Hummingbirds belong to the order Apodiformes, meaning, "unfooted birds." There are three families in this order: Trochilidae (hummingbirds), Hemiprocnidae (tree swifts), and Apodidae (swifts). The family Trochilidae belongs to its own Suborder, Trochili. Although the number of genera and species in this group changes continually, currently there are 102 recognized genera and 328 species of hummingbirds. The hummingbird family is divided into two sub-families: Phaethornithinae (hermits) composed of 34 species and a larger group, Trochilinae (trochilines or "typical" hummingbirds), with 294 species.
Hummingbirds feed primarily on the nectar of flowers and supplement their diet with small insects. They have evolved unique characteristics such as narrow elongated beaks, extendable tongues and hovering flight, all of which allow them to exploit nectar resources.
Most hummingbird species are polygynous (males mate with more than one female) and are sexually dimorphic (sexes do not look alike); males (especially trochilines) often have bright iridescent feathers while females have more cryptic coloration. Some male hummingbirds have elaborate ornamentation such as elongated tail feathers and iridescent crests. Male hermits display together in large groups called leks while trochilines are mainly territorial; their courtship often involves dramatic aerial displays.
Known for their small size (the smallest species of hummingbird weighs 2 g), rapid wing movements and heartbeat, hummingbirds can compensate for their high energetic requirements by going into torpor during cold nights. This is especially important for those species found at high elevation where nighttime temperatures can dip below freezing.
Hummingbirds are found in a variety of habitats and while their range includes much of the New World, most hummingbird species are Neotropical.
Hummingbirds are found only in the New World in the Nearctic and Neotropics. Their range extends from Alaska to Labrador in the North to Tierra del Fuego in the south and from Barbados to the Juan Fernandes islands. Most species are tropical and sub-tropical and live between 10 degrees N and 25 degrees S lattitude. More than half of all species of hummingbird are found in Brazil and Ecuador.
Biogeographic Regions: nearctic (Native ); neotropical (Native )
Hummingbirds are known for their small size, long, thin bills, and amazing agility in flight. The smallest hummingbirds, reddish hermits (Phaethornis ruber) and bee hummingbirds (Mellisuga helenae) weigh less than 2 g while giant hummingbirds (Patagona gigas) weigh 19 to 21 g. Most species weigh 2.5 to 6.5 g and are 6 to 12 cm in length. Their bills are a variety of shapes; bill length and shape are often good indicators of the types of flowers each species feeds on. Hummingbirds have extendable bifurcated tongues that are used to extract nectar from flowers.
As the name of their order, Apodiformes (“unfooted birds”) suggests, hummingbirds have characteristically small feet. They are unable to walk on the ground and will fly rather than walk in order to shift on a perch.
Hummingbirds have many skeletal and flight muscle adaptations that allow for hovering and high maneuverability in flight. They are the only birds that truly hover and are capable of both forward and backward flight. The characteristic humming sound they make in flight is caused by modified outer primary feathers and is the basis for their common name. Hummingbirds can achieve a forward speed of 45 km per hour and their wingbeat ranges from 70 to 80 beats per second in smaller birds to 10 to 15 beats per second in giant hummingbirds. Their heartbeat is equally rapid ranging from 500 to 600 beats per minute while resting to over 1000 beats per minute when active.
There are two sub-families of hummingbird, hermits (Phaethornithinae) and “typical” hummingbirds or trochilines (Trochilinae). Hermits generally have brownish, grayish and reddish colors and no iridescence. Trochilines often have iridescent feathers of metallic red, orange, green and blue. Iridescence is seen most in male hummingbirds and occurs on the head, upperparts and underparts. Some males also have elegant ornamentation such as bright throat gorgets, crests and elongated tail feathers.
Hummingbirds are sexually dimorphic. Females can be bigger than males, but males are usually more colorful and can have additional adornments. Female hummingbirds have more cryptic coloration than males, most likely so that they do not attract predators to the nest when incubating and feeding chicks. The plumage of immature birds is usually similar to that of females.
Sexual Dimorphism: female larger; sexes colored or patterned differently; male more colorful; ornamentation
Other Physical Features: endothermic ; bilateral symmetry
Hummingbirds feed and nest in a wide variety of terrestrial habitats, both temperate and tropical. The main habitat requirement for hummingbirds is a large number of nectar producing flowers. This requirement is satisfied in a number of different habitats: arid scrub, desert oasis, coastal lowland, tropical rainforest, Neararctic pine forests, and alpine tundra. Hummingbirds can be found in habitats from coastal areas at sea level to mountainous areas at an elevation of 5000 m.
