Equus caballus - Linnaeus, 1758
Horse
Other English Common Names: Feral Horse
Taxonomic Status: Accepted
Related ITIS Name(s): Equus caballus Linnaeus, 1758 (TSN 180691)
French Common Names: cheval
Spanish Common Names: Caballo
Unique Identifier: ELEMENT_GLOBAL.2.103569
Element Code: AMATA01010
Informal Taxonomy: Animals, Vertebrates - Mammals - Other Mammals
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Mammalia Perissodactyla Equidae Equus
Genus Size: C - Small genus (6-20 species)
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Concept Reference
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Concept Reference: Wilson, D. E., and D. M. Reeder (editors). 1993. Mammal species of the world: a taxonomic and geographic reference. Second edition. Smithsonian Institution Press, Washington, DC. xviii + 1206 pp. Available online at: http://www.nmnh.si.edu/msw/.
Concept Reference Code: B93WIL01NAUS
Name Used in Concept Reference: Equus caballus
Taxonomic Comments: Equus przewalskii has been included in E. caballus by most recent authors. Some authors have proposed that the specific name be changed to ferus because the name caballus was based on domestic animals. Jones et al. (1992) and Grubb (in Wilson and Reeder 1993, 2005) continued to use the name E. caballus (see Grubb, in Wilson and Reeder 2005, for discussion of nomenclature).

Electrophoretic and immunologic analyses indicate the feral herds from 4 eastern U.S. barrier islands apparently are not genetically unique (Goodloe et al. 1991).
Conservation Status
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NatureServe Status

Global Status: GNA
Global Status Last Reviewed: 04Sep2003
Global Status Last Changed: 04Sep2003
Rounded Global Status: GNA - Not Applicable
Nation: United States
National Status: NNA (05Sep1996)
Nation: Canada
National Status: NNA (29Dec2011)

U.S. & Canada State/Province Status
United States Arizona (SNA), California (SNA), Colorado (SNA), Georgia (SNA), Idaho (SNA), Maryland (SNA), Montana (SNA), Navajo Nation (SNA), Nevada (SNA), New Mexico (SNA), North Carolina (SNA), Oregon (SNA), Rhode Island (SNA), Texas (SNA), Utah (SNA), Virginia (SNA), Wyoming (SNA)
Canada Alberta (SNA), British Columbia (SNA), Nova Scotia (SNA), Yukon Territory (SNA)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent Comments: Native to Eurasia. Domesticated worldwide. Feral in Portugal, Spain, France, Greece, Iran, Sri Lanka, Australia, New Zealand, Colombia, Hispaniola, Canada, U.S., Galapagos, and probably other oceanic islands. Feral in many western U.S. states, mostly in the Great Basin (Nevada, and portions of Oregon, California, and Utah), with large numbers also in the Red Desert of southwestern Wyoming, and smaller populations elsewhere in Wyoming and in Arizona, Colorado, Idaho, Montana, and New Mexico. Free-ranging feral horses occur also on some Atlantic coast barrier islands (Assateague Island, Virginia and Maryland; Shackleford Banks, North Carolina; Carrot Island, North Carolina; Cumberland Island, Georgia). Feral horses on Ocracoke Island, North Carolina are maintained in an enclosure. Formerly feral in Hawaii (see Tomich 1986 and Kramer 1971 for history of horse in Hawaii).

Population Size: 10,000 to >1,000,000 individuals
Population Size Comments: As of the early 1980s, there were about 40,000-60,000 wild horses in the western U.S.; largest number in Nevada (Slade and Godfrey 1982); estimate was 40,000 in 1988.

