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Equus caballus

What do they look like?

Horses have oval-shaped hooves, long tails, short hair, long slender legs, muscular and deep torso build, long thick necks, and large elongated heads. The mane is a region of coarse hairs, which extends along the dorsal side of the neck in both domestic and wild species. The teeth are specialized for grazing, with cheekteeth that are complex and grow continually. Thick, winter coats start developing in September and October, are fully grown by December. Winter coats begin to shed in the spring and summer coats are more sleek and thin.

Domestication of horses has led to wide variation in the characteristics of breeds of horses. Coats vary in color, from white to black and including reds, browns, and yellows, as well as a wide variety of patterns, such as spots and pinto patterns. Size can vary depending on the breed, but can range from 227 to 900 kg in mass and 0.9 to 1.7 meters in height.

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    227 to 900 kg
    500.00 to 1982.38 lb
  • Range length
    220 to 280 cm
    86.61 to 110.24 in
  • Average basal metabolic rate
    0.11 cm3.O2/g/hr

Where do they live?

The ancestors of horses were found from northernmost Africa, throughout mainland Europe, and east through Asia. In the Late Glacial period they were also found throughout North America, but they became extinct there between 8,000 and 10,000 years ago. Domestic horses are now found throughout much of the world in association with humans.

What kind of habitat do they need?

Horses are adaptable and occupy a wide variety of habitats under domestication. Preferred habitats are cool, temperate grasslands, steppes, and savannahs, but they also occupy semi-deserts, swamps, marshes, and woodlands. (Bennett and Hoffmann, 1999)

How do they reproduce?

Male horses herd females during the mating season and defend them against other males, who may be trying to mate with the females. Males fight with other males through kicking and biting. Status in the herd determines which animals have access to resources; alpha males dominate access to resources, followed by females and their young, and then juveniles and females without young.

Horses usually breed in the warm, summer months. Pregnancy lasts from 287 to 419 days, which means that birth can be in either spring or autumn of the next year. Usually only one foal is produced each year, twins are rare.

Births occur at night and in a quiet location. Foals are born well-developed, usually able to stand within an hour of birth and walk within four to five hours to follow their mother. For their first month, the young stay close to their mother and nurse for brief and frequent periods. In their second month they start to forage independently and begin the weaning process, which could take up to two years for wild foals. In domesticated horses, foals are often weaned between four and six months old.

Foals double in weight week for four weeks. It takes females four to five years, and males six to seven years, to reach full reproductive maturity.

  • How often does reproduction occur?
    Horses may breed up to once each year.
  • Breeding season
    Horses generally breed from April to June.
  • Range number of offspring
    1 to 2
  • Average number of offspring
  • Range gestation period
    287 to 419 days
  • Average gestation period
    335 days
  • Range weaning age
    24 (high) months
  • Range time to independence
    2 to 3 years
  • Range age at sexual or reproductive maturity (female)
    11 to 48 months
  • Average age at sexual or reproductive maturity (female)
    36 months
  • Average age at sexual or reproductive maturity (male)
    6 years
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    973 days

Foals are able to walk on their own shortly after birth, but still need parental assistance. Although they are well-developed, they rely heavily on their mother and their social group (herd) for protection against predators and food until they begin to forage on their own. Studies show that wild horses leave the herd they were born in when they are two to three years old.

  • Parental Investment
  • precocial
  • female parental care
  • pre-fertilization
    • provisioning
    • protecting
      • male
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female
  • maternal position in the dominance hierarchy affects status of young

How long do they live?

Horse lifespan is dependent on several factors, including breed variations and environment. Typically, domestic horses have a lifespan of 25 to 30 years, although a maximum of 61 years has been attained. The longest living horse in wild as of 1974 was 36 years. Factors on lifespan of E. caballus include: nutrition, activity, number of reproduction cycles, reproductive status, disease, dental health, and physical activity. (Bennett and Hoffmann, 1999; Ensminger, 1969)

How do they behave?

Horses are social mammals. In wild or feral populations they form herds with a social hierarchy. These herds, can have up to 26 mares, 5 stallions, and various ages of young. Horse herds have a well-established social hierarchy, with alpha males being dominant and spending the majority of their time defending the herd from predators or competing males.

Horses are active at different times of the day, depending on the season. In hot weather, horses graze in morning or evenings to avoid mid-day high temperatures. They sleep in segments throughout the day, which are usually not more than two hours long. They also avoid laying down for more than an hour at a time if possible, and can be seen sleeping while standing up.

  • Range territory size
    0.59 to 17.68 km^2

Home Range

Wild horses generally stay close to water sources. One study in a feral population in New Zealand showed that home range sizes were between 0.96 to 17.68 square kilometers, with a density of 0.48 to 3.22 individuals per square kilometer. Larger herds occupy larger home ranges. Seasonal movements and changes in home range are usually associated with water and food availability, temperature, and topography.

