Zebras Etoscha
   HOME

TheInfoList



OR:

Zebras (, ) (subgenus ''Hippotigris'') are African equines with distinctive black-and-white striped
coat A coat typically is an outer garment for the upper body as worn by either gender for warmth or fashion. Coats typically have long sleeves and are open down the front and closing by means of buttons, zippers, hook-and-loop fasteners, toggles, a ...
s. There are three
living Living or The Living may refer to: Common meanings *Life, a condition that distinguishes organisms from inorganic objects and dead organisms ** Living species, one that is not extinct *Personal life, the course of an individual human's life * Hu ...
species: the
Grévy's zebra Grévy's zebra (''Equus grevyi''), also known as the imperial zebra, is the largest living wild equid and the most threatened of the three species of zebra, the other two being the plains zebra and the mountain zebra. Named after Jules Grévy, i ...
(''Equus grevyi''), plains zebra (''E. quagga''), and the
mountain zebra The mountain zebra (''Equus zebra'') is a zebra species in the family Equidae, native to southwestern Africa. There are two subspecies, the Cape mountain zebra (''E. z. zebra'') found in South Africa and Hartmann's mountain zebra (''E. z. hartman ...
(''E. zebra''). Zebras share the genus ''Equus'' with
horses The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...
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 stripes, with most evidence supporting them as a deterrent for biting flies. Zebras inhabit eastern and
southern Africa Southern Africa is the southernmost subregion of the African continent, south of the Congo and Tanzania. The physical location is the large part of Africa to the south of the extensive Congo River basin. Southern Africa is home to a number of ...
and can be found in a variety of habitats such as savannahs,
grasslands A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natural ...
, woodlands,
shrubland Shrubland, scrubland, scrub, brush, or bush is a plant community characterized by vegetation dominated by shrubs, often also including grasses, herbs, and geophytes. Shrubland may either occur naturally or be the result of human activity. It m ...
s, and mountainous areas. Zebras are primarily grazers and can subsist on lower-quality vegetation. They are preyed on mainly by
lions The lion (''Panthera leo'') is a large cat of the genus ''Panthera'' native to Africa and India. It has a muscular, broad-chested body; short, rounded head; round ears; and a hairy tuft at the end of its tail. It is sexually dimorphic; adult ...
, and typically flee when threatened but also bite and kick. Zebra species differ in
social behaviour Social behavior is behavior among two or more organisms within the same species, and encompasses any behavior in which one member affects the other. This is due to an interaction among those members. Social behavior can be seen as similar to an ...
, with plains and mountain zebra living in stable
harems Harem (Persian: حرمسرا ''haramsarā'', ar, حَرِيمٌ ''ḥarīm'', "a sacred inviolable place; harem; female members of the family") refers to domestic spaces that are reserved for the women of the house in a Muslim family. A hare ...
consisting of an adult male or
stallion A stallion is a male horse that has not been gelded (castrated). Stallions follow the conformation and phenotype of their breed, but within that standard, the presence of hormones such as testosterone may give stallions a thicker, "cresty" nec ...
, several adult females or
mares A mare is an adult female horse or other equine. In most cases, a mare is a female horse over the age of three, and a filly is a female horse three and younger. In Thoroughbred horse racing, a mare is defined as a female horse more than four y ...
, and their young or
foals A foal is an equine up to one year old; this term is used mainly for horses, but can be used for donkeys. More specific terms are colt for a male foal and filly for a female foal, and are used until the horse is three or four. When the foal is ...
; 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 A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal. In international politics, a territory is usually either the total area from which a state may extract power resources or an ...
which attract females and the species is promiscuous. Zebras communicate with various vocalisations, body postures and facial expressions.
Social grooming Social grooming is a behavior in which social animals, including humans, clean or maintain one another's body or appearance. A related term, allogrooming, indicates social grooming between members of the same species. Grooming is a major soci ...
strengthens social bonds in plains and mountain zebras. Zebras' dazzling stripes make them among the most recognisable mammals. They have been featured in art and stories in Africa and beyond. Historically, they have been highly sought after by exotic animal collectors, but unlike
horses The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...
and donkeys, zebras have never been truly domesticated. The
International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
(IUCN) lists the Grévy's zebra as
endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...
, the mountain zebra as vulnerable and the plains zebra as near-threatened. The 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 Italian, Spanish or Portuguese. Its origins may lie in the
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
''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 The Iberian Peninsula (), ** * Aragonese and Occitan: ''Peninsula Iberica'' ** ** * french: Péninsule Ibérique * mwl, Península Eibérica * eu, Iberiar penintsula also known as Iberia, is a peninsula in southwestern Europe, defi ...
during the Middle Ages. In 1591, Italian explorer
Filippo Pigafetta Filippo Pigafetta (1533–1604) was an Italian mathematician and explorer. Pigafetta's ''Relatione del reame del Congo'' (A Report of the Kingdom of Congo and of the Surrounding Countries) 1591 was translated into English, Latin (as ''Regnum Congo ...
recorded "zebra" being used to refer to the African animals by Portuguese visitors to the continent. In ancient times, the African zebra was called ''hippotigris'' ("horse tiger") by the
Greeks The Greeks or Hellenes (; el, Έλληνες, ''Éllines'' ) are an ethnic group and nation indigenous to the Eastern Mediterranean and the Black Sea regions, namely Greece, Cyprus, Albania, Italy, Turkey, Egypt, and, to a lesser extent, oth ...
and Romans. 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 the UK and the
Commonwealth A commonwealth is a traditional English term for a political community founded for the common good. Historically, it has been synonymous with "republic". The noun "commonwealth", meaning "public welfare, general good or advantage", dates from the ...
. The pronunciation with a long initial vowel remains standard in US English.