Other NatureServe Conservation Status Information

Distribution
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Global Range: Native to Eurasia. Domesticated worldwide. Feral in Portugal, Spain, France, Greece, Iran, Sri Lanka, Australia, New Zealand, Colombia, Hispaniola, Canada, U.S., Galapagos, and probably other oceanic islands. Feral in many western U.S. states, mostly in the Great Basin (Nevada, and portions of Oregon, California, and Utah), with large numbers also in the Red Desert of southwestern Wyoming, and smaller populations elsewhere in Wyoming and in Arizona, Colorado, Idaho, Montana, and New Mexico. Free-ranging feral horses occur also on some Atlantic coast barrier islands (Assateague Island, Virginia and Maryland; Shackleford Banks, North Carolina; Carrot Island, North Carolina; Cumberland Island, Georgia). Feral horses on Ocracoke Island, North Carolina are maintained in an enclosure. Formerly feral in Hawaii (see Tomich 1986 and Kramer 1971 for history of horse in Hawaii).

U.S. States and Canadian Provinces
Color legend for Distribution Map
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States AZexotic, CAexotic, COexotic, GAexotic, IDexotic, MDexotic, MTexotic, NCexotic, NMexotic, NNexotic, NVexotic, ORexotic, RIexotic, TXexotic, UTexotic, VAexotic, WYexotic
Canada ABexotic, BCexotic, NSexotic, YTexotic

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted. For information on how to obtain shapefiles of species ranges see our Species Mapping pages at www.natureserve.org/conservation-tools/data-maps-tools.

Range Map Compilers: NatureServe, 2005

Ecology & Life History
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Reproduction Comments: On Assateague Island, breeding activity peaks in May and June, foaling peaks in April and May; weaning occurs at age 1 year (or 2-3 years if the female does not foal in consecutive years) (Kirkpatrick and Turner 1991). Gestation averages about 340 days. Postpartum estrus occurs 7-11 days after birth. In general, first reproduction by females occurs at age 2 years, and the highest foaling rates occur among females 6-15 years old (Garrott et al. 1991). In Idaho, 36% of the 2-year-olds were pregnant, 85% of 6-15-year-olds; no yearlings were pregnant; at least 50% of the eligible mares were pregnant in consecutive years (Seal and Plotka 1983). In Nevada, Oregon, and Wyoming, about 60-80% of the females two years of age or older were pregnant, as were some yearling females. In Montana, females did not reproduce until 3 years old; annual foaling rate of adult females was 36-56% (Garrot and Taylor 1990). See also Bowling and Touchberry (1990) for information on reproduction of Great Basin horses. Foaling rate was 33% and 63% in two separate herds on Assateague Island, Maryland and Virginia (Kirkpatrick and Turner 1991).
Ecology Comments: Common social group: several females led by dominant male; females usually do not change group membership; young males are expelled from group at 1-3 years, form bachelor groups.

Annual home range usually is less than 25 sq km (but up to 300 sq km in Wyoming).

In Montana, annual survival usually was high (93-99%), sometimes as low as 50%; population growth was 18% annually in population maintained by removal at 120-150 (Garrot and Taylor 1990).

In the western U.S., females tend to have greater survivorship than do males early in life, but males tend to be more frequent than are females in the oldest age classes (>10 years) (Garrott 1991).

In the southern Great Basin of Nevada, mountain lion predation on the young was believed to be a major population limiting factor (Greger and Romney 1999).

Non-Migrant: Y
Locally Migrant: N
Long Distance Migrant: N
Terrestrial Habitat(s): Grassland/herbaceous, Shrubland/chaparral, Woodland - Conifer
Habitat Comments: In West, shrubby sagebrush plains and mountains, juniper woodland; ranges include grazing area, shelter, water, and shade (Slade and Godfrey 1982). Often on ridgetops.
Adult Food Habits: Herbivore
Immature Food Habits: Herbivore
Food Comments: Grasses and grass-like plants comprise bulk of diet; also browses on shrubs in winter. In the West, generally visits water hole once per day; may dig to water in dry river bed. (Slade and Godfrey 1982).
Economic Attributes
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Economic Comments: Some regard it as pest, citing fouling of water, competition with domestic stock, or displacement of native ungulates (pronghorn, bighorn sheep).

Under Wild Horse and Burro Act, can be adopted for use in riding or as pet; Act generally prohibits commercial exploitation.

