Temporal range: Early Miocene to present
|Female black-chinned hummingbird|
For a taxonomic list of genera, see:
For an alphabetic species list, see:
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 (2.5 g).
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, and nightly when not foraging, they go into torpor, a state similar to hibernation, slowing metabolic rate 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 hummingbirds and plants. Due to this exceptional evolutionary pattern, as many as 25 hummingbird species are able to coexist in a specific region.
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.
Within the same biogeographic area (e.g., North America, the West Indies, or temperate South America) the oldest hummingbird clades are as old as their oldest food plant clades. The same is true for the sword-billed hummingbird (Ensifera ensifera), one of the morphological most extreme species and one of its main food plant clades (Passiflora section Tacsonia).
Co-evolution with ornithophilous flowers
Hummingbirds are specialized nectarivores and are tied to the ornithophilous flowers upon which they feed. 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 a high proportion 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, the 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 species diversity is greatest, possible ancestors of extant hummingbirds may have lived in parts of Europe to what is southern Russia today.
Between 325 and 340 species of hummingbirds are described, 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 (after the tyrant flycatchers).
Fossil hummingbirds are known from the Pleistocene of Brazil and the Bahamas; however, neither has yet been scientifically described, and fossils and subfossils of a few extant species are 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. 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.
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 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 about 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. 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%). 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%, 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 night-time torpor, body temperature falls from 40 to 18°C, 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 GFR ceases, preserving needed compounds such as 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 nonterritorial 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 hummingbird similar in size to the broad-tailed hummingbird, and at least 11 years 2 months for a much larger buff-bellied hummingbird.
|This section needs additional citations for verification. (April 2015)|
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 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 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. As a result, by 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 birds produced 75% of their weight support during the downstroke and 25% during the upstroke, with the wings making a "figure 8" motion.
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 moth. 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 bodies, 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, about 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.
Hummingbirds can not make the courtship dive sound when missing their outer tail feathers, and 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. 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 tails, including the wings of the calliope hummingbird, broad-tailed hummingbird, rufous hummingbird, Allen's hummingbird, and 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. 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
- Ffavors 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 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 a range from the southeastern United States to Ontario, 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 southward in fall to spend winter in Mexico, the Caribbean Islands, 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 southwestern 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 farther north than any other species of hummingbird, often breeding in large numbers in temperate western North America and wintering in increasing numbers along the coasts of subtropical Gulf of Mexico and Florida, rather than in western or central Mexico. By migrating in spring as far north as the Yukon or southern Alaska, the rufous hummingbird migrates more extensively and 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.
As calculated by displacement of body size, the rufous hummingbird makes perhaps the longest migratory journey of any bird in the world. At just over 3 in long, rufous birds travel 3,900-miles one-way from Alaska to Mexico in late summer, a distance equal to 78,470,000 body lengths. By comparison, the 13-inch-long Arctic tern makes a one-way flight of about 11,185 miles, or 51,430,000 body lengths, just 65% of the body displacement during migration by rufous hummingbirds.
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 long bills that allow them to probe deep into flowers with long corollae. Thornbills have short, sharp bills adapted for feeding from flowers with short corollae and piercing the bases of longer ones. The sicklebills' extremely decurved bills are adapted to extracting nectar from the curved corollae 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 a hummingbird feeds 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 mm to as long as 100 mm (about 4 in).
Hummingbirds drink with their tongues by rapidly lapping nectar. Their tongues have tubes which run down their lengths and help the hummingbirds drink the nectar. While capillary action was believed to be 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 around 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 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 on a dry-matter basis. Hummingbirds 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, 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 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. 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, but 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 attacking larger song sparrow
Hummingbird and honey bee sizes compared
- AeroVironment Nano Hummingbird — artificial hummingbird
- Macroglossum stellatarum — hummingbird hawk-moth
- Hemaris — sphinx moths (hummingbird moths) confused with hummingbirds
- Clark, C. J.; Dudley, R. (2009). "Flight costs of long, sexually selected tails in hummingbirds". Proceedings of the Royal Society B: Biological Sciences 276 (1664): 2109–2115. doi:10.1098/rspb.2009.0090. PMC 2677254. PMID 19324747.
- Ridgely RS, Greenfield PG (2001). The Birds of Ecuador, Field Guide (1 ed.). Cornell University Press. ISBN 0801487218.
- Suarez, R. K. (1992). "Hummingbird flight: Sustaining the highest mass-specific metabolic rates among vertebrates". Experientia 48 (6): 565–70. doi:10.1007/bf01920240. PMID 1612136.
