Hummingbirds areÂ birds that comprise the familyÂ Trochilidae. They are among the smallest of birds, most species measuring in the 7.5â€“13Â cm (3â€“5Â in) range. Indeed, the smallestÂ extant bird species is a hummingbird, the 5-cmÂ Bee Hummingbird. They canÂ hover in mid-air by rapidly flapping theirÂ wings 12â€“90 times per second (depending on the species). They can also fly backwards, and are the only group of birds able to do so.Â Their English name derives from the characteristicÂ hum made by their rapid wing beats. They can fly at speeds exceeding 15Â m/s (54Â km/h, 34Â mi/h).
Hummingbirds drinkÂ nectar, a sweet liquid inside certain flowers. Like bees, they are able to assess the amount of sugar in the nectar they eat; they reject flower types that produce nectar that is less than 10% sugar and prefer those whose sugar content is stronger. Nectar is a poor source ofÂ nutrients, so hummingbirds meet their needs forÂ protein,Â amino acids,Â vitamins,Â minerals, etc. by preying onÂ insects andÂ spiders.
Most hummingbirds have bills that are long and straight or nearly so, but in some species the bill shape is adapted for specialized feeding.Â Thornbills have short, sharp bills adapted for feeding from flowers with shortÂ corollas and piercing the bases of longer ones. The Sicklebills’ extremely decurved bills are adapted to extracting nectar from the curved corollas of flowers in the familyÂ Gesneriaceae. The bill of theÂ Fiery-tailed Awlbill has an upturned tip, as in theÂ Avocets. The maleÂ Tooth-billed Hummingbird has barracuda-like spikes at the tip of its long, straight bill.