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51-568: Animals that undergo daily torpor include birds (even tiny hummingbirds , notably Cypselomorphae ) and some mammals, including many marsupial species, rodent species (such as mice ), and bats . During the active part of their day, such animals maintain normal body temperature and activity levels, but their metabolic rate and body temperature drop during a portion of the day (usually night) to conserve energy. Some animals seasonally go into long periods of inactivity, with reduced body temperature and metabolism, made up of multiple bouts of torpor. This

102-478: A black bear , enter torpor and switch to multi-day cycles rather than rely on a circadian rhythm. However, it is seen that both captive and wild bears express similar circadian rhythms when entering torpor. Bears entering torpor in a simulated den with no light expressed normal but low functioning rhythms. The same was observed in wild bears denning in natural areas. The function of circadian rhythms in black, brown , and polar bears suggest that their system of torpor

153-589: A museum drawer in Stuttgart ; 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

204-478: A body temperature 12 °C lower than normal. This reduction in metabolism allows it to conserve 30% of fat stores amassed from the previous day. Torpor can be a strategy of animals with unpredictable food supplies. For example, high-latitude living rodents use torpor seasonally when not reproducing. These rodents use torpor as means to survive winter and live to reproduce in the next reproduction cycle when food sources are plentiful, separating periods of torpor from

255-468: A female at speeds around 23 m/s (83 km/h; 51 mph). The sexes differ 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 away from territory. Hummingbirds begin mating when they are

306-575: A fitness advantage. Benefits of maintaining internal temperatures include increased foraging time and less susceptibility to extreme drops in temperature. This adaptation of increasing body temperature to forage has been observed in small nocturnal mammals when they first wake up in the evening. Although homeothermy lends advantages such as increased activity levels, small mammals and birds maintaining an internal body temperature spend up to 100 times more energy in low ambient temperatures compared to ectotherms. To cope with this challenge, these animals maintain

357-645: A high metabolic rate dependent on foraging for sugars from flower nectar. Hummingbird legs are short with feet having three toes pointing forward and one backward – the hallux . The toes of hummingbirds are formed as claws with ridged inner surfaces to aid gripping onto flower stems or petals. Hummingbirds do not walk on the ground or hop like most birds, but rather shuffle laterally and use their feet to grip while perching, preening feathers, or nest-building (by females), and during fights to grab feathers of opponents. Hummingbirds apply their legs as pistons for generating thrust upon taking flight, although

408-441: A high proportion of sucrose , whereas insect-pollinated flowers typically produce more concentrated nectars dominated by fructose and glucose . Eastern long-eared bat The eastern long-eared bat ( Nyctophilus bifax ) is a small flying mammal, a vespertilionid bat. It is found in eastern Australia and Papua New Guinea . The first description of the species was published in 1915 by Oldfield Thomas , based on

459-542: A male type specimen obtained from the Herberton district in the north of Queensland . Alternate names, aside from eastern long-eared bat, include the northern or north Queensland long-eared bat. A species of Nyctophilus , smaller insectivorous bats of the widespread and diverse family Vespertilionidae , the common evening bats. The flight of the species is sometimes in quick and straight directions, less usual in other nyctophilus species, but they are able to assume

510-508: A much lower body temperature, staying just over ambient temperature rather than at normal operating temperature. This reduction in body temperature and metabolic rate allows the prolonged survival of animals capable of entering torpid states. In 2020, scientists reported evidence of the torpor in Lystrosaurus living ~250 Mya in Antarctica – the oldest evidence of a hibernation-like state in

561-442: A small number of flower species. Even in the most specialized hummingbird–plant mutualisms, 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 likely because it had to compete with long-billed hummingbirds having an advantage for nectar foraging from specialized flowers, consequently leading

