BEHAVIOR OF FERAL HORSES AND PONIES 1 William D. McCort2 The University of Wyoming, Laramie 82071 Downloaded from https://academic.oup.com/jas/article-abstract/58/2/493/4665525 by University of Warwick user on 17 November 2019 Summary lived 15 or more yr. Horses and ponies have An overview of the behavior of feral horses been reported to spend a great deal of time and and ponies is presented. Three major types of effort on fecal and urine marking. social groups have been described: 1) harem (Key Words: Behavior, Feral, Horse, Pony, groups, 2) multiple male and female groups and Social Organization.) 3) bachelor male groups. A herd has been proposed as another type of social structure consisting of groups of horses that follow similar movement patterns within a common I ntroduction home range. Horses and ponies usually occupy A major part of the evolution of horses, home ranges (undefended, nonexclusive areas). Equus caballus, occurred in North America However, two studies reported horses occupying (Simpson, 1951; Colbert, 1955). Horses mi- territories (defended, exclusive areas). The grated to other continents via land bridges and, number of animals that occupies a particular approximately 11,000 yr ago, horses became home range and their movements within the extinct in North America (NRC, 1980). Span- home range are strongly influenced by food iards reintroduced horses to North America quantity, quality and seasonal changes. Group starting with Columbus in 1493 and continuing encounters are frequent because home ranges into the 16th century. Since then, horses usually overlap, and group integrity is main- escaped or were released by their owners and talned by the male(s) of the group. Horses and have been feral since the 1600's or 1700's. The ponies have intragroup and intergroup domi- horses adapted very well to their feral existence nance hierarchies. Recent findings have indicated and by the early 1800's, there were roughly 2 that stallions are not always dominant over million feral horses in North America (Thomas, mares. Most studies of mating behavior suggested 1979). Horse populations declined with in- large variance in male reproductive success, creased expansion of civilization and ex- because most of the matings were performed by ploitation by man. There were only 15,000 to harem or dominant group males. In contrast, 30,000 feral horses remaining in the United males in multiple male and female groups in the States and 2,000 to 4,000 in Western Canada Red Desert of Wyoming shared mating privileges. by 1959 (McKnight, 1959). Federal protection, The number of horse and pony foals as a however, has permitted an increase to about percentage of the total population in each 60,000 feral horses in the current population study ranged from 13 to 23%. Most foals were throughout the Western United States (NRC, born during April to June. Mortality was 1980). There are roughly 1,400 feral horses in highest among foals, while some feral horses Canada (Salter, 1979). The objective of this paper is to provide an overview of the behavior of feral horses and ponies. Feral horse and pony studies have ~Presented at the symposium 'Ethograms of demonstrated that these animals are extremely Feral Livestock and their Application to Contem- porary Livestock Production and Experimentation,' adaptable to a wide range of habitat types and Joint Can.-Amer. Soc. of Anita. Sci. Annu. Meet., conditions. It is not surprising that domestic Univ. of Guelph; August 8--11, 1982. horses and ponies are successfuUy managed 2Present address: The Pennsylvania State Univ., under numerous schemes. Nevertheless, better 204 William L. Henning Building, University Park, PA 16802. management plans can be made as more is Received November 15, 1982. understood about the behavior of horses and Accepted August 8, 1983. ponies. 493 JOURNAL OF ANIMALSCIENCE, Vol. 58, No. 2, 1984 494 McCORT Social Groups in the Red Desert of Wyoming were multiple Numerous authors have reported on the male and female groups. The Red Desert social organization of feral horses and ponies multiple male and female groups were on the (Collery, 1969; PeUegrini, 1971; Tyler, 1972; average larger than harem groups. Average Feist and McCullough, 1975, 1976; Welsh, group size, computed in each of the 3 yr of Downloaded from https://academic.oup.com/jas/article-abstract/58/2/493/4665525 by University of Warwick user on 17 November 2019 1975; Clutton-Brock et al., 1976; Keiper, 1976, Miller's study, ranged from 9.3 to 9.6 for 1979; Berger, 1977; Green and Green, 1977; multiple male and female groups and from Nelson, 1978; Boyd, 1979; Miller, 1979, 1981, 5.8 to 6.8 for harem groups. Multiple male and 1983; Miller and Denniston, 1979; Wells female groups in the Red Desert changed adult and yon Goldschmidt-Rothschild, 1979; composition less often than harem groups. Zervanos and Keiper, 1979; Rubenstein, 