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T/N 294 

Filing Code 4700 

Date Issued March 19 7 7 


Bureau of Land Management 

U.S. Forest Service 


by Mark Zarn, Thomas Heller and 
Kay Collins, Research Biologist 
Conservation Library 
Denver Public Library 


. L35 

no . 294 Additional copies of Technical Notes are ava 

liable from DSC, Federal Center Building 50, Denver, Colo.. 80225 


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Introduction 1 

Species Description 1 

General 1 

Colors 3 

Size of Horses 5 

Length of Life 5 

Aging Horses 5 

Locomotion 6 

Population Characteristics 7 

Distribution 8 

Population Status 9 

Origin and History of Wild Horses 11 

Origin of Wild Horses 11 

Domestication of the Horse 12 

Influence of Horses on History 13 

The Horse in America 14 

The Wild Horse Controversy 15 

Reproduction 17 

Sexual Behavior in Females 17 

Sexual Behavior in the Stallion . 19 

Foaling 19 

Reactions of Other Horses to Mating 20 

Food Habits 20 

Senses 25 

Vision 25 

Smell and Taste 25 

Hearing 26 

Tactile Sensations 27 

Social Organization and Behavior 28 

General 28 

Aggressiveness 29 

Family Groups 31 

Home Range 32 

Territoriality 34 

Vocalizations 35 

Postures and Facial Expressions 35 

Grooming 37 

Play 38 

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Sleep and Rest 39 

Pawing 40 

Eliminative Behavior 40 

Scent or Visual Boundary Marking 41 

Water and Watering Behavior 42 

Foal Behavior 43 

Coprophagy in Foals 45 

Predation and Disease 45 

Predation 45 

Disease 45 

Competition and Relationships with Other Animals . . 48 

Competition 48 

Relationships with Other Animals 48 

Wild Horse Management 49 

Population Management 49 

Population Control 51 

Methods of Capture 51 

Management Plans 53 

Current Problems 53 

Advantages of Wild Horses 53 

Disadvantages of Wild Horses 54 

Research Needs ..... 54 

Current Research 54 

Designated Wild Horse Ranges 54 

Legislation Concerning Wild Horses 55 

Organizations Concerned With the Welfare of Wild 

Horses 55 

Glossary 56 

Appendices 57 

Literature Cited 66 


Appendix 1 Labeled Points of the Horse 

Appendix 2 Three Types of Lumbar Vertebrae Found in Wild Horses 

Appendix 3 Coat Color in Horses 

Appendix 4 Gaits of the Horse, Drawn from Cine Film 

Appendix 5 Features of Equid Evolution: Skull, Foot Structure, 

Dentition and Diet 
Appendix 6 List of Plants Making up 2% or More of the Diet of 

Wild Horses in the Western United States 
Appendix 7 Historical Distribution of Horses 
Appendix 8 Map Showing Distribution of Wild Horses in the 

Western United States 


The purpose of this report is to provide personnel of the U. S. 
Forest Service and U. S. Bureau of Land Management with a 
literature review and summary of available information on wild 

The scientific and recorded factual information on America's 
wild horses is extremely limited. Klingel (1972), who has 
spent many years studying the wild Equidae of Africa, states 
that, except for social organization, all members of the genus 
are very much alike. As a result, many portions of this tech- 
nical note were summarized from data on domestic horses or 
from data on other members of the Equidae . Therefore, the 
validity of much of the information as it applies to America's 
wild horses will have to stand the test of future research. 

Only a relatively small number of people know very much about 
wild horses. Certain individuals such as ranchers and those 
few who have chased them, lived near, or been around them all 
their lives often possess a remarkable store of knowledge on 
their habits and general ecology. Thus, there is a consider- 
able amount of anecdotal information that cannot be quoted 
because it cannot be verified. 

The problems of management are extremely complicated. We are 
not dealing with a homogenous population of wild animals. At 
the extremes are those horses that have been in the wild for 
many generations and are capable of surviving under the harshest 
of conditions. At the other end are those animals only a step 
or two away from domestication that have not as yet fully 
adapted to their environment. Management of horses as truly 
wild animals would consider little or no interference by man; 
however, this approach could be hazardous and is almost an 
impossibility under the increasing pressures for various land 
uses. Other types of management, related to game animals or 
to livestock, are hamstrung by lack of biological data and may 
be restricted by special interest groups or the emotional issues 

Species Description 

General . The family Equidae , to which the horse belongs, 
also includes donkeys, zebras, onagers and all their ancestors 
back to eohippus. All the living Equidae represent a single 
genus, Equus , with six species. Domestic horses and their wild 
relatives form one species; the asses, both domestic and wild, 
another; the onagers a third; zebras comprise the other three 

The genus Equus includes all members of the family Equidae 
and their immediate ancestors during the last Ice Age. Equus 
caballus includes only the domestic horse and wild relatives so 
closely related to it that they are capable of interbreeding and 
producing fertile offspring (Simpson, 1951). 

The andulusian horse that came to America was reconstructed from 
old paintings and records by Cabrera. The animal was small to 
medium in type, rather close to the ground, had a wide chest, 
ample barrel, a muscular, rather short neck, and a rounded 
sloping croup with a low- set tail. The latter two character- 
istics are also typical of Barb points (Simpson, 1951). 

The Spanish Barb Wild Horse Research Farm describes the Barb: 
it is small (under 14 hands) and weighs about 800 pounds. The 
front legs join the deep narrow chest in a reversed V. The 
withers are low. The ergots are small or non-existent, the 
chestnuts small, smooth, and soft and do not peel as they do 
on draft breeds. The croup is low with the back legs well under 
it. The back is short with 17 pairs of ribs and either five 
lumbar vertebrae or the sixth fused to the fifth. The head is 
small, not over 18 inches from the pole to the end of the nasal 
bone. The ears are small, rimmed with black; light hair grows 
out of the center of the ear. The muzzle is also small and 
has crescent-shaped nostrils. 

Colors are solid, roan, or grulla, which shades from slate to 
mouse brown. The mane, tail, hooves and legs below the knee 
are black. The hair on the back of the legs grows in a curl 
and comb . 

The present-day wild horse, due to many years of cross breeding 
with abandoned, lost or stolen domestic breeds is, in most 
cases, little different than any other domestic light horse 
(Beebe and Johnson, 1964). Ryden (1970) states that there are 
only a few hundred pure-blooded descendants of the original 
Spanish horses and these are in captivity in special registers 
in North and South America. She also states that the Spanish 
horse's traits often appear in animals that have as little as 
3.0 percent Spanish ancestry. 

The significance of the number of lumbar vertebrae to determine 
whether a horse has Spanish ancestry or not is open to question. 
Stecher (1962) studied the lateral joints in the caudal lumbar 
region of horses. He examined the skeletal remains of 245 
horses of nine species obtained from various sources. The 
horses were classified according to whether they had five or 
six lumbar vertebrae. Skeletal specimens included the domestic 
horse, the arabian, the Shetland pony, Przewalski's horse, the 
hybrid mule, two species of asses and two of zebras. The Shet- 
land pony was the only species in which all samples (eight) 

contained six lumbar vertebrae; the Hemoine ( Equus hemoinus ) , 
the Mongolian wild ass, was the only species in which all 
samples (nine) contained five lumbar vertebrae. Skeletons of 
ten arabians showed three with five and seven with six verte- 
brae. Two domestic horses had five and one half, and one 
Grevy's zebra ( Equus grevyi) had seven lumbar vertebrae. 

Edwards (1970) states that arabian horses, regardless of their 
purity, do not always have five lumbar vertebrae any more than 
Przewalski's horse always had five or six. It depended on who 
you were talking to. 

Howell (1945) wrote that the American Museum of Natural History 
stated in a letter to him that the proper number of lumbar 
vertebrae for the arabian is five while that of other horses is 
six. The statement was qualified by stating that the point 
which constitutes a lumbar vertebrae is its transverse processes 
whereas a dorsal vertebrae is determined by the attachments of 
ribs in place of transverse processes. Therefore, it is safer 
to say that arab horses have 23 dorso-lumbars while other 
varieties have 24. 

Feist (1971) and Hall (1972) reported skeletal examples of 
three types of lumbar vertebrae in the Pryor Mountain horses. 
The Barb type have five lumbar vertebrae and 17 pairs of ribs; 
the Andulusian have five and a half, with the last three fused; 
and the modern breeds of today (except the Arabian) have six 
lumbar vertebrae with no fusion. Appendix 2 depicts three 
types of lumbar vertebrae found in equids. 

Colors . Since local color names vary from one geographical 
area to another, it is difficult to portray true horse colors 

The original Andulusian horse encompasses the entire range of 
horse colors. Spotting occurs, but is not especially character- 
istic (Simpson, 1951). Smith (1841) wrote that all South 
American feral horses bore the stamp of the domesticated races 
of old Spain. His personal observations indicated that they 
were mostly of similar color though every color seen in Europe 
existed among them. Grey, or shades of grey, were most common 
in the northern mountain regions, and shades of bay in the 
pampas. Black was the rarest color. Hoyt (1886), an old 
mustanger, wrote that ninety percent of the feral horses on 
the panhandle of Texas were bay, dark brown, or black, and that 
other colors were rare. Cook (1919), writing in 1870, stated 
that on the plains area east of the Rockies, color in wild 
mustangs consisted of cream, buckskin or mouse and that black 
stripes above the knees or hocks and along the middle of the 
back from mane to tail commonly occurred. Worcester (1945, p. 
416), in an historical review of Spanish horses among the 

Indians, stated that David Thompson, an early explorer, commented 
on hoof color in Indian horses: "The yellow hoof with white 
hair is a brittle hoof and soon wears away; for this reason, as 
much as possible, the natives take only black-hoofed horses on 
their war expeditions." 

Gremmel (1939), writing in the Journal of Heredity , stresses 
physical differences in horse coat colors from an histological 
point of view. He lists the basic colors and the patterns that 
occur within these basics (see Appendix 3). 

Dobie (1952) devoted a chapter to the dun color in wild horses 
(p. 299): 

The dun and the stripe are always waiting to come 
back. All colors but gray and roan are, in bio- 
logical language, recessive to dun. I cannot draw up 
tables of dates and numbers, but to me it is evident 
that for three and a half centuries, say from 1520 to 
1880, dun was progressively emerging over the American 
continents among descendents of horses marked sparsely 
by that color when Spaniards planted them. Before that 
time selective breeding had driven the dun color into 
hiding; feral life brought it back. 

There is a wild coat pattern gene in horses. Przewalski's 
horse is not uniform black but has a distinctly concealing 
color. The general body color is a neutral gray but peripheral 
areas, including mane, tail, dorsal stripe and legs, are black. 
The primitive type coat color depends upon four dominant genes. 
Recessive mutations have modified each of them. However, they 
form the basis of domestic color varieties, many of which would 
be unable to survive in wild populations because they lack 
concealing value (Castle, 1954). Feist (1971) listed eight 
basic colors for the Pryor Mountain horses. Variations to these 
basics that appear on legs, manes or tails were classified as 
secondary markings. Hall (1972, p. 19) noted that the Pryor 
Mountain herd seemed to be reverting back to the original 
mustang type. Among other characteristics he refers to color. 
"The reversion of colors to the blue corn, buckskins, and bays 
with line stripes down their back, along their withers and on 
their legs." 

There are many reports that stallions often show color prefer- 
ences for the mares they select for their harems and will reject 
those whose color does not meet their requirements (Dobie, 1952; 
Feist, 1971; Ryden, 1970). Since color vision has not been 
scientifically established in horses (Hafez, e_t al, 1969; 
Smythe, 1966), the selection of certain colored mares may be 
based on brightness or intensity rather than hue. 

Size of horses . There are no extensive records of wild 
horse sizes or weights. The original Spanish horse was small, 
rarely attaining 15 hands. Some of the Indian mounts reached 
only 12 to 13 hands. Present-day stallions seldom exceed 1000 
pounds, and mares may be as light as 700 pounds (Ryden, 1970). 
In the Pryor Mountain herd, females averaged 600 to 750 pounds 
and males, 800 to 850 pounds (Hall, 1972). Cook (1919), who 
wrote of the period from 1870 to 1880, estimated that the 
average wild horse weighed about 800 pounds. Schwartz (1949) 
reported that wild horses sold to fox ranches and other outlets 
that buy horses for slaughter averaged between 750 and 850 
pounds but some of them weighed as much as 1250 pounds. Horses 
from the North often weighed more than those from the South due 
to more draft blood from escapees of the World War I period; 
however, the horses in certain parts of Oregon were small, 
averaging 800 pounds in weight. The Fort Apache herds, which 
had as high a percentage of wild mustang blood as any, averaged 
about 650 to 700 pounds (Wyman, 1945). 

A factor affecting the growth of wild horses, and one of the 
reasons many of them remain smaller than domestic horses, is 
their restricted diet. They rarely eat grain like domestic 
horses, and their diet is often deficient in minerals and 
vitamins, plus the fact that salt and adequate water are not 
always available to them (Beebe and Johnson, 1964). Other 
writers also mention inadequate and poor quality of food as a 
reason for the small size of wild horses (Ensminger, 1951; Hall, 
1972; Ryden, 1970). 

The maturation rate in wild horses is slower than in domestic 
horses. Two- and three-year-old horses often appear to be 
yearlings (Ryden, 1970; Hall, 1972). 