- "Hummingbirds". Nationalzoo.si.edu. Retrieved 2013-04-01.
- "Hummingbirds' 22-million-year-old history of remarkable change is far from complete". ScienceDaily. 3 April 2014. Retrieved 30 September 2014.
- Baldwin, M. W.; Toda, Y.; Nakagita, T.; O'Connell, M. J.; Klasing, K. C.; Misaka, T.; Edwards, S. V.; Liberles, S. D. (2014). "Evolution of sweet taste perception in hummingbirds by transformation of the ancestral umami receptor". Science 345 (6199): 929. doi:10.1126/science.1255097. PMID 25146290.
- Stiles, Gary (1981). "Geographical Aspects of Bird Flower Coevolution, with Particular Reference to Central America". Annals of the Missouri Botanical Garden 68 (2): 323–351. doi:10.2307/2398801. JSTOR 2398801.
- Rodríguez-Gironés, M. A.; Santamaría, L. (2004). "Why Are So Many Bird Flowers Red?". PLoS Biol 2 (10): e350. doi:10.1371/journal.pbio.0020350. PMC 521733. PMID 15486585.
- Altschuler, D. L. (2003). "Flower Color, Hummingbird Pollination, and Habitat Irradiance in Four Neotropical Forests". Biotropica 35 (3): 344–355. doi:10.1646/02113. JSTOR 30043050.
- Nicolson, S. W. & Fleming, P. A. (2003). "Nectar as food for birds: the physiological consequences of drinking dilute sugar solutions". Plant Syst. Evol. 238: 139–153. doi:10.1007/s00606-003-0276-7.
- Mayr, Gerald (March 2005). "Fossil Hummingbirds of the Old World" (PDF). Biologist 52 (1): 12–16.
- McGuire, J. A.; Witt, C. C.; Altshuler, D. L.; Remsen Jr, J. V. (2007). "Phylogenetic systematics and biogography of hummingbirds: Bayesian and maximum likelihood analyses of partitioned data and selection of an appropriate partitioning strategy". Systematic Biology 56 (5): 837–856. doi:10.1080/10635150701656360. PMID 17934998.
- "Oldest hummingbird fossil found". Cbc.ca. 2004-05-06. Retrieved 2009-01-25.
- Bleiweiss, Robert; Kirsch, John A. W.; Matheus, Juan Carlos (1999). "DNA-DNA hybridization evidence for subfamily structure among hummingbirds" (PDF). Auk 111 (1): 8–19. doi:10.2307/4088500.
- Ksepka, Daniel T.; Clarke, Julia A.; Nesbitt, Sterling J.; Kulp, Felicia B.; Grande, Lance (2013). "Fossil evidence of wing shape in a stem relative of swifts and hummingbirds (Aves, Pan-Apodiformes)". Proceedings of the Royal Society B 280: 1761. doi:10.1098/rspb.2013.0580.
- Altshuler, D. L.; Dudley, R (2002). "The ecological and evolutionary interface of hummingbird flight physiology". The Journal of experimental biology 205 (Pt 16): 2325–36. PMID 12124359.
- Chambers, Lanny. "About Hummingbirds". Hummingbirds.net. Retrieved 25 January 2009.
- Hargrove, J. L. (2005). "Adipose energy stores, physical work, and the metabolic syndrome: Lessons from hummingbirds". Nutrition Journal 4: 36. doi:10.1186/1475-2891-4-36. PMC 1325055. PMID 16351726.
- Hainsworth, Reed; Wolf, Larry (May 1993). "Hummingbird Feeding". Wildbird Magazine.
- Chen, Chris Chin Wah; Welch, Kenneth Collins (2014). "Hummingbirds can fuel expensive hovering flight completely with either exogenous glucose or fructose". Functional Ecology 28 (3): 589–600. doi:10.1111/1365-2435.12202.
- Welch Jr, K. C.; Suarez, R. K. (2007). "Oxidation rate and turnover of ingested sugar in hovering Anna's (Calypte anna) and rufous (Selasphorus rufus) hummingbirds". Journal of Experimental Biology 210 (Pt 12): 2154–62. doi:10.1242/jeb.005363. PMID 17562889.
- Suarez, R. K.; Gass, C. L. (2002). "Hummingbirds foraging and the relation between bioenergetics and behavior". Comparative Biochemistry and Physiology. Part A 133 (2): 335–343. doi:10.1016/S1095-6433(02)00165-4. PMID 12208304.
