Hummingbirds are

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

s native to the

Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. Along with th ...

and comprise the biological family Trochilidae. With about 366 species and 113

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

, they occur from

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...

Tierra del Fuego Tierra del Fuego (, ; Spanish for "Land of the Fire", rarely also Fireland in English) is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of the main island, Isla G ...

, but most species are found in

Central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known as ...

and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

. About 28 hummingbird species are listed as

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...

or critically endangered, with numerous species declining in population. Hummingbirds have varied specialized characteristics to enable rapid, maneuverable flight, exceptional metabolic capacity, adaptations to high altitude, sensitive visual and communication abilities, and long-distance migration in some species. Among all birds, male hummingbirds have the widest diversity of

plumage Plumage ( "feather") is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, ...

color, particularly in blues, greens, and purples. Hummingbirds are the smallest mature birds, measuring in length. The smallest is the bee hummingbird, which weighs less than , and the largest is the giant hummingbird, weighing . Noted for long

beak The beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for eating, preening, manipulating objects, killing prey, fighting, probing for food ...

s, hummingbirds are specialized for feeding on flower nectar, but all species also consume small insects. They are known as hummingbirds because of the humming sound created by their beating wings, which flap at high frequencies audible to other birds and humans. They hover at rapid wing-flapping rates, which vary from around 12 beats per second in the largest species to 80 per second in small hummingbirds. Hummingbirds have the highest mass-specific metabolic rate of any homeothermic animal. To conserve energy when food is scarce and at night when not foraging, they can enter

torpor Torpor is a state of decreased physiological activity in an animal, usually marked by a reduced body temperature and metabolic rate. Torpor enables animals to survive periods of reduced food availability. The term "torpor" can refer to the time ...

, a state similar to

hibernation Hibernation is a state of minimal activity and metabolic depression undergone by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It most ...

, and slow their

metabolic rate Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...

to 1/15 of its normal rate. While most hummingbirds do not

migrate Migration, migratory, or migrate may refer to: Human migration * Human migration, physical movement by humans from one region to another ** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...

, the rufous hummingbird has one of the longest migrations among birds, traveling twice per year between Alaska and

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

, a distance of about . Hummingbirds split from their

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

, the

swifts Swift or SWIFT most commonly refers to: * SWIFT, an international organization facilitating transactions between banks ** SWIFT code * Swift (programming language) * Swift (bird), a family of birds It may also refer to: Organizations * SWIFT, ...

and

treeswift Treeswifts or crested swifts are a family, the Hemiprocnidae, of aerial near passerine birds, closely related to the true swifts. The family contains a single genus, ''Hemiprocne'', with four species. They are distributed from India and Southeast ...

s, around 42 million years ago. The common ancestor of extant hummingbirds is estimated to have lived 22 million years ago in South America.

Description

Bee hummingbird (Mellisuga helenae) adult male non-breeding

Hummingbirds are small birds (weighing ) with long, narrow bills. The

iridescent Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear to gradually change color as the angle of view or the angle of illumination changes. Examples of iridescence include soap bubbles, feathers, butterfl ...

colors and highly specialized feathers of many species (mainly in males) give some hummingbirds exotic common names, such as sun gem, fairy, woodstar, sapphire or

sylph A sylph (also called sylphid) is an air spirit stemming from the 16th-century works of Paracelsus, who describes sylphs as (invisible) beings of the air, his elementals of air. A significant number of subsequent literary and occult works have be ...

. Hummingbirds have a limited distribution in the

New World The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. 3 ...

, with more than 300 species in Central and

, and only about 15 native species, along with 9 vagrant species, in the United States and Canada. The northernmost hummingbird is the rufous (''Selasphorus rufus''), which breeds as far north as coastal

and throughout

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

, while the ruby-throated hummingbird breeds in eastern Canada and eastern United States, migrating to spend winter in the

Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean Se ...

region, eastern Mexico, and Central American countries. A total population estimate for the ruby-throated hummingbird is 34 million birds, making it the most populous among hummingbirds in the United States and Canada, while some species are endangered and in decline, with only a few hundred remaining. Hummingbirds have compact bodies with relatively long, bladelike wings having anatomical structure enabling

helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...

-like flight in any direction, including the ability to hover. Particularly while hovering, the wing beats produce the humming sounds, which also may function to alert other birds. In some species, the tail feathers produce sounds used by males during courtship flying. Hummingbirds have extremely rapid wing-beats as high as 80 per second, supported by a high metabolic rate dependent on foraging for sugars from flower nectar. Hummingbirds have low-volume songs that resemble scratches or squeaks. Of those species that have been measured during flying in wind tunnels, the top flight speeds of hummingbird exceed . During

courtship Courtship is the period wherein some couples get to know each other prior to a possible marriage. Courtship traditionally may begin after a betrothal and may conclude with the celebration of marriage. A courtship may be an informal and private m ...

, some male species dive from of height above a female at speeds around . The sexes are different in feather coloration, with males having distinct brilliance and ornamentation of head, neck, wing, and breast feathers. The most typical feather ornament in males is the gorget a bib-like iridescent neck-feather patch that changes brilliance with the viewing angle to attract females and warn male competitors for territory. Hummingbird females build a nest as a small cup using spider webs,

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.pea-shaped white eggs the smallest of any bird are incubated over 2-3 weeks in late spring. Fed by regurgitation only from the mother, the chicks fledge in about 3 weeks.

Superficially similar species

Some species of sunbirds an

Old World The "Old World" is a term for Afro-Eurasia that originated in Europe , after Europeans became aware of the existence of the Americas. It is used to contrast the continents of Africa, Europe, and Asia, which were previously thought of by the ...

species restricted in distribution to Eurasia, Africa, and Australia resemble hummingbirds in appearance and behavior, but are not related to hummingbirds, as their resemblance is due to convergent evolution. The

hummingbird moth ''Hemaris'' is a genus of sphinx moths in the subfamily Macroglossinae, which is native to the Holarctic.Kitching, I. J. and J. Cadiou (2000). ''Hawkmoths of the World. An Annotated and Illustrated Revisionary Checklist (Lepidoptera: Sphingidae ...

has flying and feeding characteristics similar to those of a hummingbird. Hummingbirds may be mistaken for hummingbird hawk-moths, which are large, flying insects with hovering capabilities, and exist only in Eurasia.

Range

Hummingbirds are restricted to the Americas from south central Alaska to

, 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

hillstar The hillstars are hummingbirds of the genus ''Oreotrochilus''. They are native to the Andes in South America. The '' Urochroa'' hillstars are not closely related. Species list Their genus contains seven species: * Ecuadorian hillstar (''Oreotr ...

s occur even in alpine Andean highlands at altitudes up to . 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 The Atlantic Forest ( pt, Mata Atlântica) is a South American forest that extends along the Atlantic coast of Brazil from Rio Grande do Norte state in the northeast to Rio Grande do Sul state in the south and inland as far as Paraguay and th ...