Taxonomy

Zebras are classified in the genus ''
Equus Equus may refer to: * ''Equus'' (genus), a genus of animals including horses, donkeys and zebras * ''Equus'' (play), a play by Peter Shaffer * ''Equus'' (film), a film adaptation of the Peter Shaffer play * Equus (comics), a comic book characte ...
'' (known as equines) along with
horses The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...
and asses. These three groups are the only living members of the family Equidae. The plains zebra and
mountain zebra The mountain zebra (''Equus zebra'') is a zebra species in the family Equidae, native to southwestern Africa. There are two subspecies, the Cape mountain zebra (''E. z. zebra'') found in South Africa and Hartmann's mountain zebra (''E. z. hartman ...
were traditionally placed in the
subgenus In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...
''Hippotigris'' (C. H. Smith, 1841) in contrast to the
Grévy's zebra Grévy's zebra (''Equus grevyi''), also known as the imperial zebra, is the largest living wild equid and the most threatened of the three species of zebra, the other two being the plains zebra and the mountain zebra. Named after Jules Grévy, i ...
which was considered the sole species of subgenus ''Dolichohippus'' (Heller, 1912). Groves and Bell (2004) placed all three species in the subgenus ''Hippotigris''. A 2013
phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
study found that the plains zebra is more closely related to Grévy's zebras than mountain zebras. The extinct quagga was originally classified as a distinct species. Later genetic studies have placed it as the same species as the plains zebra, either a subspecies or just the southernmost population. Molecular evidence supports zebras as a
monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...
lineage Lineage may refer to: Science * Lineage (anthropology), a group that can demonstrate its common descent from an apical ancestor or a direct line of descent from an ancestor * Lineage (evolution), a temporal sequence of individuals, populati ...
. ''Equus'' originated in North America and direct paleogenomic sequencing of a 700,000-year-old middle Pleistocene horse
metapodial Metapodials are long bones of the hand (metacarpals) and feet (metatarsal The metatarsal bones, or metatarsus, are a group of five long bones in the foot, located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. ...
bone from Canada implies a date of 4.07 million years ago (mya) for the most recent common ancestor of the equines within the range of 4.0 to 4.5 mya. 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. The cladogram of ''Equus'' below is based on Vilstrup and colleagues (2013) and Jónsson and colleagues (2014):


