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  • Zebras 

    Zebras (US/ˈziːbrəz/UK/ˈzɛbrəz, ˈziː-/)[2] (subgenus Hippotigris) are African equines with distinctive black-and-white striped coats. There are three living species: Grévy’s zebra (Equus grevyi), the plains zebra (E. quagga), and the mountain zebra (E. zebra). Zebras share the genus Equus with horses and asses, the three groups being the only living members of the family Equidae. Zebra stripes come in different patterns, unique to each individual. Several theories have been proposed for the function of these patterns, with most evidence supporting them as a deterrent for biting flies. Zebras inhabit eastern and southern Africa and can be found in a variety of habitats such as savannahsgrasslands, woodlands, shrublands, and mountainous areas.

    Zebras are primarily grazers and can subsist on lower-quality vegetation. They are preyed on mainly by lions, and typically flee when threatened but also bite and kick. Zebra species differ in social behaviour, with plains and mountain zebra living in stable harems consisting of an adult male or stallion, several adult females or mares, and their young or foals; while Grévy’s zebra live alone or in loosely associated herds. In harem-holding species, adult females mate only with their harem stallion, while male Grévy’s zebras establish territories which attract females and the species is promiscuous. Zebras communicate with various vocalisations, body postures and facial expressions. Social grooming strengthens social bonds in plains and mountain zebras.

    Zebras’ dazzling stripes make them among the most recognizable mammals. They have been featured in art and stories in Africa and beyond. Historically, they have been highly sought by exotic animal collectors, but unlike horses and donkeys, zebras have never been completely domesticated. The International Union for Conservation of Nature (IUCN) lists Grévy’s zebra as endangered, the mountain zebra as vulnerable and the plains zebra as near-threatened. The quagga (E. quagga quagga), a type of plains zebra, was driven to extinction in the 19th century. Nevertheless, zebras can be found in numerous protected areas.

    Etymology

    The English name “zebra” derives from ItalianSpanish or Portuguese.[3][4] Its origins may lie in the Latin equiferus, meaning “wild horse”. Equiferus appears to have entered into Portuguese as ezebro or zebro, which was originally used for a legendary equine in the wilds of the Iberian Peninsula during the Middle Ages. In 1591, Italian explorer Filippo Pigafetta recorded “zebra” being used to refer to the African animals by Portuguese visitors to the continent.[5] In ancient times, the zebra was called hippotigris (“horse tiger”) by the Greeks and Romans.[5][6]

    The word zebra was traditionally pronounced with a long initial vowel, but over the course of the 20th century the pronunciation with the short initial vowel became the norm in British English.[7] The pronunciation with a long initial vowel remains standard in American English.[8]

    Taxonomy

    Further information: Evolution of the horse

    Zebras are classified in the genus Equus (known as equines) along with horses and asses. These three groups are the only living members of the family Equidae.[9] The plains zebra and mountain zebra were traditionally placed in the subgenus Hippotigris (C. H. Smith, 1841) in contrast to the Grévy’s zebra which was considered the sole species of subgenus Dolichohippus (Heller, 1912).[10][11][12] Groves and Bell (2004) placed all three species in the subgenus Hippotigris.[13] A 2013 phylogenetic study found that the plains zebra is more closely related to Grévy’s zebras than mountain zebras.[14] The extinct quagga was originally classified as a distinct species.[15] Later genetic studies have placed it as the same species as the plains zebra, either a subspecies or just the southernmost population.[16][17] Molecular evidence supports zebras as a monophyletic lineage.[14][18][19]

    Equus originated in North America and direct paleogenomic sequencing of a 700,000-year-old middle Pleistocene horse metapodial bone from Canada implies a date of 4.07 million years ago (mya) for the most recent common ancestor of the equines within a range of 4.0 to 4.5 mya.[20] Horses split from asses and zebras around this time and equines colonised Eurasia and Africa around 2.1–3.4 mya. Zebras and asses diverged from each other close to 2 mya. The mountain zebra diverged from the other species around 1.6 mya and the plains and Grévy’s zebra split 1.4 mya.[21]

    A 2017 mitochondrial DNA study placed the Eurasian Equus ovodovi and the subgenus Sussemionus lineage as closer to zebras than to asses.[22] However, other studies disputed this placement, finding the Sussemionus lineage basal to the zebra+asses group, but suggested that the Sussemionus lineage may have received gene flow from zebras.[23]

    Photograph of a Quagga mare
    Quagga mare at London Zoo, 1870, the only specimen photographed alive. This animal was historically considered a separate species but is now considered a subspecies or population of plains zebra.

    The cladogram of Equus below is based on Vilstrup and colleagues (2013) and Jónsson and colleagues (2014):[14][21]

    EquusZebrasMountain zebra (E. zebraPlains zebra (E. quaggaGrévy’s zebra (E. grevyiWild assesKiang (E. kiangOnager (E. hemionusAfrican wild ass (E. africanusHorsesHorse (E. ferus caballusPrzewalski’s horse (E. ferus przewalski

    Extant species

    NameDimensionsDescriptionDistributionSubspeciesChromosomesImage
    Grévy’s zebra (Equus grevyi)Body length: 250–300 cm (98–118 in)
    Tail length: 38–75 cm (15–30 in)
    Shoulder height: 125–160 cm (49–63 in)
    Weight: 352–450 kg (776–992 lb).[24]
    Thin, elongated skull, robust neck and conical ears; narrow striping pattern with concentric rump stripes, white belly and tail base and white line around the ashy muzzle.[9][25][26]Eastern Africa including the Horn;[25] arid and semiarid grasslands and shrublands.[27]Monotypic[25]46[27]
    Plains zebra (Equus quagga)Body length: 217–246 cm (85–97 in)
    Tail length: 47–56 cm (19–22 in)
    Shoulder height: 110–145 cm (43–57 in)
    Weight: 175–385 kg (386–849 lb).[24]
    Thick bodied with relatively short legs and an obtusely-shaped skull profile with a protruding forehead and a more recessed nose area;[9][28] broad stripes, horizontal on the rump, with northern populations having more extensive striping while populations further south have whiter legs and bellies and more brown “shadow” stripes while the snout is black.[9][29][30][31]Eastern and southern Africasavannahs, grasslands and open woodlands.[32]6[13] or monotypic[17]44[33]
    Mountain zebra (Equus zebra)Body length: 210–260 cm (83–102 in)
    Tail length: 40–55 cm (16–22 in)
    Shoulder height: 116–146 cm (46–57 in)
    Weight: 204–430 kg (450–948 lb).[24]
    Eye sockets more circular and positioned farther back, a squarer nuchal crestdewlap present under neck and compact hooves; stripes intermediate in width between the other species, with gridiron and horizontal stripes on the rump, while the belly is white and the black muzzle is lined with chestnut or orange.[34][9][35][27]Southwestern Africa; mountains, rocky uplands and Karoo shrubland.[32][34][31]2[34]32[27]

    Fossil record

    A fossil skull of Equus mauritanicu
    Fossil skull of Equus mauritanicus

    In addition to the three living species, some fossil zebras and relatives have also been identified. Equus koobiforensis is an early equine basal to zebras found in the Shungura FormationEthiopia and the Olduvai GorgeTanzania, and dated to around 2.3 mya.[36] E. oldowayensis is identified from remains in Olduvai Gorge dating to 1.8 mya.[37] Fossil skulls of E. mauritanicus from Algeria which date to around 1 mya appears to show affinities with the plains zebra.[38][39] E. capensis, known as the Cape zebra, appeared around 2 mya and lived throughout southern and eastern Africa.[1][37] Non-African equines that may have been basal to zebras include E. sansaniensis of Eurasia (circa 2.5 mya) and E. namadicus (circa 2.5 mya) and E. sivalensis (circa 2.0 mya) of the Indian subcontinent.[36]

    Grévy’s × plains zebra hybrid, alongside plains zebras.