, Central America or southern

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 Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...

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,Williamson, S. L. (2002). ''A Field Guide to Hummingbirds of North America'' (Peterson Field Guide Series). Houghton Mifflin, Boston. and the only hummingbird to be recorded outside of the Americas, having occurred in the Chukchi Peninsula of Russia.

Taxonomy and systematics

The family Trochilidae was introduced in 1825 by Irish zoologist

Nicholas Aylward Vigors Nicholas Aylward Vigors (1785 – 26 October 1840) was an Ireland, Irish zoologist and politician. He popularized the classification of birds on the basis of the quinarian system. Early life Vigors was born at Old Leighlin, County Carlow on 17 ...

with ''

Trochilus The streamertails are hummingbirds in the genus ''Trochilus'', that are endemic to Jamaica. It is the type genus of the family Trochilidae. Today most authorities consider the two taxa in this genus as separate species, but some (e.g. AOU ...

'' as the type genus. In traditional taxonomy, hummingbirds are placed in the order Apodiformes, which also contains the swifts, but 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 and what is southern Russia today. Around 366 hummingbirds have been identified. They have been traditionally divided into two

subfamilies In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

: the hermits (subfamily Phaethornithinae) and the typical hummingbirds (subfamily Trochilinae, all the others). Molecular phylogenetic studies have shown, though, that the hermits are sister to the topazes, making the former definition of the Trochilinae not

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

. The hummingbirds form nine major

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

s: the topazes and jacobins, the hermits, the mangoes, the coquettes, the brilliants, the giant hummingbird (''Patagona gigas''), the

mountaingem Mountaingems are a genus of hummingbirds, ''Lampornis,'' which inhabit mountainous regions from the south-western United States to the Isthmus of Panama. These are medium-sized to large (10–13 cm) hummingbirds with shortish slightly curve ...

s, the

bees Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyletic lineage within the superfamil ...

, and the emeralds. The topazes and jacobins combined have the oldest split with the rest of the hummingbirds. The hummingbird family has the third-greatest number of species of any bird family (after the tyrant flycatchers and the tanagers). Fossil hummingbirds are known from the Pleistocene of Brazil and the Bahamas, but 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, Gerald Mayr 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 Stuttgart (; Swabian: ; ) is the capital and largest city of the German state of Baden-Württemberg. It is located on the Neckar river in a fertile valley known as the ''Stuttgarter Kessel'' (Stuttgart Cauldron) and lies an hour from the ...

; they had been unearthed in a clay pit at Wiesloch–Frauenweiler, south of Heidelberg, Germany, and, because hummingbirds were assumed to have 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 35 to 40 million years ago; this indicates that the split between these two lineages indeed occurred around that time. The areas where these early fossils have been found had a climate quite similar to that of the northern Caribbean or southernmost

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

during that time. The biggest remaining mystery at present is what happened to hummingbirds in the roughly 25 million years between the primitive ''Eurotrochilus'' and the modern fossils. The astounding morphological

adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the po ...

s, the decrease in size, and the dispersal to the Americas and extinction in Eurasia all occurred during this timespan.

DNA–DNA hybridization In genomics, DNA–DNA hybridization is a molecular biology technique that measures the degree of genetic similarity between pools of DNA sequences. It is usually used to determine the genetic distance between two organisms and has been used ext ...

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 bird fossil unearthed in Wyoming was found to be a predecessor to both hummingbirds and swifts before the groups diverged.

Evolution

Hummingbirds are thought to have split from other members of Apodiformes, the insectivorous swifts (family Apodidae) and

s (family Hemiprocnidae), about 42 million years ago, probably in Eurasia. Despite their current New World distribution, the earliest species of hummingbird occurred in the early

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

( Rupelian about 34–28 million years ago) of Europe, belonging to the genus ''Eurotrochilus,'' having similar morphology to modern hummingbirds.

Phylogeny

A phylogenetic tree unequivocally indicates that modern hummingbirds originated in South America, with the last common ancestor of all living hummingbirds living around 22 million years ago. A map of the hummingbird family tree – reconstructed from analysis of 284 species – shows rapid diversification from 22 million years ago. Hummingbirds fall into nine main clades – the topazes, hermits, mangoes, brilliants, coquettes, the giant hummingbird, mountaingems,

, and emeralds – defining their relationship to

nectar Nectar is a sugar-rich liquid produced by plants in glands called nectaries or nectarines, either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualists ...

-bearing flowering plants which attract hummingbirds into new geographic areas.

Molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

studies of the hummingbirds have shown that the family is composed of nine major clades. When Edward Dickinson and

James Van Remsen Jr. James Vanderbeek "Van" Remsen Jr. (born September 21, 1949) is an American ornithologist. His main research field is the Neotropical avifauna. In 1999, he founded the South American Classification Committee.J. V. Remsen Jr.: The South American Cla ...

updated the '' Howard and Moore Complete Checklist of the Birds of the World'' for the 4th edition in 2013, they divided the hummingbirds into six subfamilies. Molecular phylogenetic studies determined the relationships between the major groups of hummingbirds. In the cladogram below, the English names are those introduced in 1997. The Latin names are those introduced in 2013. 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 140 hummingbird species can coexist in a specific region, such as the Andes range. The hummingbird evolutionary tree shows one key evolutionary factor appears to have been an altered taste receptor that enabled hummingbirds to seek nectar. Upon maturity, males of a particular species, ''Phaethornis longirostris,'' the long-billed hermit, appear to be evolving a dagger-like weapon on the beak tip as a secondary sexual trait to defend mating areas.

Geographic diversification

The Andes Mountains appear to be a particularly rich environment for hummingbird evolution because diversification occurred simultaneously with mountain uplift over the past 10 million years. Hummingbirds remain in dynamic diversification inhabiting ecological regions across South America, North America, and the Caribbean, indicating an enlarging evolutionary radiation. Within the same geographic region, hummingbird clades coevolved with nectar-bearing plant clades, affecting mechanisms of pollination. The same is true for the

sword-billed hummingbird The sword-billed hummingbird (''Ensifera ensifera''), also known as the swordbill, is a neotropical species of hummingbird from the Andean regions of South America. It is the only member in the genus ''Ensifera.'' Among the largest species of ...

(''Ensifera ensifera''), one of the morphologically most extreme species, and one of its main food plant clades (''Passiflora'' section ''Tacsonia'').

