Hummingbirds, small, vibrant birds of the family Trochilidae, are native to the Americas, ranging from Alaska to Tierra del Fuego, with the highest diversity near the equator. Their size varies from the tiny 5 cm bee hummingbird, weighing less than 2 g, to the largest species at 23 cm and weighing up to 24 g. Known for the humming noise made by their rapidly flapping wings, they can hover in mid-air with wing beats from 12 to 80 times per second and achieve speeds over 54 km/h. Splitting from swifts about 42 million years ago, hummingbirds have a fossil-recorded ancestor in South America 22 million years ago. Hummingbirds feed mainly on nectar but also eat insects and spiders. Remarkably, they possess the highest metabolism relative to their size of any warm-blooded animal and can enter a hibernation-like state called torpor to conserve energy.