Length of life in wild horses . There is little data on 
the lifespan of horses in the wild state. Domestic horses 
that reach their twenties are considered old; however, it is 
not uncommon for horses to reach their thirties and some have 
been recorded that survived past forty years of age (Simpson, 
1951). The maximum life span of horses in the Pryor Mountains 
is ten to fourteen years and their maximum breeding period is 
five to six years (Hall, 1972). Dobie (1952) relates that 
Black Kettle, a famous and legendary wild horse that was cap- 
tured past his prime, lived to about thirty years of age. 

Aging horses . The age of horses is generally determined 
by the amount of wear of their teeth. The mature male has forty 
teeth; a young animal, male or female, has twenty- four teeth. 
The mature female lacks tushes and therefore has thirty-six 
teeth. In horses up to five years of age the numbers of perma- 
nent and milk teeth are noted. From six to twelve years, age 
is estimated by the number of cups or indentations in the 

incisor teeth. After twelve years, age may be judged by the 
cross section and slant of the incisors. Learning to determine 
age in horses is a matter of practical experience. When a 
horse exceeds twelve years, even the most experienced investi- 
gators have difficulty in determining accurate age (Ensminger, 
1951). Horses that live in areas of sandy or gritty soils 
show increased dental wear. Under these conditions a six- year- 
old horse may appear to be ten years old (Bone, 1964). 

Locomotion . It is only since the development of the camera 
that man has learned accurately how a horse coordinates its 
four legs during execution of the various speeds of movement. 

Horsemen recognize as many as twelve gaits in horses, but these 
are all variations of the walk, trot, pace and gallop. The pace 
is included because a few horses pace naturally. The canter, 
which is a slow gallop, usually has to be taught. The lope, 
recognized by western horsemen, is a smooth gallop or canter 
which sometimes verges on a four-beat rhythm similar to a run- 
ning walk. 

The walk has a four-beat cadence with the succession of foot- 
falls being left-fore, right-hind, right-fore, left-hind. The 
body is alternately supported on three and on two legs. The 
trot is a faster gait with a two-beat cadence where the diagonal 
legs move together so that the sequence of feet striking the 
ground is left- fore, right-hind followed by right-fore, left- 
hind. Twice in each stride there is an interval when all four 
feet are off the ground. The pace has similar rhythm to the 
trot but the two legs of the same side, not the diagonals, move 
together. It is a slow, broken pace tending toward a walk. 

The gallop is the horse's fastest gait and differs from the 
others in not being symmetrical on the two sides. It may be 
led either on one side or the other. The cadence is three 
beat, with a broken rhythm that occurs as beat, pause, beat, 
quick double beat, beat, pause, etc. The pause represents the 
short period when all four feet are off the ground, which 
occurs only once in each stride. The sequence of footfall for 
the left lead is left-fore, right-hind, left-hind and right-fore, 
the latter two almost together with the hind foot slightly 
ahead. The right-hind foot is lifted almost immediately as the 
left hind foot comes down and before the right fore foot strikes. 
Normally, at no time are three of the horse's feet on the 
ground. The right lead is a mirror image of the left lead. In 
an extended gallop there may be four beats, as opposed hind 
and fore feet strike at perceptible intervals; however, the 
break after the placing of the lead foot still distinguishes 
the cadence. Horses can be taught to lead either right or left 
or to change from one lead to the other while galloping. This 
is important if the animal is to turn rapidly, because a horse 

making a sharp left turn on the right lead is liable to fall 
(Simpson, 1951; Tricker and Tricker, 1966). 

Few horses jump regularly unless they are taught. This may be 
due in part to their lack of binocular vision which prevents 
them from judging the correct take-off distances (Hafez et al, 

Drawings from a motion picture strip (Appendix 4) depict leg 
positions of the horse while walking, trotting and galloping. 

Population Characteristics 

Some of the properties of a collective group of organisms or 
populations are density, birth rate, death rate, age distri- 
bution, biotic potential, dispersion and growth form. Genetic 
characteristics such as adaptiveness , reproductive fitness, and 
persistence (leaving descendants over long periods of time) are 
also directly related to populations (Odum, 1971). 

There are three major age groups in a population, the pre- 
reproductive, the reproductive and the post- reproductive. In 
a rapidly growing population, growth may be exponential due to 
a high birthrate and each successive generation will be more 
numerous. This results graphically in a pyramid age structure. 
The graphic representation of a stable population is bell shaped, 
The pre-reproductive and reproductive age groups are fairly 
equal in size and the post- reproductive age group remains small. 
If the birth rate is drastically reduced the reproductive, 
post- reproductive age groups increase proportionally which 
results in an urn-shaped graph representative of a declining 
population (Boughey, 1968). 

Odum (1971) describes characteristics of populations in regard 
to age structure. An expanding population contains a large 
proportion of young animals; a stationary population a more 
even distribution of age classes; a declining population a large 
proportion of old individuals. 

The population density of wild horses, like that of any other 
animals, must be in tune with and not exceed the carrying 
capacity of the available habitat. Other than this general 
observation and the limited data that Hall (1972) and Feist 
(1971) collected on the Pryor Mountain horses, there is no 
scientific information available on optimum population levels, 
the results of overcrowding, competition, or the effects of a 
degrading habitat. However, there is evidence that wild horse 
densities could be reduced, through improper management and 
control, to a level that could lead to their extinction either 
locally or nationally. 

There is a critical population size that varies from species 
to species. Once the population density of a particular species 
goes below this level it is doomed to extinction regardless of 
efforts to save it. Prime examples are the passenger pigeon 
which died out completely even though hunting had ceased and 
there were still several thousand remaining birds scattered 
over North America; the Heath hen, although rigorously protected 
(after the population level had become small) , suffered the 
same fate. 

Since their social life plays an important part in locating 
feeding areas, raising their young and defending against 
enemies, gregarious animals such as the ungulates are particu- 
larly susceptible to the danger of extinction when their density 
reaches a certain level. A number of factors may determine 
this critical population size. Three of the more important of 
these are: (1) males fail to find females due to low density, 
(2) courtship behavior is inhibited by local low population 
density, (3) the remaining population is too small to resist 
predators and competitors (Ziswiler, 1967). Erhenfeld (1972) 
adds another factor: the population size may be too small for 
reproduction to compensate for losses from disease, climatic 
conditions, or natural disasters. 

Distribution of Wild Horses 

The public land administered by the Bureau of Land Management 
and the U. S. Forest Service that contain habitat for wild 
horses are located in Arizona, California, Colorado, Idaho, 
Montana, Nevada, New Mexico, Utah and Wyoming. The largest 
concentrations of wild horses are in Nevada, Wyoming and Oregon. 

Their distribution is generally limited to areas where accessi- 
bility is limited, population of humans is sparse, and the 
terrain rugged. Their range is also limited by availability 
of forage, water and the numbers of fences or barriers that 
restrict movement. The total extent of wild horse habitat on 
lands not federally administered is not known. Thousands of 
acres of these lands are not fenced and the wild horses have 
access to them. 

Populations of wild horses in the grassland biome are small, a 
few have been reported in New Mexico and in Montana. The 
greatest numbers inhabit the cold desert and the pinon- juniper 
type of the woodland-brushland biome. Seasonally, in some areas 
they range into the montane coniferous forest biome. In general 
this biome is too cold in the winter for the horses to remain 
there year round. See map, appendix 8-. 

Population Status 

The proceedings of the first National Advisory Board meeting 
for wild horses and burros (January 1973) reported an estimated 
total of 2000 horses on Forest Service controlled lands and 
16,878 horses on Bureau of Land Management controlled lands. 

Both agencies state that 1975 population estimates, as presented 
below, are of much higher quality than their earlier data due 
primarily to more intensive efforts and improved methods of 
censusing. Bureau of Land Management controlled lands are 
listed by state; Forest Service lands by forest region. Data 
on state, private and other lands is not available. (See map, 
Appendix 8) . 

Bureau of Land Management Wild Horse Inventory Data as of May 1, 1975 
(Prepared by Milton Frei, U.S. Bureau of Land Mgt., Denver, Colo.) 

Estimates of Population 

Animals Claimed 





















New Mexico 










49,658* 14,115 

* Includes animals claimed, proof of ownership 
still has to be determined under Section 5 of 
the 1971 Wild Horse and Burro Act 

National Forest Wild Free-Roaming Horse Inventory Data (Estimate) 
(Adapted from a letter dated April 15, 1975, from the Assistant 
Director for Environmental Coordination, U.S. Forest Service) 

No. of 
Population Animals 
Region National Forest as of 1-1-75 Claimed 

1 Custer 8 

Region Total 




Region Total 


Apache- Si tgreaves 



Santa Fe 





Region Total 234 






















Region Total 




Los Padres 


Region Total 879 

Malheur 174 44 

Ochoco 60 1 

Region Total 234 45 

GRAND TOTAL 2,755 74 


O rigin and History of Wild Horses 

Origin . Present-day horses of all kinds have descended from 
a small, four-toed, rodent-like creature whose name many people 
are familiar with, eohippus, or the dawn horse. The correct 
scientific name, however, is Hyracotherium . This came about 
because early scientists (1838) did not recognize that the 
fossil remains of a small animal found near Suffolk, England 
was related to horses, and compared the remains to the Hyraxes, 
which the fossils closely resembled. Hyraxes are comparable 
in size and external appearance to rodents and lagomorphs. When 
similar fossils were found in North America at a later date the 
principle of evolution had become well established and they 
were recognized as horse ancestors. Charles Marsh of Yale 
University gave them the euphonius name, eohippus. Since 
Hyracotherium is much the older of the two names, under the 
rules of zoological nomenclature it is the correct one to use. 

Eohippus lived at the same time in both Europe and North America, 
appearing in both places at the very beginning of the Eocene. 
No direct ancestors of eohippus have been found on either 
continent. There were several species of eohippus which varied 
greatly in size, the smallest being not much over 10 inches in 
height at the shoulder, the largest about 20 inches. Four toes 
occurred on the front foot of eohippus, each ending in a 
separate small hoof. The hind foot had only three functional 
toes. The animal was already distinctly herbivorous, with 
teeth modified for browsing rather than grazing (Simpson, 1951). 

In the beginning of the Cenozoic Era of geologic time (70 to 75 
million years ago) the British Isles and North America were 
attached as part of the supercontinent of Laurasia, which also 
included Greenland and Europe north of the Alps and east to the 
Himalayas. During the long period when Laurasia was separating, 
animals were able to migrate back and forth on the land bridges 
that still connected Europe and North America. During this time 
eohippus evolved and occupied both North America and Europe. 
Not long after this the continents separated and migration 
ceased. In Europe for an unknown reason eohippus became extinct. 
In North America through a period of about fifty million years 
eohippus evolved into Mercyhippus , an animal with high crowned 
teeth which permitted it to graze rather than browse. It was 
also larger, about the size of a small pony of today. 

After Mercyhippus there is a gap in the fossil records from 
about six million years ago to about 600,000 B.C., during which 
time Mercyhippus evolved into Equus caballus , the true horse, 
having a single toe on each foot. No fossil remains of horses 
have been found in North America for the pleistocene epoch, the 
Great Ice Age. The scanty records that were available came 
mostly from Eurasia. Perhaps when the ice melted, fossil records 


were washed away in the huge floods that followed. Equus 
caballus may have evolved from some of its North American 
ancestors that crossed the land bridge which connected Alaska 
and Siberia during this period. Changes in conditions which 
are still unclear brought the horse back to North America about 
600,000 B.C. Fossil records dating from this time to about 
7000 B.C. have been found in many places on the North American 
continent. After 7000 B.C., horses again vanished along with 
several other species of large grasseaters. There was no such 
extinction of species in Europe. As the ice sheet melted, 
Europe warmed and the forests encroached on the grasslands. 
Grazing herds were forced eastward onto the steppes of southern 
Russia and western Asia. Tribes of early hunters followed the 
herds, became semi-nomadic and by 5000 B.C. had hunting dogs 
and had domesticated the onager (Asian wild ass) and reindeer 
(Simpson, 1951; Haines, 1971). Appendix 5 depicts features of 
horse evolution. 

Domestication of the horse . By about 4000 B.C. two, and 
possibly three, species of E. caballus had developed in the 
Eurasian grasslands. Around the Black and Caspian Seas the 
"Tarpan" and in Mongolia or Manchuria Przewalski's horse had 
developed. A third subspecies, depicted as a forest horse, was 
larger than the other two and existed in Polish forests until 
the middle of the eighteenth century. Disagreement exists as 
to whether it was a true subspecies. 

Truly wild horses were common from Europe through central Asia 
in early historic times. The European breed called "Tarpan" is 
now extinct and it is uncertain if Przewalski's horse survives 
in pure form. There is general agreement, however, that the 
"Tarpan" was the first domesticated horse. 

Later, Indo-Europeans invaded the region from the southeast and 
possibly tamed a few horses. By 4000 B.C. they were using 
horses to pull carts. Horse culture spread north and east into 
Mongolia and turned many tribes into nomads. About 2000 B.C. 
tribesmen from the Asian steppes crossed the Iranian plateau 
with horses and overran the entire near east. A thousand years 
later horses appeared in North Africa, west to Gibraltar, and 
north and west through Europe as far as Scandinavia, Spain, 
France, and the British Isles. The earliest records of horses 
in Greece appear about 1700 B.C., in Egypt, 1600 B.C. and in India, 
1500 B.C. By 1000 B.C., and possibly earlier, they had reached 
Spain. The first horses that were imported from north of the 
Caucasus were small, stocky animals, more commonly used for 
pulling carts and chariots than riding. Later the Egyptians 
involved in trading and breeding horses crossed these with the 
more fleet horses that came from the Libyans or Numidians of 
North Africa. 