    Hybridisation

    Main article: Zebroid

    Fertile hybrids have been reported in the wild between plains and Grévy’s zebra.[40] Hybridisation has also been recorded between the plains and mountain zebra, though it is possible that these are infertile due to the difference in chromosome numbers between the two species.[41] Captive zebras have been bred with horses and donkeys; these are known as zebroids. A zorse is a cross between a zebra and a horse; a zonkey, between a zebra and a donkey; and a zoni, between a zebra and a pony. Zebroids are often born sterile with dwarfism.[42]

    Characteristics

    Further information: Equine anatomy

    Mounted skeleton of a Grévy's zebra Cranium, complete skeleton, left forefoot frontal, left forefoot side
    Skeleton of a Grévy’s zebra at the State Museum of Natural History Karlsruhe

    As with all wild equines, zebras have barrel-chested bodies with tufted tails, elongated faces and long necks with long, erect manes. Their thin legs are each supported by a spade-shaped toe covered in a hard hoof. Their dentition is adapted for grazing; they have large incisors that clip grass blades and rough molars and premolars well suited for grinding. Males have spade-shaped canines, which can be used as weapons in fighting. The eyes of zebras are at the sides and far up the head, which allows them to look over the tall grass while feeding. Their moderately long, erect ears are movable and can locate the source of a sound.[9][29][35]

    Unlike horses, zebras and asses have chestnut callosities present only on their front legs. In contrast to other living equines, zebras have longer front legs than back legs.[35] Diagnostic traits of the zebra skull include: its relatively small size with a straight dorsal outline, protruding eye sockets, narrower rostrum, less conspicuous postorbital bar, separation of the metaconid and metastylid of the tooth by a V-shaped canal and rounded enamel wall.[43]

    Stripes

    “Zebra stripes” redirects here. For other uses, see Zebra stripes (disambiguation).

    An illustration showing the three living zebra species
    Comparative illustration of living zebra species

    Zebras are easily recognised by their bold black-and-white striping patterns. The coat appears to be white with black stripes, as indicated by the belly and legs when unstriped, but the skin is black.[44][45][46] Young or foals are born with brown and white coats, and the brown darkens with age.[28][25] A dorsal line acts as the backbone for vertical stripes along the sides, from the head to the rump. On the snout they curve toward the nostrils, while the stripes above the front legs split into two branches. On the rump, they develop into species-specific patterns. The stripes on the legs, ears and tail are separate and horizontal.[44]

    Striping patterns are unique to an individual and heritable.[47] During embryonic development, the stripes appear at eight months, but the patterns may be determined at three to five weeks. For each species there is a point in embryonic development where the stripes are perpendicular to the dorsal line and spaced 0.4 mm (0.016 in) apart. However, this happens at three weeks of development for the plains zebra, four weeks for the mountain zebra, and five for Grévy’s zebra. The difference in timing is thought to be responsible for the differences in the striping patterns of the different species.[44]

    Various abnormalities of the patterns have been documented in plains zebras. In “melanistic” zebras, dark stripes are highly concentrated on the torso but the legs are whiter. “Spotted” individuals have broken up black stripes around the dorsal area.[48] There have even been morphs with white spots on dark backgrounds.[49] Striping abnormalities have been linked to inbreeding.[48] Albino zebras have been recorded in the forests of Mount Kenya, with the dark stripes being blonde.[50] The quagga had brown and white stripes on the head and neck, brown upper parts and a white belly, tail and legs.[51]

    Function

    The function of stripes in zebras has been discussed among biologists since at least the 19th century.[52] Popular hypotheses include the following:

    • The crypsis hypothesis suggests that the stripes allow the animal to blend in with its environment or break up its outline. This was the earliest hypothesis and proponents argued that the stripes were particularly suited for camouflage in tall grassland and woodland habitat. Alfred Wallace also wrote in 1896 that stripes make zebras less noticeable at night. Biologist Tim Caro notes that zebras graze in open habitat and do not behave cryptically, being noisy, fast, and social and do not freeze when a predator is near. In addition, the camouflaging stripes of woodland living ungulates like bongos and bushbucks are much less vivid with less contrast with the background colour.[53] A 1987 Fourier analysis study concluded that the spatial frequencies of zebra stripes do not line up with their environment,[54] while a 2014 study of wild equine species and subspecies could not find any correlations between striping patterns and woodland habitats.[55] Melin and colleagues (2016) found that lions and hyenas do not appear to perceive the stripes when they are a certain distance away at daytime or nighttime, thus making the stripes useless in blending in except when the predators are close enough by which they could smell or hear their target. They also found that the stripes do not make the zebra less noticeable than solidly coloured herbivores on the open plains. They suggested that stripes may give zebras an advantage in woodlands, as the dark stripes could line up with the outlines of tree branches and other vegetation.[56]
    Closeup shot of mountain zebra stripes
    Closeup of mountain zebra stripes
    • The confusion hypothesis states that the stripes confuse predators, be it by: making it harder to distinguish individuals in a group as well as determining the number of zebras in a group; making it difficult to determine an individual’s outline when the group runs away; reducing a predator’s ability to keep track of a target during a chase; dazzling an assailant so they have difficulty making contact; or making it difficult for a predator to deduce the zebra’s size, speed and direction via motion dazzle. This theory has been proposed by several biologists since at least the 1970s.[57] A 2014 computer study of zebra stripes found that they may create a wagon-wheel effect and/or barber pole illusion when in motion. The researchers concluded that this could be used against mammalian predators or biting flies.[58] The use of the stripes for confusing mammalian predators has been questioned. The stripes of zebras could make groups seem smaller, and thus more likely to be attacked. Zebras also tend to scatter when fleeing from attackers and thus the stripes could not break up an individual’s outline. Lions, in particular, appear to have no difficulty targeting and catching zebras when they get close and take them by ambush.[59] In addition, no correlations have been found between the number of stripes and populations of mammal predators.[55] Hughes and colleagues (2021) concluded that solidly grey and less contrasted patterns are more likely to escape being caught when in motion.[60]
    • The aposematic hypothesis suggests that the stripes serve as warning colouration. This hypothesis was first suggested by Wallace in 1867 and discussed in more detail by Edward Bagnall Poulton in 1890. As with known aposematic mammals, zebras are recognizable up close, live in more open environments, have a high risk of predation and do not hide or act inconspicuous. However, Caro notes that stripes do not work on lions because they frequently prey on zebras, though they may work on smaller predators, and zebras are not slow-moving enough to need to ward off threats. In addition, zebras do not possess adequate defenses to back up the warning pattern.[61]
    • The social function hypothesis states that stripes serve a role in intraspecific or individual recognition, social bonding, mutual grooming or a signal of fitnessCharles Darwin wrote in 1871 that “a female zebra would not admit the addresses of a male ass until he was painted so as to resemble a zebra” while Wallace stated in 1871 that: “The stripes therefore may be of use by enabling stragglers to distinguish their fellows at a distance”. Regarding species and individual identification, Caro notes that zebra species have limited range overlap with each other and horses can recognise each other using visual communication.[62] In addition, no correlation has been found between striping and social behaviour or group numbers among equines,[55] and no link has been found between fitness and striping.[63]
    • The thermoregulatory hypothesis suggests that stripes help to control a zebra’s body temperature. In 1971, biologist H. A. Baldwin noted that heat would be absorbed by the black stripes and reflected by the white ones. In 1990, zoologist Desmond Morris suggested that the stripes create cooling convection currents.[64] A 2019 study supported this, finding that where the faster air currents of the warmer black stripes meet those of the white, air swirls form. The researchers also concluded that during the hottest times of the day, zebras erect their black hair to release heat from the skin and flatten it again when it gets cooler.[65] Larison and colleagues (2015) determined that environmental temperature is a strong predictor for zebra striping patterns.[66] Others have found no evidence that zebras have lower body temperatures than other ungulates whose habitat they share, or that striping correlates with temperature.[67][55] A 2018 experimental study which dressed water-filled metal barrels in horse, zebra and cattle hides concluded that the zebra stripes had no effect on thermoregulation.[68]
    Comparison of horse fly flight patterns on horses and zebras
    Comparison of flight patterns and contact/landings of horse flies around domestic horses (a-c) and plains zebras (d-f).[69]
    • The fly protection hypothesis holds that the stripes deter blood-sucking flies. Horse flies, in particular, spread diseases that are lethal to equines such as African horse sicknessequine influenzaequine infectious anemia and trypanosomiasis. In addition, zebra hair is about as long as the mouthparts of these flies.[55] This hypothesis is the most strongly supported by the evidence.[69][70] It was found that flies preferred landing on solidly coloured surfaces over those with black-and-white striped patterns in 1930 by biologist R. Harris,[71] and this was proposed to have been a function of zebra stripes in a 1981 study.[72] A 2014 study found a correlation between striping and overlap with horse and tsetse fly populations and activity.[55] Other studies have found that zebras are rarely targeted by these insect species.[73] Caro and colleagues (2019) studied captive zebras and horses and observed that neither could deter flies from a distance, but zebra stripes kept flies from landing, both on zebras and horses dressed in zebra print coats.[69] There does not appear to be any difference in the effectiveness of repelling flies between the different zebra species; thus the difference in striping patterns may have evolved for other reasons.[70] White or light stripes painted on dark bodies have also been found to reduce fly irritations in both cattle and humans.[74][75] The effect even extends to pelts, with zebra pelts being less attractive to flies than unstriped impala pelts.[70] How the stripes repel flies is less clear.[70] A 2012 study concluded that they disrupt the polarised light patterns these insects use to locate water and habitat,[76] though subsequent studies have refuted this.[77][78][79] Stripes do not appear to work like a barber pole against flies since checkered patterns also repel them.[77][80] There is also little evidence that zebra stripes confuse the insects via visual distortion or aliasing.[77] Takács and colleagues (2022) suggest that, when the animal is in sunlight, temperature gradients between the warmer dark stripes and cooler white stripes prevent horseflies from detecting the warm blood vessels underneath.[78] Caro and colleagues (2023) conclude that the insects are disoriented by the high colour contrast and relative thinness of the patterns.[77]