Coevolution with ornithophilous flowers

Purple-throated carib hummingbird feeding

Hummingbirds are specialized

nectarivore In zoology, a nectarivore is an animal which derives its energy and nutrient requirements from a diet consisting mainly or exclusively of the sugar-rich nectar produced by flowering plants. Nectar as a food source presents a number of benefits a ...

s tied to the ornithophilous flowers upon which they feed. This coevolution implies that morphological traits of hummingbirds, such as bill length, bill curvature, and body mass are correlated with morphological traits of plants, such as

corolla Corolla may refer to: *Corolla (botany), the petals of a flower, considered as a unit *Toyota Corolla, an automobile model name * Corolla (headgear), an ancient headdress in the form of a circlet or crown * ''Corolla'' (gastropod), a genus of moll ...

length, curvature, and volume. Some species, especially those with unusual bill shapes, such as the sword-billed hummingbird and the sicklebills, are coevolved with a small number of flower species. Even in the most specialized hummingbird–plant mutualisms, though, the number of food plant lineages of the individual hummingbird species increases with time. The bee hummingbird (''Mellisuga helenae'') – the world's smallest bird – evolved to

dwarfism Dwarfism is a condition wherein an organism is exceptionally small, and mostly occurs in the animal kingdom. In humans, it is sometimes defined as an adult height of less than , regardless of sex; the average adult height among people with dw ...

likely because it had to compete with long-billed hummingbirds having an advantage for nectar foraging from specialized flowers, consequently leading the bee hummingbird to more successfully compete for flower foraging against insects. Colibri-thalassinus-001-edit

Many plants pollinated by hummingbirds produce flowers in shades of red, orange, and bright pink, though the birds take nectar from flowers of other colors as well. Hummingbirds can see wavelengths into the near-ultraviolet, but hummingbird-pollinated 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 Sucrose, a disaccharide, is a sugar composed of glucose and fructose subunits. It is produced naturally in plants and is the main constituent of white sugar. It has the molecular formula . For human consumption, sucrose is extracted and refined ...

, whereas insect-pollinated flowers typically produce more concentrated nectars dominated by

fructose Fructose, or fruit sugar, is a Ketose, ketonic monosaccharide, simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and galacto ...

and glucose. Hummingbirds and the plants they visit for nectar have a tight coevolutionary association, generally called a plant–bird

mutualistic network Mutualism describes the ecological Biological interaction, interaction between two or more species where each species has a net benefit. Mutualism is a common type of ecological interaction. Prominent examples include most vascular plants engag ...

. These birds show high specialization and modularity, especially in communities with high species richness. These associations are also observed when closely related hummingbirds, for example two species of the same genus, visit distinct sets of flowering species.

Sexual dimorphisms

Hummingbirds exhibit sexual size dimorphism according to

Rensch's rule Rensch's rule is a biological rule on allometrics, concerning the relationship between the extent of sexual size dimorphism and which sex is larger. Across species within a lineage, size dimorphism increases with increasing body size when the male ...

, in which males are smaller than females in small-bodied species, and males are larger than females in large-bodied species. The extent of this sexual size difference varies among clades of hummingbirds. For example, the Mellisugini clade (bees) exhibits a large size dimorphism, with females being larger than males. Conversely, the Lesbiini clade (coquettes) displays very little size dimorphism; males and females are similar in size. Sexual dimorphisms in bill size and shape are also present between male and female hummingbirds, where in many clades, females have longer, more curved bills favored for accessing nectar from tall flowers. For males and females of the same size, females tend to have larger bills. Sexual size and bill differences likely evolved due to constraints imposed by courtship, because mating displays of male hummingbirds require complex aerial maneuvers. Males tend to be smaller than females, allowing conservation of energy to forage competitively and participate more frequently in courtship. Thus, sexual selection favors smaller male hummingbirds. Female hummingbirds tend to be larger, requiring more energy, with longer beaks that allow for more effective reach into crevices of tall flowers for nectar. Thus, females are better at foraging, acquiring flower nectar, and supporting the energy demands of their larger body size. Directional selection thus favors the larger hummingbirds in terms of acquiring food. Another evolutionary cause of this sexual bill dimorphism is that the selective forces from competition for nectar between the sexes of each species drives sexual dimorphism. Depending on which sex holds territory in the species, the other sex having a longer bill and being able to feed on a wide variety of flowers is advantageous, decreasing intraspecific competition. For example, in species of hummingbirds where males have longer bills, males do not hold a specific territory and have a lek mating system. In species where males have shorter bills than females, males defend their resources, so females benefit from a longer bill to feed from a broader range of flowers.

Feather colors

The hummingbird plumage coloration gamut, particularly for blue, green, and purple colors in the gorget and crown of males, occupies 34% of the total color space for bird feathers. White (unpigmented) feathers have the lowest incidence in the hummingbird color gamut. Hummingbird plumage color diversity evolved from sexual and social selection on plumage coloration, which correlates with the rate of hummingbird species development over millions of years. Bright plumage colors in males are part of aggressive competition for flower resources and mating. The bright colors result both from pigmentation in the feathers and from prismal cells within the top layers of feathers of the head, gorget, breast, back and wings. When

sunlight Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth's atmosphere, and is obvious as daylight when t ...

hits these cells, it is split into wavelengths that reflect to the observer in varying degrees of intensity, with the feather structure acting as a diffraction grating. Iridescent hummingbird colors result from a combination of refraction and pigmentation, since the diffraction structures themselves are made of melanin, a pigment, and may also be colored by

carotenoid Carotenoids (), also called tetraterpenoids, are yellow, orange, and red organic compound, organic pigments that are produced by plants and algae, as well as several bacteria, and Fungus, fungi. Carotenoids give the characteristic color to pumpki ...

pigmentation and more subdued black, brown or gray colors dependent on melanin. By merely shifting position, feather regions of a muted-looking bird can instantly become fiery red or vivid green. In courtship displays for one example, males of the colorful

Anna's hummingbird Anna's hummingbird (''Calypte anna'') is a medium-sized bird species of the family Trochilidae. It was named after Anna Masséna, Duchess of Rivoli. It is native to western coastal regions of North America. In the early 20th century, Anna's hu ...

orient their bodies and feathers toward the sun to enhance the display value of iridescent plumage toward a female of interest. One study of Anna's hummingbirds found that dietary protein was an influential factor in feather color, as birds receiving more protein grew significantly more colorful crown feathers than those fed a low-protein diet. Additionally, birds on a high-protein diet grew yellower (higher hue) green tail feathers than birds on a low-protein diet.

Specialized characteristics and metabolism

Humming

Hummingbirds are named for the prominent humming sound their wingbeats make while flying and hovering to feed or interact with other hummingbirds. Humming serves communication purposes by alerting other birds of the arrival of a fellow forager or potential mate. The humming sound derives from aerodynamic forces generated by both the downstrokes and upstrokes of the rapid wingbeats, causing oscillations and harmonics that evoke an acoustic quality likened to that of a

musical instrument A musical instrument is a device created or adapted to make musical sounds. In principle, any object that produces sound can be considered a musical instrument—it is through purpose that the object becomes a musical instrument. A person who pl ...