Living species


Fossil record

In addition to the three living species, some fossil zebras and relatives have also been identified. ''Equus koobiforensis'' is an early equine
basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...
to zebras found in the Shungura Formation,
Ethiopia Ethiopia, , om, Itiyoophiyaa, so, Itoobiya, ti, ኢትዮጵያ, Ítiyop'iya, aa, Itiyoppiya officially the Federal Democratic Republic of Ethiopia, is a landlocked country in the Horn of Africa. It shares borders with Eritrea to the ...
and the
Olduvai Gorge The Olduvai Gorge or Oldupai Gorge in Tanzania is one of the most important paleoanthropology, paleoanthropological localities in the world; the many sites exposed by the gorge have proven invaluable in furthering understanding of early human ev ...
,
Tanzania Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands and ...
, and dated to around 2.3 mya. ''E. oldowayensis'' is identified from remains in Olduvai Gorge dating to 1.8 mya. Fossil skulls of ''E. mauritanicus'' from Algeria which date to around 1 mya appears to show affinities with the plains zebra. '' E. capensis'', known as the Cape zebra, appeared around 2 mya and lived throughout southern and eastern Africa. 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. A 2017 mitochondrial DNA study placed the Eurasian ''E. ovodovi'' and the subgenus ''Sussemionus'' lineage as closer to zebras than to asses.


Hybridisation

Fertile hybrids have been reported in the wild between plains and Grévy's zebra. 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. Captive zebras have been bred with horses and donkeys; these are known as
zebroids A zebroid is the offspring of any cross between a zebra and any other equine to create a hybrid. In most cases, the sire is a zebra stallion. Offspring of a donkey sire and zebra dam are called a donkra and offspring of a horse sire and a zebr ...
. 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 A pony is a type of small horse ('' Equus ferus caballus''). Depending on the context, a pony may be a horse that is under an approximate or exact height at the withers, or a small horse with a specific conformation and temperament. Compared ...
. Zebroids are often born sterile with
dwarfism Dwarfism is a condition wherein an organism is exceptionally small, and mostly occurs in the animal kingdom. In humans, it is sometimes defined as an adult height of less than , regardless of sex; the average adult height among people with dw ...
.


Characteristics

As with all wild equines, zebra have barrel-chested bodies with tufted tails, elongated faces and long necks with long, erect
manes In ancient Roman religion, the ''Manes'' (, , ) or ''Di Manes'' are chthonic deities sometimes thought to represent souls of deceased loved ones. They were associated with the ''Lares'', ''Lemures,'' '' Genii'', and ''Di Penates'' as deities ('' ...
. Their thin legs are each supported by a spade-shaped toe covered in a hard hoof. Their
dentition Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiolo ...
is adapted for
grazing In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...
; 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. Unlike horses, zebras and asses have chestnut callosities present only on their front legs. In contrast to other living equines, zebra have longer front legs than back legs. Diagnostic traits of the zebra skull include: its relatively small size with a straight profile, more projected eye sockets, narrower rostrum, reduced
postorbital bar The postorbital bar (or postorbital bone) is a bony arched structure that connects the frontal bone of the skull to the zygomatic arch, which runs laterally around the eye socket. It is a trait that only occurs in mammalian taxa, such as most streps ...
, separation of the
metaconid Many different terms have been proposed for features of the tooth crown in mammals. The structures within the molars receive different names according to their position and morphology. This nomenclature was developed by Henry Fairfield Osborn ...
and metastylid of the tooth by a V-shaped canal and rounded enamel wall.