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612-469: A state similar to hibernation , and slow their metabolic rate to 1 ⁄ 15 of its normal rate. While most hummingbirds do not migrate , the rufous hummingbird has one of the longest migrations among birds, traveling twice per year between Alaska and Mexico , a distance of about 3,900 miles (6,300 km). Hummingbirds split from their sister group , the swifts and treeswifts , around 42 million years ago. The oldest known fossil hummingbird

663-471: A typical slower fluttering hover to capture prey. The foraging methods includes gleaning, taking insects from foliage or bark of plants, and adopts a perching stratagem or takes to the ground. The species resides under the loose papery bark of melaleuca , amongst dense foliage, or in tree hollows . The distribution range is associated with wet forest habitat between Cape York and the north of New South Wales , rainforest and vegetation at permanent water are

714-714: A vertebrate animal. Slowing metabolic rate to conserve energy in times of insufficient resources is the primarily noted purpose of torpor. This conclusion is largely based on laboratory studies where torpor was observed to follow food deprivation. There is evidence for other adaptive functions of torpor where animals are observed in natural contexts: Animals that can enter torpor rely on biological rhythms such as circadian and circannual rhythms to continue natural functions. Different animals will manage their circadian rhythm differently, and in some species it's seen to completely stop (such as in European hamsters ). Other organisms, such as

765-1085: A way to dramatically cut the cost of a human expedition to Mars by putting the crew in extended torpor for 90 to 180 days. Traveling while hibernating would reduce astronauts' metabolic functions and minimize requirements for life support during multi-year missions. Hummingbirds Hummingbirds are birds native to the Americas and comprise the biological family Trochilidae . With approximately 366 species and 113 genera , they occur from Alaska to Tierra del Fuego , but most species are found in Central and South America . As of 2024, 21 hummingbird species are listed as endangered 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

816-406: A year old. Sex occurs over 3–5 seconds when the male joins its cloaca with the female's, passing sperm to fertilize the female's eggs. Hummingbird females build a nest resembling a small cup about 1.5 inches (3.8 cm) in diameter, commonly attached to a tree branch using spider webs, lichens , moss, and loose strings of plant fibers (image). Typically, two pea -shaped white eggs (image) –

867-775: Is Eurotrochilus , from the Rupelian Stage of Early Oligocene Europe. Hummingbirds are the smallest known and smallest living avian theropod dinosaurs . The iridescent 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 . Across the estimated 366 species, hummingbird weights range from as small as 2 grams (0.071 oz) to as large as 20 grams (0.71 oz). They have characteristic long, narrow beaks (bills) which may be straight (of varying lengths) or highly curved. The bee hummingbird – only 6 centimetres (2.4 in) long and weighing about 2 grams (0.071 oz) –

918-784: Is due to convergent evolution . The hummingbird moth 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. Hummingbirds are restricted to the Americas from south central 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 m (17,100 ft). The greatest species richness

969-552: Is evolutionarily advanced. Torpor has been shown to be a strategy of small migrant birds to preserve their body energy stores . Hummingbirds, resting at night during migration, were observed to enter torpor which helped to conserve fat stores during migration or cold nights at high altitude. This strategy of using torpor to preserve energy stores, such as fat, has also been observed in wintering chickadees. Black-capped chickadees , living in temperate forests of North America, do not migrate south during winter. The chickadee can maintain

1020-419: Is greatest, possible ancestors of extant hummingbirds may have lived in parts of Europe and what is southern Russia today. As of 2023, 366 hummingbird species have been identified. They have been traditionally divided into two subfamilies : the hermits (subfamily Phaethornithinae) and the typical hummingbirds (subfamily Trochilinae , all the others). Molecular phylogenetic studies have shown, though, that

1071-598: 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

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1122-448: Is known as hibernation if it occurs during winter or aestivation if it occurs during the summer. Daily torpor, on the other hand, is not seasonally dependent and can be an important part of energy conservation at any time of year. Torpor is a well-controlled thermoregulatory process and not, as previously thought, the result of switching off thermoregulation. Marsupial torpor differs from non-marsupial mammalian ( eutherian ) torpor in