How do they communicate with each other?

In horses, the nostrils, muzzle, whiskers, and cheeks all have whiskers that are used to perceive the environment through touch. Vision is the primary means of perceiving the environment in horses. Ears are long, slender, and upright, which aid in auditory perception. Although their sense of smell is important, it is not the chief means of perception and provides a smaller role than vision or the sensitive receptors on the nostrils, muzzle, whiskers, or cheeks.

Horses communicate with each other mainly through facial gestures and vocalizations. Grunting, biting, shoving, and kicking may occur among herd members to establish or reinforce the hierarchy structure and express dominance.

Horses have an array of facial gestures. Positive reactions include raising of the lips to expose upper teeth, similar to a smile, and head bobbing or pointing the ears forward and erect. Aggressive facial gestures include the ears being laid back and the nostrils closed while exposing the same teeth.

What do they eat?

Horses are true grazers, eating mainly grasses and other grassland plants. Domesticated horse diets are often supplemented with some grains, such as oats, flax, and barley.

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

What eats them and how do they avoid being eaten?

Natural predators of wild horses are likely to have been mainly wolves, coyotes, and mountains lions. Predators mainly prey on elderly, ill, or young animals. When a herd is threatened by a predator, the alpha male may attack it through biting and kicking with the hooves. Females protect their young in a similar manner. Humans are also predators of horses, both historically and currently.

What roles do they have in the ecosystem?

The domestication of horses contributed to the development of agricultural societies and changed the mobility and political relationships between different human populations. As grazing animals, horses influence diversity and structure of the ecosystems in which they live. In some places horses have been important in seed dispersal of certain trees. There are over 150 species of parasites documented in horses. (Bennett and Hoffmann, 1999; Hardin, 1997)

Species (or larger taxonomic groups) that are mutualists with this species

Do they cause problems?

Feral horse populations may be disruptive to ecosystems that are not adapted to the presence of large equid grazers. They can compete with other grazing animals for resources and cause damage to native vegetation.

How do they interact with us?

Horses are economically very important to humans now and historically. They have been used as a food source, have been critical in the transportation of people and goods, have played important roles in military campaigns, in sport and recreation, and in agricultural development. Horses are also beloved companion animals and widely used in therapeutic approaches. In agriculture, horses are used to pull plows and carriages and their manure is an important fertilizer. Horse hairs are used in various products. (Ensminger, 1969)

  • Ways that people benefit from these animals:
  • pet trade
  • food
  • body parts are source of valuable material
  • research and education
  • produces fertilizer

Are they endangered?

Domesticated horses are abundant in many areas around the world. Their closest relatives, Przewalski's wild horses were listed as endangered on the IUCN Red List, endangered under the U.S. Endangered Species Act, and on Appendix I of CITES.

Some more information...


Christopher Clement (author), University of Alaska Fairbanks, Laura Prugh (editor), University of Washington, Tanya Dewey (editor), University of Michigan-Ann Arbor.


Biosecurity Queensland. Pest animal risk assessment: Feral horse (Equus caballus). PR09-4511. Brisbane: The State of Queensland, Department of Employment, Economic Development and Innovation. 2009.

Bennett, D., R. Hoffmann. 1999. Equus caballus Linnaeus, 1758. Mammalian Species, No. 628: 1-14.

Boyd, L., S. King. 2014. "Equus ferus ssp. przewalskii" (On-line). The IUCN Red List of Threatened Species. Accessed November 02, 2014 at

Cameron, E., W. Linklater, K. Stafford, E. Minot. 2003. Social grouping and maternal behaviour in feral horses (Equus caballus): the influence of males on maternal protectiveness. Behavioral Ecology and Sociobiology, 53(2): 92-101.

Ensminger, M. 1969. Horses and Horsemanship. Danville, Illinois: The Interstate Printers & Publishers, Inc.

Hansen, R. 1976. Foods of Free-Roaming Horses in Southern New Mexico. Journal of Range Management, 29(4): 347.

Hardin, D. 1997. "Controlling Internal Parasites of Horses" (On-line pdf). Accessed December 09, 2014 at

Linklater, W., E. Cameron, E. Minot, K. Stafford. 1999. Stallion harassement and the mating system of horses. Animal Behaviour, 58(2): 295-306.

Linklater, W., E. Cameron, K. Stafford, C. Veltman. 2000. Social and spatial structure and range use by Kaimanawa wild horses (Equus caballus: Equidae). New Zealand Journal of Ecology, 24(2): 139-152.

Wallner, B., G. Brem, M. Müller, R. Achmann. 2003. Fixed nucleotide differences on the Y chromosome indicate clear divergence between Equus przewalskii and Equus caballus. Animal Genetics, 34: 453-456.

University of Michigan Museum of ZoologyNational Science Foundation

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Clement, C. 2015. "Equus caballus" (On-line), Animal Diversity Web. Accessed April 12, 2024 at

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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