Stripes

Zebras are easily recognised by their bold black-and-white striping patterns. The
coat A coat typically is an outer garment for the upper body as worn by either gender for warmth or fashion. Coats typically have long sleeves and are open down the front and closing by means of buttons, zippers, hook-and-loop fasteners, toggles, a ...
appears to be white with black stripes, as indicated by the belly and legs when unstriped, but the skin underneath is black. Young or
foal A foal is an equine up to one year old; this term is used mainly for horses, but can be used for donkeys. More specific terms are colt for a male foal and filly for a female foal, and are used until the horse is three or four. When the foal i ...
s are born with brown and white coats, and the brown darkens with age. 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. Striping patterns are unique to an individual and heritable. During
embryonic development An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm ...
, 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 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. Various abnormalities of the patterns have been documented in plains zebras. In
melanistic The term melanism refers to black pigment and is derived from the gr, μελανός. Melanism is the increased development of the dark-colored pigment melanin in the skin or hair. Pseudomelanism, also called abundism, is another variant of pi ...
zebras, dark stripes are highly concentrated on the torso but the legs are whiter. "Spotted" individuals display disruptions in black striping patterns between the shoulders and hips. There have even been morphs with white spots on dark backgrounds. Striping abnormalities have been linked to
inbreeding Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and o ...
. Albino zebras have been recorded in the forests of
Mount Kenya Mount Kenya (Kikuyu: ''Kĩrĩnyaga'', Kamba, ''Ki Nyaa'') is the highest mountain in Kenya and the second-highest in Africa, after Kilimanjaro. The highest peaks of the mountain are Batian (), Nelion () and Point Lenana (). Mount Kenya is locat ...
, with the dark stripes being blonde. The quagga had brown and white stripes on the head and neck, brown upper parts and a white belly, tail and legs.


