Equus zebra

Geographic Range

There are two distinct subspecies of mountain zebras ( Equus zebra ): Cape mountain zebras, E. z. zebra , and Hartmann's mountain zebras, E. z. hartmannae . Cape mountain zebras are found only in South Africa. Natural populations are found in the Mountain Zebra National Park (MZNP), Gamka Mountain Reserve, and in the Kamanassie Mountains. Populations of Cape mountain zebras have also been established in Karoo National Park, Karoo Nature Reserve, Commando Drift Nature Reserve, De Hoop Nature Reserve, and Tsolwana Game Ranch. Hartmann’s mountain zebras range from South West Africa into extreme southwest Angola. Their distribution is highly discontinuous.

• Biogeographic Regions
• ethiopian ethiopian
  • native native

Habitat

Mountain zebras inhabit slopes and plateaus in mountainous areas of South Africa and Namibia (South West Africa). Cape mountain zebras may occur up to 2,000 meters above sea level, but move to lower elevations in the winter. The habitat in South Africa provides regular precipitation and a fairly constant food-supply year round. Hartmann’s mountain zebras differ from Cape mountain zebras in that they occupy an arid region in a mountainous transition zone on the edge of the Namib Desert. Surface water is patchy in this area and as a result, E. z. hartmannae must wander between the mountains and sand flats in order to find patches of grass.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• desert or dune desert or dune
• mountains mountains

Physical Description

Equus zebra is a fairly large-sized, striped member of the horse family. Adult mountain zebras have a head and body length of 210 to 260 cm, and a tail length of 40 to 55 cm. Shoulder height ranges from 116 to 150 cm. Mountain zebras typically weigh between 240 and 372 kg. Adult Cape mountain zebra mares average 234 kg and stallions usually weigh 250 to 260 kg. Adult Hartmann's mountain zebrasare slightly larger, with mares averaging 276 kg, and stallions averaging 298 kg. Stallions 7 years and older have a mean weight of 343 kg, and a mean shoulder height of 144.5 cm.

The ground color on the body is white, with black to deep brown stripes which continue through the short, erect mane. The stripes on the head and body are narrow and more numerous than those on the rump, and the legs are striped to the hooves. The posterior portion of the dorsal stripe forms a distinctive “gridiron” pattern that continues onto the tail and extends to the whisk near the tip. The muzzle is black.

Both subspecies of E. zebra are good climbers and have exceptionally hard and pointed hooves compared to other equines. The most distinguishing characteristic is the presence of a dewlap, or fold of skin, hanging from the throat.

The color pattern of E. zebra is intermediate between Burchell’s zebra and Grevy’s zebra . Equus zebra can be distinguished from E. burchelli by having a dewlap; narrower and more numerous stripes on the head and body; broader stripes on the hindquarters with no “shadow” stripes; a “gridiron” pattern on the rump; white under-parts with a mid-ventral black stripe on the chest and belly; and ears that are more than 200 mm long.

Cape mountain zebras are slightly smaller than Hartmann’s mountain zebras. The upper 2 to 3 dark stripes on the rump are very broad, whereas they are less so in Hartmann’s mountain zebras, where some of the white stripes may be more broad than the dark stripes.

• Other Physical Features
• endothermic endothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger

Reproduction

Mountain zebras have a polygynous mating system. They form small breeding herds that consist of one adult stallion and 1 to 5 mares with young. Breeding herds remain stable over many years and mares usually remain in a herd for life.

The mating system of E. zebra results in a surplus of stallions. These stallions join bachelor groups which form “the reservoir from which herd stallions are recruited.” (Penzhorn 1988) New breeding bands may be formed when a bachelor stallion obtains a young mare from a maternal herd, or an older mare from a fragmented herd, although the latter is not as common.

If a dominant stallion is successfully driven away from his herd by a challenging stallion, the herd is taken over as a unit by the newcomer. Serious fighting, including kicking and biting, may occur when another stallion attempts to take over a herd.

Herd stallions approach each other and perform a challenge ritual when two breeding herds come into contact. The challenge ritual consists of nasonasal and nasogential contact, and body rubbing. Both stallions then continue grazing and will eventually move back to their own herds. Sometimes herds will join to form larger temporary populations.