    Behaviour and ecology

    Mountain zebra dust bathing
    Mountain zebra dustbathing in Namibia

    Zebras may travel or migrate to wetter areas during the dry season.[28][29] Plains zebras have been recorded travelling 500 km (310 mi) between Namibia and Botswana, the longest land migration of mammals in Africa.[81] When migrating, they appear to rely on some memory of the locations where foraging conditions were best and may predict conditions months after their arrival.[82] Plains zebras are more water-dependent and live in moister environments than other species. They usually can be found 10–12 km (6.2–7.5 mi) from a water source.[28][29][31] Grévy’s zebras can survive almost a week without water but will drink it every day when given the chance, and their bodies maintain water better than cattle.[83][25] Mountain zebras can be found at elevations of up to 2,000 m (6,600 ft).[84] Zebras sleep for seven hours a day, standing up during the day and lying down during the night. They regularly use various objects as rubbing posts and will roll on the ground.[29]

    Plains zebras drinking at a river
    Plains zebras at Okavango DeltaBotswana

    A zebra’s diet is mostly grasses and sedges, but they will opportunistically consume bark, leaves, buds, fruits, and roots. Compared to ruminants, zebras have a simpler and less efficient digestive system. Nevertheless, they can subsist on lower-quality vegetation. Zebras may spend 60–80% of their time feeding, depending on the availability of vegetation.[9][29] The plains zebra is a pioneer grazer, mowing down the upper, less nutritious grass canopy and preparing the way for more specialised grazers like wildebeest, which depend on shorter and more nutritious grasses below.[85]

    Zebras are preyed on mainly by lions. Leopardscheetahsspotted hyenasbrown hyenas and wild dogs pose less of a threat to adults.[86] Biting and kicking are a zebra’s defense tactics. When threatened by lions, zebras flee, and when caught they are rarely effective in fighting off the big cats.[87] In one study, the maximum speed of a zebra was found to be 50 km/h (31 mph) while a lion was measured at 74 km/h (46 mph). Zebras do not escape lions by speed alone but by sideways turning, especially when the cat is close behind.[88] With smaller predators like hyenas and dogs, zebras may act more aggressively, especially in defense of their young.[89]

    Social behaviour

    See also: Horse behaviour

    A group of six plains zebra
    A plains zebra group

    Zebra species have two basic social structures. Plains and mountain zebras live in stable, closed family groups or harems consisting of one stallion, several mares, and their offspring. These groups have their own home ranges, which overlap, and they tend to be nomadic. Stallions form and expand their harems by herding young mares away from their birth harems. The stability of the group remains even when the family stallion is displaced. Plains zebras groups gather into large herds and may create temporarily stable subgroups within a herd, allowing individuals to interact with those outside their group. Females in harems can spend more time feeding, and gain protection both for them and their young. The females have a linear dominance hierarchy with the high-ranking females having lived in the group longest. While traveling, the most dominant females and their offspring lead the group, followed by the next most dominant; the family stallion trails behind. Young of both sexes leave their natal groups as they mature; females are usually herded by outside males to become part of their harems.[9][29][90]

    In the more arid-living Grévy’s zebras, adults have more fluid associations and adult males establish large territories, marked by dung piles, and mate with the females that enter them.[29][9] Grazing and drinking areas tend to be separated in these environments and the most dominant males establish territories near watering holes, which attract females with dependent foals and those who simply want a drink, while less dominant males control territories away from water with more vegetation, and only attract mares without foals.[91] Mares may travel through several territories but remain in one when they have young. Staying in a territory offers a female protection from harassment by outside males, as well as access to resources.[90][92]

    Three Grévy's zebras grazing
    Group of Grévy’s zebras grazing

    In all species, excess males gather in bachelor groups. These are typically young males that are not yet ready to establish a harem or territory.[9][29] With the plains zebra, the oldest males are the most dominant and group membership is stable.[29] Bachelor groups tend to be at the boundaries of herds and during group movements, the bachelors follow behind or along the sides.[31] Mountain zebra bachelor groups may also include young females that have left their natal group early, as well as old, former harem males. A territorial Grévy’s zebra stallion may allow non-territorial bachelors in their territory, however when a mare in oestrous is present the territorial stallion keeps other stallions at bay. Bachelors prepare for their future harem roles with play fights and greeting/challenge rituals, which make up most of their activities.[29]

    Fights between males usually occur over mates and involve biting and kicking. In plains zebra, stallions fight each other over recently matured mares to bring into their group and her father will fight off other males trying to abduct her. As long as a harem stallion is healthy, he is not usually challenged. Only unhealthy stallions have their harems taken over, and even then, the new stallion slowly takes over, peacefully displacing the old one. Agonistic behaviour between male Grévy’s zebras occurs at the border of their territories.[29]

    Communication

    A pair of Plains zebra facing each other and rubbing heads on the others body
    Plains zebras mutually grooming

    Zebras produce a number of vocalisations and noises. The plains zebra has a distinctive, barking contact call heard as “a-ha, a-ha, a-ha” or “kwa-ha, kaw-ha, ha, ha”.[28][29] The mountain zebra may produce a similar sound while the call of Grévy’s zebra has been described as “something like a hippo‘s grunt combined with a donkey’s wheeze”. Loud snorting and rough “gasping” in zebras signals alarm. Squealing is usually made when in pain, but can also be heard in friendly interactions. Zebras also communicate with visual displays, and the flexibility of their lips allows them to make complex facial expressions. Visual displays also consist of head, ear, and tail postures. A zebra may signal an intention to kick by dropping back its ears and whipping its tail. Flattened ears, bared teeth and a waving head may be used as threatening gestures by stallions.[29]

    Individuals may greet each other by mutually touching and rubbing, sniffing their genitals and resting their heads on their shoulders. They then may caress their shoulders against each other and lay their heads on one another. This greeting usually occurs between harem or territorial males or among bachelor males playing.[29] Plains and mountain zebras strengthen their social bonds with grooming. Members of a harem nibble and rake along the neck, shoulder, and back with their teeth and lips. Grooming usually occurs between mothers and foals and between stallions and mares. Grooming establishes social rank and eases aggressive behaviour,[29][93] although Grévy’s zebras generally do not perform social grooming.[25]

