Male bee hummingbirds (mellisuga helenae), which live in Cuba, weigh 0.056 ounces and are 2.75 inches in length. The bill and tail account for half of this length.
Hummingbirds are birds in the family Trochilidae, and are native to the Americas. They can hover in mid-air by rapidly flapping their wings 12-90 times per second (depending on the species). They can also fly backwards, and are the only group of birds able to do so. Their English name derives from the characteristic hum made by their rapid wing beats. They can fly at speeds exceeding 15 m/s (54 km/h; 34 mph).
Hummingbirds feed on the nectar of plants and are important pollinators, especially of deep-throated, tubular flowers. Like bees, they are able to assess the amount of sugar in the nectar they eat; they reject flower types that produce nectar which is less than 10% sugar and prefer those whose sugar content is stronger. Nectar is a poor source of nutrients, so hummingbirds meet their needs for protein, amino acids, vitamins, minerals, etc. by preying on insects and spiders, especially when feeding young.
Most hummingbirds have bills that are long and straight or nearly so, but in some species the bill shape is adapted for specialized feeding. Thornbills have short, sharp bills adapted for feeding from flowers with short 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 family Gesneriaceae. The bill of the Fiery-tailed Awlbill has an upturned tip, as in the Avocets. The male Tooth-billed Hummingbird has barracuda-like spikes at the tip of its long, straight bill.
The two halves of a hummingbird's bill have a pronounced overlap, with the lower half (mandible) fitting tightly inside the upper half (maxilla). When hummingbirds feed on nectar, the bill is usually only opened slightly, allowing the tongue to dart out and into the interior of flowers.
Like the similar nectar-feeding sunbirds and unlike other birds, hummingbirds drink by using protrusible grooved or trough-like tongues.
Hummingbirds do not spend all day flying, as the energy cost would be prohibitive; the majority of their activity consists simply of sitting or perching. Hummingbirds feed in many small meals, consuming many small invertebrates and up to five times their own body weight in nectar each day. They spend an average of 10-15% of their time feeding and 75-80% sitting and digesting.
Aerodynamics of flight
Hummingbird flight has been studied intensively from an aerodynamic perspective using wind tunnels and high-speed video cameras.
Writing in Nature, the biomechanist Douglas Warrick and coworkers studied the Rufous Hummingbird, Selasphorus rufus, in a wind tunnel using particle image velocimetry techniques and investigated the lift generated on the bird's upstroke and downstroke. They concluded that their subjects produced 75% of their weight support during the down-stroke and 25% during the up-stroke. Many earlier studies had assumed (implicitly or explicitly) that lift was generated equally during the two phases of the wingbeat cycle, as is the case of insects of a similar size. This finding shows that hummingbirds' hovering is similar to, but distinct from, that of hovering insects such as the hawk moths.
The Giant Hummingbird's wings beat at 8–10 beats per second, the wings of medium-sized hummingbirds beat about 20–25 beats per second and the smallest beat 70 beats per second.
Hummingbirds are found only in the Americas, from southern Alaska to Tierra del Fuego, including the Caribbean. The majority of species occur in tropical Central and South America, but several species also breed in temperate areas. Only the migratory Ruby-throated Hummingbird breeds in continental North America east of the Mississippi River and Great Lakes. The Black-chinned Hummingbird, its close relative and another migrant, is the most widespread and common species in the western United States, while the Rufous Hummingbird is the most widespread species in western Canada.
Most hummingbirds of the U.S. and Canada migrate south in fall to spend the northern winter in Mexico or Central America. A few southern South American species also move to the tropics in the southern winter. A few species are year-round residents in the warmer coastal and interior desert regions. Among these is Anna's Hummingbird, a common resident from southern California inland to southern Arizona and north to southwestern British Columbia.
The Rufous Hummingbird is one of several species that breed in western North America and are wintering in increasing numbers in the southeastern United States, rather than in tropical Mexico. Thanks in part to artificial feeders and winter-blooming gardens, hummingbirds formerly considered doomed by faulty navigational instincts are surviving northern winters and even returning to the same gardens year after year. Individuals that survive winters in the north, however, may have altered internal navigation instincts that could be passed on to their offspring. The Rufous Hummingbird nests farther north than any other species and must tolerate temperatures below freezing on its breeding grounds. This cold hardiness enables it to survive temperatures well below freezing, provided that adequate shelter and feeders are available.
Hummingbirds will also take sugar water from artificial feeders. Such feeders allow people to observe and enjoy hummingbirds up close while providing the birds with a reliable source of energy, especially when flower blossoms are less abundant.
Only white granulated sugar is proven safe to use in hummingbird feeders. A ratio of 1 cup sugar to 4 cups water is a common recipe. Boiling and then cooling this mixture before use has been recommended to help deter the growth of bacteria and yeasts. Powdered sugars contain corn starch as an anti-caking agent; this additive can contribute to premature fermentation of the solution. Brown, turbinado, and "raw" sugars contain iron, which can be deadly to hummingbirds if consumed over long periods. Honey is made by bees from the nectar of flowers, but it contains sugars that are less palatable to hummingbirds and promotes the growth of microorganisms that may be dangerous to their health.
Red food dye is often added to homemade solutions. Commercial products sold as "instant nectar" or "hummingbird food" may also contain preservatives and/or artificial flavors as well as dyes. The long-term effects of these additives on hummingbirds have not been studied, but studies on laboratory animals indicate the potential to cause disease and premature mortality at high consumption rates. Although some commercial products contain small amounts of nutritional additives, hummingbirds obtain all necessary nutrients from the insects they eat. This renders the added nutrients unnecessary.
Other animals are also attracted to hummingbird feeders. Bees and wasps are attracted to the nectar and may crawl into the feeder, where they may become trapped. Ants are also attracted to the nectar. Orioles, woodpeckers, bananaquits, and other animals are known to drink from hummingbird feeders, sometimes tipping them and draining the liquid. Sometimes a large hummingbird drives its smaller brethren away from a feeder.
To lure flying insects away from feeders, hang several, and provide one feeder with a 3 to 1 mix. The insects will be attracted to the sweeter solution and it won't hurt the hummers to sample it.