. The humming sound of hummingbirds is unique among flying animals, compared to the whine of mosquitoes, buzz of

bee Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyly, monophyletic lineage within the ...

s, and "whoosh" of larger birds. The wingbeats causing the hum of hummingbirds during hovering are achieved by elastic recoil of wing strokes produced by the main flight muscles: the

pectoralis major The pectoralis major () is a thick, fan-shaped or triangular convergent muscle, situated at the chest of the human body. It makes up the bulk of the chest muscles and lies under the breast. Beneath the pectoralis major is the pectoralis minor, a ...

(the main downstroke muscle) and

supracoracoideus Bird anatomy, or the physiological structure of birds' bodies, shows many unique adaptations, mostly aiding flight. Birds have a light skeletal system and light but powerful musculature which, along with circulatory and respiratory systems capabl ...

(the main upstroke muscle).

Vision

Although hummingbird eyes are small in diameter (5–6 mm), they are accommodated in the skull by reduced skull ossification, and occupy a larger proportion of the skull compared to other birds and animals. Further, hummingbird eyes have large corneas, which comprise about 50% of the total transverse eye diameter, combined with an extraordinary density of

retinal ganglion cell A retinal ganglion cell (RGC) is a type of neuron located near the inner surface (the ganglion cell layer) of the retina of the human eye, eye. It receives visual information from photoreceptor cell, photoreceptors via two intermediate neuron typ ...

s responsible for visual processing, containing some 45,000 neurons per mm². The enlarged cornea relative to total eye diameter serves to increase the amount of light perception by the eye when the pupil is dilated maximally, enabling

nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...

flight. During evolution, hummingbirds adapted to the navigational needs of visual processing while in rapid flight or hovering by development of the exceptionally dense array of retinal neurons, allowing for increased spatial resolution in the lateral and frontal visual fields. Morphological studies of the hummingbird brain showed that neuronal hypertrophy relatively the largest in any bird exists in a region called the '' pretectal nucleus lentiformis mesencephali'' (called the ''nucleus of the optic tract'' in mammals) responsible for refining dynamic visual processing while hovering and during rapid flight. The enlargement of the brain region responsible for visual processing indicates an enhanced ability for perception and processing of fast-moving visual stimuli encountered during rapid forward flight, insect foraging, competitive interactions, and high-speed courtship. A study of broad-tailed hummingbirds indicated that hummingbirds have a fourth color-sensitive visual cone (humans have three) that detects ultraviolet light and enables discrimination of non-spectral colors, possibly having a role in flower identity, courtship displays, territorial defense, and predator evasion. The fourth color cone would extend the range of visible colors for hummingbirds to perceive ultraviolet light and color combinations of feathers and gorgets, colorful plants, and other objects in their environment, enabling detection of as many as five non-spectral colors, including purple, ultraviolet-red, ultraviolet-green, ultraviolet-yellow, and ultraviolet-purple. Hummingbirds are highly sensitive to stimuli in their visual fields, responding to even minimal motion in any direction by reorienting themselves in midflight. Their visual sensitivity allows them to precisely hover in place while in complex and dynamic natural environments, functions enabled by the lentiform nucleus which is tuned to fast-pattern velocities, enabling highly-tuned control and collision avoidance during forward flight.

Metabolism

With the exception of insects, hummingbirds have the highest metabolism of all animals – a necessity to support the rapid beating of their wings during hovering and fast forward flight. During flight and hovering, oxygen consumption per gram of muscle tissue in a hummingbird is about 10 times higher than that measured in elite human athletes. Hummingbirds achieve this extraordinary capacity for oxygen consumption by an exceptional density and proximity of capillaries and

mitochondria A mitochondrion (; ) is an organelle found in the Cell (biology), cells of most Eukaryotes, such as animals, plants and Fungus, fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosi ...

in their flight muscles. 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 maximize 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 rapid enough to satisfy their extreme metabolic demands as indicated by a 2017 review showing that hummingbirds have in their flight muscles a mechanism for "direct oxidation" of sugars into maximal

ATP ATP may refer to: Companies and organizations * Association of Tennis Professionals, men's professional tennis governing body * American Technical Publishers, employee-owned publishing company * ', a Danish pension * Armenia Tree Project, non ...

yield to support a high metabolic rate for hovering, foraging at altitude, and migrating. This adaptation occurred through the evolutionary loss of a key gene, fructose-bisphosphatase 2 (''FBP2''), coinciding with the onset of hovering by hummingbirds estimated by fossil evidence to be some 35 million years ago. Without ''FBP2'',

glycolysis Glycolysis is the metabolic pathway that converts glucose () into pyruvate (). The free energy released in this process is used to form the high-energy molecules adenosine triphosphate (ATP) and reduced nicotinamide adenine dinucleotide (NADH ...

and mitochondrial respiration in flight muscles are enhanced, enabling hummingbirds to metabolize sugar more efficiently for energy. By relying on newly ingested sugars to fuel flight, hummingbirds reserve their limited fat stores to sustain their overnight fasting or to power migratory flights. Studies of hummingbird metabolism address how a migrating ruby-throated hummingbird can cross of the Gulf of Mexico on a nonstop flight. This hummingbird, like other long-distance migrating birds, stores fat as a fuel reserve augmenting its weight by as much as 100%, then enabling metabolic fuel for flying over open water. The heart rate of hummingbirds can reach as high as 1,260 beats per minute, a rate measured in a blue-throated hummingbird with a breathing rate of 250 breaths per minute at rest.

Hemoglobin adaptation to altitude

Dozens of hummingbird species live year-round in tropical mountain habitats at high altitudes, such as in the Andes over ranges of to where the partial pressure of oxygen in the air is reduced, a condition of hypoxic challenge for the high metabolic demands of hummingbirds. In Andean hummingbirds living at high elevations, researchers found that the oxygen-carrying protein in blood hemoglobin had increased oxygen- binding affinity, and that this adaptive effect likely resulted from evolutionary mutations within the hemoglobin molecule via specific amino acid changes due to natural selection.

Heat dissipation

The high metabolic rate of hummingbirds – especially during rapid forward flight and hovering – produces increased body heat that requires specialized mechanisms of thermoregulation for heat dissipation, which becomes an even greater challenge in hot, humid climates. Hummingbirds dissipate heat partially by

evaporation Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...

through exhaled air, and from body structures with thin or no feather covering, such as around the eyes, shoulders, under the wings ( patagia), and feet. While hovering, hummingbirds do not benefit from the heat loss by air convection during forward flight, except for air movement generated by their rapid wing-beat, possibly aiding convective heat loss from the extended feet. Smaller hummingbird species, such as the calliope, appear to adapt their relatively higher surface-to-volume ratio to improve convective cooling from air movement by the wings. When air temperatures rise above , thermal gradients driving heat passively by convective dissipation from around the eyes, shoulders, and feet are reduced or eliminated, requiring heat dissipation mainly by evaporation and exhalation. In cold climates, hummingbirds retract their feet into breast feathers to eliminate skin exposure and minimize heat dissipation.