    Reproduction and parenting

    See also: Horse breeding

    A pair of Grévy's zebras mating
    Captive Grévy’s zebras mating

    Among plains and mountain zebras, the adult females mate only with their harem stallion, while in Grévy’s zebras, mating is more polygynandrous and the males have larger testes for sperm competition.[91][94] Female zebras have five to ten day long oestrous cycles; physical signs include a swollen, everted (inside out) labia and copious flows of urine and mucus. Upon reaching peak oestrous, mares spread-out their legs, lift their tails and open their mouths when in the presence of a male. Males assess the female’s reproductive state with a curled lip and bared teeth (flehmen response) and the female will solicit mating by backing in. Gestation is typically around a year. A few days to a month later, mares can return to oestrus.[29] In harem-holding species, oestrus in a female becomes less noticeable to outside males as she gets older, hence competition for older females is virtually nonexistent.[28]

    Mountain zebra suckling a foal
    Mountain zebra suckling a foal

    Usually, a single foal is born, which is capable of running within an hour of birth.[9] A newborn zebra will follow anything that moves, so new mothers prevent other mares from approaching their foals as they become more familiar with the mother’s striping pattern, smell and voice.[25] At a few weeks old, foals begin to graze, but may continue to nurse for eight to thirteen months.[9] Living in an arid environment, Grévy’s zebras have longer nursing intervals and young only begin to drink water three months after birth.[95]

    In plains and mountain zebras, foals are cared for mostly by their mothers, but if threatened by pack-hunting hyenas and dogs, the entire group works together to protect all the young. The group forms a protective front with the foals in the centre, and the stallion will rush at predators that come too close.[29] In Grévy’s zebras, young stay in “kindergartens” when their mothers leave for water. These groups are tended to by the territorial male.[95] A stallion may look after a foal in his territory to ensure that the mother stays, though it may not be his.[90] By contrast, plains zebra stallions are generally intolerant of foals that are not theirs and may practice infanticide and feticide via violence to the pregnant mare.[96]

    Human relations

    Cultural significance

    San rock art depicting a zebra
    San rock art depicting a zebra

    With their distinctive black-and-white stripes, zebras are among the most recognizable mammals. They have been associated with beauty and grace, with naturalist Thomas Pennant describing them in 1781 as “the most elegant of quadrupeds”. Zebras have been popular in photography, with some wildlife photographers describing them as the most photogenic animal. They have become staples in children’s stories and wildlife-themed art, such as depictions of Noah’s Ark. In children’s alphabet books, the animals are often used to represent the letter ‘Z’. Zebra stripe patterns are popularly used for body paintings, dress, furniture and architecture.[97]

    Zebras have been featured in African art and culture for millennia. They are depicted in rock art in Southern Africa dating from 28,000 to 20,000 years ago, though less often than antelope species like eland. How the zebra got its stripes has been the subject of folk tales, some of which involve it being scorched by fire. The Maasai proverb “a man without culture is like a zebra without stripes” has become popular in Africa. The San people connected zebra stripes with water, rain and lightning, and water spirits were conceived of having these markings.[98]

    Illustration of a business's "Zebra Stripes" logo
    “Zebra Stripes,” trademark for the defunct Glen Raven Cotton Mills Company

    For the Shona people, the zebra is a totem animal and is glorified in a poem as an “iridescent and glittering creature”. Its stripes have symbolised the union of male and female and at the ruined city of Great Zimbabwe, zebra stripes decorate what is believed to be a domba, a school meant to prepare girls for adulthood. In the Shona language, the name madhuve means “woman/women of the zebra totem” and is a name for girls in Zimbabwe. The plains zebra is the national animal of Botswana and zebras have been depicted on stamps during colonial and post-colonial Africa. For people of the African diaspora, the zebra represented the politics of race and identity, being both black and white.[99]

    In cultures outside of its range, the zebra has been thought of as a more exotic alternative to the horse; the comic book character Sheena, Queen of the Jungle, is depicted riding a zebra and explorer Osa Johnson was photographed riding one. The film Racing Stripes features a captive zebra ostracised from the horses and ends up being ridden by a rebellious girl. Zebras have been featured as characters in animated films like KhumbaThe Lion King and the Madagascar films and television series such as Zou.[100]

    Zebras have been popular subjects for abstractmodernist and surrealist artists. Such art includes Christopher Wood‘s Zebra and ParachuteLucian Freud‘s The Painter’s Room and Quince on a Blue Table and the various paintings of Mary Fedden and Sidney NolanVictor Vasarely depicted zebras as black and white lines and connected in a jigsaw puzzle fashion. Carel Weight‘s Escape of the Zebra from the Zoo during an Air Raid was based on a real life incident of a zebra escaping during the bombing of London Zoo and consists of four comic book-like panels. Zebras have lent themselves to products and advertisements, notably for ‘Zebra Grate Polish’ cleaning supplies by British manufacturer Reckitt and Sons and Japanese pen manufacturer Zebra Co., Ltd.[101]

    Captivity

    A portrait of a zebra by George Stubbs
    Zebra (1763) by George Stubbs. A portrait of Queen Charlotte‘s zebra

    Zebras have been kept in captivity since at least the Roman Empire. In later times, captive zebras have been shipped around the world, often for diplomatic reasons. In 1261, Sultan Baibars of Egypt established an embassy with Alfonso X of Castile and sent a zebra and other exotic animals as gifts. In 1417, a zebra was gifted to the Chinese people by Somalia and displayed before the Yongle Emperor. The fourth Mughal emperor Jahangir received a zebra from Ethiopia in 1620 and Ustad Mansur made a painting of it. In the 1670s, Ethiopian Emperor Yohannes I exported two zebras to the Dutch governor of Jakarta. These animals would eventually be given by the Dutch to the Tokugawa Shogunate of Japan.[102]

    When Queen Charlotte received a zebra as a wedding gift in 1762, the animal became a source of fascination for the people of Britain. Many flocked to see it at its paddock at Buckingham Palace. It soon became the subject of humour and satire, being referred to as “The Queen’s Ass”, and was the subject of an oil painting by George Stubbs in 1763. The zebra also gained a reputation for being ill-tempered and kicked at visitors.[103] In 1882, Ethiopia sent a zebra to French president Jules Grévy, and the species it belonged to was named in his honour.[10]

    Walter Rothschild with a carriage drawn by four zebra
    Walter Rothschild with a zebra carriage

    Attempts to domesticate zebras were largely unsuccessful. It is possible that having evolved under pressure from the many large predators of Africa, including early humans, they became more aggressive, thus making domestication more difficult.[104] However, zebras have been trained throughout history. In Rome, zebras are recorded to have pulled chariots during amphitheatre games starting in the reign of Caracalla (198 to 217 AD).[105] In the late 19th century, the zoologist Walter Rothschild trained some zebras to draw a carriage in England, which he drove to Buckingham Palace to demonstrate that it can be done. However, he did not ride on them knowing that they were too small and aggressive.[106] In the early 20th century, German colonial officers in East Africa tried to use zebras for both driving and riding, with limited success.[107]

    Conservation

    Mountain zebra hide
    Mountain zebra hide

    As of 2016–2019, the IUCN Red List of mammals lists Grévy’s zebra as endangered, the mountain zebra as vulnerable and the plains zebra as near-threatened. Grévy’s zebra populations are estimated at less than 2,000 mature individuals, but they are stable. Mountain zebras number near 35,000 individuals and their population appears to be increasing. Plains zebra are estimated to number 150,000–250,000 with a decreasing population trend. Human intervention has fragmented zebra ranges and populations. Zebras are threatened by hunting for their hide and meat, and habitat destruction. They also compete with livestock and have their travelling routes obstruct by fences.[108][109][110] Civil wars in some countries have also caused declines in zebra populations.[111] By the early 20th century, zebra skins were being used to make rugs and chairs. In the 21st century, zebras may be taken by trophy hunters as zebra skin rugs sell for $1,000 to $2,000. Trophy hunting was rare among African peoples though the San were known to hunt zebra for meat.[112]

    A herd of Grévy's zebras in Samburu National Reserve
    Endangered Grévy’s zebras in Samburu National Reserve

    The quagga (E. quagga quagga) population was hunted by early Dutch settlers and later by Afrikaners to provide meat or for their skins. The skins were traded or used locally. The quagga was probably vulnerable to extinction due to its restricted range, and because they were easy to find in large groups. The last known wild quagga died in 1878.[113] The last captive quagga, a female in Amsterdam’s Natura Artis Magistra zoo, lived there from 9 May 1867 until it died on 12 August 1883.[114] The Cape mountain zebra, a subspecies of mountain zebra, nearly went extinct due to hunting and habitat destruction, with less than 50 individuals left by the 1950s. Protections from South African National Parks allowed the population to rise to 2,600 by the 2010s.[115]