Due to the prevalence of hummingbird feeders and cultivated gardens, hummingbirds can sometimes be found in urban and suburban areas with few natural food sources. There are also some agricultural crops, such as banana and coffee that can support hummingbirds.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: tundra ; desert or dune ; forest ; rainforest ; scrub forest ; mountains
Other Habitat Features: urban ; suburban ; agricultural
Hummingbirds are nectivores and insectivores; approximately 90% of their diet comes from nectar and 10% from arthropods (flies (Diptera), wasps (Hymenoptera), spiders (Araneae), beetles (Coleoptera), and ants (Hymenoptera)). Thin, elongated hummingbird bills are well adapted to exploit nectar sources. Hummingbird pollinated flowers are usually brightly colored, scentless and have long, tubular corollas. The shape of a hummingbird’s bill determines the species of flower it can feed on. In fact, co-evolution of flower shape and bill shape is a well-studied phenomenon. Hummingbirds have also developed specialized flight structures that allow them to hover in front of flowers while feeding. Without the ability to hover, hummingbirds would not be able to obtain nectar from flowers. In addition, hummingbirds have specialized, bifurcated tongues that they can extend to reach nectar from within a flower. They use capillary action to draw the nectar along their tongue.
Because hummingbirds have a high basal metabolic rate, they can drink their body mass in nectar in less than a day. They get some amino acids from pollen and protein from insects (which they catch by hawking or hover-gleaning). When nectar resources are scarce, hummingbirds will also feed on sap from holes in trees made by sapsuckers (Sphyrapicus).
Co-existing species of hummingbirds will specialize on certain flowers or subdivide the habitat. They will either defend nectar resources on a territory or move between patches of flower-rich areas, a behavior called traplining.
Primary Diet: carnivore (Insectivore , Eats non-insect arthropods); herbivore (Nectarivore ); omnivore
Many species of plants rely on hummingbirds for pollination. For some species, hummingbirds are their sole pollinators. In Brazil alone, hummingbirds pollinate 58 different plant species.
Hummingbirds often pick up nectar mites (Acari) when they visit flowers. The mites climb onto the hummingbird’s bill and into the nostrils. Here they are transported from flower to flower. The mites do not harm the birds; they reproduce on the plants and eat pollen and nectar. At least forty species of mites have been described.
Ecosystem Impact: pollinates
- nectar mites (Acari)
Adult hummingbirds have few predators. Known predators include snakes (Serpentes), forest falcons (Micrastur, that catch hermits during lekking), and pygmy-owls (Glaucidium). Nest predators are the biggest threat to hummingbirds. These include jays (Corvidae), toucans (Ramphastidae), and some bats (Micro-chiroptera).
Female hummingbirds have more cryptic coloration than male hummingbirds. This is thought to be an adaptation that allows the females to be more camouflaged and avoid attracting predators when incubating. Females will fly to their nests in zigzags or semi-circles to avoid leading a predator directly to the nest. Hummingbirds have also been seen mobbing predators.
- snakes (Serpentes)
- forest falcons (Micrastur)
- pygmy-owls (Glaucidium)
- jays (Corvidae)
- toucans (Ramphastidae)
- bats (Microchiroptera)
Anti-predator Adaptations: cryptic
This list may not be complete but is based on published studies.
Known prey organisms
nectar and floral
Based on studies in:
USA: Arizona, Sonora Desert (Desert or dune)
This list may not be complete but is based on published studies.
Life History and Behavior
Both male and female hummingbirds have species-specific calls. Calls are usually short, high-pitched chips but some species have more drawn-out, musical songs. Singing is used both to attract mates and deter intruders. The humming noise made by wings during flight may also be a form of communication, especially in dive displays. Nestlings in domed or semi-domed nests will make begging calls but those in open cup nests will not. Fledglings make contact calls to communicate with their mothers when they are out of sight and begging calls when they are close by. Alarm calls may also be given when predators are nearby.
Hummingbirds, like most other birds do not have a well-developed sense of smell. They have color vision and unlike most vertebrates, are sensitive to ultra-violet light between 325 to 360 nanometers. Ultra-violet perception may help the birds find food since some flowers have ultra-violet color patterns. Male coloration is a cue used by females and conspecific competitors to assess dominance, quality and species identity.
Communication Channels: visual ; acoustic
Perception Channels: visual ; ultraviolet; tactile ; acoustic ; chemical
Both male and female hummingbirds usually live from 6 to 12 years and have been known to survive up to 17 years in captivity. It is difficult to estimate annual survival, but for North American species it is thought to be 30 to 45 percent.
Hummingbirds are polygynous; males interact with females only to breed and provide no parental care. Females are responsible for nest building, incubation and post-hatching parental care. Males attract mates using song, iridescent plumage and dramatic display flights. Depending on the species, males display at lekking grounds, defended territories, traditional display grounds, or singing posts.
Mating System: polygynous
Hummingbirds breed during the season with peak nectar availability. Most hummingbirds build cup nests, but a few build domed or semi-domed nests that provide more protection than an open cup nest. Nest height ranges from a few centimeters above the ground to 10 to 30 meters. Nests are camouflaged with lichen, moss, dead leaves, bark, etc. and are held together with spider webs. They are sometimes lined with feathers, fur, hair, or plant down. Nests take 5 to 10 days to build and are often re-used year to year.
