BEHAVIOR OF AND 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, , , 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). caballus, occurred in 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 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 are not always dominant over million feral horses in North America (Thomas, . 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 Red Desert of Wyoming shared mating privileges. by 1959 (McKnight, 1959). Federal protection, The number of horse and pony 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 (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. and pony studies have ~Presented at the symposium 'Ethograms of demonstrated that these animals are extremely Feral 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 and , 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). Home ranges reported for km 2 in winter (Zervanos and Keiper, 1979). horses and ponies varied in size from .8 to 303 Daily movements of the Assateague ponies km 2 (Tyler, 1972; Welsh, 1975; Feist and during the summer included the utilization of McCullough, 1976; Berger, 1977; Green and two or three different habitat types. However, Green, 1977; Zervanos and Keiper, 1979; winter movements were within a single habitat Rubenstein, 1981; Salter and Hudson, 1982; during the entire day. Miller, 1983). Home ranges have well-defined boundaries that remain unchanged during Group Encounters periods of months to years. Two or more Because home ranges overlap, horse and groups may share common areas because home pony groups often come into close contact with ranges often overlap. For example, only 10% of each other. During such encounters, the adult a study area (74.5 km 2) in the Pryor Mountain males maintain the integrity of their groups. Range, located on the Wyoming- Male interactions vary from distant posturing Montana border, was used exclusively by just and threats to physical contact. Usually en- one harem (Feist and McCullough, 1976). Also, counters end with posturing and threats, and some Red Desert horse home ranges overlapped one or both of the males move their groups almost completely (Miller, 1983). Although not farther apart (Miller, 1981; Salter and Hudson, as common, territories (defended, exclu- 1982; R. Hall and J. F. Kirkpatrick, unpublished sive areas) have been reported for horses on data). However, interactions can escalate into Shackleford Island, located off the coast of fights and chases between males, which also (Rubenstein, 1981), and for result in increased distances between groups. horses in the Wassuk Range of Western Nevada Salter and Hudson (1982) reported 9 of 16 (Pellegrini, 1971). interactions between group males in Western Food quantity, quality and seasonal changes Alberta, Canada, involved the males leaving have a strong influence on the number of their groups and meeting each other usually on animals that occupy a particular home range a flat, open site between their groups. The and on their movements within that home males approached each other with their heads range. A positive correlation between group size held high and tails partially outstretched. Fecal and available forage biomass on home ranges deposition and(or) sniffing of feces were was found for ponies occupying Assateague observed during eight of the nine meetings. Island National Seashore (Zervanos and Keiper, Mutual naso-nasal, naso-genital and(or) naso- 1979). Home range size and group size were not anal sniffing occurred during four of these correlated for the Assateague ponies nor for the meetings. Biting and kicking resulted during New Forest ponies in (Tyler, 1972). only three meetings and chasing in one. Berger Hence, larger groups required an increase in (1977) reported a higher than usual number of total available forage biomass, which did not fights between stallions with 11 out of 20 necessarily mean an increase in home range encounters that resulted in fights. Berger sizes. suggested that drought conditions may have Although home range boundaries generally been responsible for the atypically high number remain the same on a yearly basis, the extent of of fights. home range use within those boundaries may Females and offspring appear to be little vary seasonally as water and forage availability involved in group encounters and usually change. Red Desert horses were reported to continue their previous activity, stand and have seasonal movements within their home watch the males interact or group up and stand ranges that resulted in a rotation system and wait for their to return (Feist and 496 McCORT