Function

The function of stripes in zebras has been discussed among biologists since at least the 19th century. Popular hypotheses include the following: * The
crypsis In ecology, crypsis is the ability of an animal or a plant to avoid observation or detection by other animals. It may be a predation strategy or an antipredator adaptation. Methods include camouflage, nocturnality, subterranean lifestyle and ...
hypothesis was proposed by Alfred Wallace in 1896 and suggests that the stripes allow the animal to blend in with its environment or break out its outline so predators can not perceive it as a single entity. In 1871,
Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended fr ...
remarked that "the zebra is conspicuously striped, and stripes on the open plains of South Africa cannot afford any protection". Zebras graze in open habitat and do not behave cryptically, being noisy, fast, and social. They do not freeze when detecting a predator. In addition, lions and hyenas do not appear to perceive the stripes when they are certain distance away during daytime, thus making the stripes useless in disrupting the outline. Stripes also do not appear to make zebras more difficult to find than more solidly coloured animals of similar size, and predators may still be able to detect them by scent or hearing. The camouflaging stripes of woodland living ungulates like bongos and bushbucks are much less vivid with less contrast with the background colour. In addition, unlike
tiger The tiger (''Panthera tigris'') is the largest living cat species and a member of the genus '' Panthera''. It is most recognisable for its dark vertical stripes on orange fur with a white underside. An apex predator, it primarily preys on u ...
stripes, the spatial frequencies of zebra stripes do not line up with their environment. A 2014 study could not find any correlations between striping patterns and woodland habitats. * 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 Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...
. This theory has been proposed by several biologists since at least the 1970s. A 2014 computer study of zebra stripes found that they may create a wagon-wheel effect and/or
barber pole illusion The barberpole illusion is a visual illusion that reveals biases in the processing of visual motion in the human brain. This visual illusion occurs when a diagonally striped pole is rotated around its vertical axis (horizontally), it appears as th ...
when in motion. The researchers concluded that this could be used against mammalian predators or biting flies. 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. In addition, no correlations have been found between the amount of stripes and populations of mammal predators. * 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 Sir Edward Bagnall Poulton, FRS HFRSE FLS (27 January 1856 – 20 November 1943) was a British evolutionary biologist, a lifelong advocate of natural selection through a period in which many scientists such as Reginald Punnett doubted its i ...
in 1890. As with known aposematic mammals, zebras are recognisable up close, live in more open environments, have a high risk of predation and do not hide or act inconspicuous. However they are frequently preyed on by lions, suggesting that stripes do not work on them but may on smaller predators, and are not slow-moving enough to need to ward off threats. They also do not possess adequate defenses to back up the warning pattern. * The social function hypothesis states that stripes serve a role in intraspecific or individual recognition, social bonding, mutual grooming or a signal of fitness. 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, zebras have limited range overlap with each other and horses can recognise each other using visual communication. In addition, no correlation has been found between striping and social behaviour or group numbers among equines, and no link has been found between fitness and striping. * The
thermoregulatory Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
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 Desmond John Morris FLS ''hon. caus.'' (born 24 January 1928) is an English zoologist, ethologist and surrealist painter, as well as a popular author in human sociobiology. He is known for his 1967 book ''The Naked Ape'', and for his televisi ...
suggested that the stripes create convection currents which bring down the animal's body temperature. A study from 2015 determined that environmental temperature is a strong predictor for zebra striping patterns. 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. During the hottest times of the day, zebras may erect the black hair to release heat from the skin and flatten it to retain heat when it gets cooler. Others have found no evidence that zebras have lower body temperatures than other ungulates whose habitat they share, or that striping correlates with temperature. A 2018 experimental study which dressed water-filled metal barrels in horse, zebra and cattle hides found that zebra stripes have no effect on thermoregulation. * The fly protection hypothesis holds that the stripes deter biting flies. Horse flies, in particular, spread diseases that are lethal to equines such as
African horse sickness African horse sickness (AHS) is a highly infectious and deadly disease caused by ''African horse sickness virus''. It commonly affects horses, mules, and donkeys. It is caused by a virus of the genus ''Orbivirus'' belonging to the family ''Reovir ...
,
equine influenza Equine influenza (horse flu) is the disease caused by strains of influenza A that are enzootic in horse species. Equine influenza occurs globally, previously caused by two main strains of virus: equine-1 (H7N7) and equine-2 (H3N8). The OIE now cons ...
, equine infectious anemia and
trypanosomiasis Trypanosomiasis or trypanosomosis is the name of several diseases in vertebrates caused by parasitic protozoan trypanosomes of the genus ''Trypanosoma''. In humans this includes African trypanosomiasis and Chagas disease. A number of other diseas ...
. In addition, zebra hair is about as long as the mouthparts of these flies. Caro and colleagues (2019) reported this hypothesis as the "emerging consensus among biologists". 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. A 2012 study concurred this and concluded that the stripes reflect contrasting light patterns rather than the more consistent patterns these insects use to locate food and habitat. A 2014 study found a correlation between striping and overlap with horse and
tsetse fly Tsetse ( , or ) (sometimes spelled tzetze; also known as tik-tik flies), are large, biting flies that inhabit much of tropical Africa. Tsetse flies include all the species in the genus ''Glossina'', which are placed in their own family, Glo ...
populations and activity. Other studies have found that zebras are rarely targeted by these insect species. Caro and colleagues studied captive zebras and horses and found that neither could deter flies from a distance, but zebra stripes made it difficult for flies to make a landing, both for zebras and horses dressed in zebra print coats. A 2020 study found that zebra stripes do not dazzle or work like a barber pole against flies since checkered patterns also repel them. White or light stripes painted on dark bodies have also been found to reduce fly irritations in both cattle and humans. In addition to the stripes, zebra can also defend against flies by swatting their tails.