    Zebras can be found in numerous protected areas. Important areas for Grévy’s zebra include Yabelo Wildlife Sanctuary and Chelbi Sanctuary in Ethiopia and Buffalo SpringsSamburu and Shaba National Reserves in Kenya.[108] The plains zebra inhabits the Serengeti National Park in Tanzania, Tsavo and Masai Mara in Kenya, Hwange National Park in Zimbabwe, Etosha National Park in Namibia, and Kruger National Park in South Africa.[110] Mountain zebras are protected in Mountain Zebra National ParkKaroo National Park and Goegap Nature Reserve in South Africa as well as Etosha and Namib-Naukluft Park in Namibia.[109][116]

  • Giant panda

    The giant panda (Ailuropoda melanoleuca), also known as the panda bear or simply panda, is a bear species endemic to China. It is characterised by its white coat with black patches around the eyes, ears, legs and shoulders. Its body is rotund; adult individuals weigh 100 to 115 kg (220 to 254 lb) and are typically 1.2 to 1.9 m (3 ft 11 in to 6 ft 3 in) long. It is sexually dimorphic, with males being typically 10 to 20% larger than females. A thumb is visible on its forepaw, which helps in holding bamboo in place for feeding. It has large molar teeth and expanded temporal fossa to meet its dietary requirements. It can digest starch and is mostly herbivorous with a diet consisting almost entirely of bamboo and bamboo shoots.

    The giant panda lives exclusively in six montane regions in a few Chinese provinces at elevations of up to 3,000 m (9,800 ft). It is solitary and gathers only in mating seasons. It relies on olfactory communication to communicate and uses scent marks as chemical cues and on landmarks like rocks or trees. Females rear cubs for an average of 18 to 24 months. The oldest known giant panda was 38 years old.

    As a result of farming, deforestation and infrastructural development, the giant panda has been driven out of the lowland areas where it once lived. The Fourth National Survey (2011–2014), published in 2015, estimated that the wild population of giant pandas aged over 1.5 years (i.e. excluding dependent young) has increased to 1,864 individuals, based on this number and using the available estimated percentage of cubs in the population (9.6%) the IUCN estimated the total number of Pandas to be approximately 2,060.[1][3] Since 2016, it has been listed as Vulnerable on the IUCN Red List. In July 2021, Chinese authorities also classified the giant panda as vulnerable. It is a conservation-reliant species. By 2007, the captive population comprised 239 giant pandas in China and another 27 outside the country. It has often served as China’s national symbol, appeared on Chinese Gold Panda coins since 1982 and as one of the five Fuwa mascots of the 2008 Summer Olympics held in Beijing.

    Etymology

    The word panda was borrowed into English from French, but no conclusive explanation of the origin of the French word panda has been found.[4] The closest candidate is the Nepali word ponya, possibly referring to the adapted wrist bone of the red panda, which is native to Nepal. In many older sources, the name “panda” or “common panda” refers to the red panda (Ailurus fulgens),[5] which was described some 40 years earlier and over that period was the only animal known as a panda.[6] The binomial name Ailuropoda melanoleuca means black and white (melanoleuca) cat-foot (ailuropoda).[7]

    Since the earliest collection of Chinese writings, the Chinese language has given the bear many different names, including  (貘, ancient Chinese name for giant panda),[8] huāxióng (花熊; “spotted bear”) and zhúxióng (竹熊; “bamboo bear”).[9] The most popular names in China today are dàxióngmāo (大熊貓; lit. ’giant bear cat’), or simply xióngmāo (熊貓; lit. ’bear cat’). As with the word panda in English, xióngmāo (熊貓) was originally used to describe just the red panda, but dàxióngmāo (大熊貓) and xiǎoxióngmāo (小熊猫; lit. ’little bear cat’) were coined to differentiate between the species.[9]

    In Taiwan, another popular name for panda is the inverted dàmāoxióng (大貓熊; lit. ’giant cat bear’), though many encyclopedias and dictionaries in Taiwan still use the “bear cat” form as the correct name. Some linguists argue, in this construction, “bear” instead of “cat” is the base noun, making the name more grammatically and logically correct, which have led to the popular choice despite official writings.[9] This name did not gain its popularity until 1988, when a private zoo in Tainan painted a sun bear black and white and created the Tainan fake panda incident.[10][11]

    Taxonomy

    For many decades, the precise taxonomic classification of the giant panda was under debate because it shares characteristics with both bears and raccoons.[12] In 1985, molecular studies indicated that the giant panda is a true bear, part of the family Ursidae.[13][14] These studies show it diverged about 19 million years ago from the common ancestor of the Ursidae;[15] it is the most basal member of this family and equidistant from all other extant bear species.[15][16]

    Subspecies

    The Qinling panda has a light brown-and-white pattern

    Two subspecies of giant panda have been recognized on the basis of distinct cranial measurements, colour patterns, and population genetics.[17]

    • The nominate subspeciesA. m. melanoleuca, consists of most extant populations of the giant panda. These animals are principally found in Sichuan and display the typical stark black and white contrasting colours.[18]
    • The Qinling pandaA. m. qinlingensis,[19] is restricted to the Qinling Mountains in Shaanxi at elevations of 1,300–3,000 m (4,300–9,800 ft). The typical black and white pattern of Sichuan giant pandas is replaced with a light brown and white pattern.[17] The skull of A. m. qinlingensis is smaller than its relatives, and it has larger molars.[20]

    A detailed study of the giant panda’s genetic history from 2012 confirms that the separation of the Qinling population occurred about 300,000 years ago, and reveals that the non-Qinling population further diverged into two groups, named the Minshan and the QionglaiDaxianglingXiaoxianglingLiangshan group respectively, about 2,800 years ago.[21]

    Phylogeny

    Of the eight extant species in the bear family Ursidae, the giant panda’s lineage branched off the earliest.[22][23]

    UrsidaeGiant panda (Ailuropoda melanoleucaSpectacled bear (Tremarctos ornatusUrsinae (black, brown, sloth, sun, and polar bears) 

    Distribution and habitat

    The giant panda is endemic to China. It is found in small, fragmented populations in six mountainous regions in the country, mainly in Sichuan, and also in neighbouring Shaanxi and Gansu.[24] Successful habitat preservation has seen a rise in panda numbers, though loss of habitat due to human activities remains its biggest threat. In areas with a high concentration of medium-to-large-sized mammals—such as domestic cattle, a species known to degrade the landscape—the giant panda population is generally low. This is mainly attributed to the panda’s avoidance of interspecific competition.[25][26]

    The species has been located at elevations of 2,400 to 3,000 m (7,900 to 9,800 ft) above sea level.[27] They frequent habitats with a healthy concentration of bamboos, typically old-growth forests, but may also venture into secondary forest habitats.[28] The Daxiangling Mountain population inhabits both coniferous and broadleaf forests.[29] Additionally, the Qinling population often selects evergreen broadleaf and conifer forests, while pandas in the Qionglai mountainous region exclusively select upland conifer forests. The remaining two populations, namely those occurring in the Liangshan and Xiaoxiangling mountains, predominantly occur in broadleaf evergreen and conifer forests.[13]: 137–148 

    Giant pandas once roamed across Southeast Asia from Myanmar to northern Vietnam. Their range in China spanned much of the southeast region. By the Pleistocene, climate change affected panda populations, and the subsequent domination of modern humans led to large-scale habitat loss.[30][31] In 2001, it was estimated that the range of the giant panda had declined by about 99% of its range in earlier millenniums.[32]

    Description

    The skull of a giant panda at the Smithsonian Museum of Natural History

    Close-up of giant panda at ZooParc in Beauval, France

    The giant panda has a body shape typical of bears. It has black fur on its ears, limbs, shoulders and around the eyes. The rest of the animal’s coat is white.[33] The bear’s distinctive coloration appears to serve as camouflage in both winter and summer environments as they do not hibernate. The white areas serve as camouflage in snow, while the black shoulders and legs conceal them in shade.[34] Studies in the wild have found that when viewed from a distance, the panda displays disruptive coloration, while up close, they rely more on blending in.[35] The black ears may be used to display aggression,[34] while the eye patches might facilitate them identifying one another.[34][36] The giant panda’s thick, woolly coat keeps it warm in the cool forests of its habitat.[33]