Torpor

The metabolism of hummingbirds can slow at night or at any time when food is not readily available; the birds enter a deep-sleep state (known as

) to prevent energy reserves from falling to a critical level. One study of broad-tailed hummingbirds found that body weight decreased linearly throughout torpor at a rate of 0.04 g per hour. During nighttime torpor, body temperature in a Caribbean hummingbird was shown to fall from 40 to 18 °C, with heart and breathing rates both slowed dramatically (heart rate of roughly 50 to 180 bpm from its daytime rate of higher than 1000 bpm). Recordings from a ''

Metallura phoebe The black metaltail (''Metallura phoebe'') is a species of hummingbird in the "coquettes", tribe Lesbiini of subfamily Lesbiinae. It is endemic to Peru.HBW and BirdLife International (2020) ''Handbook of the Birds of the World and BirdLife Inte ...

'' hummingbird in noctural torpor at around in the Andes mountains showed that body temperature fell to 3.3 °C (38 °F), the lowest known level for a bird or non-hibernating mammal. During cold nights at altitude, hummingbirds were in torpor for 2-13 hours depending on species, with cooling occurring at the rate of 0.6 °C per minute and rewarming at 1-1.5 °C per minute. High-altitude Andean hummingbirds also lost body weight in negative proportion to how long the birds were in torpor, losing about 6% of weight each night. During torpor, to prevent dehydration, the kidney function declines, preserving needed compounds, such as glucose, water, and nutrients. 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. A hummingbird with a higher fat percentage will be less likely to enter a state of torpor compared to one with less fat, as a bird can use the energy from its fat stores. Torpor in hummingbirds appears to be unrelated to nighttime temperature, as it occurs across a wide temperature range, with energy savings of such deep sleep being more related to the

photoperiod Photoperiodism is the physiological reaction of organisms to the length of night or a dark period. It occurs in plants and animals. Plant photoperiodism can also be defined as the developmental responses of plants to the relative lengths of light a ...

and duration of torpor.

Kidney function

The dynamic range of metabolic rates in hummingbirds requires a parallel dynamic range in kidney function. During a day of nectar consumption with a corresponding high water intake that may total five times the body weight per day, hummingbird kidneys process water via glomerular filtration rates (GFR) in amounts proportional to water consumption, thereby avoiding overhydration. During brief periods of water deprivation, however, such as in nighttime torpor, GFR drops to zero, preserving body water. Hummingbird kidneys also have a unique ability to control the levels of

electrolyte An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon dis ...

s after consuming nectars with high amounts of sodium and chloride or none, indicating that kidney and glomerular structures must be highly specialized for variations in nectar mineral quality. Morphological studies on Anna's hummingbird kidneys showed adaptations of high capillary density in close proximity to nephrons, allowing for precise regulation of water and electrolytes.

Song, vocal learning, and hearing

Many hummingbird species exhibit a diverse vocal repertoire of chirps, squeaks, whistles and buzzes. Vocalizations vary in complexity and spectral content during social interactions, foraging, territorial defense, courtship, and mother-nestling communication. Territorial vocal signals may be produced in rapid succession to discourage aggressive encounters, with the chirping rate and loudness increasing when intruders persist. During the breeding season, both male and female hummingbirds vocalize as part of courtship. Hummingbirds exhibit vocal production learning to enable song variation "dialects" that exist across the same species. For example, the blue-throated hummingbird's song differs from typical oscine songs in its wide frequency range, extending from 1.8 kHz to about 30 kHz. It also produces ultrasonic vocalizations which do not function in communication. As blue-throated hummingbirds often alternate singing with catching small flying insects, it is possible the ultrasonic clicks produced during singing disrupt insect flight patterns, making insects more vulnerable to predation. Anna's, Costa's, long-billed hermits, and Andean hummingbirds have song dialects that vary across habitat locations and phylogenetic clades. The avian vocal organ, the

syrinx In classical Greek mythology, Syrinx (Greek Σύριγξ) was a nymph and a follower of Artemis, known for her chastity. Pursued by the amorous god Pan, she ran to a river's edge and asked for assistance from the river nymphs. In answer, sh ...

, plays an important role in understanding hummingbird song production. What makes the hummingbird's syrinx different from that of other birds in the Apodiformes order is the presence of internal muscle structure, accessory cartilages, and a large tympanum that serves as an attachment point for external muscles, all of which are adaptations thought to be responsible for the hummingbird's increased ability in pitch control and large frequency range. Hummingbird songs originate from at least seven specialized nuclei in the forebrain. A

genetic expression Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product that enables it to produce end products, protein or non-coding RNA, and ultimately affect a phenotype, as the final effect. The ...

study showed that these nuclei enable vocal learning (ability to acquire vocalizations through imitation), a rare trait known to occur in only two other groups of birds ( parrots and songbirds) and a few groups of mammals (including humans, whales and dolphins, and bats). Within the past 66 million years, only hummingbirds, parrots, and songbirds out of 23 bird orders may have independently evolved seven similar forebrain structures for singing and vocal learning, indicating that evolution of these structures is under strong

epigenetic In biology, epigenetics is the study of stable phenotypic changes (known as ''marks'') that do not involve alterations in the DNA sequence. The Greek prefix '' epi-'' ( "over, outside of, around") in ''epigenetics'' implies features that are "o ...

constraints possibly derived from a common ancestor. Generally, birds have been assessed to vocalize and hear in the range of 2–5 kHz, with hearing sensitivity falling with higher frequencies. In the Ecuadorian hillstar (''Oreotrochilus chimborazo''), vocalizations were recorded in the wild to be at a frequency above 10 Hz, well outside of the known hearing ability of most birds. Song system nuclei in the hummingbird brain are similar to those songbird brains, but the hummingbird brain has specialized regions involved for song processing.

Lifespan

Hummingbirds have unusually 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 fledging, those that survive may occasionally live a decade or more. Among the better-known North American species, the typical lifespan is probably 3 to 5 years. For comparison, the smaller shrews, among the smallest of all mammals, seldom live longer than 2 years. The longest recorded lifespan in the wild relates to 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.Patuxent Wildlife Research Center, Bird Banding Laboratory
Longevity Records AOU Numbers 3930–4920
2009-08-31. Retrieved 2009-09-27.

Predators

Praying mantises have been observed as predators of hummingbirds. Other predators include dragonflies, frogs, orb-weaver spiders, and other birds, such as the roadrunner.