There are several theories concerning the development of modern 
horses. One of the most popular at present is that all the 
light, fast, Mediterranean and mideastern horses arose from a 
single original stock now represented by the Arabian. If this 
is true, the Numidian horses now represented by the Barb (named 
from Barbary, an old African country west of Libya) were of 
common origin with the Arabian. The Barb and Arabian, however, 
as far back as they can be traced, are of distinct types. They 
are both light and fast, but the former lacks the wedge-shaped 
head, the dished profile and protruding eyes of the Arabian. 
Both supposedly have 23 lumbar vertebrae, whereas 24 is the 
usual number in all other breeds . 

A heavy horse capable of carrying armored knights was first 
developed in Germany, France and the British Isles. The early 
horse of Spain was a heavy breed similar to those used in 
France and Germany. When the Moors invaded and conquered Spain, 
the Spaniards recognized the superiority of Moor horses which 
were mostly Barb with perhaps some mix of Arabian. They crossed 
their own Norse Dun breed with the Barb-Arabian mixture. The 
product, called the Jennet, was so superior that for the next 
several centuries Spain was renowned for the quality of its 
horses, especially those from the Andulusia area of Spain. 

The Andulusian type is the breed that was first brought to 
the new world by Spanish conquistadors. Later it escaped onto 
our western plains and the pampas of South America and became 
the wild horse of the West and of Argentina (Simpson, 1951; 
Ryden, 1970; Haines, 1971). 

Influence of horses on history . Since their domestication, 
horses have had a profound influence on history. Perhaps the 
most significant has been the use of horses in warfare. They 
have been involved in every war up until recent times, and only 
within the present century has the development of horses for 
military use ceased to be the main concern of breeders. 

The Mohammedan and Mongolian conquests were made possible by 
horses. In the seventeenth century the Mohammedans were stopped 
by the Franks only because the Franks were clad in armor and 
mounted on heavy, strong horses. The Mongolians were never 
really stopped; their empire collapsed because of its unwieldy 

Horses since ancient time have been important sources of power 
for agriculture and transportation, for recreation, as status 
symbols or emblems of wealth and authority, for food, leather, 
and other products. The horse is still essential as a source 
of rural power and transportation in many countries. 


The American nation was built on horsepower and even today, when 
the horse is no longer essential, it remains a part of our 
culture. The mechanized age lessened the importance of the 
horse as a principle factor in American development, but it 
still has use for riding, hunting, recreation and as an animal 
that people like to be associated with (Simpson, 1951). 

The horse in America . It is difficult to state flatly how 
or where horses first escaped or were stolen from the Spaniards 
and reverted to a wild state. On Columbus' second voyage in 
1493 he landed horses from Andulusia in the West Indies. Ponce 
de Leon brought horses from Cuba or Puerto Rico to the coast 
of Florida in 1521. Cortez carried horses with him when he 
discovered the Aztec civilization in 1519. Horses were intro- 
duced into the pampas of South America by Pedro Mendoza in 1535. 
However, it is likely that wild horses which later covered the 
pampas came from Chile and not from the small number Mendoza 
abandoned. During the early years of exploration, horses were 
sent in nearly every ship leaving Spanish ports. The Spaniards 
also established breeding farms in the West Indian colonies of 
Cuba, Puerto Rico and Santo Domingo, and stocked them with the 
finest stallions and brood mares that had been brought out of 
Spain. So many horses were transported that Spain finally 
placed an embargo on the animals because they lacked enough 
horses for home use. At one critical point horses were in such 
short supply that the breeding farms in the West Indies were 
forced to import more Barbs from North Africa, thus the Barb 
was once again introduced into the line (Simpson, 1951; Ryden, 
1970; Haines, 1971). 

Indian tribes in Texas and New Mexico were probably the first to 
obtain horses. The Apaches and Comanches got horses by raiding 
the Spanish camps; they sold or bartered horses to other tribes 
as did Spanish and French traders. Soon horses spread to the 
Navajos, Zunis, Utes, and other tribes in the Southwest and 
thence to tribes in the southern plains and northern plains. 
By 1750 even the Blackfoot Indians in Canada had horses (Smith, 

There are no reliable estimates of the number of feral horses 
in the U. S. during the late 1700 's to early 1800' s. This was 
the time of maximum horse population. McKnight (1959) estimates 
anywhere between 2 and 5 million. The greatest numbers occurred 
in the Southwest, with the most densely populated ranges in 
west central Texas. 

The introduction of barbed wire and fencing marked the end of 
the wild horses on the Great Plains and significantly reduced 
their numbers elsewhere. At the end of the 19th century most 
wild horse concentrations were to be found west of the Rocky 
Mountains . 


The Boer War in South Africa created a large demand for horses. 
Thousands of wild horses were caught and shipped to Africa, and 
since many died en route or were killed in action, the demand 
continued until the war ended in 1902. During World War I, 
amateur and professional horse hunters found they could sell 
all the wild horses they could catch. 

In the early 1920' s four new markets developed that helped fur- 
ther decrease wild horse herds: the use of horse meat for 
chicken feed, pet foods, human food and an increase in horse 
use by southern farmers when cotton prices dropped and tractors 
became too expensive. The demand was partly supplied by trained 
mustangs captured from wild bands. 

The blood of remaining wild herds was further diluted during 
the depression of the thirties. Large numbers of marginal 
farmers and ranchers went out of business. These early settlers, 
unable to sell their domestic horses, released or abandoned 
them. Many of these joined the roving bands of wild horses. 

The passage of the Taylor Grazing Act in 1934 also affected 
wild horses, since stockmen became reluctant to share their 
assigned grazing areas with wild horses. As a result, ranchers, 
professional horse catchers, and the federal agencies cooperated 
on drives to remove the horses. When this Act became law it 
was estimated that there were some 150,000 wild horses remaining 
on public lands in the eleven western states. 

World War II brought temporary relief but after the war, efforts 
to rid the range of wild horses was again initiated. During 
the late 1940' s and 50' s, over 100,000 horses were removed from 
Nevada rangelands, while smaller numbers were removed from 
other western ranges (Denhardt, 1948; McKnight, 1959; Smith, 
1969; Ryden, 1970). (See historical distribution of wild 
horses, Appendix 7) 

The wild horse controversy . The controversy over wild 
horses simmered for many years. Public concern for the plight 
of the wild horse gradually increased as people became aware 
that the methods of capture were barbarous, the treatment 
brutal and inhumane, and the final product, pet or chicken food. 
During the 1920' s chicken feed producers in California persuaded 
the railroads to ship horses as "chicken feed" thus eliminating 
the need for humane treatment during transit. 

One of the results, and the primary one, was a rash of articles 
and stories in national magazines and in the news media about 
wild horses. Millions of people who had never heard of wild 
horses were now concerned and they reacted by writing letters 
to their elected representatives (McKnight, 1959). 


Several different philosophies concerning wild horses emerged. 
One group, including many stockmen and trained scientists do 
not consider the wild horse wild. They claim it is a mixture 
of many breeds of the domestic horse-- that the blood of the 
original Spanish horse is so diluted as to be almost nonexistent. 
They also consider it a nuisance and a pest. Another group 
favors native wildlife and where there is competition they feel 
that the horse should be removed or rigidly controlled. A 
very large number of people view the wild horse as a symbol of 
the old West and that all wild horses should remain wherever they 
are. A more moderate group leans toward multiple use. They 
feel that the wild lands are for the use of all animals and 
that the condition of the land and vegetation has first prior- 
ity but that there is a place for the wild horse. They are 
strongly opposed to brutality or inhumane treatment when popu- 
lations have to be controlled (Crain, 1973; McKnight, 1959). 

As a result of continued public concern, Congress has passed 
two federal laws to protect wild horses. Public Law 86-234, passed 
in 1959, prohibits pollution of water holes for trapping and the 
use of aircraft or motorized vehicles to capture or kill wild 
horses. Public Law 92-195, passed in 1971, places wild horses 
and burros roaming on national resource lands under the juris- 
diction of the Secretaries of Interior and Agriculture for 
protection, management and control. It provides a penalty for 
harassing, capturing, killing or selling wild horses or burros 
and prohibits the processing of either animal into any commercial 
product. It also provides for the establishment of an advisory 
board to make recommendations to the Secretaries on management 
and protection of wild horses and burros. The above statute 
omits national parks and monuments. 

The first advisory board, composed of nine members, met on four 
occasions during their initial year, 1973. Meetings were held 
in Salt Lake City, Utah; Denver, Colorado; Billings, Montana; 
and Lake Havasu City, Arizona. All of the meetings were open 
to the public. The members of the first advisory board are 
listed below: 

Name Address 

Dr. Charles Wayne Cook 4800 Venturi Lane 

Fort Collins, CO 80521 

Mrs. Velma Johnston 140 Greenstone Dr. 

Reno, NV 89503 

Mrs. Paul Twyne 629 River Bend Rd. 

Great Falls, VA 22066 


Dr. Roger Hungerford 

University of Arizona 
Tucson, AZ 85721 

Mr. Ed Pierson 

Mr. Ben Glading 

Dr. Floyd W. Frank 

Mr. Roy Young 

Mr. Dean Prosser, Jr, 

Box E 

Laporte, CO 85035 

1413 El Tejon Way 
Sacramento, CA 95826 

1395 Walenta Way 
Moscow, ID 83843 

P. 0. Box 588 
Elko, NV 89801 

P. 0. Box 206 
Cheyenne, WY 82001 


Sexual behavior in females . During diestrous, if the 
stallion attempts to mount, the mare displays defensive reactions 
varying from aggressiveness to disinterest. As estrous approaches, 
the mare may allow the stallion to smell and bite her. When 
ready to copulate, the tail is lifted and held to the side, the 
pelvis lowered and the hind legs spread. The intensity of 
estrous behavior varies between individual mares and peaks just 
before ovulation (Hafez et al, 1969). The behavior of adult 
pony mares in full estrous was usually passive after a stallion 
had shown interest. They stand quietly with hind legs straddled, 
tail raised and often turn their head to touch the stallion's 
muzzle. On occasions they squeal, urinate in small amounts or 
paw the air with the forefeet (Tyler, 1972). 

Domestic mares generally show estrous at 15 to 24 months of age. 
The estrous periods recur at approximate 21-day intervals within 
a range of 18 to 27 days. The length of the estrous period 
varies from 5 to 8 days but may be longer in early spring. The 
average gestation period is 340 days plus or minus 30 days. 
Postpartum estrous usually occurs seven to eleven days after 
foaling (Ensminger, 1951). 

Under domestication the average conception rate of horses is 
less than 50 percent. In the wild state, when horses had access 
to good forage and water it was not uncommon for the conception 
rate to be as high as 90 percent (Ensminger, 1951). The method 
of determining the conception rate for wild horses was not 


Within the body of literature on horses, there is inconsistency 
pertaining to the nature and length of the breeding seasons. 
The terms "polyestrous" and "breeding season" are often mis- 
interpreted. Mares can be classified into three categories, 
monoestrous, true polyestrous and transitory polyestrous. Wild 
breeds are monoestrous. They exhibit several estrous cycles 
during a restricted breeding season that coincides with the 
longest days of the year. Wild mares may show sexual receptivity 
throughout the year but they do not necessarily breed all year 
round (Berliner, 1958; Hafez et al, 1969). Clegg and Ganong 
(1969) report that domestic mares will breed at any season if 
they are well fed. When mares are maintained on grass they 
frequently show anestrous during the winter. They suggest 
that nutritional factors are partly responsible. The mare is 
predominantly a spring breeder; therefore she would be expected 
to respond to increasing rather than decreasing day length 
(Clegg and Ganong, 1969). A wild mare will go barren until 
the following year if she is not bred in the spring or early 
summer (Feist, 1971). 

Burkhardt (1947) studied the influence of light on the repro- 
ductive activity of domestic mares. He divided anestrous mares 
into four groups. One group received artificial illumination 
to increase day length. Another group was exposed to ultra- 
violet light applied to the flank and belly. The mares in this 
latter group had their eyes hooded. Estrous appeared in the 
group receiving extended day length about 30 days earlier than 
the control. The estrous cycle of those receiving light on the 
flank and belly was normal. The author suggested that since 
irradiation of the ovaries did not alter the estrous cycle, the 
receptor organ was probably the eye. Nishikawa et a_l (1952) 
exposed anestrous mares to increased day length from mid- 
November until the end of February. They concluded that light 
was a factor but not the only one controlling reproductive 
activity in mares. 

Hall (1972) says that the majority of mares in the Pryor Mountain 
herd do not enter estrous until they are three years old. He 
does not think that these horses have adjusted their estrous 
cycles to the optimum period for foal survival. He relates 
reproductivity to nutrition since the first foals (1971 and 
1972) were observed in April and the majority of the mares were 
through foaling by mid-July. When the horses have been on 
green spring forage a sufficient time for their nutritional 
state to improve they enter estrous. Their reproductive period 
starts at about four and ends at about nine years of age. 
Tyler (1972) reported that most pony mares foaled for the first 
time when three or four years old but some not until they were 
five years old. Very few of the 141 mares that were 3 years 
old or more foaled in each of the 3 years of study. Foaling 
in alternate years was common; so were abortions during the late 
autumn, winter and early spring. 