    The panda’s skull shape is typical of durophagous carnivorans. It has evolved from previous ancestors to exhibit larger molars with increased complexity and expanded temporal fossa.[37][38] A study revealed that a 117.5 kg (259 lb) giant panda had a bite force of 1298.9 Newton (BFQ 151.4) at canine teeth and 1815.9 Newton (BFQ 141.8) at carnassial teeth.[39] Adults measure around 1.2 to 1.9 m (3 ft 11 in to 6 ft 3 in) long, including a tail of about 10–15 cm (3.9–5.9 in), and 60 to 90 cm (24 to 35 in) tall at the shoulder.[40][41] Males can weigh up to 160 kg (350 lb).[42] Females are generally 10–20% smaller than males.[43] They weigh between 70 kg (150 lb) and 125 kg (276 lb).[44][40][45] The average weight for adults is 100 to 115 kg (220 to 254 lb).[46]

    The giant panda’s paw has a digit similar to a thumb and five fingers; the thumb-like digit – actually a modified sesamoid bone – helps it to hold bamboo while eating.[47][48] The giant panda’s tail, measuring 10 to 15 cm (3.9 to 5.9 in), is the second-longest in the bear family, behind the sloth bear.[43]

    Ecology

    Diet

    Pandas eating bamboo

    Duration: 34 seconds.0:34Subtitles available.CCPandas eating, standing, and playing

    Despite its taxonomic classification as a carnivoran, the giant panda’s diet is primarily herbivorous, with approximately 99% of its diet consisting of bamboo.[49] However, the giant panda still has the digestive system of a carnivore, as well as carnivore-specific genes,[50] and thus derives little energy and little protein from the consumption of bamboo. The ability to break down cellulose and lignin is very weak, and their main source of nutrients comes from starch and hemicelluloses. The most important part of their bamboo diet is the shoots, that are rich in starch and have up to 32% protein content. Accordingly, pandas have evolved a higher capability to digest starches than strict carnivores.[51] Raw bamboo is toxic, containing cyanide compounds. Pandas’ body tissues are less able than herbivores to detoxify cyanide, but their gut microbiomes are significantly enriched in putative genes coding for enzymes related to cyanide degradation, suggesting that they have cyanide-digesting gut microbes.[52] It has been estimated that an adult panda absorbs 54.8–66.1 mg (0.846–1.020 gr) of cyanide a day through its diet. To prevent poisoning, they have evolved anti-toxic mechanisms to protect themselves. About 80% of the cyanide is metabolized to less toxic thiocyanate and discharged in urine, while the remaining 20% is detoxified by other minor pathways.[53]

    During the shoot season (April–August), pandas store a large amount of food in preparation for the months succeeding this seasonal period, in which pandas live off a diet of bamboo leaves.[54] The giant panda is a highly specialised animal with unique adaptations, and has lived in bamboo forests for millions of years.[55] The average giant panda eats as much as 9 to 14 kg (20 to 31 lb) of bamboo shoots a day to compensate for the limited energy content of its diet. Ingestion of such a large quantity of material is possible and necessary because of the rapid passage of large amounts of indigestible plant material through the short, straight digestive tract.[56][57] It is also noted, however, that such rapid passage of digesta limits the potential of microbial digestion in the gastrointestinal tract,[56] limiting alternative forms of digestion. Given this voluminous diet, the giant panda defecates up to 40 times a day.[58] The limited energy input imposed on it by its diet has affected the panda’s behavior. The giant panda tends to limit its social interactions and avoids steeply sloping terrain to limit its energy expenditures.[59]

    Two of the panda’s most distinctive features, its large size and round face, are adaptations to its bamboo diet. Anthropologist Russell Ciochon observed: “[much] like the vegetarian gorilla, the low body surface area to body volume [of the giant panda] is indicative of a lower metabolic rate. This lower metabolic rate and a more sedentary lifestyle allows the giant panda to subsist on nutrient poor resources such as bamboo.”[59] The giant panda’s round face is the result of powerful jaw muscles, which attach from the top of the head to the jaw.[59] Large molars crush and grind fibrous plant material.[60]

    A panda feeding on bamboo

    The morphological characteristics of extinct relatives of the giant panda suggest that while the ancient giant panda was omnivorous 7 million years ago (mya), it only became herbivorous some 2–2.4 mya with the emergence of A. microta.[60][61] Genome sequencing of the giant panda suggests that the dietary switch could have initiated from the loss of the sole umami taste receptor, encoded by the genes TAS1R1 and TAS1R3 (also known as T1R1 and T1R3), resulting from two frameshift mutations within the T1R1 exons.[50] Umami taste corresponds to high levels of glutamate as found in meat and may have thus altered the food choice of the giant panda.[62] Although the pseudogenisation (conversion into a pseudogene) of the umami taste receptor in Ailuropoda coincides with the dietary switch to herbivory, it is likely a result of, and not the reason for, the dietary change.[60][50][62] The mutation time for the T1R1 gene in the giant panda is estimated to 4.2 mya[60] while fossil evidence indicates bamboo consumption in the giant panda species at least 7 mya,[61] signifying that although complete herbivory occurred around 2 mya, the dietary switch was initiated prior to T1R1 loss-of-function.[63]

    Pandas eat any of 25 bamboo species in the wild, with the most common including Fargesia dracocephala[63] and Fargesia rufa.[64] Only a few bamboo species are widespread at the high altitudes pandas now inhabit. Bamboo leaves contain the highest protein levels; stems have less.[65] Because of the synchronous flowering, death, and regeneration of all bamboo within a species, the giant panda must have at least two different species available in its range to avoid starvation. While primarily herbivorous, the giant panda still retains decidedly ursine teeth and will eat meat, fish, and eggs when available. In captivity, zoos typically maintain the giant panda’s bamboo diet, though some will provide specially formulated biscuits or other dietary supplements.[66]

    Pandas will travel between different habitats if they need to, so they can get the nutrients that they need and to balance their diet for reproduction.[67]

    Interspecific interactions

    Although adult giant pandas have few natural predators other than humans, young cubs are vulnerable to attacks by snow leopardsyellow-throated martens,[68] eagles, feral dogs, and the Asian black bear. Sub-adults weighing up to 50 kg (110 lb) may be vulnerable to predation by leopards.[69]

    Giant pandas are sympatric with other large mammals and bamboo feeders, such as the takin (Budorcas taxicolor). The takin and giant panda share a similar ecological niche, and they consume the same resources. When competition for food is fierce, pandas disperse to the outskirts of takin distribution. Other possible competitors include but is not limited to, the Eurasian wild pig (Sus scrofa), Chinese goral (Naemorhedus griseus) and the Asian black bear (Ursus thibetanus). Giant pandas avoid areas with a mid-to-high density of livestock, as they depress the vegetation.[70] The Tibetan Plateau is the only known area where both giant and red pandas can be found. Although sharing near-identical ecological niches, competition between the two species has rarely been observed. Nearly 50% of their respective distribution overlaps, and successful coexistence is achieved through distinct habitat selection.[71]

    Pathogens and parasites

    A captive female died from toxoplasmosis, a disease caused by an obligate intracellular parasitic protozoan known as Toxoplasma gondii that infects most warm-blooded animals, including humans.[72] They are likely susceptible to diseases from Baylisascaris schroederi, a parasitic nematode known to infect giant panda intestines. This nematode species is known to give pandas baylisascariasi, a deadly disease that kills more wild pandas than any other cause. Additionally, the population is threatened by canine distemper virus (CDV)canine parvovirusrotaviruscanine adenovirus, and canine coronavirus. Bacteria, such as Clostridium welchiiProteus mirabilisKlebsiella pneumoniae, and Escherichia coli, may also be lethal.[73]