- Bakken, B. H.; McWhorter, T. J.; Tsahar, E.; Martinez del Rio, C. (2004). "Hummingbirds arrest their kidneys at night: diel variation in glomerular filtration rate in Selasphorus platycercus". The Journal of Experimental Biology 207 (25): 4383–4391. doi:10.1242/jeb.01238. PMID 15557024.
- Skutch, Alexander F. & Singer, Arthur B. (1973). The Life of the Hummingbird. New York: Crown Publishers. ISBN 0-517-50572-X.
- Hainsworth, F. R.; Wolf, L. L. (1970). "Regulation of oxygen consumption and body temperature during torpor in a hummingbird, Eulampis jugularis". Science 168 (3929): 368–9. doi:10.1126/science.168.3929.368. PMID 5435893.
- Hiebert, S. M. (1992). "Time-dependent thresholds for torpor initiation in the rufous hummingbird (Selasphorus rufus)". Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology 162 (3): 249–55. PMID 1613163.
- Hiebert, S. M.; Salvante, K. G.; Ramenofsky, M; Wingfield, J. C. (2000). "Corticosterone and nocturnal torpor in the rufous hummingbird (Selasphorus rufus)". General and comparative endocrinology 120 (2): 220–34. doi:10.1006/gcen.2000.7555. PMID 11078633.
- Powers, D. R.; Brown, A. R.; Van Hook, J. A. (2003). "Influence of normal daytime fat deposition on laboratory measurements of torpor use in territorial versus nonterritorial hummingbirds". Physiological and biochemical zoology : PBZ 76 (3): 389–97. doi:10.1086/374286. PMID 12905125.
- Churchfield, Sara. (1990). The natural history of shrews. Cornell University Press. pp. 35–37. ISBN 0-8014-2595-6.
- Patuxent Wildlife Research Center, Bird Banding Laboratory. Longevity Records AOU Numbers 3930–4920 2009-08-31. Retrieved 2009-09-27.
- Oniki, Y; Willis, E. O. (2000). "Nesting behavior of the swallow-tailed hummingbird, Eupetomena macroura (Trochilidae, Aves)". Brazilian journal of biology = Revista brasleira de biologia 60 (4): 655–62. PMID 11241965.
- "Hummingbird Q&A: Nest and eggs". Operation Rubythroat: the Hummingbird Project, Hilton Pond Center for Piedmont Natural History. 2014. Retrieved 21 June 2014.
- Hummingbird Characteristics. learner.org
- Rayner, J.M.V. (1995). "Dynamics of vortex wakes of flying and swimming vertebrates". Symp. Soc. Exp. Biol. 49: 131–155. PMID 8571221.
- Warrick DR, Tobalske BW, Powers DR (2005). "Aerodynamics of the hovering hummingbird". Nature 435 (7045): 1094–7. doi:10.1038/nature03647. PMID 15973407.
- Sapir, N; Dudley, R (2012). "Backward flight in hummingbirds employs unique kinematic adjustments and entails low metabolic cost". Journal of Experimental Biology 215 (Pt 20): 3603–11. doi:10.1242/jeb.073114. PMID 23014570.
- Tobalske BW, Warrick DR, Clark CJ, Powers DR, Hedrick TL, Hyder GA, Biewener AA (2007). "Three-dimensional kinematics of hummingbird flight". J Exp Biol 210 (13): 2368–82. doi:10.1242/jeb.005686. PMID 17575042.
- Tobalske, B. W.; Biewener, A. A.; Warrick, D. R.; Hedrick, T. L.; Powers, D. R. (2010). "Effects of flight speed upon muscle activity in hummingbirds". Journal of Experimental Biology 213 (Pt 14): 2515–23. doi:10.1242/jeb.043844. PMID 20581281.
- Gill V (30 July 2014). "Hummingbirds edge out helicopters in hover contest". BBC News. Retrieved 1 Sep 2014.
- Fernández, M. J.; Dudley, R; Bozinovic, F (2011). "Comparative energetics of the giant hummingbird (Patagona gigas)". Physiological and Biochemical Zoology 84 (3): 333–40. doi:10.1086/660084. PMID 21527824.
- Morelle R (November 8, 2011). "Hummingbirds shake their heads to deal with rain". BBC News. Retrieved March 22, 2014.
- St. Fleur N (July 20, 2012). "Hummingbird rain trick: New study shows tiny birds alter posture in storms (video)". Huffington Post. Retrieved March 22, 2014.
- Clark, C. J.; Feo, T. J. (2008). "The Anna's hummingbird chirps with its tail: A new mechanism of sonation in birds". Proceedings of the Royal Society B: Biological Sciences 275 (1637): 955–62. doi:10.1098/rspb.2007.1619. PMC 2599939. PMID 18230592.