Sexual behavior in the stallion . There are three distinct 
phases of sexual behavior in the stallion: courtship, erection 
and mounting, and intromission and ejaculation. Sex drive is 
manifested throughout the year. Courtship is important for 
successful mating because the stallion depends upon erotic 
stimuli to achieve vascular engorgement of the penis. This is 
elicited by visual, auditory, tactile, and olfactory sensory 
modalities. The relative importance of these varies among 
species (Hafez et al, 1962). During courtship the stallion, 
after smelling the mare, exhibits the flehmen posture and some- 
times snorts or whinnies and nibbles or licks the mare before 
mounting (Hafez £t al, 1969; Feist, 1971; Tyler, 1972). True 
precopulatory behavior of stallions was often very brief. 
Usually it was longer with young mares than with older, more 
experienced mares. The older mares also rejected sexual advances 
by colts and bit or kicked at them when they attempted sniffing. 
Adult stallions chased colts away from adult estrous mares but 
allowed them to copulate with young females up to 4 years of 
age (Tyler, 1972). 

Blakeslee (1974) was told by the owners of the free-roaming 
appaloosa horses that they had observed only one instance of a 
foal being killed by a stallion, and this occurred in a fenced 
enclosure. Tyler (1972) stated that three stallions were 
probably responsible for the death of six foals and the injury 
of several others. She attributed these actions to frustration- 
induced aggression caused by mares (who were not in full estrous) 
rejecting the stallions' sexual advances. 

Proper copulatory patterns are apparent in many stallions at 10 
to 12 months of age. However, domestic stallions are generally 
not placed in service until three years of age (Enflminger, 1951; 
Hafez et al, 1962). In the Pryor Mountain herd, Hall (1972) 
states that the testes of stallions do not descend until they are 
three years of age. 

Reproductive activity in the stallion, like the mare, is also 
influenced by light. Reduced light diminished the quantity 
and quality of semen whereas increased light produced an 
opposite reaction (Nishikawa &t_ _al, 1952). 

Foaling . With normal presentation a domestic mare foals in 
fifteen to thirty minutes. The foal is usually born while the 
mare is lying on her side with her legs stretched out. In 
normal birth the front feet with heels down appear first, 
followed by the nose which rests on the front legs. The hind 
legs and feet are last (Ensminger, 1951). 

Blakeslee (1974) reported that she was advised by the owners of 
the free- roaming appaloosa horses that any birth on the open 
range lasting much longer than 10 minutes meant that the mare 


was having difficulty. Tyler (1972) observed a pony birth that 
was completed within 25 minutes from the time the mare lay down. 
Appaloosa mares generally gave birth while lying in an upright 
position with the forelegs stretched out in front and the body 
weight resting on the sternum (Blakeslee, 1974). New Forest 
ponies delivered while lying fully recumbent (Tyler, 1972). 

Blakeslee (1974) stated that appaloosa mares showed no preference 
for a birth site other than to tend to avoid the night grazing 
area because most mares foaled at night. Birth sites with 
respect to vegetation or topography were not determined because 
all observed births were on the winter range which was flat to 
rolling, and the surrounding vegetation similar. She also 
reported that appaloosa mares almost without exception isolated 
themselves before giving birth, and the dominant mares went 
greater distances from the group than the subordinate mares. 
Feist (1971) did not observe any births within the Pryor Mountain 
herd but did find foal skeletons in secluded areas. Tyler (1972) 
reported that pony mares chose a variety of birth sites, some- 
times secluded, sometimes near their group companions or close 
to busy roads. Dobie (1952) and Ryden (1971) stated that the 
only time wild stallions permit a mare to leave the group is when 
she is about to foal. 

Dominant appaloosa mares spent longer times at the birth site 
and did not rejoin their family groups with their foals as soon 
as subordinate mares. Mares in their last month of pregnancy 
or geldings sometimes adopted the foals of primiparous or 
subordinate mares. When this occurred the foal, being unable 
to nurse, usually died. Some parturient mares permit another 
mare to accompany and remain near them at the birth site. This 
associate is nearly always a mare without a foal of her own 
(Blakeslee, 1974). 

Reaction of other horses to mating . Tyler (1972) observed 
yearlings, foals and sometimes dominant pony mares attempt to 
prevent mating by either kicking at the stud or estrous mare or 
by placing themselves between the mare and stud. Feist (1971) 
observed other mares kicking at both the estrous mare and stud, 
and Blakeslee (1974) observed other mares kicking at the stud. 
Neither writer reported interference by foals or yearlings. 

Food Habits 

Probably the most important change that occurred in horse 
evolution was the transition from a browsing to a grazing 
animal. The teeth of early horses were efficient for eating a 
large variety of foods as long as the food was soft and did not 
wear down the teeth too rapidly. Early horses could not have 
lived on grass even if it were available because it would have 


worn out their teeth at an early age. As grasses became more 
abundant (determined from fossil grass seeds) many browsing 
animals unable to adapt, disappeared. The horse exploited this 
change by evolving teeth that permitted them to change from 
browsing to grazing. The present tooth pattern of equids 
developed during the Miocene and has not changed greatly since 
that time. After the new type of dentition was developed, 
horses could eat most any vegetable matter including harsh 
prairie grasses. Three main changes occurred: tooth patterns 
changed to permit grinding, crown height increased to give 
longer life to the teeth, and a cementum layer developed. The 
cement filled the valleys and pits in the teeth and prevented 
food from lodging and decaying; it also prevented the brittle 
enamel crests of the teeth from breaking. The tooth system of 
the present-day horse is highly specialized for eating grass 
which, due to its high silica content, is a very harsh food. 
As a result, the teeth of horses wear down rapidly. As they 
wear, the teeth in the upper jaw move down and those in the 
lower jaw move up so that a grinding surface is maintained at 
the same level. When the teeth are worn to the roots and can 
no longer grind, the horse will starve. Generally, however, 
most wild horses die of other causes before this occurs (Simpson, 

As the teeth of horses changed, undoubtedly digestive adapta- 
tions also occurred, but since fossil records leave no evidence 
this cannot be substantiated (Simpson, 1951). 

Although the horse is a grazer he can eat and apparently survive 
on a wide variety of foods. In various parts of the world 
horses are fed grapevines, leaves of lime, lawn clippings, 
garden refuse, garbage, bamboo leaves, and even dried fish 
(Ensminger, 1951). 

The digestive tract of the horse is smaller than that of a 
ruminant and is not able to handle as much roughage. However, 
since bacterial action similar to that in a ruminant takes place 
in the caecum and colon, the horse does not need high quality 
protein in its diet. This is not true of young colts, however, 
since much less bacterial synthesis takes place (Ensminger, 1951). 

The esophageal and intestinal opening of the horse are close 
together, thus water passes quickly through the stomach and 
small intestine. No food leaves the horse's stomach until it 
is about two thirds full. As the horse eats, partially digested 
food passes out into the small intestine in a continuous stream-- 
as a result, up to three times the capacity of the stomach may 
pass out during a large meal. Emptying of the stomach slows 
only when eating stops, and the stomach is never empty unless 
the horse has not eaten for several days. Some of the digested 
food is absorbed by the stomach but most absorption takes place 


in the intestines. Within the small intestine the food 
remains quite fluid and passes through rapidly. 

The large intestine is divided into five components: the 
caecum, large colon, small colon, rectum, and anus. Some 
bacterial action and synthesis of vitamins takes place in the 
caecum, but the greater part of digestion, including bacterial 
action and absorption of nutrients, occurs within the large 
colon (Hanauer, 1973). 

The efficiency of the extraction of protein from foods of 
various composition is similar for cattle and horses (Glover 
and Duthie, 1958). There are important differences, however, 
in the mechanism of digestion between horses and ruminants. 
The ruminant maximizes the use of protein at the expense of 
energy. The mechanical and chemical breakdown of plant cells 
within the rumen is so thorough that relatively complete 
extraction of the cell contents takes place. This process of 
recycling for efficiency limits the passage of food through 
the digestive tract. When the ingested food contains large 
quantities of lignified cell walls the rate of passage is 
slowed and the overall assimilation of protein may be quite 
low. Under these conditions the animal may not be able to meet 
its maintenance requirements unless it has the opportunity to 
selectively graze components of the vegetation that contain 
cells with thin walls and a high concentration of protein. 

In the horse, fermentation of cellulose occurs in the colon 
and large intestine, but the simple stomach remains the prin- 
cipal site of protein extraction. The slow process of cell 
breakdown that occurs in the ruminant is avoided and proteins 
are quickly assimilated as amino acids. The horse achieves 
almost equal efficiency with the ruminant in protein extraction 
through quantity rather than quality. Food passes through its 
digestive system almost twice as fast as it does in a cow; 
therefore, the horse can support itself on forage too low in 
protein to support a cow or other large ruminant, but it must 
maintain a much higher rate of intake (Bell, 1970, 1971). 

In general the smaller the animal the higher is its metabolic 
rate. However, there is a degree of overlap between ruminants 
and non- ruminants from the effect of body size on metabolic 
rate. For relative maintenance (per unit weight per unit time) 
small animals need more protein and energy than large animals. 
They will lose weight more rapidly and be less competitive than 
a larger animal if they are both on a submaintenance diet. The 
reverse is true for an absolute maintenance (per animal per 
unit time) diet. With equal quality of food intake the smaller 
animal needs less food and as a result has more time to eat 
enough for maintenance. The smaller animal can thus afford to 
be more selective in its grazing habits and survive on a 


sparse food supply that would starve the larger animal (Bell, 
1970, 1971). 

The year-round food habits of present-day wild horses have 
never been extensively studied. In some areas where these 
animals still survive, their habitat includes rough terrain, 
sparse vegetation and adverse climate. It is possible that 
the food habits of these animals are considerably different 
from the animals that live in less harsh environments. 

Hansen (1975, personal communication) reports that he has been 
unable to find a single scientific publication on the diet of 
the domestic or wild horse on pasture or rangeland. His 
studies indicate that, under ordinary range conditions, 80 to 
95% of the diet (on a dry-weight basis) of wild horses consists 
of grasses and grasslike plants and that they consume more 
browse than they do forbs. Appendix 6 lists some of the plants 
Hansen has found to be common in wild horse diets in the western 

Captured wild horses of both Asia and America do not readily 
change their dietary habits to include concentrated feeds as 
do their domestic counterparts (Hafez et al, 1962). 

Dobie (1952) wrote that captured wild horses preferred cotton- 
wood bark to grain and that they were very adept at pawing 
through snow for their food. Hall (1972) made random feeding 
site observations during 1968 and 1969 on the Pryor Mountain 
herd. The major food item during spring, summer and fall con- 
sisted of grasses. During the winter they utilized brushy 
species, primarily saltbush ( Atriplex spp.), rabbitbush 
( Chrysothamnus spp.) and big sagebrush ( Artemisia tridentata ) , 
along with any remaining grass. 

In Britain, Tyler (1972) conducted behavioral studies on the 
semi-wild herds of New Forest ponies. The herds are annually 
harvested for the sale of certain animals, primarily yearlings 
and foals, and the numbers of stallions are controlled. Other 
than this they lead a wild existence, remain free and forage 
for themselves throughout the year. 

Their habitat consisted of deciduous woodland, heathland, grass- 
land, valley bogs, and open water in ponds, ditches and 

The bulk of the ponies 1 food during the summer was purple moor 
grass, Molinia caerulea , along with small amounts of Agrostis , 
Festuca , Lolium and Cynosurus spp. Certain animals spent much 
time wading in ponds grazing Glyceria spp., Carex spp. and most 
small flowering plants. Bracken ( Pteridium aquilinum ) was the 
only other food plant eaten in quantity. Between autumn and 


spring, leaves and shoots of brambles (Rubus spp.), oak ( Quercus 
robar) and beech ( Fagus sylvatica ) were eaten. 

The normal daily pattern of the ponies was completely disrupted 
when acorns were abundant as they spent most of the day foraging 
for these. In 1964 the deaths of 42 ponies were attributed to 
poisoning from eating acorns. When snow was on the ground 
leaves of holly ( Ilex aquifolium ) and gorse ( Ulex europaeus ) 
provided almost the only food. These plants were grazed as 
high as the animals could reach (approximately 8 feet). 

The author reported that when hay was fed during the winter 
there were a few groups of ponies that never approached the 
hay piles and apparently did not recognize it as food. 

Feist (1971) spoke only qualitatively on feeding habits of the 
Pryor Mountain herd. Grass was preferred but in short supply 
so that the animals were forced to supplement their diet with 
other types of vegetation. Where water was abundant they ate 
marsh grasses, weeds and forbs. Among woody plants, he observed 
horses grazing the new growth of saltbush, greasewood ( Sarcobatus 
vermiculatus ) , black sage brush ( Artemisia nova ) and on rare 
occasions Utah juniper ( Juniperus osteosperma ) and mountain 
mahogany ( Cercocarpus spp.). He noted horses pawing up and 
eating the roots of winter fat ( Eurotia lanata ) and two species 
of milkvetch ( Astragalus kentrophyta and A. gilviflorus ) . He 
also reported sighting a mature, an immature and a yearling 
female eating old feces from a stud pile during the summer 

Appaloosa horses grazed for 1% to 3 hours before resting, and 
on the summer range they spent much less time grazing during the 
day than they did on the winter range. They were observed 
grazing practically all species of grass plus elk thistle 
(Cirsium spp.) and lichens and bark from quaking aspen ( Populus 
tremuloides ) . Although sagebrush, shrubby cinquefoil ( Potentilla 
fruticosa L.) and prickly pear cactus ( Opuntia polycantha Haw.) 
were abundant they were never observed eating these species 
(Blakeslee, 1974). 

When short of grass, domestic horses will eat leaves of trees 
and shrubs and peel bark from young trees (Smythe, 1966). 