Ecology and behaviour

Zebras may travel or
migrate Migration, migratory, or migrate may refer to: Human migration * Human migration, physical movement by humans from one region to another ** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...
to wetter areas during the dry season. Plains zebras have been recorded travelling between Namibia and Botswana, the longest land migration of mammals in Africa. 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. Plains zebras are more water-dependent and live in moister environments than other species. They usually can be found from a water source. 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. Mountain zebras can be found at elevations of up to . 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. A zebra's diet is mostly
grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns an ...
es and
sedge The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus ''Carex'' wit ...
s, but they will opportunistically consume
bark Bark may refer to: * Bark (botany), an outer layer of a woody plant such as a tree or stick * Bark (sound), a vocalization of some animals (which is commonly the dog) Places * Bark, Germany * Bark, Warmian-Masurian Voivodeship, Poland Arts, ...
, leaves, buds, fruits, and roots. Compared to
ruminants Ruminants ( suborder Ruminantia) are hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. The ...
, 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. The plains zebra is a pioneer grazer, mowing down the upper, less nutritious grass canopy and preparing the way for more specialised grazers, which depend on shorter and more nutritious grasses below. Zebras are preyed on mainly by lions. Leopards, cheetahs,
spotted hyenas The spotted hyena (''Crocuta crocuta''), also known as the laughing hyena, is a hyena species, currently classed as the sole extant member of the genus ''Crocuta'', native to sub-Saharan Africa. It is listed as being of least concern by the IUC ...
,
brown hyena The brown hyena (''Parahyaena brunnea''), also called strandwolf, is a species of hyena found in Namibia, Botswana, western and southern Zimbabwe, southern Mozambique and South Africa. It is the only extant species in the genus ''Parahyaena''. It ...
s and
wild dogs Wild Dogs is an American heavy metal band from Portland, Oregon, formed loosely in 1981 by original members Jeff Mark, Danny Kurth, Matt McCourt, and Pete Holmes. The band has since released six albums, three live albums and one DVD. Wild Dogs ...
pose less of a threat to adults.
Nile crocodile The Nile crocodile (''Crocodylus niloticus'') is a large crocodilian native to freshwater habitats in Africa, where it is present in 26 countries. It is widely distributed throughout sub-Saharan Africa, occurring mostly in the central, eastern ...
s also prey on zebras when they near water. 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. In one study, the maximum speed of a zebra was found to be while a lion was measured at . Zebras do not escape lions by speed alone but by sideways turning, especially when the cat is close behind. With smaller predators like hyenas and dogs, zebras may act more aggressively, especially in defense of their young.


Social structure

Zebra species have two basic social structures. Plains and mountain zebras live in stable, closed family groups or
harems Harem (Persian: حرمسرا ''haramsarā'', ar, حَرِيمٌ ''ḥarīm'', "a sacred inviolable place; harem; female members of the family") refers to domestic spaces that are reserved for the women of the house in a Muslim family. A hare ...
consisting of one
stallion A stallion is a male horse that has not been gelded (castrated). Stallions follow the conformation and phenotype of their breed, but within that standard, the presence of hormones such as testosterone may give stallions a thicker, "cresty" nec ...
, several
mares A mare is an adult female horse or other equine. In most cases, a mare is a female horse over the age of three, and a filly is a female horse three and younger. In Thoroughbred horse racing, a mare is defined as a female horse more than four y ...
, and their offspring. These groups have their own
home ranges A home range is the area in which an animal lives and moves on a periodic basis. It is related to the concept of an animal's territory which is the area that is actively defended. The concept of a home range was introduced by W. H. Burt in 1943. He ...
, which overlap, and they tend to be nomadic. Stallions form and expand their harems by recruiting young mares from their natal (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 being the ones that have 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. In the more arid-living Grévy's zebras, adults have more fluid associations and adult males establish large
territories A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal. In international politics, a territory is usually either the total area from which a state may extract power resources or an ...
, marked by dung piles, and mate with the females that enter them. 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. 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. In all species, excess males gather in
bachelor group A bachelor herd is a herd of (usually) juvenile male animals who are still sexually immature or 'harem'-forming animals who have been thrown out of their parent groups but not yet formed a new family group. It may also refer to a group of males who ...
s. These are typically young males that are not yet ready to establish a harem or territory. With the plains zebra, the oldest males are the most dominant and group membership is stable. Bachelor groups tend to be at the boundaries of herds and during group movements, the bachelors trail behind or occupy the sides. 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 The estrous cycle (, originally ) is the set of recurring physiological changes that are induced by reproductive hormones in most mammalian therian females. Estrous cycles start after sexual maturity in females and are interrupted by anestrous p ...
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. 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 family stallion 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.


Communication

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". The mountain zebra may produce a similar sound while the call of the 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. Individuals may greet each other by rubbing and sniffing and then mutually rub their cheeks, and move along their bodies towards each other's genitals to sniff. 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. 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. Although Grévy's zebras generally do not perform social grooming.