    Behavior

    The giant panda is a terrestrial animal and primarily spends its life roaming and feeding in the bamboo forests of the Qinling Mountains and in the hilly province of Sichuan.[74] Giant pandas are generally solitary.[55] Each adult has a defined territory and a female is not tolerant of other females in her range. Social encounters occur primarily during the brief breeding season in which pandas in proximity to one another will gather.[75] After mating, the male leaves the female alone to raise the cub.[33] Pandas were thought to fall into the crepuscular category, those who are active twice a day, at dawn and dusk; however, pandas may belong to a category all of their own, with activity peaks in the morning, afternoon and midnight. The low nutrition quality of bamboo means pandas need to eat more frequently, and due to their lack of major predators they can be active at any time of the day.[76] Activity is highest in June and decreases in late summer to autumn with an increase from November through the following March.[77] Activity is also directly related to the amount of sunlight during colder days.[77] There is a significant interaction of solar radiation, such that solar radiation has a stronger positive effect on activity levels of panda bears.[77]

    Pandas communicate through vocalisation and scent marking such as clawing trees or spraying urine.[44] They are able to climb and take shelter in hollow trees or rock crevices, but do not establish permanent dens. For this reason, pandas do not hibernate, which is similar to other subtropical mammals, and will instead move to elevations with warmer temperatures.[78] Pandas rely primarily on spatial memory rather than visual memory.[79] Though the panda is often assumed to be docile, it has been known to attack humans on rare occasions.[80][81][82] Pandas have been known to cover themselves in horse manure to protect themselves against cold temperatures.[83]

    The species communicates foremost through a blatting sound; they achieve peaceful interactions through the emission of this sound. When in oestrus, a female emits a chirp. In hostile confrontations or during fights, the giant panda emits vocalizations such as a roar or growl. On the other hand, squeals typically indicate inferiority and submission in a dispute. Other vocalizations include honks and moans.[84]

    Olfactory communication

    Giant pandas heavily rely on olfactory communication to communicate with one another. Scent marks are used to spread these chemical cues and are placed on landmarks like rocks or trees.[85] Chemical communication in giant pandas plays many roles in their social situations. Scent marks and odors are used to spread information about sexual status, whether a female is in estrus or not, age, gender, individuality, dominance over territory, and choice of settlement.[85] Giant pandas communicate by excreting volatile compounds, or scent marks, through the anogenital gland.[85][86] Giant pandas have unique positions in which they will scent mark. Males deposit scent marks or urine by lifting their hind leg, rubbing their backside, or standing in order to rub the anogenital gland onto a landmark. Females, however, exercise squatting or simply rubbing their genitals onto a landmark.[85][87]

    The season plays a major role in mediating chemical communication.[88] Depending on the season, mainly whether it is breeding season or not, may influence which odors are prioritized. Chemical signals can have different functions in different seasons. During the non-breeding season, females prefer the odors of other females because reproduction is not their primary motivation. However, during breeding season, odors from the opposite sex will be more attractive.[88][89] Because they are solitary mammals and their breeding season is so brief, female pandas secrete chemical cues in order to let males know their sexual status.[89] The chemical cues female pandas secrete can be considered to be pheromones for sexual reproduction.[89] Females deposit scent marks through their urine which induces an increase in androgen levels in males.[89] Androgen is a sex hormone found in both males and females; testosterone is the major androgen produced by males. Civetone and decanoic acid are chemicals found in female urine which promote behavioral responses in males; both chemicals are considered giant panda pheromones.[89] Male pandas also secrete chemical signals that include information about their sexual reproductivity and age, which is beneficial for a female when choosing a mate.[85][88] For example, age can be useful for a female to determine sexual maturity and sperm quality.[90] Pandas are also able to determine when the signal was placed, further aiding in the quest to find a potential mate.[90] However, chemical cues are not just used for communication between males and females, pandas can determine individuality from chemical signals. This allows them to be able to differentiate between a potential partner or someone of the same sex, which could be a potential competitor.[90]

    Chemical cues, or odors, play an important role in how a panda chooses their habitat. Pandas look for odors that tell them not only the identity of another panda, but if they should avoid them or not.[90] Pandas tend to avoid their species for most of the year, breeding season being the brief time of major interaction.[90] Chemical signaling allows for avoidance and competition.[87][88] Pandas whose habitats are in similar locations will collectively leave scent marks in a unique location which is termed “scent stations”.[90] When pandas come across these scent stations, they are able to identify a specific panda and the scope of their habitat. This allows pandas to be able to pursue a potential mate or avoid a potential competitor.[90]

    Pandas can assess an individual’s dominance status, including their age and size, via odor cues and may choose to avoid a scent mark if the signaler’s competitive ability outweighs their own.[87] A panda’s size can be conveyed through the height of the scent mark.[87][91] Since larger animals can place higher scent marks, an elevated scent mark advertises a higher competitive ability. Age must also be taken into consideration when assessing a competitor’s fighting ability. For example, a mature panda will be larger than a younger, immature panda and possess an advantage during a fight.[87]

    Reproduction

    A giant panda cub

    Giant pandas reach sexual maturity between the ages of four and eight, and may be reproductive until age 20.[92] The mating season is between March and May, when a female goes into estrus, which lasts for two or three days and only occurs once a year.[93] When mating, the female is in a crouching, head-down position as the male mounts her from behind. Copulation time ranges from 30 seconds to five minutes, but the male may mount her repeatedly to ensure successful fertilisation. The gestation period is somewhere between 95 and 160 days – the variability is due to the fact that the fertilized egg may linger in the reproductive system for a while before implanting on the uterine wall.[93] Giant pandas give birth to twins in about half of pregnancies.[94] If twins are born, usually only one survives in the wild. The mother will select the stronger of the cubs, and the weaker cub will die due to starvation. The mother is thought to be unable to produce enough milk for two cubs since she does not store fat.[95] The father has no part in helping raise the cub.[33]

    When the cub is first born, it is pink, blind, and toothless,[33] weighing only 90 to 130 g (3.2 to 4.6 oz), or about ⁠1/800⁠ of the mother’s weight,[12] proportionally the smallest baby of any placental mammal.[96] It nurses from its mother’s breast six to 14 times a day for up to 30 minutes at a time. For three to four hours, the mother may leave the den to feed, which leaves the cub defenseless. One to two weeks after birth, the cub’s skin turns grey where its hair will eventually become black. Slight pink colour may appear on the cub’s fur, as a result of a chemical reaction between the fur and its mother’s saliva. A month after birth, the colour pattern of the cub’s fur is fully developed. Its fur is very soft and coarsens with age. The cub begins to crawl at 75 to 80 days;[12] mothers play with their cubs by rolling and wrestling with them. The cubs can eat small quantities of bamboo after six months, though mother’s milk remains the primary food source for most of the first year. Giant panda cubs weigh 45 kg (99 lb) at one year and live with their mothers until they are 18 months to two years old. The interval between births in the wild is generally two years.[97]

    Initially, the primary method of breeding giant pandas in captivity was by artificial insemination, as they seemed to lose their interest in mating once they were captured.[98] This led some scientists to trying methods such as showing them videos of giant pandas mating[99] and giving the males sildenafil (commonly known as Viagra).[100] In the 2000s, researchers started having success with captive breeding programs, and they have now determined giant pandas have comparable breeding to some populations of the American black bear, a thriving bear species.[101][74]

    In July 2009, Chinese scientists confirmed the birth of the first cub to be successfully conceived through artificial insemination using frozen sperm.[102] The technique for freezing the sperm in liquid nitrogen was first developed in 1980 and the first birth was hailed as a solution to the dwindling availability of giant panda semen, which had led to inbreeding.[103][104] Panda semen, which can be frozen for decades, could be shared between different zoos to save the species.[102][105] As of 2009, it is expected that zoos in destinations such as San Diego in the United States and Mexico City will be able to provide their own semen to inseminate more giant pandas.[104]

    Attempts have also been made to reproduce giant pandas by interspecific pregnancy where cloned panda embryos were implanted into the uterus of an animal of another species. This has resulted in panda fetuses, but no live births.[106]

    Human interaction

    Early references

    Main article: Mo (Chinese zoology)

    In Ancient China, people thought pandas to be rare and noble creatures – the Empress Dowager Bo was buried with a panda skull in her vault. The grandson of Emperor Taizong of Tang is said to have given Japan two pandas and a sheet of panda skin as a sign of goodwill. Unlike many other animals in Ancient China, pandas were rarely thought to have medical uses. The few known uses include the Sichuan tribal peoples’ use of panda urine to melt accidentally swallowed needles, and the use of panda pelts to control menstruation as described in the Qin dynasty encyclopedia Erya.[107]