1173-544: Is the world's smallest bird and smallest warm-blooded vertebrate . Hummingbirds have compact bodies with relatively long, bladelike wings having anatomical structure enabling helicopter -like flight in any direction, including the ability to hover. Particularly while hovering, the wing beats produce the humming sounds, which 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

1224-544: The International Union for Conservation of Nature Red List of Threatened Species in 2024, 8 hummingbird species are classified as critically endangered , 13 are endangered , 13 are vulnerable , and 20 species are near-threatened . Two species – the Brace's emerald ( Riccordia bracei ) and Caribbean emerald ( Riccordia elegans ) – have been declared extinct . Of the 15 species of North American hummingbirds that inhabit

1275-501: 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 during that time. The biggest remaining mystery at present is what happened to hummingbirds in

1326-578: The cladogram below, the English names are those introduced in 1997. The scientific names are those introduced in 2013. Florisuginae – topazes Phaethornithinae – hermits Polytminae – mangoes Heliantheini – brilliants Lesbiini – coquettes Patagoninae – giants Lampornithini – mountain gems Mellisugini – bees Trochilini – emeralds While all hummingbirds depend on flower nectar to fuel their high metabolisms and hovering flight, coordinated changes in flower and bill shape stimulated

1377-456: 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 . 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

1428-411: 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 length, curvature, and volume. Some species, especially those with unusual bill shapes, such as the sword-billed hummingbird and the sicklebills , are coevolved with

1479-458: 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 ( Ensifera ensifera ), one of the morphologically most extreme species, and one of its main food plant clades ( Passiflora section Tacsonia ). Hummingbirds are specialized nectarivores tied to

1530-399: The United States and Canada indicate that the ruby-throated hummingbird numbers are around 34 million, rufous hummingbirds are around 19 million, black-chinned , Anna's , and broad-tailed hummingbirds are about 8 million each, calliopes at 4 million, and Costa's and Allen's hummingbirds are around 2 million each. Several species exist only in the thousands or hundreds. According to

1581-428: The United States and Canada, several have changed their range of distribution, while others showed declines in numbers since the 1970s, including in 2023 with dozens of hummingbird species in decline. As of the 21st century, rufous, Costa's, calliope, broad-tailed, and Allen's hummingbirds are in significant decline, some losing as much as 67% of their numbers since 1970 at nearly double the rate of population loss over

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1632-669: The bee hummingbird to more successfully compete for flower foraging against insects. Many plants pollinated by hummingbirds produce flowers in shades of red, orange, and bright pink, although the birds take nectar from flowers of other colors. 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) containing

1683-439: The characteristics of arousal. Eutherian arousal relies on a heat-producing brown adipose tissue as a mechanism to accelerate rewarming. The mechanism of marsupial arousal is unknown, but appears not to rely on brown adipose tissue. The evolution of torpor likely accompanied the development of homeothermy . Animals capable of maintaining a body temperature above ambient temperature when other members of its species would not have

1734-441: The common spiny mouse it spends more time in a torpid state. A drop in temperature from torpor has been shown to reduce the ability of parasites to reproduce. In temperate zones, the reproductive rates of ectoparasites on bats decrease when the bats enter torpor. In regions where bats don't undergo torpor, the parasites maintain a consistent reproductive rate throughout the year. In 2013, SpaceWorks Engineering began researching

1785-739: The comparably small Ecuador has about 130 species. The family Trochilidae was introduced in 1825 by Irish zoologist Nicholas Aylward Vigors with Trochilus 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

1836-421: The earliest species of hummingbird occurred in the early Oligocene ( Rupelian about 34–28 million years ago) of Europe, belonging to the genus Eurotrochilus, having similar morphology to modern hummingbirds. 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

1887-493: 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 that 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,

1938-456: The hermits are sister to the topazes , making the former definition of the Trochilinae not monophyletic . The hummingbirds form nine major clades : the topazes and jacobins , the hermits, the mangoes , the coquettes , the brilliants , the giant hummingbird ( Patagona gigas ), the mountaingems , the bees , and the emeralds . The topazes and jacobins combined have the oldest split with