Reproduction

Male hummingbirds do not take part in nesting. Most species build a cup-shaped nest on the branch of a tree or shrub. 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 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. Hummingbirds stay in the nest for 18–22 days, after which they leave the nest to forage on their own, although the mother bird may continue feeding them for another 25 days.

Flight

Hummingbird flight has been studied intensively from an aerodynamic perspective using wind tunnels and high-speed video cameras. 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. Hummingbird wake Pengo

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 Electromyography (EMG) is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph to produce a record called an electromyogram. An electromyog ...

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. Presumably due to rapid wingbeats for flight and hovering, hummingbird wings have adapted to perform without an alula. The giant hummingbird's wings beat as few as 12 per second, and the wings of typical hummingbirds beat up to 80 times per second. As air density decreases, for example, at higher altitudes, the amount of power a hummingbird must use to hover increases. Hummingbird species adapted for life at higher altitudes, therefore, have larger wings to help offset these negative effects of low air density on lift generation. 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.

Wingbeats and flight stability

The highest recorded wingbeats for wild hummingbirds during hovering is 88 per second, as measured for the

purple-throated woodstar The purple-throated woodstar (''Philodice mitchellii'') is a species of hummingbird in tribe Mellisugini of subfamily Trochilinae, the "bee hummingbirds". It is found in Colombia, Ecuador, and Panama.HBW and BirdLife International (2020) ''Hand ...

(''Calliphlox mitchellii'') weighing 3.2 g. The number of beats per second increases above "normal" while hovering during courtship displays (up to 90 per second for the calliope hummingbird, ''Selasphorus calliope''), a wingbeat rate 40% higher than its typical hovering rate. During turbulent airflow conditions created experimentally in a wind tunnel, hummingbirds exhibit stable head positions and orientation when they hover at a feeder. When wind gusts from the side, hummingbirds compensate by increasing wing-stroke amplitude and stroke plane angle and by varying these parameters asymmetrically between the wings and from one stroke to the next. They also vary the orientation and enlarge the collective

surface area The surface area of a solid object is a measure of the total area that the surface of the object occupies. The mathematical definition of surface area in the presence of curved surfaces is considerably more involved than the definition of arc ...

of their tail feathers into the shape of a fan. While hovering, the visual system of a hummingbird is able to separate apparent motion caused by the movement of the hummingbird itself from motions caused by external sources, such as an approaching predator. In natural settings full of highly complex background motion, hummingbirds are able to precisely hover in place by rapid coordination of vision with body position.

Feather sounds

Courtship dives

When courting, the male Anna's hummingbird ascends some above a female, before diving at a speed of , equal to 385 body lengths/sec – producing a high-pitched sound near the female at the nadir of the dive. This downward acceleration during a dive is the highest reported for any vertebrate undergoing a voluntary aerial maneuver; in addition to acceleration, the speed relative to body length is the highest known for any vertebrate. For instance, it is about twice the diving speed of

peregrine falcon The peregrine falcon (''Falco peregrinus''), also known as the peregrine, and historically as the duck hawk in North America, is a Cosmopolitan distribution, cosmopolitan bird of prey (Bird of prey, raptor) in the family (biology), family Falco ...

s in pursuit of prey. At maximum descent speed, about 10 g of gravitational force occur in the courting hummingbird during a dive (Note: G-force is generated as the bird pulls out of the dive). The outer tail feathers of male Anna's (''Calypte anna'') and ''Selasphorus'' hummingbirds (e.g., Allen's, calliope) vibrate during courtship display dives and produce an audible chirp caused by aeroelastic flutter. Hummingbirds cannot 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 Flutter may refer to: Technology * Aeroelastic flutter, a rapid self-feeding motion, potentially destructive, that is excited by aerodynamic forces in aircraft and bridges * Flutter (American company), a gesture recognition technology company acqu ...

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 while flying, hovering, or diving, including the wings of the calliope hummingbird, broad-tailed hummingbird, rufous hummingbird, Allen's hummingbird, and the

streamertail The streamertails are hummingbirds in the genus ''Trochilus'', that are endemic to Jamaica. It is the type genus of the family Trochilidae. Today most authorities consider the two taxa in this genus as separate species, but some (e.g. AOU) cont ...

species, as well as the tail of the Costa's hummingbird and the black-chinned hummingbird, and a number of related species. The

harmonic A harmonic is a wave with a frequency that is a positive integer multiple of the ''fundamental frequency'', the frequency of the original periodic signal, such as a sinusoidal wave. The original signal is also called the ''1st harmonic'', the ...

s of sounds during courtship dives vary across species of hummingbirds.

Wing feather trill

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 a trill. 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 trill serves several purposes: It announces the sex and presence of a male bird; it provides audible aggressive defense of a feeding territory and an intrusion tactic; it enhances communication of a threat; and it favors mate attraction and courtship.

Migration

Relatively few hummingbirds migrate as a percentage of the total number of species; of the roughly 366 known hummingbird species, only 12–15 species migrate annually, particularly those in North America. Most hummingbirds live in the

Amazonia The Amazon rainforest, Amazon jungle or ; es, Selva amazónica, , or usually ; french: Forêt amazonienne; nl, Amazoneregenwoud. In English, the names are sometimes capitalized further, as Amazon Rainforest, Amazon Forest, or Amazon Jungle. ...

-Central America tropical rainforest belt, where seasonal temperature changes and food sources are relatively constant, obviating the need to migrate. As the smallest living birds, hummingbirds are relatively limited at conserving heat energy, and are generally unable to maintain a presence in higher latitudes during winter months, unless the specific location has a large food supply throughout the year, particularly access to flower nectar. Other migration factors are seasonal fluctuation of food, climate, competition for resources, predators, and inherent signals. Most North American hummingbirds 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 Florida, California, and the far southwestern desert regions of the US. Among these are Anna's hummingbird, a common resident from southern Arizona and inland California, and the buff-bellied hummingbird, a winter resident from Florida across the Gulf Coast to

South Texas South Texas is a region of the U.S. state of Texas that lies roughly south of—and includes—San Antonio. The southern and western boundary is the Rio Grande, and to the east it is the Gulf of Mexico. The population of this region is about 4.96 ...

. Ruby-throated hummingbirds are common along the Atlantic flyway, and migrate in summer from as far north as

Atlantic Canada Atlantic Canada, also called the Atlantic provinces (french: provinces de l'Atlantique), is the region of Eastern Canada comprising the provinces located on the Atlantic coast, excluding Quebec. The four provinces are New Brunswick, Newfoundlan ...