1981; Miller believed that multiple male and female Salter and Hudson, 1982; R. Hall and J. F. groups required separate consideration from Kirkpatrick, unpublished data). The overall harem groups because the two types of groups results from the different studies are consistent differed not only in band size and stability, but and similar. Three major types of social groups also in mating behavior and dominance structure. have been described: 1) harem groups, 2) Bachelor male groups are composed entirely multiple male and female groups and 3) bachelor of male horses or ponies. In contrast to harem male groups. groups and multiple male and female groups, Harem groups consist of one adult male, one bachelor groups are unstable in composition, to several adult females and their offspring. although some authors have reported long-term Harems are stable with very few changes in associations between some males (Miller, 1979; composition during periods of months to years. Salter and Hudson, 1982). Bachelor male Those changes in membership that do occur are groups are formed by young males that have often due to the emmigration and immigration been forced out of their family groups and(or) of young ranging in age from 1 to 3 yr old by older males that have lost membership in a (Feist and McCullough, 1975; Green and Green, harem or multiple male and female group. 1977; Nelson, 1978; Boyd, 1979; Salter and Group sizes reported varied from lone bachelors Hudson, 1982; R. Hall and J. F. Kirkpatrick, to groups of 16 (Feist and McCullough, 1975; unpublished data). Harem group composition is Welsh, 1975; Keiper, 1976; Berger, 1977; Green the type most often described by authors. and Green, 1977; Nelson, 1978; Miller, 1979; Average group sizes reported for horses ranged Rubenstein, 1981; Salter and Hudson, 1982; R. from 3.4 to 12.3, with a minimum of 2 and a Hall and J. F. Kirkpatrick, unpublished data). maximum of 21 horses/group (Feist and The herd has been proposed recently as McCullough, 1975; Welsh, 1975 ; Berger, 1977; another type of social structure by Miller and Nelson, 1978; Miller, 1979; Rubenstein, 1981; Denniston (1979). They suggested that a herd is Salter and Hudson, 1982; R. Hall and J. F. a structured social unit made up of groups Kirkpatrick, unpublished data). Group size of (bands) of horses. Miller and Denniston found a single-male pony groups on Assateague Island, nearly linear intergroup dominance order located along the coast of Maryland and Virginia, among horse groups in the Red Desert that ranged from 5 to 26 and averaged 14 ponies/ determined priority of access to limited water. group (Keiper, 1976). The horses within each group appeared to Multiple male and female groups have more recognize the horses in other groups and as a than one adult male, one to several adult group would yield access to a water site to females and their offspring. Group compositions those groups with a higher dominance status. are stable over time like harems. Many authors Females as well as males participated in dis- have not described these groups as a separate placing or threatening members of a subordinate type of social structure but have often catego- group at the water source. Miller (1983) also rized them as harems. However, numerous reported that some of these groups had similar authors have noted multiple male and female movement patterns within overlapping home groups in their study populations (Feist, 1971; ranges and revised the definition of a herd as a Welsh, 1975; Keiper, 1976; Green and Green, structured social unit made up of groups 1977; Nelson, 1978; Miller, 1979; Salter and (bands) of horses that follow similar movement Hudson, 1982; R. Hall and J. F. Kirkpatrick, patterns within a common home range. The unpublished data). Miller (1979) reported that intergroup recognition, dominance hierarchy 23 to 45% of the horse groups that he identified and similar movements within common home FERAL HORSES AND PONIES 495 ranges suggest that a social structure of groups in which horses grazed particular areas of their of horses does indeed exist. Herd structures are home range during the same season each year not well documented in the literature and (Miller, 1983). Areas used within home ranges further studies are needed to clarify the nature in the Grand Canyon, Arizona, were largest of herds. during late winter-early spring and decreased to Downloaded from https://academic.oup.com/jas/article-abstract/58/2/493/4665525 by University of Warwick user on 17 November 2019 a minimum size about a water source during Home Ranges July-early August when ambient temperatures Harem groups, multiple male and female and drought had increased (Berger, 1977). groups and bachelor groups of horses and Average home range sizes for the Assateague ponies usually occupy home ranges (undefended, ponies varied from 6.48 km ~ in summer to 4.32 nonexclusive areas).