Clutch size is two and eggs are white, non-glossy and an elliptical oval shape. Because some species of hermits will lay eggs in another female’s nest, clutches of more than two can sometimes be found. There is a 48-hour interval between egg laying. The size of hummingbird eggs range from 8 by 11 mm in bee hummingbirds (Mellisuga helenae) to 12 by 20 mm in giant hummingbirds (Patagona gigas). The average weight of an egg is 0.4 to 1.4 g. Incubation usually lasts 16 to 19 days. If females begin incubating after the first egg is laid, hatching of the two eggs can occur 48 hours apart. If she waits until the second egg is laid, hatching occurs synchronously. Nestling period is 23 to 26 days; hatchlings are altricial with almost no feathers and eyes closed. Females brood young for 7 to 12 days, at which point the young are able to control their own body temperature. Fledglings continue to be fed by the female for 18 to 25 days after they have left the nest.
Female hummingbirds can have two broods per year when conditions permit and will re-nest if a brood is lost. Most nest failure is due to depredation.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
Only female hummingbirds are involved in parental care; they must incubate eggs, brood young hatchlings, and feed the chicks as nestlings and fledglings. Hummingbird chicks are altricial and stay in the nest for 23 to 26 days. When they first hatch, young hummingbirds have few feathers and cannot thermoregulate. The female must brood the young for 7 to 12 days until they can maintain their body temperature. Females feed nestlings nectar and arthropods approximately twice every hour. Fledglings are fed by the female for 18 to 25 days and gradually learn to forage by themselves.
Parental Investment: altricial ; female parental care
Evolution and Systematics
The beak of the hummingbird can snap closed to capture insects due to stored elastic energy.
"The hummingbird beak, specialized for feeding on floral nectars, is also uniquely adapted to eating flying insects. During insect capture the beak often appears to close at a rate that cannot be explained by direct muscular action alone. Here we show that the lower jaw of hummingbirds has a shape and compliance that allows for a controlled elastic snap. Furthermore, hummingbirds have the musculature needed to independently bend and twist the sides of the lower jaw. According to both our simple physical model and our elastic instability calculation, the jaw can be smoothly opened and then snapped closed through an appropriate sequence of bending and twisting actions by the muscles of the lower jaw." (Smith et al. 2011:41)
Part of the trick lies in how the hummingbird's beak is built. While other insect-eating birds such as swifts and nighthawks have a cartilaginous hinge near the base of their beaks, hummingbird beaks are solid bone. They're also incredibly thin, so that the lower beaks are stiff yet springy. The researchers' mathematical model revealed that the downward bend of the hummingbird's lower beak puts stress on the bone, storing elastic energy which eventually powers its sudden snap closure. (From Smith 2011, EurekaAlert)
Learn more about this functional adaptation.
The feathers of hummingbirds are iridescent due to the inhomogeneous interference structure of platelets on feather barbules.
"To summarize, hummingbird iridescence is due to interference colors produced by a stack of about three films whose optical thickness is one-half the peak wave length. Each film is a mosaic of platelets of elliptical form. Each platelet is about 2.5 microns long and one micron wide. The platelets are not homogeneous and consist of air bubbles encased in a matrix of refractive index about two. The different hummingbird colors are produced by a combination of effects. The platelet thickness decreases moderately as one passes from red through green to blue, and the air content increases simultaneously. In theory, of course, platelet thickness could remain constant and the color change would arise solely by variation in air content. Conversely air content could be constant and the platelet thickness varied. Nature for reasons best known to herself has elected to vary both factors together.” (Greenewalt et al. 1960:253)
"First, we repeated the examination of barbular surfaces with the optical microscope. We confirmed the presence of the platelet mosaic on the iridescent surfaces of fifty or so hummingbird species. Only the platelets are colored; the interstices are dark. The platelets are minute, about 2.5 microns across the long axis of the ellipse, and one micron across the short axis. Ten thousand of them laid end to end would measure a little over an inch. Their size varies little throughout the hummingbird species which we have examined. The length of 2.5 microns is a good average and the limits of variation would be no more than 30 per cent either way. Along its length the barbule is divided into cells separated by diagonal lines crossing the width of the barbule. At the points where the barbule joins the ramus and where the pennulum develops, the colored platelets disappear and one sees only a few random uncolored or faintly colored ellipses in these areas. The barbule proper then has a surface which is 15-20 microns wide and 100 microns long, divided by diagonal boundary lines into a series of cells which look like parallelograms, each cell made up of a mosaic of 100 or more beautifully colored elliptical platelets” (Greenewalt et al. 1960:250).
Learn more about this functional adaptation.
The metabolism of hummingbirds allows them to survive the night when food is unavailable by slowing to a hibernation-like state called torpor.
"At night, when they cannot see to fly and the flowers have closed, the birds have no alternative but to shut down all their systems, lower their body temperature and, in effect, hibernate until dawn." (Attenborough 1995:119)
"Hummingbirds use periods of inactivity between feeding bouts and torpor to conserve energy and enable them to survive nocturnal starvation.14 During torpor, the hummingbird metabolism is adjusted downward to achieve up to 60% energy savings." (Fowler and Miller 2003:235)
Learn more about this functional adaptation.
