Hummingbirds are birds native to the Americas and constitute the biological family Trochilidae. There are about 360 species. They occur from Alaska to Tierra del Fuego but the vast majority of the species are found in the tropics. They are small birds, most species measuring 7.5–13 cm (3–5 in) in length. The smallest extant hummingbird species is the 5 cm (2.0 in) bee hummingbird, which weighs less than 2.0 g (0.07 oz). The largest hummingbird species is the 23 cm (9.1 in) giant hummingbird, weighing 18–24 g (0.63–0.85 oz). They are specialized for feeding on nectar but all species also consume insects or spiders.