National Geographic:

Unlike other birds, such as pigeons, a hummingbird can fly in multiple directions, including backward and sideways. Its wings can beat up to 100 times per second. Its brain, at 4.2 percent of body weight, is proportionally the largest among birds and second largest in the animal kingdom.

“The world’s smallest birds” is just one of several distinctions that hummingbird species claim. They’re the only birds that can hover in still air for 30 seconds or more. They’re the only birds with a “reverse gear”—that is, they can truly fly backward. And they’re the record holders for the fastest metabolic rate of any vertebrate on the planet: A 2013 University of Toronto study concluded that if hummingbirds were the size of an average human, they’d need to drink more than one 12-ounce can of soda for every minute they’re hovering, because they burn sugar so fast.

Typically amazing video and images in this piece. Hummingbirds are fascinating little creatures.