Intestines of hummingbirds rapidly take up glucose by using glucose transporters in intestinal mucosa.
"Intestinal transit time is about 15 minutes, during which time, using a high density of glucose transporters in the intestinal mucosa, some 99% of ingested glucose is absorbed." (Fowler and Miller 2003: 235)
Learn more about this functional adaptation.
Molecular Biology and Genetics
Statistics of barcoding coverage
Specimens with Sequences:1434
Specimens with Barcodes:1385
Species With Barcodes:240
Two species of hummingbird are known to be extinct: Brace’s emerald (Chlorostilbon bracei) and Gould’s emerald (Chlorostilbon elegans). There are 9 species listed as critically endangered by the IUCN, 11 listed as endangered and 9 listed as vulnerable. Major threats to hummingbirds are habitat loss, degradation, and fragmentation. Most of the North American species are protected under the Migratory Bird Treaty Act. No hummingbirds are listed by ESA, but almost all, if not all are listed by CITES.
Habitat destruction in the tropics does not threaten hummingbirds as much as it does some other Neotropical species. Hummingbirds can usually find nesting habitat even in human modified landscapes; cleared areas may still produce flowering plants and some plantations (banana and coffee) can support hummingbirds. Feeders and garden flowers have also allowed population and range increases in some North American species.
Relevance to Humans and Ecosystems
There are no known adverse affects of hummingbirds on humans.
In the past, hummingbirds were actively hunted for feathers that were used to make jewelry and adorn clothing. They were also captured for human amusement in zoos and private collections. Hummingbirds are still sold in markets as aphrodisiacs; although there is no scientific evidence that they work.
Beyond the ecosystem services hummingbirds provide (pollination of a wide variety of plant species), perhaps their biggest economic influence can be seen in the market for hummingbird feeders and eco-tourism.
Positive Impacts: body parts are source of valuable material; ecotourism ; source of medicine or drug ; pollinates crops
The hummingbird, or Trochilidae, family provides vital pollination services to thousands of plant species. Hummingbirds are considered nectarivorous, meaning they feed mostly on plant nectar, although they do eat insects as well. While hummingbirds feed, pollen from flowers stick to the birds' bills and is transferred to the pistils of other flowers. Because of the hummingbird's unique means of flight, it must consume almost twice its body weight in nectar daily and can visit up to 1,500 flowers per day.
Hummingbirds are New World birds that constitute the family Trochilidae. They are among the smallest of birds, most species measuring in the 7.5–13 cm (3–5 in) range. Indeed, the smallest extant bird species is a hummingbird, the 5-cm bee hummingbird, weighing less than a U.S. penny.
They are known as hummingbirds because of the humming sound created by their beating wings which flap at high frequencies audible to humans. They hover in mid-air at rapid wing-flapping rates, typically around 50 times per second, allowing them also to fly at speeds exceeding 15 m/s (54 km/h; 34 mph), backwards.
Hummingbirds have the highest metabolism of any homeothermic animal. To conserve energy when food is scarce, they have the ability to go into a hibernation-like state (torpor) where their metabolic rate is slowed to 1/15th of its normal rate.
- 1 Evolution
- 2 Systematics
- 3 Specialized characteristics and metabolism
- 4 Reproduction
- 5 Wing structure and colors
- 6 Aerodynamics of flight
- 7 Feather sonation
- 8 Range
- 9 Migration
- 10 Diet and specializations for food gathering
- 11 Superficially similar birds
- 12 In myth and culture
- 13 Gallery
- 14 See also
- 15 References
- 16 External links
A map of the hummingbird family tree—reconstructed from analysis of 284 of the world's 338 known species—shows rapid diversification from 22 million years ago. Hummingbirds fall into nine main clades defining their relationship to nectar-bearing flowering plants, and the birds' continued spread into new geographic areas.
While all hummingbirds depend on flower nectar to fuel their high metabolisms and hovering flight, coordinated changes in flower and bill shape stimulated the formation of new species of both hummingbirds and plants. Due to this exceptional evolutionary pattern, as many as 25 hummingbird species are able to coexist in specific regions because their food needs are the same.
The hummingbird evolutionary tree shows that ancestral hummingbirds splitting from insectivorous swifts (family Apodidae) and treeswifts (family Hemiprocnidae) about 42 million years ago, probably in Eurasia. One key evolutionary factor appears to be an altered taste receptor that enabled hummingbirds to seek nectar. By 22 million years ago, the ancestral species of current hummingbirds became established in South America where environmental conditions stimulated further diversification.
The Andes Mountains appear to be a particularly rich environment for hummingbird evolution (140 hummingbird species live in the Andes today) because diversification occurred simultaneously with mountain uplift over the past 10 million years.
Co-evolution with ornithophilous flowers
Hummingbirds are specialized nectarivores and are tied to the ornithophilous flowers they feed upon. Some species, especially those with unusual bill shapes such as the sword-billed hummingbird and the sicklebills, are co-evolved with a small number of flower species.