McCullough, 1976; Salter and Hudson, 1982). however, the Red Desert adult females as well However, Miller and Denniston (1979) reported as the males participated in dominant- that females participated along with male subordinate interactions. Red Desert adult groupmates when threatening another group of females led the aggression toward other groups horses at water. during five out of 59 encounters in which one Downloaded from https://academic.oup.com/jas/article-abstract/58/2/493/4665525 by University of Warwick user on 17 November 2019 Interactions between harem or multiple male horse could be distinguished as leading the and female group males with bachelor males aggression at the water source. Positive corre- also involve posturing, defecation and threats. lations between group size and the number of However, a higher proportion of the bachelor groups dominated were determined for the male encounters results in fights. Salter and Grand Canyon and Red Desert horses. Nfo Hudson (1982) recorded 11 out of 15 harem correlation between group dominance and the male - bachelor male encounters involved number of adult males in the group was found biting and kicking. In contrast, there were only for the Red Desert horses. ~ree fights out of 16 encounters between Dominance relationships have been described harem males. Males in multiple male and female among females, but are sometimes characterized groups may cooperate with each other to ward as unstable. No consistent dominance relation- off intruders. This would in part explain the ships were found among harem females in the higher stability of multiple male and female Pryor Mountains. The female hierarchies were groups over harem groups found in the Red considered to be neither well developed nor Desert (Miller, 1981). well expressed with the harem males dominating the females (Feist and McCullough, 1976). Dominance Relationships However, Houpt and Keiper (1982) found that Intragroup dominance hierarchies have been the stallion was not always dominant over the reported for each type of social group for mares. They found that the most dominant horses and ponies. Observations of aggressive ponies in groups on Assateague were the oldest interactions at a water source in the Grand mares and not the stallions. Also, geldings were Canyon revealed linear dominance hierarchies the most dominant ponies in domestic groups, within each of four harems (Berger, 1977). The with many of the mares also dominant over stallion was dominant to the mares in three of intact group stallions and other geldings. Mares these four harems. Dominance hierarchies have been recorded as dominant over stallions were determined among the males in multiple in other studies as well (Berger, 1977; Wells and male and female groups in the Red Desert yon Goldschmidt-Rothschild, 1979). (Miller, 1981). The majority of aggressive Mating encounters among these males, however, resulted in no apparent dominance or subordi- Harem females are mated almost exclusively nation. Bachelor male groups have strong by the single adult male in harem groups (Feist dominance hierarchies. Dominant males in the and McCullough, 1975; Miller, 1981; Salter and Pryor Mountains herded the other bachelors Hudson, 1982). However, males from other like a harem and interacted with males from bands or bachelor groups do manage at times to other groups (Feist and McCuLlough, 1976). obtain access to and mate nongroup females. The dominant bachelor was always the male Harem males performed 85.7% (n = 21) of the that interacted with harem group stallions and matings in the Red Desert and 87.5% (n = 8) of was the most likely male to obtain a female. the matings in the Pryor Mountains (Feist and Three bachelors obtained females in the Pryor McCullough, 1976; Miller, 1981). Nelson Mountains. Each of these males had been the (1978) reported 17 of 19 copulations observed dominant male of his bachelor group. in the Jicarilla District, New Mexico were by Intergroup dominance hierarchies are often dominant harem stallions, but nine of these determined at water sources where there is matings were with females belonging to another increased aggressive interaction between groups group. of horses and ponies attempting to drink. Most of the matings in multiple male and Intergroup dominance ranks have been described female groups are performed by the dominant for horses in the Wassuk Range, Grand Canyon male (Welsh, 1975; Salter and Hudson, 1982). and the Red Desert (PeUegrini, 1971; Berger, However, Miller (1981) found that out of 81 1977; Miller and Denniston, 1979). In contrast matings in multiple male and female groups in to Grand Canyon and Wassuk Range horses, the Red Desert, 49% were performed by FERAL HORSES AND PONIES 497 dominant males, 42% by subordinate males and Foals as a percentage of the total population in 9% by males from other groups. Further- the studies ranged from 13 to 23% and averaged more, there was aggression between the males 17.1%. Horses and ponies in older age classes during breeding in only 10 out of 67 fuUy expressed as a percentage of the total population

recorded mating sequences. Subordinate males averaged 11.6% for yearlings, 12.0% for 2-yr- Downloaded from https://academic.oup.com/jas/article-abstract/58/2/493/4665525 by University of Warwick user on 17 November 2019 in the Pryor Mountains also bred mares in their olds, 10.4% for 3-yr-olds and 51.8% for 4-yr-olds groups at times (R. HaU and J. F. Kirkpatrick, and older. unpublished data). Miller (1981) proposed Foaling seasons reported in the literature three breeding systems for Red Desert multiple were very similar (Tyler, 1972; Feist and male and female groups: 1) several males McCullough, 1975; Nelson, 1978; Boyd, 1979; breeding serially with one within a group, Keiper, 1979; Salter and Hudson, 1982). Most 2) consort pair formation and 3) nearly exclusive foals were born during April to June of each breeding by the dominant male. It was not clear year. Because horses and ponies have postpar- to Miller which of the three breeding