• Mating System
• polygynous polygynous

The breeding season of mountain zebras lasts throughout the year. In E. z. zebra , there is a birth peak from December to February. In E. z. harmannae , births peak from November to April.

The gestation period for both subspecies is approximately one year, and one foal is produced per breeding season. Foals are about 25 kg at birth, and head and body length is about 120 cm. Foals are weaned at around 10 months of age.

The age of sexual maturity in E. zebra differs between males and females. The testes of E. z. hartmannae reach maximum size at approximately 42 months of age. Males are capable of aquiring and holding a herd at 5 to 6 years. Female mountain zebras first produce foals at between 3 and 6 years of age, with the mean age at first foaling being 66.5 months. Females have an inter-birth interval of 1 to 3 years, and may remain reproductively active until about 24 years of age.

• Key Reproductive Features
• iteroparous iteroparous
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• viviparous viviparous
• post-partum estrous

Mountain zebra young are born well developed. For the first few weeks, foals remain close to their dams (mothers). The dam prevents interaction between the foal and other herd members by threatening any individual that comes too close.

The duration of lactation varies in E. zebra , and the final weaning time apparently depends upon the approaching birth of a sibling. Mares usually nurse foals in bouts of 90 seconds to 2 minutes. The suckling time typically consists of 3 periods. There is an initial suckling period lasting about 1 minute which is followed by a resting period of a few seconds. The second and final suckling period lasts for 10 to 20 seconds. For the first 3 months of life, foals typically nurse at hourly intervals during the day, after which, suckling frequency decreases. Foals often begin to nibble at grass when they are only a few days old. They are weaned after approximately 10 months of age.

Most E. zebra foals leave their maternal herds in summer. Equus zebra zebra young leave their maternal herds of their own volition. Not only are foals not forced out by the dominant herd stallion, but the stallion may actively try to prevent them from leaving. Foals leave the herd between 13 and 37 months of age, with an average age of 22 months. On average, foals leave their maternal herd 3 months after the birth of a sibling, and as such, the looming birth of a sibling does not appear to be particularly important to the timing of departure. In contrast, Hartmann’s mountain zebra mares try to expel their 14 to 16 month old foals from the herd before the birth of a sibling. After varying intervals, colts and fillies may rejoin their maternal herds for short periods.

The role of males in parental care is not direct. They may play some role in protecting the young of the herd.

• Parental Investment
• precocial precocial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-independence
  • protecting
    • male
    • female
• post-independence association with parents

Lifespan/Longevity

The life span of mountain zebras in the wild is usually 20 or more years. The oldest documented mountain zebra in captivity is an E. z. hartmannae that was 29 years and 6 months.

Behavior

Equus zebra is a social species with populations consisting of breeding herds and bachelor groups. Mountain zebras are non-territorial but breeding herds occupy home ranges with extensive overlap. When a breeding herd separates, the home ranges of the resulting herds include the home range of the original herd, but are larger. Penzhorn (1982a) found that this illustrates the role of mares in delimiting group activities, and therefore, in defining the home range of a breeding herd.

There are social hierarchies within a breeding herd. The stallion is the dominant member of the herd, with an evident linear hierarchy existing among mares of small herds. In newly established herds, the stallion must actively prevent mares and foals from leaving. In larger, often longer-established herds, the stallion's role is relatively passive, and social hierarchies are harder to determine because each herd member appears to know its relative position. Although dominant mares are more likely to initiate most herd activities, there is no straightforward correlation between dominance and leadership.

In Cape mountain zebras, estrus and the birth of a foal can influence the social hierarchy by causing mares to temporarily rise in standing. However, Penzhorn (1984) found that reproductive success is not essential for social dominance. A foal's hierarchical position is more or less determined by its size, but foals also receive some benefits from the status of the mother when she is nearby.

Bachelor groups also have a rank hierarchy, but it is less stable than that of breeding herds.