Many plants pollinated by hummingbirds produce flowers in shades of red, orange, and bright pink, though the birds will take nectar from flowers of many colors. Hummingbirds can see wavelengths into the near-ultraviolet, but their flowers do not reflect these wavelengths as many insect-pollinated flowers do. This narrow color spectrum may render hummingbird-pollinated flowers relatively inconspicuous to most insects, thereby reducing nectar robbing. Hummingbird-pollinated flowers also produce relatively weak nectar (averaging 25% sugars w/w) containing high concentrations of sucrose, whereas insect-pollinated flowers typically produce more concentrated nectars dominated by fructose and glucose.
In traditional taxonomy, hummingbirds are placed in the order Apodiformes, which also contains the swifts. However, some taxonomists have separated them into their own order, Trochiliformes. Hummingbirds' wing bones are hollow and fragile, making fossilization difficult and leaving their evolutionary history poorly documented. Though scientists theorize that hummingbirds originated in South America, where there is the greatest species diversity, possible ancestors of extant hummingbirds may have lived in parts of Europe to what is southern Russia today.
There are between 325 and 340 species of hummingbird, depending on taxonomic viewpoint, divided into two subfamilies, the hermits (subfamily Phaethornithinae, 34 species in six genera), and the typical hummingbirds (subfamily Trochilinae, all the others). However, recent phylogenetic analyses suggest that this division is slightly inaccurate, and that there are nine major clades of hummingbirds: the topazes and jacobins, the hermits, the mangoes, the coquettes, the brilliants, the giant hummingbird (Patagona gigas), the mountain-gems, the bees, and the emeralds. The topazes and jacobins combined have the oldest split with the rest of the hummingbirds. The hummingbird family has the second greatest number of species of any bird family on Earth (after the tyrant flycatchers).
Fossil hummingbirds are known from the Pleistocene of Brazil and the Bahamas; however, neither has yet been scientifically described, and there are fossils and subfossils of a few extant species known. Until recently, older fossils had not been securely identifiable as those of hummingbirds.
In 2004, Dr Gerald Mayr of the Senckenberg Museum in Frankfurt am Main identified two 30-million-year-old hummingbird fossils and published his results in the journal Science. The fossils of this primitive hummingbird species, named Eurotrochilus inexpectatus ("unexpected European hummingbird"), had been sitting in a museum drawer in Stuttgart; they had been unearthed in a clay pit at Wiesloch–Frauenweiler, south of Heidelberg, Germany, and, because it was assumed that hummingbirds never occurred outside the Americas, were not recognized to be hummingbirds until Mayr took a closer look at them.
Fossils of birds not clearly assignable to either hummingbirds or a related, extinct family, the Jungornithidae, have been found at the Messel pit and in the Caucasus, dating from 40–35 mya; this indicates that the split between these two lineages indeed occurred at that date. The areas where these early fossils have been found had a climate quite similar to that of the northern Caribbean or southernmost China during that time. The biggest remaining mystery at the present time is what happened to hummingbirds in the roughly 25 million years between the primitive Eurotrochilus and the modern fossils. The astounding morphological adaptations, the decrease in size, and the dispersal to the Americas and extinction in Eurasia all occurred during this timespan. DNA-DNA hybridization results suggest that the main radiation of South American hummingbirds took place at least partly in the Miocene, some 12 to 13 million years ago, during the uplifting of the northern Andes.
In 2013, a 50-million-year-old fossil bird unearthed in Wyoming was found to be a predecessor to both hummingbirds and swifts before the groups diverged.
Lists of species and genera
Specialized characteristics and metabolism
With the exception of insects, hummingbirds while in flight have the highest metabolism of all animals, a necessity in order to support the rapid beating of their wings during hovering and fast forward flight. Their heart rate can reach as high as 1,260 beats per minute, a rate once measured in a blue-throated hummingbird, with a breathing rate of 250 breaths per minute, even at rest. During flight, oxygen consumption per gram of muscle tissue in a hummingbird is approximately 10 times higher than that seen for elite human athletes.
Hummingbirds consume more than their own weight in nectar each day, and to do so they must visit hundreds of flowers daily. Hummingbirds are continuously hours away from starving to death and are able to store just enough energy to survive overnight.
Hummingbirds are rare among vertebrates in their ability to rapidly make use of ingested sugars to fuel energetically expensive hovering flight, powering up to 100% of their metabolic needs with the sugars they drink (in comparison, human athletes max out at around 30%). One study showed that hummingbirds can use newly ingested sugars to fuel hovering flight within 30–45 minutes of consumption. These data suggest that hummingbirds are able to oxidize sugar in flight muscles at rates high enough to satisfy their extreme metabolic demands. By relying on newly ingested sugars to fuel flight, hummingbirds can reserve their limited fat stores to sustain them overnight fasting or to power migratory flights.