systems tum estrus, the foaling season is also the breed- was most prevalent in multiple male and female ing season. Females usually begin breeding groups. However, the overall result was that when they are 2 yr old and when 3 yr old. most of the mares were bred by more than one However, most females in the Pryor Mountains male. Of 22 females from both harems and did not reach sexual maturity until they were 3 multiple male and female bands, 13 were yr old (Feist and McCullough, 1976; R. Hall mounted by more than one stallion. The and J. F. Kirkpatrick, unpublished data). There apparent contrast between the mating behavior are reports of yearlings showing signs of estrus of males in multiple male and female groups in and mating, but these matings seldom produce the Red Desert and males studied in other areas offspring. The percentage of adult females that suggests more research is needed on this partic- foal increases with age. The number of females ular type of social group. that foal varies from 0 to 33% (~ = 13%) for between a male and his daughters, 3-yr-olds, 38 to 78% (~ = 54%) for 3-yr-olds between a mare and her sons or between and older, 42 to 86% (~ = 61%)for 4-yr-olds siblings does not appear to occur very often and older and according to Welsh (1975), 52 to within horse groups. Many male and female 84% (-~ = 66%) for 5-yr-olds and older (NRC, offspring leave their natal groups prior to or at 1980). sexual maturity (Feist and McCullough, 1975, Mortality is highest among foals in their first 1976; Green and Green, 1977; Salter and year. Data on first year survival rates are Hudson, 1982; R. Hall and J. F. Kirkpatrick, sketchy in the literature, but reports suggest 20 unpublished data). Some females, however, to 25% first year mortality (NRC, 1980). have been observed to stay and foal within their Causes of foal mortality include weaknesses at natal groups (Boyd, 1980). Young females birth, rejection by the mare or inattentiveness either leave on their own or are abducted by of the mare, miring in mud, severe winters and males from other groups. Young males also separation from mares (Tyler, 1972; Green and leave voluntarily or are forcefully expelled from Green, 1977; Boyd, 1979). Boyd (1979) their groups by other adult males. Assemblages reported that 78% of Red Desert mares 3 yr old of young males and females have been reported and older and 86% of mares 4 yr old and older (Keiper, 1976). More commonly, however, foaled in 1978. Additionally, 86% of these foals females join other harems or multiple male and survived to 1 mo of age, 82% to 2 mo of age, female groups, and males join bachelor groups. and all of these survived to 1 yr. Natality decreased and survival increased after a severe Demography winter preceding the 1979 foaling season. Only The National Academy of Sciences' Com- 53% of the mares 3 yr old and older and 54% of mittee on Wild and Free-Roaming Horses and the mares 4 yr old and older foaled in 1979. Burros compiled a comprehensive summary of Survival of these foals was 100% to 1 mo of age age composition data from nine studies including and 98% to 2 mo of age. Survival to yearling the Bureau of Land Management's records on status was not known. A similar inverse rela- 8,764 horses captured from feral populations in tionship between natality and survival rates was four states (NRC, 1980). Because age composi- described by Welsh (1973) for horses on Sable tions of horse and pony populations were Island, which is approximately 300 km South- similar, these data were summarized together. east of Halifax, Nova Scotia. Boyd suggested 498 McCORT that the lower natality rate was due to abortion, in other adult male excretions. Males often stillbirths and weak foals that died soon after investigate and defecate on top of each other's birth as a result of winter stress. This would feces when they leave their groups to challenge have lowered the number of foals actually each other. Salter and Hudson (1982) reported

observed and recorded. Those foals that survived that 62% of all male-male interactions involved Downloaded from https://academic.oup.com/jas/article-abstract/58/2/493/4665525 by University of Warwick user on 17 November 2019 shortly after birth would be the healthier defecation and(or) sniffing. Miller (1981) found and stronger foals and would likely continue to that 25% of all aggressive encounters in the Red survive. This could explain the paradoxical Desert during his study involved smelling higher survival rate after severe winters. Morta- and(or) marking of fecal piles and that 69% of lity rates for horses and ponies 1 yr old and encounters at established fecal piles involved older are even less known than foal mortality marking. Males have been reported to compete to rates. The Committee on Wild and Free-Roaming be the last to defecate on a fecal pile. Usually the Horses and Burros (NRC, 1980) cites several most dominant is the last to defecate. Miller studies with data ranging from 86.6 to 97% sur- (1981) observed pairs of males alternately vival for these older age classes. Feist and McCul- marking the same fecal piles as often as eight lough (1975) found 10 of 35 carcasses of horses times in succession. that had died at ages greater than 15 yr old. Adult males also defecate on other fecal Marking piles when not challenged