Management Summary
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Management Requirements: Regulated by Wild Horse and Burro Act of 1971. Most lands having wild horses are managed by BLM, which periodically gathers horses from herd management units and places them in captivity; as of the early 1990s, horses that were not disposed of through the "Adopt-A-Horse" program were maintained in captivity (they could not be sold or destroyed).

Major management problem is keeping populations down to levels that avoid overgrazing or competition with other species (Slade and Godfrey 1982). Garrott et al. (1991) concluded that many populations in the western U.S. currently are being maintained at levels below which density-dependent responses operate and are increasing at or near their biological maximum.

Studies in Great Basin indicated that sterilization of dominant males will reduce but not eliminate foal production; female contraceptive implants could be effectively targeted to specific age classes (e.g. females 6-8 years old were much more likely to reproduce than older or younger females) (Bowling and Touchberry 1990). See Kirkpatrick et al. (1990) for information on a remotely delivered immunocontraception technique. See Garrott (1991) and Turner and Kirkpatrick (1991) for additional discussion of the potential and limitations of fertility control.

Goodloe et al. (1991) noted that local historic and economic values might require maintenance of feral horse populations on some eastern U.S. barrier islands; however, ecological and genetic criteria justify reducing the size of these populations; recommended minimum population sizes were 72 on Assateague Island National Seashore, Maryland; 155 on Chincoteague National Wildlife Refuge, Virginia; and 122 on Cumberland Island, Georgia. Annual removal of foals from the Chincoteague NWR herd results in higher foaling rates relative to the population on Assateague Island National Seashore, where management is minimal (Kirkpatrick and Turner 1991).

Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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Element Ecology & Life History Edition Date: 24Nov1993
Element Ecology & Life History Author(s): Hammerson, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • Berger, J. 1986. Wild horses of the Great Basin. Social competition and population size. Univ. Chicago Press, Chicago. xxii + 326 pp.

  • Bowling, A. T., and R. W. Touchberry. 1990. Parentage of Great Basin feral horses. J. Wildl. Manage. 54:424-429.

  • Boyles, J. S. 1986. Managing America's wild horses and burros. J. Equine Vet. Sci. 6:261-265.

  • Bradley, R.D., L.K. Ammerman, R.J. Baker, L.C. Bradley, J.A. Cook. R.C. Dowler, C. Jones, D.J. Schmidly, F.B. Stangl Jr., R.A. Van den Bussche and B. Würsig. 2014. Revised checklist of North American mammals north of Mexico, 2014. Museum of Texas Tech University Occasional Papers 327:1-28. Available at: <http://www.nsrl.ttu.edu/publications/opapers/ops/OP327.pdf> (Accessed April 1, 2015)

  • Eberhardt, L. L., A. K. Majorowicz, and J. A. Wilcox. 1982. Apparent rates of increase for two feral horse herds. J. Wildl. Manage. 46:367-374.

  • Ganskopp, D., and M. Vavra. 1986. Habitat use by feral horses in the northern sagebrush steppe. J. Range Manage. 39:207-212.

  • Garrot, R. A., and L. Taylor. 1990. Dynamics of a feral horse population in Montana. J. Wildl. Manage. 54:603-612.

  • Garrott, R. A. 1991a. Feral horse fertility control: potential and limitations. Wildl. Soc. Bull. 19:52-58.

  • Garrott, R. A. 1991b. Sex ratios and differential survival of feral horses. J. Anim. Ecol. 60:929-937.

  • Garrott, R. A., D. B. Siniff, and L. L. Eberhardt. 1991b. Growth rates of feral horse populations. J. Wildl. Manage. 55:641-648.

  • Garrott, R. A., T. C. Eagle, and E. D. Plotka. 1991a. Age-specific reproduction in feral horses. Can. J. Zool. 69:738-743.

  • Goodloe, R. B., et al. 1991. Genetic variation and its management implications in eastern U.S. feral horses. J. Wildl. Manage. 55:412-421.