, returning to Mexico, South America, southern Texas, and Florida to winter. During winter in southern Louisiana, black-chinned, buff-bellied, calliope, Allen's, Anna's, ruby-throated, rufous, broad-tailed, and broad-billed hummingbirds are present. The rufous hummingbird breeds farther north than any other species of hummingbird, often breeding in large numbers in temperate North America and wintering in increasing numbers along the coasts of the 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 long, rufous hummingbirds travel one-way from Alaska to Mexico in late summer, a distance equal to 78,470,000 body lengths, then make the return journey in the following spring. By comparison, the -long

Arctic tern The Arctic tern (''Sterna paradisaea'') is a tern in the family Laridae. This bird has a circumpolar breeding distribution covering the Arctic and sub-Arctic regions of Europe (as far south as Brittany), Asia, and North America (as far south a ...

makes a one-way flight of about , 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.

Feeding

For nutrition, hummingbirds eat a variety of insects, including mosquitoes, fruit flies, gnats in flight, or aphids on leaves and spiders in their webs. The lower beak of hummingbirds is flexible and can bend as much as 25 degrees when it widens at the base, making a larger surface for catching insects. Hummingbirds hover within insect swarms in a method called "hover- hawking" to facilitate feeding. To supply energy needs, hummingbirds drink nectar, a sweet liquid inside certain flowers. Like bees, they are able to assess the amount of sugar in the nectar they drink; 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 other

nutrient A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...

s, requiring hummingbirds to meet their nutritional needs by consuming insects. 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 nectar (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 20% of their time feeding and 75–80% sitting and digesting. Because their high metabolism makes them vulnerable to

starvation Starvation is a severe deficiency in caloric energy intake, below the level needed to maintain an organism's life. It is the most extreme form of malnutrition. In humans, prolonged starvation can cause permanent organ damage and eventually, dea ...

, hummingbirds are highly attuned to food sources. Some species, including many found in North America, are territorial and try to guard food sources (such as a feeder) against other hummingbirds, attempting to ensure a future food supply. Additionally, hummingbirds have an enlarged hippocampus, a brain region facilitating spatial memory used to map flowers previously visited during nectar foraging. Hummingbird beaks are flexible and their 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 The fiery-tailed awlbill (''Avocettula recurvirostris'') is a species of hummingbird in the subfamily Polytminae, the mangoes. It is found in Brazil, Ecuador, French Guiana, Guyana, Suriname, and Venezuela.Remsen, J. V., Jr., J. I. Areta, E. Bo ...

has an upturned tip adapted for feeding on nectar from tubular flowers while hovering. Hummingbird bill sizes range from about 5 mm to as long as 100 mm (about 4 in). When catching insects in flight, a hummingbird's jaw

flexes Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relative ...

downward to widen the beak for successful capture.

Perception of sweet nectar

Perception of sweetness in nectar evolved in hummingbirds during their

genetic divergence Genetic divergence is the process in which two or more populations of an ancestral species accumulate independent genetic changes (mutations) through time, often leading to reproductive isolation and continued mutation even after the populations hav ...

from insectivorous swifts, their closest bird relatives. Although the only known sweet sensory receptor, called T1R2, is absent in birds, receptor expression studies showed that hummingbirds adapted a carbohydrate receptor from the

T1R1 Taste receptor type 1 member 1 is a protein that in humans is encoded by the ''TAS1R1'' gene. Structure The protein encoded by the ''TAS1R1'' gene is a G protein-coupled receptor with seven trans-membrane domains and is a component of the he ...

- T1R3 receptor, identical to the one perceived as umami in humans, essentially repurposing it to function as a nectar sweetness receptor. This adaptation for taste enabled hummingbirds to detect and exploit sweet nectar as an energy source, facilitating their distribution across geographical regions where nectar-bearing flowers are available.

Tongue as a micropump

Hummingbirds drink with their long tongues by rapidly lapping nectar. Their tongues have semicircular tubes which run down their lengths to facilitate nectar consumption via rapid pumping in and out of the nectar. While capillary action was believed to be what drew nectar into these tubes, high-speed photography 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 over a period of 14

millisecond A millisecond (from '' milli-'' and second; symbol: ms) is a unit of time in the International System of Units (SI) equal to one thousandth (0.001 or 10−3 or 1/1000) of a second and to 1000 microseconds. A unit of 10 milliseconds may be called ...

s per lick at a rate of up to 20 licks per second. The tongue, which is forked, is compressed until it reaches nectar, then the tongue springs open, the rapid action traps the nectar which moves up the grooves, like a

pump A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action, typically converted from electrical energy into hydraulic energy. Pumps can be classified into three major groups according to the method they u ...

action, with capillary action not involved. Consequently, tongue flexibility enables accessing, transporting and unloading nectar via pump action, not by a capillary

syphon A siphon (from grc, σίφων, síphōn, "pipe, tube", also spelled nonetymologically syphon) is any of a wide variety of devices that involve the flow of liquids through tubes. In a narrower sense, the word refers particularly to a tube in a ...

as once believed. Ruby-Throated Hummingbird

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, which 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 may reduce the amount of pollination their feeding naturally provides. White granulated sugar is used in hummingbird feeders in a 20% concentration as a common recipe, although hummingbirds will defend feeders more aggressively when sugar content is at 35%, indicating preference for nectar with higher sugar content. Organic and "raw" sugars contain iron, which can be harmful, and brown sugar,

agave syrup ''Agave'' (; ; ) is a genus of monocots native to the hot and arid regions of the Americas and the Caribbean, although some ''Agave'' species are also native to tropical areas of North America, such as Mexico. The genus is primarily known for i ...

molasses Molasses () is a viscous substance resulting from refining sugarcane or sugar beets into sugar. Molasses varies in the amount of sugar, method of extraction and age of the plant. Sugarcane molasses is primarily used to sweeten and flavour foods ...

, and artificial sweeteners also should not be used.

Honey Honey is a sweet and viscous substance made by several bees, the best-known of which are honey bees. Honey is made and stored to nourish bee colonies. Bees produce honey by gathering and then refining the sugary secretions of plants (primar ...

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 was once thought to be a favorable ingredient for the nectar in home feeders, but it is unnecessary. Commercial products sold as "instant nectar" or "hummingbird food" may also contain preservatives or artificial flavors, as well as dyes, which are unnecessary and potentially harmful. Although some commercial products contain small amounts of nutritional additives, hummingbirds obtain all necessary nutrients from the insects they eat, rendering added nutrients unnecessary.

Visual cues of foraging

Hummingbirds have exceptional visual acuity providing them with discrimination of food sources while foraging. Although hummingbirds are thought to be attracted to color while seeking food, such as red flowers or artificial feeders, experiments indicate that location and flower nectar quality are the most important " beacons" for foraging. Hummingbirds depend little on visual cues of flower color to beacon to nectar-rich locations, but rather they use surrounding landmarks to find the nectar reward. In at least one hummingbird species – the

green-backed firecrown The green-backed firecrown (''Sephanoides sephaniodes'') is a hummingbird in the "coquettes", tribe Lesbiini of subfamily Lesbiinae. It is found in Argentina, mainland Chile, and the Juan Fernández Islands.HBW and BirdLife International (2020) ...