Colostrum, the milk secreted by the mare the first few days 
after partruition, is very important to the newborn foal. It 
is not only different in chemical composition from the mare's 
normal milk but contains antibodies to protect against certain 
infections, and it serves as a natural purgative (Ensminger, 



Vision . The horse is color blind and sees the landscape 
ahead as a mosaic of various shades of gray caused by differently 
lighted areas. Its eyes are incapable of breaking up a visual 
image into individual items such as trees, grass, fences, etc. 
The horse recognizes movement through changes in brightness, 
tone, and the relationship of the moving subject to fixed 
objects. Any object that remains perfectly still may go 

The eyes of the horse are set on the side of the head so that 
each eye receives a different scene. When the images are 
superimposed the horse views a flat panorama. The eye lens is 
non-elastic and the retina is arranged on a slope with the 
bottom of the retina nearer the lens than the top. Neither the 
cornea nor the lens of the horse's eye is truly shaped, thus 
horses suffer from astigmatism; they have trouble focusing on 
a subject a little way ahead and therefore often mistake a 
harmless object as something dangerous. To focus on objects 
at different distances the horse raises or lowers its head so 
that the correct part of the retina is on the subject. Although 
the horse possesses eye muscles to turn the eye in various 
directions, they are seldom used primarily because of the posi- 
tions of the eye and the fact that the neck is long and moveable. 
Generous movement of the head is absolutely necessary if the 
horse is to focus its eyes properly. When grazing, the horse 
is able to view objects from every direction by moving its head. 
Objects to the rear can be seen between its legs. A horse sees 
most and farthest when it stands still with head erect and the 
forehead and muzzle perpendicular to the ground. In this 
position it can probably see all the landscape for several 
hundred yards around by alternate use of frontal and lateral 
vision. Horses move the head into position to look straight 
ahead and the ears point forward. When a horse is paying 
attention to objects on either side of the body it cannot see 
very well in front of the body; in like manner when it is 
staring straight ahead it cannot see what goes on on either side 
(Smythe, 1966). 

Smell and taste . It is often difficult to disassociate 
taste from smell in horses. Some horses will accept a strong 
smell and refuse on taste, whereas others will reject strong 
smelling substances without tasting. Domestic horses have a 
liking for salt, sugar, and honey. They dislike most strongly 
aromatic substances such as peppermint, eucalyptus, thyme, and 
fats or anything of a meaty nature. 

The true nostrils of the horse open into the nasal chamber which 
contains large turbinated bones that are very brittle and covered 
with mucous membranes. The nasal surfaces contain areas of 


closely packed smell buds and olfactory nerve endings. They 
also have a false nostril which runs upward as a blind pouch. 
Horses are nose breathers with the nostril size varying con- 
siderably among individuals. They do not open their mouths or 
drop the tongue until completely exhausted (Smythe, 1966). 

The muzzle of the horse is soft skinned, flexible and capable 
of receiving environmental stimuli. Sensory cells and nerve 
endings embedded in the connective tissues of the lips and 
nostrils plus the long bristling hairs that stick out in all 
directions are each capable of receiving sensory stimuli. The 
region of the lips and nose perform functions of the hand in 
man. The nose of the zebra is far more useful for orientation 
and warning against surprise attack than is the eye (Burkhardt 
et al, 1967). 

The soft palate of the horse is large and somewhat pendulous. 
It is used to block the open end of the larynx to prevent 
choking when the horse is eating or drinking. It may also drop 
into the pharynx and limit mouth breathing when the horse is 
exhausted or nearly so. 

Stallions have an acute sense of smell and can smell a mare in 
estrous at a considerable distance if she is upwind (Smythe, 

The horse's ability to smell distant water has saved the lives 
of many early riders. Old time mustangers, when following a 
band of wild horses, were very careful not to change their 
clothing because their odor would change. Most horses can 
smell snakes, and there are reports of a horse that could track 
deer. South American horses gallop about in the dark and avoid 
the burrows of hundreds of Vizcacha ( Lagidium spp.) holes, 
probably by smelling them (Dobie, 1952). 

Domestic horses will eat a great variety of drugs one would 
expect them to refuse. They are apparently unable to discrimi- 
nate between edible and poisonous plants and, being unable to 
vomit, they are unable to get rid of the poisonous ones (Hafez 
et al, 1969). 

Hearing . Horses hear over a great range of frequencies and 
can pick up sounds too slight for human ears. They have the 
advantage of a long neck and concave ears that can be moved in 
any direction to not only detect sound but also to pinpoint the 
origin. There appears to be a connection between the ears and 
nose of the horse because when the ears prick the nostrils 
dilate. When a horse's ears are laid back on the neck it is 
either a sign of temper or an indication of stress such as 
running hard. 


The pitch ranges of hearing in most domestic animals is known; 
however, horses are an exception. There has been little 
experimental work done on their hearing. 

Horses communicate with each other and other animals with a 
number of vocalizations and sounds. Mares communicate to their 
foals with a wide variety of low- toned whinnies, each of which 
appear to convey a different meaning (Smythe, 1966). Dobie 
(1952) states that the scream of a stallion is one of the most 
terrifying sounds in nature and constitutes a warning to all 
other animals and stallions within hearing distance. 

Domestic horses appreciate sounds from humans, and there are 
many stories of grooms who became famous by their abilities to 
calm frenzied horses by talking, whispering or hissing to them. 
Highly strung horses are often excited or alarmed by sounds 
that are unfamiliar such as escaping steam, fireworks, thunder, 
or even the rustling of paper. 

Horses can sense very slight ground vibrations through their 
legs and feet. When grazing, these vibrations are felt through 
the limbs, teeth, jaws and bones of the head. The footsteps 
of a man can be picked up long before they become audible 
(Smythe, 1966). South American gaucho horses which lived in a 
semi-wild state expressed great fear of Indian attacks. They 
would often come running home when an imminent Indian attack 
was still a day's ride away. A few frontiersmen trained their 
horses to fear the odor of Indians (Dobie, 1952). 

Tactile sensations . In order to maintain its normal body 
temperature of about 100.3° F., the horse sweats and shivers. 
It has the ability to sweat at a moment's notice from exertion, 
fear, or excitement. The muscular exertions expanded when 
working or running hard in such a large animal makes this a 
necessity. Sweat glands in the horse occur in the neck, certain 
parts of the back, the shoulders, axillae, and groin; however, 
there are no sweat glands in the skin of the limbs except 
between the hind thighs. Foam forms on the body and limbs 
after continued exertion when sweat pours from the suboriferous 
skin ducts, and there is a considerable amount of heat loss 
through water vapor from the breath. 

The ability of the horse to fairly rattle his skin to dislodge 
insects or when rising from the ground to remove adhering 
particles from the skin is well known. This is made possible 
by the panniculus muscle which covers the greater part of the 
body beneath the skin. The same muscle is involved in shiver- 
ing, which the horse uses to increase surface temperatures when 
it is cold. 


Many horses respond very rapidly and often vigorously to skin 
stimuli; the neck and shoulders, the skin of the lower limbs 
especially around the feet and the coronets, the heel at the 
rear of the pastern, and the skin on the ribs and flanks are 
very sensitive. Most horses appreciate scratching on the skin 
of the withers and gentle patting of the neck and face (Smythe, 

Horses have certain skin areas that are extremely sensitive to 
certain irritants, either vapor, solids or liquids. These 
include the lips and skin of the muzzle, the skin inside the 
elbows, groin, beneath the tail, the eyelids and their con- 
junctive areas, plus the skin surrounding the nasal openings 
(Hafez et al, 1969). 

Social Organization and Behavior 

General . Behavioral and social studies of truly wild horses 
are nonexistent, and it is only within the last decade or so 
that very limited attempts to study the wild horses of the 
American West has been attempted. 

Some form of close aggregation of groups of individuals or 
"clumping" is common among herbivores. Animals aggregate for 
protection from predators, mating, and facility in feeding. 
However, according to Allee's principle, each species has an 
optimum aggregation value. Densities above or below this value 
tend to act as factors in population regulation (Boughey, 1968). 

The social organization of wild horses is different than that of 
most ungulates. All wild horses belong to a harem or family 
group controlled by a dominant male, with the exception of 
adolescent males that have been ejected from the harem by the 
lead stallion, which form into small bachelor groups or bands. 
Any wild horse seen by itself is either an adolescent male, a 
male that has reached maturity and is trying to capture its 
own harem, or a crippled, diseased animal unable to keep up 
with the group. Hall (1975) states that a lone animal normally 
is an old stud that has lost his harem. He never observed one 
of these older animals in a bachelor group. 

Each harem also contains a top-ranking mare that governs daily 
activity. She leads the group to forage and water and is second 
to the stallion in command. Whenever the group runs to escape 
danger this mare takes the lead with the stallion bringing up 
the rear (Dobie, 1952; Ryden, 1970). Hall (1972) reported 
during the 1971 roundup of the Pryor Mountain horse herd that 
when a band was harassed, the lead stallion was the first to go 
off by himself. This was observed repeatedly. He also commented 
that the instinct to follow in wild horses was very strong. When 


a band lost its lead mare the remaining horses were often 
completely disoriented. 

The stallion's functions are to breed, keep the group intact, 
prevent social strife, defend against other males of the same 
species, and defend against any danger that threatens the 
family group (Dobie, 1952; Ryden, 1970). Hall (1975) doubts 
that the stallion will defend against any danger threatening 
the group other than that posed by a competing stallion. 

The protection and defense of a family group or harem by any 
animal has three main functions. It distributes the animals 
over the available environment, provides for the selection of 
the strongest male by fighting (which affects the progeny), and 
offers defense for the young (Lorenz, 1963). 

Stallions control their groups by biting, kicking, and by a 
threatening posture that includes elongating and arching the 
neck and weaving the head back and forth. This threatening 
posture is generally all that is necessary to make any member 
of the group obey (Ryden, 1970). 

Klingel (1972) states that a number of behavioral patterns are 
almost identical in the Equidae . In their social organization, 
however, there are considerable differences; two basic patterns 
exist. The plains zebra (E. quagga ) , the mountain zebra (E. 
zebra ) , the horse (E. przewalski ) and possibly the asiatic wild 
ass (E. hemionus) live in harem groups composed of one to several 
mares led by a dominant stallion. Surplus stallions form groups 
of their own. The young leave the family group in a set pattern, 
and do not establish territories. These social units move 
freely over their home ranges which they share peacefully with 
conspecifics. In opposition to this type of social behavior, 
Grevy's zebra (E_. grevyi ) and the wild ass (E. af ricanus ) dis- 
play no personal attachments between any individuals other than 
mare-foal relationships. The animals often occur singly, in 
stallion groups, mare groups, mare-foal groups and mixed herds. 
The groups are variable and their composition may change at any 
time. Some of the stallions are territorial but do not prevent 
conspecifics from entering their territory as long as they do 
not interfere with the mating activities of the territorial 
stallion. They only defend territories when there is an estrous 
mare near the boundary. Only the territorial male will court a 
mare at any one time because all the other males are subordinate 
to him. There is no order of dominance or leadership among 
adults. All adult individuals seem to be of equally low rank 
and only the mare and her foal ever search for each other when 
they are separated. 

Aggressiveness . Individual aggressiveness in vertebrates 
towards members of the same species is expressed in two ways: 


defense of a given territory and the establishment of hier- 
archies of precedence within social groups (Collias, 1970). 

Due to the potential danger, most mammals avoid fighting if 
possible. They generally resort first to aggressive display 
and threats which often result in submission or appeasement 
by the weaker opponent. Fighting seldom results in the death 
of the loser unless the environment is overcrowded. An unsound 
environment distorts the normal patterns of social behavior 
(Scott, 1958). There are many examples of increased aggression 
in crowded populations (Mathews, 1964). Crowding may also 
produce a reverse reaction when it exceeds certain levels, and 
animals may become passive and nonreactive (Southwick, 1970). 

When wild horses reached their peak numbers during the last 
century they often existed in crowded environments (Dobie, 1952), 
In the Pryor Mountains, Hall (1972) reports that they still do, 
which may account for the sometimes conflicting reports on 
behavioral patterns at different times and places among wild 
horse bands. 

Many stallions are very domineering and keep close watch over 
members of their group. Only during foaling will the stud 
permit a mare to leave the band so that she can find a secluded 
spot to foal (Dobie, 1952; Ryden, 1970). Hall (1972) reported 
that some mares appeared to be fickle and were observed away 
from their group for several days at a time. He also observed 
extreme variation in the amount of time mares remained away from 
the group during foaling (one day to several weeks). He attrib- 
uted this variation to the strength of her bonds with the group. 

If a mare with foal falls behind during an escape attempt the 
stud may kill the foal by breaking its neck or he may force the 
mare to abandon it. Studs also may often display threatening 
gestures toward humans while the band is escaping. If another 
stallion approaches the harem, the two stallions posture with 
tails arched and heads pressed together staring at each other 
until one backs down. If a fight ensues, they rear on their 
hind legs, ears back and mouth agape. They strike with their 
forefeet, bite for the jugular and often wheel and kick. During 
the encounter they shriek, snort and scream. If one falls he 
is stomped by the other. The winning stud seldom chases his 
rival for more than a short distance (Dobie, 1952; Hall, 1972; 
Ryden, 1970). 

The intolerance for other males is greater during the breeding 
season than it is at other times and reaches its lowest ebb 
during the winter months (Hall, 1972). 