Both subspecies of mountain zebra are predominately diurnal, and are active in the early morning and late afternoon to sunset. Grazing and resting occupy most of the daylight hours. Resting is done either standing up or lying down. Mountain zebras usually drink once or twice per day. During cold weather, they often look for shelter in wooded ravines and shallow caves, and visit east-facing slopes on cold mornings to sun themselves.

Breeding herds of E. z. zebra show seasonal differences in their selection of certain vegetational communities. Selection may not be just for food, but also for shelter, drinking spots, and mineral licks. Rainfall pattern also affects the distribution of mountain zebras.

Individual grooming takes the form of shaking, rubbing, scratching, nibbling, and localized muscle contractions. Individuals also usually take a dust bath daily. Mountain zebras participate in mutual grooming, which not only has a practical function, but is also important in maintaining group cohesion. Mutual grooming takes place most often between mares and foals. However, it also occurs between foals and herd stallions, mares and herd stallions, and between pairs of mares.

Although play has rarely been recorded in E. z. zebra , it is more common in E. z. hartmannae . Play patterns include racing and chasing, challenge games, and play-fighting. Challenge games usually consist of nasonasal contact followed by mutual grooming or body rubbing.

• Key Behaviors
• cursorial
• terricolous
• diurnal diurnal
• motile motile
• sedentary sedentary
• social social
• dominance hierarchies dominance hierarchies

Home Range

In the winter, breeding herds have a grazing area of 6 to 20 km2 with summer grazing areas being considerably smaller. Herds of E. z. hartmannae may cover more than a couple of thousand square miles annually searching for forage. In MZNP, the home range of E. z. zebra averages 9.4 km2 and ranges from 3.1 to 16 km2.

Communication and Perception

Mountain zebras communicate using mainly visual and auditory cues. Because no two individuals have identical stripe patterns, body pattern can be used for individual indentification. At close range, individuals can also be recognized by smell.

Among all members of the horse family, the positioning of the ears, the stretching of the corners of the mouth, the exposure of the teeth, the opening of the mouth, and the positioning of the head and tail serve as signals of an individuals’ mood or intentions. Ears laid flat back against the head signal threat, especially when accompanied by a lowered head and open mouth. During greeting rituals, mountain zebras touch noses and communicate rank by the positioning of the ears. As a gesture of inferiority, younger individuals hold their ears to the side and make chewing motions with exposed incisors when greeting adults.

Mountain zebras make a variety of vocalizations. Stallions make a high-pitched alarm call or snort to alert herd members to danger. Bachelor stallions make a drawn-out squeal when confronted by a herd stallion. In order to express contentment when feeding, mountain zebras make a soft sound caused by forcing air between closed lips.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Both subspecies of mountain zebra are herbivorous. The primary diet consists of grass but also includes browse. In MZNP, E. z. zebra directs its selection at greener plant species with a high leaf:stalk ratio. Even so, they are still coarse grazers and will exploit both stem and leaf parts of chosen grasses. Grobler (1983) found that they feed on only 26% of the available plants, and only 7 of 17 grass species present at feeding sites. The primary grass eaten is Themeda triandra . Other grasses consumed include: Cymbopogon plurinodis , Heteropogon contortus , Setaria neglecta , and Enneapogon scoparius . Cape mountain zebras of all ages also frequent mineral licks, especially during the summer.

• Primary Diet
• herbivore herbivore
  • folivore folivore

• Plant Foods
• leaves
• wood, bark, or stems
• seeds, grains, and nuts

Predation

The dominant stallion alerts other herd members to danger with a high-pitched alarm call or snort. He then takes up a defensive position to the rear of the herd while a mare, usually the one with the youngest foal, leads the rest of the herd away. Flight is the most common response to threat, and is sometimes accompanied by a defensive kick. Pulling the ears flat back against the head, lashing the tail, and lowering the head with the neck outstretched and teeth bared, is the form taken for threat behavior. Although fighting is rarely seen, it consists of biting at the opponent's head, neck, legs, and hindquarters. Mountain zebras act in response to the flight and or alarm signals of black wildebeest ( Connochaetes gnou ). However, they rarely respond to similar signals of smaller antelope species.