(''Sephanoides sephaniodes'') – flower colors preferred are in the red-green wavelength for the bird's visual system, providing a higher contrast than for other flower colors. Further, the crown plumage of firecrown males is highly iridescent in the red wavelength range (peak at 650 nanometers), possibly providing a competitive advantage of dominance when foraging among other hummingbird species with less colorful plumage. The ability to discriminate colors of flowers and plumage is enabled by a visual system having four single

cone cell Cone cells, or cones, are photoreceptor cells in the retinas of vertebrate eyes including the human eye. They respond differently to light of different wavelengths, and the combination of their responses is responsible for color vision. Cone ...

s and a double cone screened by photoreceptor oil droplets which enhance color discrimination.

Olfaction

While hummingbirds rely primarily on vision and hearing to assess competition from bird and insect foragers near food sources, they may also be able to detect by

smell Smell may refer to; * Odor, airborne molecules perceived as a scent or aroma * Sense of smell, the scent also known scientifically as olfaction * "Smells" (''Bottom''), an episode of ''Bottom'' * The Smell, a music venue in Los Angeles, Californ ...

the presence in nectar of insect defensive chemicals (such as

formic acid Formic acid (), systematically named methanoic acid, is the simplest carboxylic acid, and has the chemical formula HCOOH and structure . It is an important intermediate in chemical synthesis and occurs naturally, most notably in some ants. Es ...

) and aggregation pheromones of foraging ants, which discourage feeding.

In myth and culture

Líneas de Nazca, Nazca, Perú, 2015-07-29, DD 52

Aztecs The Aztecs () were a Mesoamerican culture that flourished in central Mexico in the post-classic period from 1300 to 1521. The Aztec people included different Indigenous peoples of Mexico, ethnic groups of central Mexico, particularly those g ...

wore hummingbird talismans, both artistic representations of hummingbirds and fetishes made from actual hummingbird parts as emblematic for vigor, energy, and propensity to do work along with their sharp beaks that symbolically 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 in art as a hummingbird. Aztecs believed that fallen warriors would be reincarnated as hummingbirds. The

Nahuatl Nahuatl (; ), Aztec, or Mexicano is a language or, by some definitions, a group of languages of the Uto-Aztecan language family. Varieties of Nahuatl are spoken by about Nahua peoples, most of whom live mainly in Central Mexico and have smaller ...

word ''huitzil'' translates to ''hummingbird''. One of the Nazca Lines depicts a hummingbird (right). Trinidad and Tobago, known as "The land of the hummingbird," displays a hummingbird on that nation's coat of arms, 1-cent coin, and

livery A livery is an identifying design, such as a uniform, ornament, symbol or insignia that designates ownership or affiliation, often found on an individual or vehicle. Livery will often have elements of the heraldry relating to the individual or ...

on its national airline, Caribbean Airlines.

Mt. Umunhum Mount Umunhum (Ohlone for "Resting Place of the Hummingbird") is a peak in the Santa Cruz Mountains, located in Santa Clara County, California. It is the fourth-highest peak in the Santa Cruz Mountains, after Loma Prieta, Crystal Peak, and Mt. ...

in the

Santa Cruz Mountains The Santa Cruz Mountains, part of the Pacific Coast Ranges, are a mountain range in central and Northern California, United States. They form a ridge down the San Francisco Peninsula, south of San Francisco. They separate the Pacific Ocean from ...

Northern California Northern California (colloquially known as NorCal) is a geographic and cultural region that generally comprises the northern portion of the U.S. state of California. Spanning the state's northernmost 48 counties, its main population centers incl ...

Ohlone The Ohlone, formerly known as Costanoans (from Spanish meaning 'coast dweller'), are a Native American people of the Northern California coast. When Spanish explorers and missionaries arrived in the late 18th century, the Ohlone inhabited the ...

for "resting place of the hummingbird". The

Hopi The Hopi are a Native American ethnic group who primarily live on the Hopi Reservation in northeastern Arizona, United States. As of the 2010 census, there are 19,338 Hopi in the country. The Hopi Tribe is a sovereign nation within the Unite ...

and Zuni cultures have a hummingbird creation myth about a young brother and sister who are starving because drought and famine have come to the land. Their parents have left to find food, so the boy carves a piece of wood into a small bird to entertain his sister. When the girl tosses the carving into the air, the bird comes to life, turning into a hummingbird. The small bird then flies to the God of Fertility and begs for rain, and the god obliges the request, which helps the crops to grow again. The

Gibson Hummingbird The Gibson Hummingbird is an acoustic guitar model/series produced by the Gibson Guitar Corporation. Unlike the other flat-top Gibson acoustics, the Hummingbird was Gibson's first square-shoulder dreadnought, similar to the dreadnoughts produce ...

is an

acoustic guitar An acoustic guitar is a musical instrument in the string family. When a string is plucked its vibration is transmitted from the bridge, resonating throughout the top of the guitar. It is also transmitted to the side and back of the instrument, ...

model described as having the shape of a hummingbird by Gibson Brands, a major guitar manufacturer. During the costume competition of the Miss Universe 2016 beauty pageant,

Miss Ecuador Miss Ecuador is a national beauty pageant in Ecuador. The current Miss Ecuador is Nayelhi González from Esmeraldas, Esmeraldas Province. She won the title on September 3, 2022 and will represent Ecuador at Miss Universe 2022. History The ver ...

, Connie Jiménez, wore a costume inspired by hummingbird wing feathers.

Gallery

File:Haeckel Trochilidae.jpg, A color plate illustration from

Ernst Haeckel Ernst Heinrich Philipp August Haeckel (; 16 February 1834 – 9 August 1919) was a German zoologist, naturalist, eugenicist, philosopher, physician, professor, marine biologist and artist. He discovered, described and named thousands of new sp ...

's '' Kunstformen der Natur'' (1899), showing a variety of hummingbirds File:AnnasHummingbird-NestCollage.png, Fallen Anna's hummingbird nest shown next to a

toothpick A toothpick is a small thin stick of wood, plastic, bamboo, metal, bone or other substance with at least one and sometimes two pointed ends to insert between teeth to remove detritus, usually after a meal. Toothpicks are also used for festive ...

for scale

Notes

References

External links

The Hummingbird Website
Hummingbird photos, videos, articles, links, frequently asked questions
High-resolution photo gallery of almost 100 species

* ttps://web.archive.org/web/20170301202153/http://www.learner.org/jnorth/tm/humm/tongue_fluid_trap.html Video of hummingbird tongue acting as a micropump during nectar feeding {{Authority control Hummingbirds * * Articles containing video clips National symbols of Trinidad and Tobago Taxa named by Nicholas Aylward Vigors