All age classes of appaloosas threaten foals, but adult mares 
are more aggressive toward foals not their own than are other 


age groups (Blakeslee, 1974). All pony mares were aggressive 
to strange foals and either threatened, kicked or bit them if 
they came close (Tyler, 1972). Feist (1971) did not find any 
consistent pattern of dominant hierarchy among the individual 
mares of the various bands in the Pryor Mountain horses. Ex- 
hibition of authority by one mare over another appeared to 
depend on a particular situation and the superior dominance of 
the stud overshadowed any formation of hierarchy among the 
mares. Hall (1972), who spent a great deal more time with 
these horses than Feist, reported a definite recognizable 
hierarchy within each band and that, once established, it 
remained fairly constant. Blakeslee (1974) stated that, among 
adult females, neither age, size, weight, nor length of time in 
the group determined dominance. The only observed character- 
istic common to dominant mares was their tendency to be aggres- 
sive. Tyler (1972) noted kicking fights between pony mares on 
several occasions, presumably to establish or maintain dominance. 
The rank order of mares, once established, was very stable and 
a mare dominant over another mare in one situation was never 
subordinate to the same mare in another situation. It was 
also noted that a subordinate mare rarely challenged a previously 
established more dominant mare. The length of time a mare lived 
in a group was not important in determining rank, and a foal 
shared status with its mother only when it was close to her. 
The rank order of mares in any one group or where several groups 
were considered was a simple linear one, but with large numbers 
the order was complicated by triangular relationships within 
the hierarchy. In one group of eight dominant mares there was 
a significant correlation between their size and rank. However, 
this did not hold true with other groups and neither size nor 
age explained the high position of some mares in hierarchies. 

Dominance between stallions and mares varied. Stallions always 
dominated where food was concerned but not in all other situa- 
tions . 

Family groups . The number of mares, yearlings and colts 
controlled by a stallion varies. Dobie (1952) reports viewing 
as many as a hundred horses in a group but adds that 15 to 20 
was the usual size. Other reports state that normal groups 
consist of one to eight mares exclusive of colts and yearlings 
(Hoyt, 1886). Wild horse bands in the Pryor Mountains and in 
Nevada averaged three to four animals composed of a stallion, 
lead mare, subordinate mares, yearlings, or colts (Hall, 1972; 
Pellegrini, 1971). When wild horses are frightened or stampede, 
the bands may join together into one large herd controlled by a 
single stallion. However, the large bands again separate into 
individual harems when they stop running (Dobie, 1952; Ryden, 


Stallion colts are usually ejected from the band at an early 
age, about two to four years. The age at which they are 
expelled seems to depend on the aggressiveness of the dominant 
stallion. These young males may remain alone near where they 
were born until they can join up with a bachelor group. If 
they join together they are controlled by a dominant stallion 
in a loosely organized group. Early writers reported as many 
as 25 of these young males in a band. Later reports indicate 
two to five animals varying from two to five years of age. 
When stallions approach the age and size at which they can 
capture a harem of their own they may leave the group and 
remain alone (Dobie, 1952; Hall, 1972; Ryden, 1970). 

Hall (1972, 1975) stated that there was often a considerable 
interchange of animals between harems. Many such interchanges 
were observed in the Pryor Mountain study. He relates the 
interchanges and the small band size to the sex ratio (607 o males, 
407 o females) , and to overcrowding. He reported that in some 
areas in Utah the band size averages six animals. In these 
cases the sex ratio is about equal and there is no evidence 
of overcrowding. 

Klingel (1965) reported that family groups among the plains 
zebra (Equus quagga ) are extremely stable and are not held 
together by the dominant stallion. In five observed cases 
where the lead stallion disappeared, the groups remained 
together until subsequently taken over by another stallion. 

Sometimes large harems have two stallions; both may breed, but 
one is always dominant. When the herd is in flight this second 
stallion runs abreast and forward of the male in command (Dobie, 
1952; Hall, 1972; Ryden, 1972). 

Home range . In any discussion of home ranges or territories 
of America's wild horses it is well to remember that these two 
items may be those imposed or strongly influenced by man. Field 
studies that will enable us to understand the diversity of ways 
these animals use the space available to them are virtually 

Every species of mammal has a home range of some type. These 
home ranges may be stationary or they may change with conditions. 
The ranges often overlap and migratory animals may have more 
than one home range. A home range may be defined as the area 
over which an animal or a group of animals travel in pursuit of 
routine activity. It may have no clearly defined boundaries 
but it must produce the energy requirements of the specific 
group of animals that occupy it. It implies a self-imposed 
restriction of movement (Burt, 1943). 


Estes (1974) claims that the actions of zebras are found in all 
members of the horse family; therefore, the only truly wild 
member of the Equidae that may furnish clues as to how wild 
horses once lived is the plains or Burchell's zebra (Equus 
Burchelli). There are still over a half million of these 
animals on the savannah of northern South Africa and the southern 
Sudan. During their annual migrations herds of zebras may 
stretch across the grasslands as far as one can see. 

Plains zebras live in stable families, or harems, of mares and 
foals, with each family of six to sixteen members controlled 
and defended (mostly from other males) by one stallion. Large 
troops of zebras are made up of these units plus bachelor herds 
which mainly consist of immature stallions. 

Both Feist (1971) and Hall (1972) reported on home ranges within 
the Pryor Mountain herd. Hall observed that the ranges varied 
seasonally with an individual band using as many as five areas. 
He observed at least 17 bands of horses using the same area at 
least part of the time. These actions were attributed to con- 
gestion and lack of adequate forage. Feist reported that home 
ranges were relatively well defined and adhered to and only 
rarely did a band leave their home range. Pellegrini (1970) 
reported that the home range of the three bands most extensively 
studied in the Wassuk Range of Nevada confined their activity 
to cube-shaped areas, while the home range of lone horses was 
linear along the boundaries of two adjacent home ranges. Among 
the New Forest ponies, home range depended on the topography 
and the nature of the habitat. Four requirements for a home 
range were necessary: grazing area, shelter, water and shade. 
When these were close together the home ranges were often small 
(200 acres). The home ranges of the different groups were very 
stable and though they were often almost identical or overlapped, 
each group tended to use a different part of the grazing area 
(Tyler, 1972). 

When the wild horses were at their peak during the last century 
many writers reported large herds. Early maps of Texas marked 
the territory between the Rio Grande and Nueces Rivers as "vast 
herds of wild horses." A Franciscan missionary reported that 
when crossing an area uninhabited by people the wild horses were 
so abundant that their trails made the area look like the most 
populated in the world and that all the grass was gone. Within 
these large herds, however, the individual bands or harem groups 
retained their identity (Dobie, 1952). 

Lorenz (1963) lists several species of animals (bison, antelope, 
and horses) which do not maintain strict home ranges or display 
territorial jealousy if there is enough food for all. 


Indians depended on the home range instinct to hold their semi- 
wild herds on reservation lands, but not all horses reveal this 
trait and as a result many of them reverted to a wild state 
(Ryden, 1970). 

Mustangs confine their feeding and flights from danger to 
certain boundary lines. This fact was well known to plainsmen 
who made a business of catching wild horses (Cook, 1919). 

Smith (1841) stated that the genuine wild horse is migratory, 
moving north in the summer and returning in early fall. The 
mixed races (feral horses) move to pastures rather than to 
points of the compass. 

Territoriality . A territory in animal populations may be 
defined as that part of the home range which is protected from 
individuals of the same species either by fighting or by other 
aggressive action. Territoriality is so widespread among the 
vertebrates and in many of the invertebrates that it must be 
considered a basic animal characteristic. Although it is not 
found in all animals nor is it always developed within strict 
boundaries among the animals that possess it, the potential 
is there whether the animal displays the characteristic or 
not (Burt, 1943). 

There is only scant evidence to indicate the degree of terri- 
toriality displayed by wild horses. 

Pellegrini (1971), in his study of Nevada herds, concluded that 
wild horses establish a territory even though no special section 
of the home range exists as a defended area. Hall (1972) reports 
that horses in the Pryor Mountains do not establish territories, 
and he is convinced that they are not territorial. The indi- 
vidual bands maintain a "sphere of intolerance," an area near 
the harem or family group in which the dominant male will 
defend against other males. This "sphere" (the distance within 
which another stallion may approach the harem) expands during the 
breeding season and contracts after it is over. During the 
winter months it may be almost nonexistent. 

Feist (1971), reporting on the same herd of horses, concluded 
that the bands or studs do not exhibit territorial behavior. 
They do, however, maintain a spacing between bands. In all 
observations this spacing was related to distance between bands 
and never to the defense of a ground area. 

The dominant males of the plains zebra do not defend a territory. 
They control moveable property rather than real estate (Estes, 


Vocalizations . Waring (1971) states that social inter- 
actions are common among both feral and domestic horses. These 
interactions occur through visual, auditory, olfactory, 
gustatory and tactile cues. He warns against using any single 
means of communication out of context. To fully understand 
the importance of sounds, all other means of communication 
must be identified and understood. 

Using American Saddle Bred horses as subjects, he tape recorded 
their vocalizations, then by spectrographic patterns he divided 
them into seven basic categories. Identified were squeals, 
nickers, whinnies, groans, blows, snorts, and snores-- the first 
four vocal, the latter three non- vocal. Breed variability may 
exist, but it probably falls within the basic sound categories 

Squeals: express threats. Nickers: anticipatory sounds prior 
to being fed; stallions in courtship; and by mares when foals 
are in jeopardy. Whinnies: uttered during distress or inquiry. 
Groans: issued during discomfort or anguish. Blows: express 
alarm or aid olfactory investigation. Snorts: used in conflict 
situations-- they may express relief or disgust. Snores: pro- 
duced during inhalation, two types were detected--one of short 
duration uttered prior to emitting an alarm blow, the second, 
of longer duration, produced while the animal was prone. The 
author indicates that all of these sounds are used by either 

Feist (1971) identified four definite vocalizations in the 
Pryor Mountain herd: the snort, neigh, nicker, and scream. He 
observed the snort as a danger signal used mostly by stallions, 
seldom by mares. The neigh was used as a distress call primarily 
by mares and younger horses of either sex. Studs used the 
neigh to call animals that had strayed or when they were in a 
build-up to a fight. The nicker was used in closed communica- 
tion and courtship. The scream was emitted exclusively by 
studs during fights. 

Hafez et al (1962) identifies the snort as a danger signal, the 
neigh or whinny as a distress call, and the nicker as a sign of 
relief or for closed communication and courtship. 

Tyler (1972) reported that the squeal was most commonly uttered 
by mares when a stallion approached and sniffed them. Mares 
also squealed when fighting or when displaying aggressiveness. 
Stallions only occasionally squealed when fighting. 

Postures and facial expressions . Tyler (1972) states that 
six expressions are recognized in equids but they are not all 
seen in true horses. She describes five of these expressions 
among the New Forest semi-wild ponies. 


Ponies yawned by holding their mouths wide open with the upper 
and lower teeth exposed and ears forward. Yawning occurred 
before or after resting, when mares in estrous were being 
sniffed by stallions, in stallions after copulating, and in 
foals after suckling. 

The greeting expression occurred when two group companions or 
a stallion and a mare met; they sometimes extended their heads 
and touched each other's muzzle and lips. These often developed 
into threat postures when the ponies laid back their ears. The 
greeting expression was also used as a preliminary to mutual 

During the flehmen posture the animal extends its neck and curls 
the upper lip so that the teeth are exposed. Schneider (1930, 
1931, 1932a, b) described the flehmen in a wide variety of 
ungulates. Hafez et al (1969) states that this expression 
commonly takes place during the precopulatory patterns of many 
ungulates. Estes (1974) states that during the flehmen, urinary 
odors are apparently assayed in an accessory olfactory system 
specialized to detect concentrations of sex hormones. In the 
New Forest ponies (Tyler, 1972) the expression was always 
observed as a reaction to some smell: by stallions after 
sniffing a mare; by stallions, mares or foals after sniffing 
urine; by mares or other ponies after sniffing fresh placentae 
or by any pony at the sight of another showing the flehmen 
posture. Blakeslee (1974) stated that the flehmen posture was 
exhibited by foals, yearlings, and adults in a variety of 
situations other than smelling urine on the ground. The 
posture was induced by touching the nose of a horse with a 
human hand and by sight of another horse urinating, or by the 
sight of another horse exhibiting the flehmen posture. Feist 
(1971) observed 55 situations of this action in the Pryor 
Mountain herd. All of them were related to olfactory responses 
and all of them were by males. 

The threat expression is characterized by backward-directed 
ears and was first described by Antonius (1937). Tyler states 
that it is absent in asses, half-asses, and Grevy's zebra 
(Equus grevyi ) ♦ The true horses do not draw up the corners of 
the mouth as do the other species of zebra. In the New Forest 
ponies mild threats were exhibited by slightly laying back the 
ears, but intense threats were expressed with the ears flat 
back and sometimes the mouth slightly open, and occurred just 
before a dominant pony attempted to bite a subordinate pony. 
Stallions also used the threat gesture when driving mares by 
stretching the neck toward the ground, ears flat, and swaying 
the head back and forth. Ryden (1970) observed similar actions 
when stallions threatened or drove mares. 


Zeeb (1959) described the snapping expression. It is character- 
ized by stretching of the neck with the ears slightly back and 
down, the corners of the mouth drawn back partly exposing the 
teeth, and the lower jaw in motion up and down. Tyler (1972) 
stated that the expression was common in the New Forest ponies 
when foals or yearlings were threatened or approached by adult 
mares or stallions. It occurred in a variety of occasions, 
most of which seemed to be released by fear. Occasionally it 
was a response of foals and even yearlings to approaching cows. 
Although it was regarded as a submissive expression it had no 
effect in preventing older animals from carrying out their 
threats. Foals and yearlings were often bit or kicked by mares 
even after they had made the snapping response. Feist (1971) 
recorded 21 instances of this behavior by young males to the 
dominant stallion. Ordinarily the stallion made no recognition 
of the submissive behavior. 