- Clark, C. J. (2009). "Courtship dives of Anna's hummingbird offer insights into flight performance limits". Proceedings of the Royal Society B: Biological Sciences 276 (1670): 3047–52. doi:10.1098/rspb.2009.0508. PMC 2817121. PMID 19515669.
- Shender, B. S.; Forster, E. M.; Hrebien, L; Ryoo, H. C.; Cammarota Jr, J. P. (2003). "Acceleration-induced near-loss of consciousness: The "A-LOC" syndrome". Aviation, space, and environmental medicine 74 (10): 1021–8. PMID 14556561.
- Clark, C. J.; Feo, T. J. (2010). "Why do Calypte hummingbirds "sing" with both their tail and their syrinx? An apparent example of sexual sensory bias". The American Naturalist 175 (1): 27–37. doi:10.1086/648560. PMID 19916787.
- Clark, C. J.; Elias, D. O.; Prum, R. O. (2013). "Hummingbird feather sounds are produced by aeroelastic flutter, not vortex-induced vibration". Journal of Experimental Biology 216 (Pt 18): 3395–403. doi:10.1242/jeb.080317. PMID 23737562.
- Clark CJ (2011). "Wing, tail, and vocal contributions to the complex acoustic signals of courting Calliope hummingbirds" (PDF). Current Zoology 57 (2): 187−196.
- Kovacevic M (2008-01-30). "Hummingbird sings with its tail feathers". Cosmos Magazine. Retrieved 2013-07-13.
- Clark, C. J. (2014). "Harmonic hopping, and both punctuated and gradual evolution of acoustic characters in selasphorus hummingbird tail-feathers". PLoS ONE 9 (4): e93829. doi:10.1371/journal.pone.0093829. PMC 3983109. PMID 24722049.
- Miller SJ, Inouye DW (1983). "Roles of the Wing Whistle in the Territorial Behaviour of Male Broad-tailed Hummingbirds (Selasphorus platycercus)". Hummingbirds.net, republished from Animal Behavior, 31, 689-700, 1983. Retrieved 13 July 2014.
- Fjeldså, J., & I. Heynen (1999). Genus Oreotrochilus. pp. 623–624 in: del Hoyo, J., A. Elliott, & J. Sargatal. eds. (1999). Handbook of the Birds of the World. Vol. 5. Barn-owls to Hummingbirds. Lynx Edicions, Barcelona. ISBN 84-87334-25-3
- Jaramillo, A., & R. Barros (2010). Species lists of birds for South American countries and territories: Chile.
- Salaman, P., T. Donegan, & D. Caro (2009). Checklist to the Birds of Colombia 2009. Conservation Colombiana 8. Fundación ProAves
- Freile, J. (2009). Species lists of birds for South American countries and territories: Ecuador.
- "The Ontario hummingbird project". The Ontario Hummingbird Project. 2013. Retrieved 3 May 2015.
- Williamson, S. L. (2002). A Field Guide to Hummingbirds of North America (Peterson Field Guide Series). Houghton Mifflin Co., Boston. ISBN 0-618-02496-4
- "The Ontario hummingbird project: migration and range maps". The Ontario Hummingbird Project. 2013. Retrieved March 23, 2014.
- "Rufous Hummingbird". Cornell University Laboratory of Ornithology. 2014. Retrieved 10 April 2014.
- "Hummingbird news: Tracking migration". http://www.learner.org/jnorth/humm/index.html. Journey North. Retrieved March 2014.
- McKinney, A. M.; Caradonna, P. J.; Inouye, D. W.; Barr, B; Bertelsen, C. D.; Waser, N. M. (2012). "Asynchronous changes in phenology of migrating Broad-tailed Hummingbirds and their early-season nectar resources". Ecology 93 (9): 1987–93. doi:10.1890/12-0255.1. PMID 23094369.
- Not All Sweetness and Light. Allaboutbirds.org. Retrieved on 2013-04-01.
- Temeles EJ (1996). "A new dimension to hummingbird-flower relationships" (PDF). Oecologia 105: 517–23. doi:10.1007/bf00330015.
- Rico-Guevara, A; Rubega, M. A. (2011). "The hummingbird tongue is a fluid trap, not a capillary tube". Proceedings of the National Academy of Sciences 108 (23): 9356–60. doi:10.1073/pnas.1016944108. PMC 3111265. PMID 21536916.
- Mosher D "High-Speed Video Shows How Hummingbirds Really Drink". Wired.com. May 2, 2011.