Especially at high temperatures, the striped pattern of E. zebra may serve as camouflage, as an adaptation to to the resultant "waviness" of the air (Klingel, 1990). At a distance of a few hundred yards, the stripes make a mountain zebra appear indistinct. To some degree, stripes may also provide protection against blood-sucking insects that transmit disease such as bot-flies and ticks.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

In addition to serving as prey for certain mammalian carnivores, mountain zebras also serve as hosts for a variety of tick, bot-fly, nematode, and cestode species. They also associate with several species of birds that presumably remove external parasites from them. As grazers, mountain zebras may also aid in seed dispersal, and the creation of habitat for smaller animals including mesopredators.

• Ecosystem Impact
• disperses seeds
• creates habitat

Economic Importance for Humans: Positive

Mountain zebras bring in money from ecotourism, and some are still harvested for their skins.

• Positive Impacts
• body parts are source of valuable material
• ecotourism ecotourism

Economic Importance for Humans: Negative

Historically, E. z. zebra was hunted for its hide, and because the species competed with livestock for grazing, interfered with agricultural interests, and allegedly broke fences.

Conservation Status

The IUCN Red List indicates that the entire species E. zebra is vulnerable (1994). The IUCN, and U.S. federal list both indicate E. z. zebra as endangered. It is also listed as endangered by CITES and is placed on Appendix I. Equus zebra hartmannae is listed as threatened by the IUCN, U.S. federal list, and is listed on Appendix II by CITES.

The major threats to E. zebra include habitat loss and degradation, invasive alien species, harvesting, persecution, and intrinsic factors such as a restricted range. Mountain Zebra National Park and other reserves were established for the protection of E. Z. zebra . As of 1995, they were estimated at over 700 individuals. During the 1950s, numbers of E. z. hartmannae were estimated at 50,000 to 75,000 individuals. In 1992 they were estimated at only about 8,000.

Additional Links

Encyclopedia of Life

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Brian Arbogast (editor, instructor), Humboldt State University, Martha Walker (author), Humboldt State University.

References

Grobler, J. 1983. Feeding habits of the Cape mountain zebra ( Equus zebra zebra Linn. 1758). Koedoe , 26: 159-168.

Joubert, E. 1972. Activity patterns shown by Hartmann zebra ( Equus zebra hartmannae ) in South West Africa with reference to climatic factors. Madoqua , 5: 33-52.

Joubert, E. 1974. Composition and limiting factors of a Khonas Hochland population of Hartmann zebra ( Equus zebra hartmannae ). Madoqua , 8: 49-53.

Joubert, E. 1974. Notes on reproduction in the Hartmann zebra ( Equus zebra hartmannae ). Madoqua , 8: 31-35.

Joubert, E. 1974. Size and growth as shown by pre-and post-natal development of the Hartmann zebra ( Equus zebra hartmannae ). Madoqua , 8: 55-58.

Joubert, E. 1972. The social organisation and associated behaviour in the Hartmann zebra ( Equus zebra hartmannae ). Madoqua , 6: 17-56.

Klingel, H. 1990. Horses. Pp. 557-596 in Grzimek's Encyclopedia of Mammals , Vol. 4, English Language Edition. New York: McGraw-Hill, Inc.

Lloyd, P. 1984. The cape mountain zebra. African Widlife , 38: 144-149.

Nowak, R. 1999. Perissodactyla;Equidae. Pp. 1020-1021 in Walker's Mammals of the World , Vol. 2, 6 Edition. Baltimore, Maryland: The Johns Hopkins University Press.

Penzhorn, B. 1984. A long-term study of social organisation and behaviour of Cape mountain zebras ( Equus zebra zebra ). Zeitschrift fur Tierpsychologie , 64: 97-146.

Penzhorn, B. 1988. Equus zebra . Mammalian Species , No. 314: 1-7.

Penzhorn, B. 1982. Habitat selection by Cape mountain zebras in the Mountain Zebra National Park. South African Journal of Wildlife Research , 12: 48-54.

Penzhorn, B. 1982. Home range sizes of Cape mountain zebras ( Equus zebra zebra ) in the Mountain Zebra National Park. Koedoe , 25: 103-108.