Grooming . Domestic horses, unlike cattle, do not groom 
each other but they may nibble each other along the withers or 
stand head to tail and flick flies off each other's faces. 
Nibbling of the withers is usually a sign of recognition and 
often may be noted when two animals meet after an interval 
(Hafez e_t al, 1969). 

Trumler (1958) classified grooming in zebras as follows: local- 
ized muscle contractions; shaking; striking one part of the 
body against another or against the ground; rubbing (includes 
rolling); scratching; nibbling; and social or mutual grooming. 
Feist (1971) stated that mutual grooming was a common part of 
the daily activities in the Pryor Mountain wild herd, accomplished 
by pulling the lips back and using the incisor teeth to groom 
the neck, withers, base of the mane and on down to the rump. 
Horses also groomed one side, then switched to groom the other 
side. Mutual grooming occurred only between herd members and 
almost all grooming combinations were observed except between 
the stud and immature males. Tyler (1972) observed all the 
above forms of grooming in the semi-wild New Forest ponies. 
Mutual grooming was a response to insect infestations, shedding 
of hair, or as a means of social contact. Each pony had only 
a small number of partners with which it groomed. These part- 
ners were usually related, unrelated group companions, or 
members of two closely associated groups. The usual grooming 
partner of a foal was its mother, another sibling or another 
foal. Mutual grooming bouts were most often initiated by the 
subordinate animal and ended by the dominant animal. Mutual 
grooming was a common activity among all age classes of appa- 
loosas. All observations of grooming were within their 
particular group, and there was no consistent pattern of 
preference for certain partners (Blakeslee, 1974). 


Feist (1971) observed 81 cases of rolling, 50 of which were in 
dust and 31 in mud and water. Although yearlings and foals 
rolled, no female yearlings or foals were observed rolling in 
dust or mud. Dusting sites were scattered throughout the range 
and were used by all bands or horses that passed by. Ponies 
usually rubbed against fixed objects such as stumps, trees or 
wooden bridges. When insects were abundant they spent long 
periods stamping, kicking at their bellies, shaking and lashing 
their tails or rolling. Rolling often occurred at the end of 
a resting period or when they encountered wet grass after a 
rain, patches of bare ground or sawdust. No special sites were 
reserved for rolling (Tyler, 1972). Appaloosa horses choose 
specific pieces of ground for rolling places, and these were 
so well used that they were denuded of vegetation and covered 
with dust. Rolling in water was common for all age classes as 
was rubbing against trees or other fixed objects (Blakeslee, 

Play . Hie word play is a human concept applied to any 
activity other than work. The term is difficult to apply to 
wild animal activity or behavior; since animals do not work 
(in the human sense of the word) they cannot be said to play. 

Human play no longer has survival value; however, in animals 
it must be assumed that it does have value. Play occurs 
among animals only when they are free of environmental or 
physiological stresses. It is a widely held view that play 
is preparation for adult activity, and the animals that have an 
opportunity to play prior to becoming adults have a selective 
advantage over those animals that are denied this opportunity. 
However, it has never been clearly shown that animals prevented 
from playing are less efficient as adults than those that play 
(Loizos, 1966). Play increases locomotive skills and may be 
used to test social dominance (Hafez e_t al, 1969). 

Feist (1971) reported that play among foals of the same band 
and foals of other bands occurred regularly. This was tolerated 
by the studs if the juveniles returned to their own bands after 
playing. Play involved running, kicking, sudden stops and 
starts, and head tossing. Foals were observed playing at all 
times of the day but primarily in early evening when tempera- 
tures had cooled. Play among other age groups was rare and if 
started was quickly ended by the dominant male. Tyler (1972) 
reported that play in young foals took the form of the foal 
galloping to and from its mother or making irregular circles 
around her. It bucked and kicked as it galloped. Sometimes 
the foal reared up at its mother or pulled at her mane and 
neck. Young foals were very inquisitive and often sniffed or 
nibbled at strange objects and then rushed back to their 
mother. Play between foals did not occur before their second 


or third week. After this period, play between foals became 
more common. Foals nibbled, groomed, or chased one another 
and kicked out with their hind legs and bucked or reared as 
they galloped. The play of colts older than four weeks differed 
from that of fillies. Colts spent long periods play fighting, 
rearing, pawing and attempting to bite. Most play fights 
between colts contained all the components of true fighting 
between adults. Play between fillies which often ended as 
mutual grooming was much less common than play between colts 
or between colts and fillies. Both colt and filly foals showed 
interest in stallions and often attempted to approach them. 
Most stallions were very tolerant and usually ignored the foals. 
Play fights were observed between stallions and colts but never 
between stallions and colts over two years old. Blakeslee 
(1974) observed similar play among foals but did not report any 
differences between the play of males and females. 

Sleep and rest . In lying down the horse brings all of its 
legs under the body, bends its knees and hocks and permits the 
chest to touch the ground before the hind quarters. When down, 
the horse either rests on one side of its chest with a fore and 
hind leg underneath or it lies on its side with all legs 
stretched out. In getting up, the forelegs are stretched out 
first followed by the rear legs pushing up the hindquarters. 
The horse may sleep very soundly for seven hours out of twenty- 
four, mostly during the heat of the day. Horses sleep standing 
up or laying down; however, it is rare to see all horses in a 
group laying down at the same time; one is always alert (Hafez 
et al, 1969). Many horses sleep on their feet and some graze 
all night (Ensminger, 1951). Ruckebusch et al (1970) studied 
behavior and physiological responses of horses during sleep. 
They state that sleeping while standing was rare in experimental 
animals but appeared to be frequent in animals maladjusted or 
insecure in their surroundings. Dobie (1952) wrote that wild 
horses never lie down altogether, many sleep on their feet and 
lay down only to roll. He relates the story of an old-time 
horseman who told him that wild horses napped regularly three 
times during the night, at about nine, eleven and just before 
dawn. Feist (1971) observed a number of situations in which 
horses rested or were sleeping. Foals spent a great deal of 
time sleeping while lying down; this decreased as they grew 
older. Mature animals only occasionally lay down and no obser- 
vations were made of an entire band lying down. Yawning and 
stretching often occurred following sleep or rest. Pellegrini 
(1971) stated that horses in the Wassuk range of Nevada travelled 
little during the night. They either stayed near water or in 
sheltered areas, apparently sleeping most of the time. They 
also rested or slept in shaded areas during the day. Both foals 
and adults spend more time resting during the winter than in 
the summer (Blakeslee, 1974; Tyler, 1972). The latter author 
attributed this difference to increased food availability during 
the summer. 


Pawing . The original function of pawing was part of the 
horse's nutritive behavior and always occurred together with 
an olfactory investigation (Odberg, 1972). 

Horses paw through snow to obtain grass or they may paw to 
remove undesirable objects (stones, cactus) that interfere with 
or block their efforts to reach desirable forage plants. Paw- 
ing was also used to search for water from dried waterways 
where it was common for early cowboys to find holes dug by 
horses as much as eight feet deep. Pawing is also their means 
of breaking ice to obtain water (Boone, 1933; Dobie, 1952; 
Odberg, 1972; Smythe, 1966). 

Horses paw for various other reasons. They have often been 
observed sniffing and pawing the areas where they are about 
to roll. Pawing may occur during the threatening behavior when 
two males meet and they may also paw during courtship if thwarted 
in their attempts to mate. Pawing and sniffing often accompany 
investigation of stud piles. Foals sometimes paw when they are 
frustrated in their attempts to feed, and mares may paw before 
foaling. Domestic horses paw at the sight of unreachable food 
given by humans or while waiting for an action they feel or 
"know" is going to happen (before a race) , or they may paw from 
boredom or nervousness when they are in their stable (Boone, 
1933; Dobie, 1952; Odberg, 1972). 

Eliminative behavior . Vigorous adult horses defecate 5 to 
12 times, and urinate 7 to 11 times per day (Hafez e_t al , 1969). 
Tyler (1972) estimated frequency of elimination in the New 
Forest ponies. Adult mares defecated on an average of once in 
just over 2 hours and urinated once every 4 to 4% hours. Foals 
urinated about once per hour in the first week or so, but this 
gradually dropped to the same frequency as adults when they 
were about a year old. Stallions frequently sniffed piles of 
feces and then defecated or less commonly urinated on the pile. 
Sometimes they did this several times in succession on different 
piles of feces. 

Horses, unlike cattle, stop whatever they are doing to urinate 
or defecate. They maintain a characteristic stance according 
to sex when eliminating; and after elimination the stallion, 
but not the mare, smells the eliminative product (Hafez et al, 
1969). Ponies stopped grazing to urinate but merely raised 
their tails and continued to graze while defecating (Tyler, 

Feist (1971) believes that there is much more significance in 
the eliminative behavior of wild horses than there is in 
domestic horses. Particularly important is the action of the 
stud in relation to other horses in the band and to other 


studs. The stud's urination behavior is directed to excrements 
of the mare, whereas his defecation behavior is used primarily 
for the stud pile. Feist further believes that this behavior 
is dominance- linked. 

Blakeslee (1974) found no evidence of dominance display by 
appaloosa stallions connected with eliminative behavior nor did 
they accumulate stud piles like wild horses. 

Scent or visual boundary markin g. The fact that wild horses 
deposit their fecal matter in one place and thus create piles 
of manure commonly referred to as "stud piles" is well known. 
There is little evidence as to the exact purpose of this type 
of behavior. It may be a form of scent marking, visual boundary 
marking or both. 

Dobie (1952) gives an account of the many early explorers, 
historians, and others who were amazed at the numerous piles of 
horse dung that lined the trails used by wild horses on both 
the South American pampas and on the western prairie. He states 
that a stallion's dung piles constitute a visual and olfactory 
notice to other stallions that he had been there. 

Shenkel (1947) concluded that scent marking legitimizes the 
leader, marks his territory and aids in making new acquaintances. 
Lyall-Watson (1964) interprets scent marking differently, stating 
that scent marking aids the animal in maintaining familiarity 
with his environment and assures him that he is within his 
home range. This interpretation suggests that scent marking is 
not used as an aggressive display for territorial defense even 
though it would be effective in maintaining a territory. 
Pellegrini (1971) indicated that mares and colts also accumu- 
late dung piles and that these piles probably served as 
boundary markers. Hall (1972) discounts the purpose of stud 
piles for marking territory because the Pryor Mountain horses 
are not territorial and the piles appeared to be randomly 
scattered. Feist (1971) agrees with Hall. "If five bands 
passed by a particular pile on a trail or on a feeding area 
in one day it would be rare if all of the studs did not defecate 
with accompanying posturing on that pile." 

Zebra stallions mark only the feces of mares in estrous 
(Klingel, 1969, 1972). He suggested that scent marking in 
zebras is vestigial behavior and probably inherited from terri- 
torial ancestors. The same author later reported that the 
marking behavior of the non- territorial equids has no known 
function. Kleiman (1966) distinguished scent marking from 
true elimination by three factors, one of which was directional 
posture. Pony stallions, when marking, oriented their elimina- 
tive products toward other piles of feces. They often walked 
from one pile of feces to another stopping to eliminate on 


several piles. Stallions usually defecated when marking; mares 
and foals more commonly urinated (Tyler, 1972). Both Feist 
(1971) and Tyler (1972) reported that the amount eliminated by 
stallions when marking was controlled and expelled in small 
quantities, compared with true elimination. Feist observed 
stallions stepping over a mare's excretion and urinating in a 
short but strong blast. Stallions were also observed defecating 
up to three times during a short period while fighting. Tyler 
noted that there was no evidence that marking had any effect on 
other stallions. 

Water and watering behavior . There is no data available 
on the amount of water needed or consumed by wild horses under 
their various habitat conditions. (Ensminger (1951) states that 
the average domestic horse will consume about 12 gallons per 
day. Stoddart et al (1975) quotes from early research on 
domestic horses and lists 10-12 gallons per day. 

Among wild horses Feist (1971) noted no consistent watering 
schedule by any band. Generally each band visited a water hole 
once a day except during very hot weather when they watered 
twice a day. Over most of the range, horses were always within 
four or five miles of a water hole. The time spent at water 
holes rarely exceeded 30 minutes. Pellegrini (1971) observed 
territorial behavior of wild horses in Nevada at water holes. 
When two bands arrived simultaneously one band was dominant. 
The less dominant band did not water until the other band had 
left the area. Hall (1972) states that in the cooler months 
horses trail a considerable distance to water but during the 
warm periods of late June, July, and August they concentrate 
on water. Frei (1975) states that wild horses in eastern 
Nevada will trail as far as 10 to 15 miles to water and seldom 
stay any closer to water than three miles. When temperatures 
reach their maximum (95° F.) during the summer the horses water 
every other day. Actual drinking time generally does not exceed 
3-4 minutes per horse, and they rarely remain near the water 
hole more than 5 minutes after drinking. Appaloosa horses 
rarely remained long at watering places, usually no longer than 
a half hour. Although the horses used well worn trails going 
to and from water, they had no set pattern for time of arrival. 
They trailed to water at a certain time for several days in 
succession and then changed their schedule (Blakeslee, 1974). 