The dynamic range of metabolic rates in hummingbirds requires a corresponding dynamic range in kidney function. The glomerulus is a cluster of capillaries in each nephron of the kidney that removes certain substances from the blood, like a filtration mechanism. The rate at which blood is processed is called the glomerular filtration rate (GFR). Most often these fluids are reabsorbed by the kidneys. GFR also slows when a bird is undergoing water deprivation. The interruption of GFR is a survival and physiological mechanism unique to hummingbirds.
Studies of hummingbirds' metabolisms are relevant to the question of how a migrating ruby-throated hummingbird can cross 800 km (500 mi) of the Gulf of Mexico on a nonstop flight. This hummingbird, like other birds preparing to migrate, stores fat as a fuel reserve, thereby augmenting its weight by as much as 100% and hence increasing potential flying time over open water.
Hummingbirds are capable of slowing their metabolism at night or any time food is not readily available, entering a hibernation-like, deep sleep state known as torpor needed to prevent energy reserves from falling to a critical level. During nighttime torpor, body temperature falls from 40oC to 18oC, with heart and breathing rates both slowed dramatically (heart rate to roughly 50 to 180 beats per minute from its daytime rate of higher than 1000).
During torpor, to prevent dehydration, the kidney glomerular filtration rate ceases, preserving needed compounds like glucose, water and nutrients. Further, body mass declines throughout nocturnal torpor at a rate of 0.04 g per hour, amounting to about 10% of weight loss each night. The circulating hormone, corticosterone, is one signal that arouses a hummingbird from torpor.
Use and duration of torpor vary among hummingbird species and are affected by whether a dominant bird defends territory, with non-territorial subordinate birds having longer periods of torpor.
Hummingbirds have long lifespans for organisms with such rapid metabolisms. Though many die during their first year of life, especially in the vulnerable period between hatching and leaving the nest (fledging), those that survive may occasionally live a decade or more. Among the better-known North American species, the average lifespan is probably 3 to 5 years. By comparison, the smaller shrews, among the smallest of all mammals, seldom live more than 2 years. The longest recorded lifespan in the wild is that of a female broad-tailed hummingbird that was banded (ringed) as an adult at least one year old, then recaptured 11 years later, making her at least 12 years old. Other longevity records for banded hummingbirds include an estimated minimum age of 10 years 1 month for a female black-chinned similar in size to the broad-tailed, and at least 11 years 2 months for a much larger buff-bellied hummingbird.
|This section does not cite any references or sources. (May 2014)|
As far as is known, male hummingbirds do not take part in nesting. Most species build a cup-shaped nest on the branch of a tree or shrub; although, a few tropical species normally attach their nests to leaves. The nest varies in size relative to the particular species—from smaller than half a walnut shell to several centimeters (1 centimeter = 0.39 inches) in diameter.
Many hummingbird species use spider silk and lichen to bind the nest material together and secure the structure. The unique properties of the silk allow the nest to expand as the young hummingbirds grow. Two white eggs are laid, which, despite being the smallest of all bird eggs, are in fact large relative to the adult hummingbird's size. Incubation lasts 14 to 23 days, depending on the species, ambient temperature and female attentiveness to the nest. The mother feeds her nestlings on small arthropods and nectar by inserting her bill into the open mouth of a nestling, and then regurgitating the food into its crop.
incubating in Copiapó, Chile
nest with two nestlings in Santa Monica, California
feeding two nestlings in Grand Teton National Park
Wing structure and colors
Many of the hummingbird species have bright plumage with exotic coloration. In many species, the coloring does not come from pigmentation in the feather structure, but instead from prism-like cells within the top layers of the feathers. When light hits these cells, it is split into wavelengths that reflect to the observer in varying degrees of intensity. The hummingbird feather structure acts as a diffraction grating. The result is that, merely by shifting position, a muted-looking bird will suddenly become fiery red or vivid green. However, not all hummingbird colors are due to the prism feather structure. The rusty browns of Allen's and rufous hummingbirds come from pigmentation. Iridescent hummingbird colors actually result from a combination of refraction and pigmentation, since the diffraction structures themselves are made of melanin, a pigment.
Aerodynamics of flight
Two studies of rufous or Anna's hummingbirds in a wind tunnel used particle image velocimetry techniques to investigate the lift generated on the bird's upstroke and downstroke. The authors concluded that the birds produced 75% of their weight support during the downstroke and 25% during the upstroke. Many earlier studies had assumed 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 hummingbird hovering is similar to, but distinct from, that of hovering insects such as the hawk moths. Further studies using electromyography in hovering rufous hummingbirds showed that muscle strain in the pectoralis major (principal downstroke muscle) was the lowest yet recorded in a flying bird, and the primary upstroke muscle (supracoracoideus) is proportionately larger than in other bird species. Hummingbird hovering has been estimated to be 20% more efficient than performed by a helicopter drone.
A slow motion video has shown how the hummingbirds deal with rain when they are flying. To remove the water from their heads, they shake their heads and body, similar to a dog shaking to shed water. Further, when raindrops collectively may weigh as much as 38% of the bird's body weight, hummingbirds shift their bodies and tails horizontally, beat their wings faster, and reduce their wings' angle of motion when flying in heavy rain.