or in the presence of Feral horses and ponies direct a great deal of another male. These piles often become very their attention toward the excretions of other large as feces accumulate from numerous males. group members and nongroup members (Pelle- Feist and McCullough (1976) determined that grini, 1971;Tyler, 1972; Feist and McCullough, of the 120 fecal piles that they found in the 1976; Berger, 1977; Miller, 1981; Salter and Pryor Mountains, 57.5% were currently in use Hudson, 1982). Typically, adult males that while 42.5% were old piles that were not in use detect a defecation or urination will smell the that year. Additionally, they found 45% of the excretion, defecate or urinate on top of the piles on or immediately beside a trail and 55% excretion and smell it again before moving away from trails. They estimated that the same away. Adult females and young are much less pile could be used 1 to 3 yr, and as piles became responsive to excretions, but have been observed old, new piles were often started beside them. to respond in a manner similar to adult males at The significance of fecal piles is not well times (Tyler, 1972). Only 4.3% of 186 defeca- understood. Klingel (1972) suggested that fecal tions and 11.2% of 107 urinations by Pryor marking is a 'vestigial pattern' inherited from Mountain horses were without any apparent ancestors such as the territorial Grevy's stimulus (Feist and McCullough, 1976). that marked territories. Pellegrini (1971) felt Marking by adult males is often within the that the fecal piles in the Wassuk Range were context of sexual behavior. Pryor Mountain marking territory boundaries. Most authors stallions responded on the average to 43.4% of claimed that marking fecal piles was not a sexually mature mare urinations and defecations. vestigial behavior. Fecal and urine marking may Stallion responses to mare excretions, however, have a function to orient horses and ponies to varied with the time of year. Harem stallions their home ranges by creating 'olfactory familiar responded to 93 and 89% of mare eliminations surroundings' (Salter and Hudson, 1982). Ewer in May and June, respectively, during the peak (1968) proposed that fecal piles could be used of the breeding season. However, stallions to avoid areas being used by others. Hence, responded to only 1% of mare eliminations horses and ponies could avoid areas with fresh from November through February (Turner et feces and enter those with old fecal piles. al., 1981). Males have often been described as Berger (1977) suggested that this might be how sniffing a mare's urine and then exhibiting the groups minimized their encounters in the Flehmen posture, which is thought to enhance Grand Canyon. However, Tyler (1972) found the introduction of oderants into the vomero- no repelling effect of fecal piles on feral stallions. nasal organ (Estes, 1972). Adult males may be R. Hall and J. F. Kirkpatrick (unpublished able to detect the onset of estrus in females in data) suggested that horses may use their fecal this manner. By excreting on top of a female's piles as a source of food during severe winters excretion, a male may be concealing the repro- when forage is not available. Others have ductive status of that female. suggested that fecal and urine marking have Adult males also show a great deal of interest visual and olfactory importance in domi- FERAL HORSES AND PONIES 499

ponies. In: R. H. Denniston (Ed.) Symposium on nance relationships, estrous state and time of the Ecology and Behavior of Wild and Feral passing through a particular area (Feist and Equids, September 6-8. pp 175-183. Univ. of McCullough, 1976; Miller, 1981). Wyoming, Laramie. Klingel, H. 1972. Social behaviour of African . Conclusion Zoologica Africana 7:175. Information on the behavior of feral horses McKnight, T. L. 1959. The wild horse today. Desert Downloaded from https://academic.oup.com/jas/article-abstract/58/2/493/4665525 by University of Warwick user on 17 November 2019 and ponies has increased greatly during the last Magazine 22(6): 7. Miller, R. 1979. Band organization and stability in 10 yr. The overview presented in this paper Red Desert feral horses. In: R. H. Denniston should make it clear that the behavior of these (Ed.) Symposium on the Ecology and Behavior equids is complex. Studies on the behavior of of Wild and Feral Equids, September 6-8. pp feral horses and ponies make it possible to more 113-128. Univ. of Wyoming, Laramie. wisely manage these free-roaming animals. Miller, R. 1981. Male aggression, dominance and breeding behavior in Red Desert feral horses. Z. Management of domestic horses and ponies is Tierpsychol. 57: 340. also enhanced. Horses and ponies are very Miller, R. 1983. Seasonal movements and home ranges adaptable to many different management of feral horse bands in Wyoming's Red Desert. J. schemes. However, an increased understanding Range Manage. 36: 199. of the behavior of feral horses and ponies Miller, R. and R. H. Denniston II. 1979. Interband dominance in feral horses. Z. Tierpsychol. 51:41. provides new insights into domestic horse Nelson, K. J. 1978. On the question of male-limited and pony behavior and management. population growth in feral horses (Equus caballus). M.S. Thesis. New Mexico State Univ., Las Cruces. 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