- Kim, W; Peaudecerf, F; Baldwin, M. W.; Bush, J. W. (2012). "The hummingbird's tongue: A self-assembling capillary syphon". Proceedings of the Royal Society B: Biological Sciences 279 (1749): 4990–6. doi:10.1098/rspb.2012.1837. PMC 3497234. PMID 23075839.
- Unwin, Mike (2011). The Atlas of Birds: Diversity, Behavior, and Conservation. Princeton University Press. p. 57. ISBN 9781400838257.
- Stevens, C. Edward; Hume, Ian D. (2004). Comparative Physiology of the Vertebrate Digestive System. Cambridge University Press. p. 126. ISBN 9780521617147.
- Stahl, J. M.; Nepi, M; Galetto, L; Guimarães, E; Machado, S. R. (2012). "Functional aspects of floral nectar secretion of Ananas ananassoides, an ornithophilous bromeliad from the Brazilian savanna". Annals of Botany 109 (7): 1243–52. doi:10.1093/aob/mcs053. PMC 3359915. PMID 22455992.
- Avalos, G; Soto, A; Alfaro, W (2012). "Effect of artificial feeders on pollen loads of the hummingbirds of Cerro de la Muerte, Costa Rica". Revista de biologia tropical 60 (1): 65–73. PMID 22458209.
- "Hummingbird Nectar Recipe". Nationalzoo.si.edu. Retrieved 2010-03-20.
- Rousseu, F; Charette, Y; Bélisle, M (2014). "Resource defense and monopolization in a marked population of ruby-throated hummingbirds (Archilochus colubris)". Ecology and Evolution 4 (6): 776–93. doi:10.1002/ece3.972. PMC 3967903. PMID 24683460.
- "Arizona Veterinary Diagnostic Laboratory Newsletter, April 2005" (PDF). Retrieved 2010-03-20.
- "Feeders and Feeding Hummingbirds (The Entire Article)". Faq.gardenweb.com. 2008-01-09. Retrieved 2009-01-25.
- "Hummingbird F.A.Q.s from the Southeastern Arizona Bird Observatory". Sabo.org. 2008-11-25. Retrieved 2009-01-25.
- Attracting Hummingbirds | Missouri Department of Conservation. Mdc.mo.gov. Retrieved on 2013-04-01.
- "Should I Add Red Dye to My Hummingbird Food?". Trochilids.com. Retrieved 2010-03-20.
- Williamson, S. (2000). Attracting and Feeding Hummingbirds. (Wild Birds Series) T.F.H. Publications, Neptune City, New Jersey. ISBN 0-7938-3580-1
- "Tucson's Hummingbird Feeder Bats". The Firefly Forest. Retrieved 2010-03-20.
- Prinzinger, R.; Schafer T. & Schuchmann K. L. (1992). "Energy metabolism, respiratory quotient and breathing parameters in two convergent small bird species : the fork-tailed sunbird Aethopyga christinae (Nectariniidae) and the chilean hummingbird Sephanoides sephanoides (Trochilidae)". Journal of thermal biology 17 (2): 71–79. doi:10.1016/0306-4565(92)90001-V.
- Werness, Hope B; Benedict, Joanne H; Thomas, Scott; Ramsay-Lozano, Tiffany (2004). The Continuum Encyclopedia of Animal Symbolism in Art. Continuum International Publishing Group. p. 229. ISBN 978-0-8264-1525-7.
- Fiona MacDonald (2008). How to Be an Aztec Warrior. National Geographic Books. p. 25. ISBN 9781426301681.
- Native Expressions: "How Hummingbird Got Fire" at the National Parks Conservation Association (archived)
- Hand fan with stuffed hummingbird, ca. 1880-1900, in the Staten Island Historical Society Online Collections Database
|Wikiquote has quotations related to: Hummingbirds|
|Wikimedia Commons has media related to Trochilidae.|
|Look up hummingbird in Wiktionary, the free dictionary.|
|Wikisource has the text of the 1920 Encyclopedia Americana article Humming-birds.|
- High-resolution photo gallery of almost 100 species
- High-resolution photo gallery of many species of Hummingbirds
- Hummingbird videos on the Internet Bird Collection
- Photographs of SouthWest U.S. Hummingbirds and International Hummingbirds
- Hummingbird Banding Research
- Hummingbird Plants Database
- Hummingbird gardens
- Hummingbird garden species, suitable for the California High Desert
- How to create a butterfly and hummingbird garden
- Hummingbird nesting data for 7 years at one site
- High-resolution photos/blog of Baby Hummingbirds