1989-455: 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 ,

2040-464: 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 , bees , and emeralds – defining their relationship to nectar -bearing flowering plants which attract hummingbirds into new geographic areas. Molecular phylogenetic studies of

2091-542: The hummingbirds have shown that the family is composed of nine major clades. When Edward Dickinson and James Van Remsen Jr. 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

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2142-422: The last 500 years. Torpor enables animals to reduce energy requirements allowing them to better survive harsh conditions. Interspecific competition occurs when two species require the same resource for energy production. Torpor increases fitness in the case of inter-specific competition with the nocturnal common spiny mouse . When the golden spiny mouse experiences reduced food availability by diet overlap with

2193-788: The previous 50 years. The ruby-throated hummingbird population – the most populous North American hummingbird – decreased by 17% over the early 21st century. Habitat loss, glass collisions, cat predation, pesticides , and possibly climate change affecting food availability, migration signals, and breeding are factors that may contribute to declining hummingbird numbers. By contrast, Anna's hummingbirds had large population growth at an accelerating rate since 2010, and expanded their range northward to reside year-round in cold winter climates. Some species of sunbirds — an Old World group restricted in distribution to Eurasia , Africa, and Australia — resemble hummingbirds in appearance and behavior, but are not related to hummingbirds, as their resemblance

2244-536: The reproduction period. The eastern long-eared bat uses torpor during winter and is able to arouse and forage during warm periods. Some animals use torpor during their reproductive cycle, as seen in unpredictable habitats. They experience the cost of a prolonged reproduction period but the payoff is survival to be able to reproduce at all. It is suggested that this daily torpor use may have allowed survival through mass extinction events . Heterotherms make up only four out of 61 mammals confirmed to have gone extinct over

2295-785: 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

2346-480: 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

2397-442: The shortness of their legs provides about 20% less propulsion than assessed in other birds. During flight, hummingbird feet are tucked up under the body, enabling optimal aerodynamics and maneuverability. Of those species that have been measured during flight, the top flight speeds of hummingbirds exceed 15 m/s (54 km/h; 34 mph). During courtship , some male species dive from 30 metres (100 ft) of height above

2448-556: The smallest of any bird – are incubated over 2–3 weeks in breeding season. Fed by regurgitation only from the mother, the chicks fledge about 3 weeks after hatching. The average lifespan of a ruby-throated hummingbird is estimated to be 3–5 years, with most deaths occurring in yearlings, although one banded ruby-throated hummingbird lived for 9 years and 2 months. Bee hummingbirds live 7–10 years. Although most hummingbird species live in remote habitats where their population numbers are difficult to assess, population studies in

2499-499: The typical environs. Drier areas nearby the wetter habitat is also used by the species, in woodland and forests that provide suitable food or refuge. They are often seen hunting at the edge of forests, using their characteristic foraging techniques; a well known population occurs at the Chillagoe-Mungana Caves National Park . In Australia, the range extends into subtropical regions, and it has been recorded from

2550-529: 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 hummingbirds and swifts before the groups diverged. Hummingbirds split from other members of Apodiformes, the insectivorous swifts (family Apodidae) and treeswifts (family Hemiprocnidae), about 42 million years ago, probably in Eurasia . Despite their current New World distribution,

2601-574: The widest diversity of plumage color, particularly in blues, greens, and purples. Hummingbirds are the smallest mature birds, measuring 7.5–13 cm (3–5 in) in length. The smallest is the 5 cm (2.0 in) bee hummingbird , which weighs less than 2.0 g (0.07 oz), and the largest is the 23 cm (9 in) giant hummingbird , weighing 18–24 grams (0.63–0.85 oz). Noted for long beaks , hummingbirds are specialized for feeding on flower nectar , but all species also consume small insects. They are known as hummingbirds because of

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