The average hummingbird weighs about 4 grams--a little less than a U.S. nickel.

A hummingbird can flap its wings about 80 times per second, causing an audible humming sound. And their wings aren't the only fast-moving body part -- they have a heart rate of approximately 1,260 beats per minute!

Hummingbirds can fly backwards and upside down. They can also beat their wings in a figure-eight pattern, which makes them the only vertebrates capable of sustained hovering.

A hummingbird's brain makes up a whopping 4.2 percent of its weight; proportionally, that's the largest of any bird's. Studies have shown that they can remember every flower they've ever visited, migration routes, and even recognize the humans that fill their feeders.

Hummingbirds have 1,000 to 1,500 feathers, the fewest number of feathers of any bird species in the world. Not only do they not need as many feathers because of their tiny size, but fewer feathers also keeps them more lightweight for easier flight.

Roughly 25 to 30 percent of a hummingbird's weight comes from its pectoral muscles. These are the broad chest muscles principally responsible for flying.

The International Ornithological Congress (IOC) recognizes 360 hummingbird species.

The bee hummingbird is native to Cuba and is only rarely spotted on other nearby islands. Barely larger than an actual bee, it is only 2-2.4 inches long and weighs a mere 0.056-0.071 ounces.

The rufous hummingbird has the longest migration of any hummingbird species, flying more than 3,000 miles from their nesting grounds in Alaska and Canada to their winter habitat in Mexico.

The record of longest living hummingbird was held by a female Broad-tailed Hummingbird. She was banded as an adult in Colorado in 1976, then recaptured in the same location in 1987 -- making her at least 12 years old.