    The creature named mo (貘) mentioned in some ancient books has been interpreted as giant panda.[107] The dictionary Shuowen Jiezi (Eastern Han Dynasty) says that the mo, from Shu (Sichuan), is bear-like, but yellow-and-black,[108] although the older Erya describes mo simply as a “white leopard”.[109] The interpretation of the legendary fierce creature pixiu (貔貅) as referring to the giant panda is also common.[110]

    During the reign of the Yongle Emperor (early 15th century), his relative from Kaifeng sent him a captured zouyu (騶虞), and another zouyu was sighted in ShandongZouyu is a legendary “righteous” animal, which, similarly to a qilin, only appears during the rule of a benevolent and sincere monarch.[111]

    In captivity

    Main articles: Giant pandas around the worldList of giant pandas, and Panda diplomacy

    See also: Category:Individual giant pandas

    Pandas have been kept in zoos as early as the Western Han Dynasty in China, where the writer Sima Xiangru noted that the panda was the most treasured animal in the emperor’s garden of exotic animals in the capital Chang’an (present Xi’an). Not until the 1950s were pandas again recorded to have been exhibited in China’s zoos.[112] Chi Chi at the London Zoo became very popular. This influenced the World Wildlife Fund to use a panda as its symbol.[113] A 2006 New York Times article outlined the economics of keeping pandas,[114] which costs five times more than keeping the next most expensive animal, an elephant. American zoos generally pay the Chinese government $1 million a year in fees, as part of a typical ten-year contract. San Diego’s contract with China was to expire in 2008, but got a five-year extension at about half of the previous yearly cost.[115] The last contract, with the Memphis Zoo in Memphis, Tennessee, ended in 2013.[114]

    Adult male giant panda at the San Diego Zoo in 2004

    In the 1970s, gifts of giant pandas to American and Japanese zoos formed an important part of the diplomacy of the People’s Republic of China (PRC), as it marked some of the first cultural exchanges between China and the West. This practice has been termed “panda diplomacy“.[116] By 1984, however, pandas were no longer given as gifts. Instead, China began to offer pandas to other nations only on 10-year loans for a fee of up to US$1,000,000 per year and with the provision that any cubs born during the loan are the property of China. As a result of this change in policy, nearly all the pandas in the world are owned by China, and pandas leased to foreign zoos and all cubs are eventually returned to China.[117][118] As of 2022, Xin Xin at the Chapultepec Zoo in Mexico City, was the last living descendant of the gifted pandas.[119]

    Since 1998, because of a WWF lawsuit, the United States Fish and Wildlife Service only allows US zoos to import a panda if the zoo can ensure China channels more than half of its loan fee into conservation efforts for giant pandas and their habitat.[120][121] In May 2005, China offered a breeding pair to Taiwan. The issue became embroiled in cross-Strait relations – due to both the underlying symbolism and technical issues such as whether the transfer would be considered “domestic” or “international” or whether any true conservation purpose would be served by the exchange.[122] A contest in 2006 to name the pandas was held in the mainland, resulting in the politically charged names Tuan Tuan and Yuan Yuan (from simplified Chinese: 团圆; traditional Chinese: 團圓; pinyintuanyuanlit. ‘reunion’, implying reunification). China’s offer was initially rejected by Chen Shui-bian, then President of Taiwan. However, when Ma Ying-jeou assumed the presidency in 2008, the offer was accepted and the pandas arrived in December of that year.[123]

    In the 2020s, certain “celebrity pandas” have gained a cult following amongst internet users, with dedicated fan accounts existing to keep tabs on the animals. Known as “giant panda fever” or “panda-monium”, individual pandas are known to get billions of views and engagements on social media, as well as product lines specifically emulating them.[124] At Chengdu Research Base of Giant Panda Breeding, certain of these “celebrity pandas” are known to garner hours-long lines specifically to see them.[124][125]

    Conservation

    The giant panda is a vulnerable species, threatened by continued habitat loss and fragmentation,[32][126] and by a very low birthrate, both in the wild and in captivity.[49] Its range is confined to a small portion on the western edge of its historical range, which stretched through southern and eastern China, northern Myanmar, and northern Vietnam. The species is scattered into more than 30 subpopulations of relatively few animals. Building of roads and human settlement near panda habitat, result in population declines. Diseases from domesticated pets and livestock is another threat. By 2100, it is estimated that the distribution of giant pandas will shrink by up to 100%, mainly due to the effects of climate change.[1] The giant panda is listed on CITES Appendix I, meaning trade of their parts is prohibited and that they require this protection to avoid extinction.[127] They have been protected and placed in category 1, by the 1988 Wildlife Protection Act.[128]

    The giant panda has been a target of poaching by locals since ancient times and by foreigners since it was introduced to the West. Starting in the 1930s, foreigners were unable to poach giant pandas in China because of the Second Sino-Japanese War and the Chinese Civil War, but pandas remained a source of soft furs for the locals. The population boom in China after 1949 created stress on the pandas’ habitat and the subsequent famines led to the increased hunting of wildlife, including pandas. After the Chinese economic reform, demand for panda skins from Hong Kong and Japan led to illegal poaching for the black market, acts generally ignored by the local officials at the time. In 1963, the PRC government set up Wolong National Nature Reserve to save the declining panda population.[129]

    Close-up of a seven-month-old panda cub

    The giant panda is among the world’s most adored and protected rare animals, and is one of the few in the world whose natural inhabitant status was able to gain a UNESCO World Heritage Site designation. The Sichuan Giant Panda Sanctuaries, located in the southwest province of Sichuan and covering seven natural reserves, were inscribed onto the World Heritage List in 2006.[130][131][132] A 2015 paper found that the giant panda can serve as an umbrella species as the preservation of their habitat also helps other endemic species in China, including 70% of the country’s forest birds, 70% of mammals and 31% of amphibians.[133]

    In 2012, Earthwatch Institute, a global nonprofit that teams volunteers with scientists to conduct important environmental research, launched a program called “On the Trail of Giant Panda”. This program, based in the Wolong National Nature Reserve, allows volunteers to work up close with pandas cared for in captivity, and help them adapt to life in the wild, so that they may breed, and live longer and healthier lives.[134] Efforts to preserve the panda bear populations in China have come at the expense of other animals in the region, including snow leopards, wolves, and dholes.[135] In order to improve living and mating conditions for the fragmented populations of pandas, nearly 70 natural reserves have been combined to form the Giant Panda National Park in 2020. With a size of 10,500 square miles, the park is roughly three times as large as Yellowstone National Park and incorporates the Wolong National Nature Reserve. Small, isolated populations run the risk of inbreeding and smaller genetic variety makes the individuals more vulnerable to various defects and genetic mutation.[136]

    Population

    In 2006, scientists reported that the number of pandas living in the wild may have been underestimated at about 1,000. Previous population surveys had used conventional methods to estimate the size of the wild panda population, but using a new method that analyzes DNA from panda droppings, scientists believed the wild population were as large as 3,000.[49] In 2006, there were 40 panda reserves in China, compared to just 13 reserves in 1998.[137] As the species has been reclassified from “endangered” to “vulnerable” since 2016, the conservation efforts are thought to be working. Furthermore, in response to this reclassification, the State Forestry Administration of China announced that they would not accordingly lower the conservation level for panda, and would instead reinforce the conservation efforts.[138]

    In 2020, the panda population of the new national park was already above 1,800 individuals, which is roughly 80 percent of the entire panda population in China. Establishing the new protected area in the Sichuan Province also gives various other endangered or threatened species, like the Siberian tiger, the possibility to improve their living conditions by offering them a habitat.[139] Other species who benefit from the protection of their habitat include the snow leopard, the golden snub-nosed monkey, the red panda and the complex-toothed flying squirrel.[140]

    In July 2021, Chinese conservation authorities announced that giant pandas are no longer endangered in the wild following years of conservation efforts, with a population in the wild exceeding 1,800.[140][141] China has received international praise for its conservation of the species, which has also helped the country establish itself as a leader in endangered species conservation.[142]: 8