  • Greger, P. D., and E. M. Romney. 1999. High foal mortality limits growth of a desert feral horse population in Nevada. Great Basin Naturalist 59:374-379.

  • Hawaii Ecosystems at Risk Project. 2005. Information index for selected alien vertebrates in Hawaii. Internet resource available at http://www.hear.org/alienspeciesinhawaii/InfoIndexVertebrates.htm. Downloaded 31 March 2005.

  • Jones, J. K., Jr., R. S. Hoffman, D. W. Rice, C. Jones, R. J. Baker, and M. D. Engstrom. 1992a. Revised checklist of North American mammals north of Mexico, 1991. Occasional Papers, The Museum, Texas Tech University, 146:1-23.

  • Kirkpatrick, J. F., I. K. M. Liu, and J. W. Turner, Jr. 1990. Remotely-delivered immunocontraception in feral horses. Wildl. Soc. Bull. 18:326-330.

  • Kirkpatrick, J. F., and J. W. Turner, Jr. 1991. Compensatory reproduction in feral horses. J. Wildl. Manage. 55:649-652.

  • Kramer, R. J. 1971. Hawaiian land mammals. Charles E. Tuttle Co., Inc., Rutland, Vermont, and Tokyo, Japan. 347 pp.

  • Monagan, D. 1982. Horse of a different culture: when horses return to the wild, does their ancient nature reappear? Science 82 3(4):46-53.

  • Seal, U. S., and E. D. Plotka. 1983. Age-specific pregnancy rates in feral horses. J. Wildl. Manage. 47:422-429.

  • Slade, L. M., and E. B. Godfrey. 1982. Wild horses. Pages 1089-1098 in Chapman, J. A., and G. A. Feldhamer, eds. Wild mammals of North America. Johns Hopkins Univ. Press, Baltimore.

  • Tirira, D. 1999. Mamíferos del Ecuador. Museo de Zoología, Pontificia Universidad Católica del Ecuador, Quito.

  • Tomich, P. Q. 1986. Mammals in Hawai'i. A synopsis and notational bibliography. Second edition. Bishop Museum Press, Honolulu. 375 pp.

  • Turner, J. W., Jr., and J. F. Kirkpatrick. 1991. New developments in feral horse contraception and their potential application to wildlife. Wildl. Soc. Bull. 19:350-359.

  • Waring, G. T. 1983. Horse behavior: the behavioral traits and adaptations of domestic and wild horses, including ponies. Park Ridge: Noyes. 292 pp.

  • Whitaker, J. O., and W. J. Hamilton. 1998. Mammals of the eastern United States. Comstock Publishing, Ithaca, New York.

  • Wilson, D. E., and D. M. Reeder (editors). 1993. Mammal species of the world: a taxonomic and geographic reference. Second edition. Smithsonian Institution Press, Washington, DC. xviii + 1206 pp. Available online at: http://www.nmnh.si.edu/msw/.

  • Wilson, D. E., and D. M. Reeder (editors). 2005. Mammal species of the world: a taxonomic and geographic reference. Third edition. The Johns Hopkins University Press, Baltimore. Two volumes. 2,142 pp. Available online at: http://vertebrates.si.edu/msw/mswcfapp/msw/index.cfm

  • Woodward, S. L., and D. P. Sponenberg. 1992. Feral livestock in America: identification of populations important for the conservation of genetic diversity. Abstract, 6th Annual Meeting of the Society for Conservation Biology, p. 148.

  • Zarn, M., T. Heeler, and K. Collins. 1977. Wild free roaming horses--status of present knowledge. USDI Bureau ofLand Manage., USDA For. Serv., DSC Federal Center, Tech. Note 294.

  • Zeiner, D. C., W. F. Laudenslayer, Jr., K. E. Mayer, and M. White, editors. 1990b. California's wildlife. Volume III. Mammals. State of California, The Resources Agency, Department of Fish and Game, Sacramento, CA. 407 pp.

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