummingbird, which weighs no more than 0.06 ounces (approximately 1.6 grams). It's the size of, well, a bee.