The outer tail-feathers of male Anna's hummingbird (Calypte anna) vibrate during courtship display dives and produce a loud chirp. When courting, the male ascends some 35 meters before diving over an interested female at a speed of 27 m/s, equal to 385 body lengths/second, producing a high-pitched sound. This downward acceleration during a dive is the highest reported body length displacement for any vertebrate undergoing a voluntary aerial maneuver; by comparison, it is about twice the diving speed of peregrine falcons in pursuit of prey. At maximum descent speed, approximately 10 g of gravitational force occurs in the courting hummingbird during a dive. By comparison to humans, this is a g-force acceleration causing near loss of consciousness in fighter pilots during flight of fixed-wing aircraft in a high-speed banked turn.
Experiments showed that hummingbirds could not make the courtship dive sound when missing their outer tail-feathers, and that those same feathers could produce the dive-sound in a wind tunnel. The bird can sing at the same frequency as the tail-feather chirp, but its small syrinx is not capable of the same volume. Further studies showed that the sound is caused by the aerodynamics of rapid air flow past tail feathers, causing them to flutter in a vibration which produces the high-pitched sound of a courtship dive.
Many other species of hummingbirds also produce sounds with their wings or tail, including the wings of broad-tailed hummingbird, rufous hummingbird, Allen's hummingbird, streamertail, as well as the tail of the Costa's hummingbird and the black-chinned hummingbird, and a number of related species. However, the harmonics of sounds during courtship dives vary across species of hummingbirds.
Male rufous and broad-tailed hummingbirds (genus Selasphorus) have a distinctive wing feature during normal flight that sounds like jingling or a buzzing shrill whistle. Studies showed that the trill arises from air rushing through slots created by the tapered tips of the ninth and tenth primary wing feathers, creating a sound loud enough to be detected by female or competitive male hummingbirds and researchers up to 100 m away.
Behaviorally, the whistle serves several purposes
- announces the sex and presence of a male bird
- provides audible aggressive defense of feeding territory and an intrusion tactic
- enhances communication of threat
- favors mate attraction and courtship
Hummingbirds are restricted to the Americas from southern Alaska to Tierra del Fuego, including the Caribbean. The majority of species occur in tropical and subtropical Central and South America, but several species also breed in temperate climates and some hillstars occur even in alpine Andean highlands at altitudes of up to 5,200 metres (17,100 ft). The greatest species richness is in humid tropical and subtropical forests of the northern Andes and adjacent foothills, but the number of species found in the Atlantic Forest, Central America or southern Mexico also far exceeds the number found in southern South America, the Caribbean islands, the United States and Canada. While fewer than 25 different species of hummingbirds have been recorded from the United States and fewer than 10 from Canada and Chile each, Colombia alone has more than 160 and the comparably small Ecuador has about 130 species. The migratory ruby-throated hummingbird breeds in the southeastern United States, while the black-chinned hummingbird, its close relative and another migrant, is the most widespread and common species in the southwestern United States. The rufous hummingbird is the most widespread species in western North America.
Most hummingbirds of the U.S. and Canada migrate south in fall to spend winter in Mexico or Central America. A few southern South American species also move north to the tropics during the southern winter. A few species are year-round residents of California and far southern desert regions of the USA. Among these are Anna's hummingbird, a common resident from southern Arizona and inland California, and buff-bellied hummingbird, an uncommon resident in subtropical woodlands of southern Texas east through the Gulf coast to the Atlantic coast of Florida. Ruby-throated hummingbirds migrate from as far north as Ontario, Canada in summer, returning to Mexico, South America, southern Texas, and Florida to winter.
The rufous hummingbird breeds further north than any other species of Hummingbird, often breeding in large numbers in temperate western North America and winter in increasing numbers in the subtropical Gulf and Florida, rather than in tropical Mexico. By migrating in spring as far north as the Yukon or southern Alaska, the rufous hummingbird nests farther north than any other hummingbird species and must tolerate occasional temperatures below freezing in its breeding territory. This cold hardiness enables it to survive temperatures below freezing, provided that adequate shelter and food are available.
The northward migration of rufous hummingbirds occurs along the Pacific flyway and may be time-coordinated with flower and tree leaf emergence in spring in early March, and also with availability of insects as food. Arrival at breeding grounds before nectar availability from mature flowers may jeopardize breeding opportunities, a factor of phenology possibly determining future migratory patterns linked to climate change.
Diet and specializations for food gathering
Hummingbirds drink nectar, a sweet liquid inside certain flowers. Like bees, they are able to assess the amount of sugar in the nectar they eat; they normally reject flower types that produce nectar that is less than 10% sugar and prefer those whose sugar content is higher. Nectar is a mixture of glucose, fructose, and sucrose, and is a poor source of nutrients, so hummingbirds meet their needs for protein, amino acids, vitamins, minerals, etc. by preying on insects and spiders.
Hummingbird bill shapes vary dramatically, as an adaptation for specialized feeding. Some species, such as hermits (Phaethornis spp.) have bills that are long allowing them to probe deep into flowers that have a long corolla. 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 opened only slightly, allowing the tongue to dart out and into the interior of flowers. Hummingbird bill sizes range from about 5 millimeters to as long as 100 millimeters (about 4 inches).