Reproduction and parenting

Among plains and mountain zebras, the adult females mate only with their harem stallion, while in Grévy's zebras, mating is more promiscuous and the males have larger testes for
sperm competition Sperm competition is the competitive process between spermatozoa of two or more different males to fertilize the same egg during sexual reproduction. Competition can occur when females have multiple potential mating partners. Greater choice and ...
. 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. Among 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. 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. Usually, a single foal is born, which is capable of running within an hour of birth. 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. At a few weeks old, foals begin to graze, but may continue to nurse for eight to thirteen months. Living in an arid environment, Grévy's zebras have longer nursing intervals and young only begin to drink water three months after birth. 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. In Grévy's zebras, young stay in " kindergartens" when their mothers leave for water. These groups are tended to by the territorial male. A stallion may look after a foal in his territory to ensure that the mother stays, though it may not be his. By contrast, plains zebra stallions are generally intolerant of foals that are not theirs and may practice
infanticide Infanticide (or infant homicide) is the intentional killing of infants or offspring. Infanticide was a widespread practice throughout human history that was mainly used to dispose of unwanted children, its main purpose is the prevention of reso ...
and feticide via violence to the pregnant mare.


Human relations


Cultural significance

With their distinctive black-and-white stripes, zebras are among the most recognisable 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 stripes are also popularly used for body paintings, dress, furniture and architecture. Zebras have been featured in African art and African culture, 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 Common eland, eland. How the zebra got its stripes has been the subject of African folklore, folk tales, some of which involve it being scorched by fire. The Maasai people, 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 lighting, and water spirits were conceived of having zebra stripes. 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 Scramble for Africa, 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. 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 ''Khumba'', ''The Lion King'' and the Madagascar (franchise), ''Madagascar'' films and television series such as ''Zou (TV series), Zou''. Zebras have been popular subjects for Abstract art, abstract, modernism, modernist and Surrealism, surrealist artists. Such art includes Christopher Wood (painter), Christopher Wood's ''Zebra and Parachute'', Lucian Freud's ''The Painter's Room'' and ''Quince on a Blue Table'' and the various paintings of Mary Fedden and Sidney Nolan. Victor 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 London Zoo#London Zoo during the Second World War, 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 (pen manufacturer), Zebra Co., Ltd.


Captivity

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 Bahri dynasty, 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 emperors, Mughal emperor Jahangir received a zebra from Ethiopia in 1620 and Ustad Mansur made a painting of it. In the 1670s, Ethiopian Empire, 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. 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. In 1882, Ethiopia sent a zebra to French president Jules Grévy, and the species it belonged to was named in his honour. 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. However, zebras have been animal training, 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). 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. In the early 20th century, German East Africa, German colonial officers in East Africa tried to use zebras for both driving and riding, with limited success.


Conservation

As of 2016–2019, the IUCN Red List of mammals lists the Grévy's zebra as
endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...
, 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. Civil wars in some countries have also caused declines in zebra populations. 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 hunting, 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. The 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. 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. 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. Zebras can be found in numerous protected areas. Important areas for the Grévy's zebra include Yabelo Wildlife Sanctuary and Chelbi Wildlife Sanctuary, Chelbi Sanctuary in Ethiopia and Buffalo Springs National Reserve, Buffalo Springs, Samburu National Reserve, Samburu and Shaba National Reserve, Shaba National Reserves in Kenya. The plains zebra inhabitats 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. Mountain zebras are protected in Mountain Zebra National Park, Karoo National Park and Goegap Nature Reserve in South Africa as well as Etosha and Namib-Naukluft Park in Namibia.


See also

* Fauna of Africa * Lord Morton's mare * Primitive markings – markings found on other equines * Zonkey (Tijuana) – a donkey painted with zebra stripes


Citations


General bibliography

* *


External links


The Quagga Project
An organisation that selectively breeds zebras to recreate the hair coat pattern of the quagga {{Featured article Zebras, * Equus (genus) Fauna of Sub-Saharan Africa Herbivorous mammals Mammal common names Mammals of Africa