Hummingbirds drink with their tongue by rapidly lapping nectar. Their tongues have tubes which run down their lengths and help the hummingbirds drink the nectar. While it had been believed that capillary action was what drew nectar into these tubes, high-speed photography has revealed that the tubes open down their sides as the tongue goes into the nectar, and then close around the nectar, trapping it so it can be pulled back into the beak. Consequently, tongue flexibility enables accessing, transporting and unloading nectar.
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 eat many small meals and consume approximately half their weight in pure sugar (twice their weight in nectar, if the nectar is 25% sugar) each day. Hummingbirds digest their food rapidly due to their small size and high metabolism; a mean retention time (MRT) of less than an hour has been reported. Hummingbirds spend an average of 10–15% of their time feeding and 75–80% sitting and digesting.
Because they starve so easily, hummingbirds are highly attuned to food sources. Some species, including many found in North America, are territorial and will try to guard food sources (such as a feeder) against other hummingbirds, attempting to ensure a future food supply for itself.
Feeders and artificial nectar
In the wild, hummingbirds visit flowers for food, extracting nectar, which is 55% sucrose, 24% glucose and 21% fructose. Hummingbirds will also take sugar-water from bird 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. A negative aspect of artificial feeders, however, is that the birds may seek less flower nectar for food, and so reduce the amount of pollination their feeding naturally provides.
White granulated sugar is the best sweetener to use in hummingbird feeders. A ratio of 1 part sugar to 4 parts water (20% sugar) is a common recipe, although hummingbirds will defend feeders more aggressively when sugar content is at 35%, indicating preference for nectar with higher sweetness and sugar content. Boiling and then cooling this mixture before use has been recommended to help deter the growth of bacteria and fungi. Powdered sugars contain corn starch as an anti-caking agent which 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 is not good to use in feeders because when it is diluted with water, microorganisms easily grow in it, causing it to spoil rapidly.
Red food dye is often added to homemade solutions, however is not necessary. Commercial products sold as "instant nectar" or "hummingbird food" may also contain preservatives and/or artificial flavors as well as dyes, and are not necessary. The long-term effects of these additives on hummingbirds have not been studied. 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 in most situations.
Other animals also visit hummingbird feeders. Bees, wasps, and ants are attracted to the sugar-water and may crawl into the feeder, where they may become trapped and drown. Orioles, woodpeckers, bananaquits, and other larger animals are known to drink from hummingbird feeders, sometimes tipping them and draining the liquid. In the southwestern United States, two species of nectar-drinking bats (Leptonycteris yerbabuenae and Choeronycteris mexicana) visit hummingbird feeders to supplement their natural diet of nectar and pollen from saguaro cacti and agaves.
Superficially similar birds
Some species of sunbirds of Africa, southern and southeastern Asia, and Australia resemble hummingbirds in appearance and behavior, as do perhaps also the honeyeaters of Australia and Pacific islands. These two groups, however, are not related to hummingbirds, as their resemblance is due to convergent evolution.
The hummingbird moth is often mistaken for a hummingbird.
In myth and culture
- Aztecs wore hummingbird talismans, the talismans being representations as well as actual hummingbird fetishes formed from parts of real hummingbirds: emblematic for their vigor, energy, and propensity to do work along with their sharp beaks that mimic instruments of weaponry, bloodletting, penetration, and intimacy. Hummingbird talismans were prized as drawing sexual potency, energy, vigor, and skill at arms and warfare to the wearer.
- The Aztec god of war Huitzilopochtli is often depicted as a hummingbird. It was also believed that fallen warriors would return to earth as hummingbirds and butterflies. The Nahuatl word huitzil (hummingbird) is an onomatopoeic word derived from the sounds of the hummingbird's wing-beats and zooming flight.
- One of the Nazca Lines depicts a hummingbird.
- The Ohlone tells the story of how Hummingbird brought fire to the world.
- Trinidad and Tobago is known as "The land of the hummingbird," and a hummingbird can be seen on that nation's coat of arms and 1-cent coin as well as its national airline, Caribbean Airlines.
- Chrysler's gear-reduction starter motor used from the early 1960s to the late 1980s was nicknamed the "Highland Park Hummingbird" after Chrysler's hometown and the starter's distinctive cranking sound.
- In the past hummingbird feathers were used due to their beauty to decorate different articles, like for example to decorate the miniature birds fitted in the singing bird boxes.
- In the late 19th century, hummingbirds were sometimes stuffed and mounted on women's hand fans.
Hummingbird feeding from a flower in the University of California Botanical Garden
Hummingbird with yellow pollen on its beak in the University of California Botanical Garden
Hummingbird attacking larger song sparrow
Hummingbird and honey bee sizes compared
- AeroVironment Nano Hummingbird — artificial hummingbird
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- Hemaris — sphinx moths (hummingbird moths) confused with hummingbirds
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