Charles Goodnight, a scout during the Civil War, told Dobie 
(1952) that wild horses, unless severely disturbed, did not 
graze more than five miles from water and that they watered at 
the same spot each day. During droughts wild horses of the 
South American pampas sometimes became so frantic that upon 
finding water they piled into it on top of each other, drowning 
and trampling to death large numbers (Dobie, 1952). Smith (1841) 


reports similar behavior in South American wild horses during 
drought periods. The thirsty animals trampled each other so 
furiously that thousands of skeletons lined their watering 
places. He suggested that these actions were probably a means 
of population control. 

Foal behavior . The following has been extracted from a 
paper by Waring (1970) who studied foal behavior in American 

Within seconds of birth the foal raises its head and assumes a 
sternal position. By pawing and by motions of the head and 
neck the foal attempts to move away from the mare; this drags 
the hind legs free of the mare's vagina and eventually severs 
the umbilical cord. 

Within 15 minutes the foal attempts to rise but often not until 
three-quarters of an hour has passed do the hind legs flex 
sufficiently to permit it to stand. The eyes, open at birth, 
show distinct binocular orientation by 25 minutes. The mare 
vocalizes to her foal within minutes after birth, and auditory 
orientation of the foal occurs within 45 minutes. The initial 
stance is unsteady and the foal shifts frequently to maintain 
its balance. Suckling motions have been observed within 55 
minutes. Nursing depends partly on the mare's willingness to 
stand still or position herself so the foal can find her 
nipples. Some foals nurse soon after standing and some do not 
succeed until almost 2 hours old. Defecation may occur prior 
to one hour of age and urination a few hours later. 

At one hour of age the foal commonly shows ability in standing 
and moving about, can see and hear, can eliminate, express 
curiosity and care-seeking behavior. During the second hour the 
colt perfects its walking and shows evidence of its attachment 
to its mother; the mare and colt may vocally respond to each 
other's sounds. Sleep begins as short naps and increases until 
it occupies much of the foal's early life. Fear of new objects 
begins. When it is two hours old, the foal may walk easily, 
lie down, nurse, follow its mother, vocalize, seek shelter 
beside her, express fear, and sleep. 

By half a day it can walk, trot, gallop, combat insects (by 
use of its tail or by kicking and nipping) , urinate in a 
manner characteristic of its sex, exhibit short periods of 
animated play, and consume small amounts of forage. The mare- 
to-foal bond begins soon after birth and is stronger than the 
reciprocal. When the two are separated, the mare may show 
extreme excitement, but the foal exhibits disorientation more 
than distress. 


Tyler (1972) observed foal behavior of the semi-wild ponies. 
Almost immediately after birth an observed foal had pushed its 
muzzle and a foreleg through the amniotic membranes. Within 
five minutes it attempted to stand, but this was thwarted by 
the mare's vigorous licking action. It stood within 33 minutes 
and suckled successfully 52 minutes after birth. Most mares 
began to lick their foals a few minutes after birth and con- 
tinued to do so for as long as a half hour. On the foals' first 
day the mares are very possessive and keep the foals away from 
all other ponies. On the second day the foals are usually able 
to recognize their mothers by smell, and the mares become less 
protective. A few foals ate or nibbled at grass on their first 
day, and some were observed in such activities as rubbing, 
rolling, scratching, stamping, shaking and nibbling. They also 
yawned and displayed the flehmen posture and snapping expression, 
First-week foals seldom strayed more than 25 yards from their 
mothers and even those up to 5 months old spent less than 107 o 
of their time more than 50 yards away from her. When a foal 
approached its mother to suckle, it often nickered, laid back 
its ears and tossed its head. The foal then moved in front of 
the mother pushing under her head before it attempted to suckle. 
It did this regardless of the direction of approach. The close 
relationship between the mare and her yearling continued even 
though the mare had a new colt. The yearling rested near its 
mother, groomed with her and followed her. Weaning usually 
occurred when foals were about a year old or at the time of 
the birth of a new foal. The author observed one pony mare 
which allowed her yearling to nurse after the birth of her 
foal, but considered this behavior atypical. Blakeslee (1974) 
stated yearlings were not generally allowed to nurse after the 
birth of the new foal. However, if a mare did not foal, her 
yearling frequently continued to nurse. 

Tyler (1972) reported that until their third or fourth month, 
pony foals, due to their short necks, straddled their forelegs 
to graze. The average amount of time spent. grazing by foals 
increased from 3.5 minutes per hour the first week to 16.3 
minutes per hour after the fourth month. Foals in their 
twelfth and thirteenth months spent a mean of 44.4 minutes per 
hour grazing. 

The author also reported that after birth, licking of the fetal 
fluids by the mare from herself and the foal seemed to be very 
important. After a mare has licked her foal, she is able to 
discriminate between it and other foals, and a relationship 
between mother and young becomes established. The great attrac- 
tion to the fetal fluids was shown by a pony mare whose colt 
fell into a ditch soon after birth. The foal was rescued and 
moved a few yards away from the mother, but the mare remained 
near the ditch and the placenta. When the colt was carried back 
to her she began to lick it and a normal relationship was 


Blakeslee (1974) stated that foals pull at and mouth various 
plants when one or more days old; however, they do not swallow 
the plant material until their teeth have cut through the gums 
at about the fifth day. Grooming in foals did not occur until 
they were about a month old, and the initial bouts usually 
were with their mothers. Very young foals had trouble drinking 
from streams, and it took them several days to learn to proper- 
ly spread their forelegs and retain their balance while drinking. 

Coprophagy in foals . Tyler (1972) reported that coprophagy 
was common in pony foals up to three or four weeks old. The 
feces eaten almost always belonged to the foal's mother, but 
on two occasions a foal was observed eating its own feces. 
Blakeslee (1974) also reported young foals eating feces, 
usually their mothers'. Older foals did not eat feces. Hafez 
et al (1962) report that adult domestic horses reject the 
feces of their own kind but that foals eat a considerable amount 
of fresh feces of adult horses. They attribute this behavior 
to the need for proper bacterial flora for the foal's intestines, 

Predation and Disease 

Predation. As far as is known, there are no scientific 
studies of predation on wild horses. The mountain lion (Felis 
concolor ) is the only large predator remaining within their 
habitat that is capable of killing an adult horse. It is 
possible that coyotes could kill foals if they were unprotected. 
Feral dogs, when hunting in packs, certainly have the capability 
to attack and kill horses, but whether they do or do not has 
never been reported. 

The only natural enemies of horses are mountain lions and wolves, 
All horses are afraid of bears but even in California where 
grizzlies were once numerous, they killed few horses. Wolves 
sometimes attacked horses but they preferred buffalo and after 
these were gone they turned to cattle. The natural prey of 
the mountain lion is deer, but once they had tasted horsemeat 
(especially foal) it became one of their favorite foods (Dobie, 

Young and Goldman (1946) cite instances of mountain lions prey- 
ing on horses in Arizona, Colorado and New Mexico. Raising 
colts and even maintaining a herd of adult horses was impossible 
in some areas due to lion predation. Once lions came addicted 
to horse flesh they often abandoned all caution. The writers 
also note that mountain lions are exceptionally fond of burro 

Diseases, pests and parasites . Outbreaks of diseases or 
infestations by pests and parasites within a wild animal popu- 
lation are often important indicators of other problems. These 


may be related to habitat, poor nutrition, overcrowding, 
competition, injury, harassment, or other reasons. 

The more common afflictions of domestic horses, unless other- 
wise indicated, have been adapted fromEnsminger (1951). It 
is possible that any one or more of the diseases could be 
present in or transmitted to wild horse herds. Symptoms, 
treatment and details are beyond the scope of this technical 

Equine abortion: Causes may be grouped into four categories 
those resulting from infection by Salmonella abortivoequina ; 
those from streptococci infection which gains entrance through 
the genital tract; a virus or epizootic type which is highly 
contagious; and those abortions that occur from miscellaneous 
causes which cannot be classified into the above categories. 
These may vary from accidents or injuries to nutritional or 
endocrine disturbances. 

Equine encephalomyelitis (sleeping sickness): a disease 
carried by 4 immunological, distinct filtrable viruses. It is 
vectored by 13 members of 3 genera of mosquitos of which Culex 
tarsalis is the most likely carrier. It may also be carried 
by spotted fever ticks ( Dermacentor venustus ) and assassin bugs 
( triatoma spp . ) . 

Equine infectious anemia (swamp fever): a very serious 
blood disease of horses and mules. It is caused by a specific 
virus that may stay in the host for years. Treatment has been 

Infectious adenitis: Also referred to as strangles or 
distemper, the disease is caused by a bacterial streptococcii. 
Transmission is usually by the inhalation or ingestion of the 
infected discharges. It is highly contagious and the organisms 
may live outside the animal's body for as long as six months. 

Glanders or farcy: A very old disease of bacterial origin. 
It may be diagnosed through the "mallein test." No cure is 

Dourine: A chronic venereal disease of horses and asses 
commonly termed equine syphilis. It is caused by a protozoa 
and is spread mostly through mating, but may be transmitted 
by biting insects. 

In 1930 the Bureau of Animal Industry reported that 177o of the 
wild horses on the San Carlos Apache Indian lands were infected 
with dourine. Later tests indicated 80% of the horses in the 
high country were infected. The Federal Bureau of Animal 
Husbandry removed about 500 horses from Nevada wild herds in 


1935 because of the presence of the disease (Wyman, 1945). The 
Bureau of Land Management in 1974 reported a suspected out- 
break of the same disease in wild horses near China Lake, 

Rabies: caused by a filtrable virus which usually occurs 
from injected saliva in a bite wound; an acute infectious 
disease of horses and all other warm-blooded animals, including 

Anthrax: also infectious to all warm-blooded animals. The 
bacillus of anthrax can survive in the soil for very long periods, 
It was the first disease in which immunization was accomplished 
by an attenuated culture by Pasteur in 1881. 

Tetanus: Caused by an extremely powerful toxin liberated 
by the tetanus organisms ( Clostridium tetanii ) . The organism 
is found in certain soils, horse dung, and sometimes in human 

Periodic opthalmia, or moon blindness: the most common 
cause of blindness in horses and mules. It is an inflammation 
of the inner portion of the equine eye and its associated 
structures. Horses of all ages are susceptible, and it may 
occur in one or both eyes (Roby et al , 1956). 

Parasites: The species and degree of harm vary in different 
parts of the world. They may be located in practically every 
tissue and cavity of the body. Some are specifically localized, 
others are migratory through different parts of the body. The 
most important of these are: the bot flies, of which there are 
three species; the strongyles with six species, the larger of 
which are commonly referred to as bloodworms or redworms; the 
ascarids or roundworms; two species of pinworms; four species 
of stomach worms; the screw worm, largely confined to the 
south and southwest; blowflies; ringworm; lice; mites; and 

Poisonous plants: Horses often eat and may be poisoned by 
many species of poisonous plants. Some plants may be eaten 
over extended periods before producing ill effects, others 
that contain acute poisons may produce visible symptoms or 
death soon after being eaten (Huffman e_t _al, 1956). 

In addition, horses are subject to colds, laryngitis, bronchitis, 
pneumonia and pleurisy (Hanauer, 1973). 


Competition and Relationships With Other Animals 

Competition . The extent, nature and degrees of competition 
between wild horses and other domestic or wild animals for 
habitat components such as food, water, space and cover or other 
requirements has never been investigated. Cook (1968), writing 
on the nutritive content of range forage for domestic ruminants, 
stated that the most critical period for grazing animals that 
inhabit seasonal ranges are those months between December and 
April when inclement weather and perhaps poor range conditions 
cause animals to lose weight excessively. When range conditions 
are poor, the degree of utilization of the forage increases 
and the digestibility and nutrient content decreases because 
animals are forced to eat the less nutritious parts of the 
plants. Thus nutritional deficiencies are common on winter 
ranges of the intermountain region. The above would also 
apply to wild horses in varying degrees over much of their 
range. Since wild horses are on the range year round, at some 
season or seasons they occupy the same range as domestic live- 
stock, elk, deer, and antelope. If, during these periods, 
forage is in short supply the various classes of herbivores 
will compete, and it is likely that the less dominant animals 
will suffer the most. 

Hansen (1975) does not think that wild horses compete strongly 
with mule deer ( Odocoileus hemionus) or antelope on most ranges, 
but he would expect them to compete with cattle since their 
diets appear to be 60 to 98 percent similar. They may compete 
moderately with domestic sheep, bighorn sheep (Ovis canadensis ) 
and elk ( Cervus canadensis ) . 

Both the Bureau of Land Management and the Forest Service 
report competition between wild horses, domestic livestock, 
and big game animals. Generally these reports have centered 
around forage supply. 

Cook (1975) states that in many areas where wild horses now 
occur the habitat is unsuitable for year-round feed requirements, 
Under the provisions of the Wild Horse Act they cannot be moved 
to suitable areas if that particular area did not previously 
contain wild horses. The author estimates that wild horses 
are increasing 20 to 30% per year, and under these conditions 
many of them will starve and the range will deteriorate. Cook 
feels that starvation, disease, and deterioration of the 
environment may not be acceptable management measures. 

Relationships with other animals . Documented information 
on the relationships between wild horses and other animals is 
extremely scarce. 


In 1828 a Mexican surveying party reported that between Laredo 
and San Antonio, Texas, deer and wild horses grazed together 
in large numbers. When wild horses were frightened and ran in 
large bands, they were sometimes joined by antelope ( Antilocapra 
americana ) (Dobie, 1952). Ryden (1970) stated that wild horses 
and buffalo ( Biso n americana ) often grazed together and that 
antelope used the horses for sentries to warn them of danger. 
During severe winters cattle often followed the horse herds so 
they could graze in areas the horses had opened up. Other 
reports conflict with these statements. Linsdale and Tomich 
(1953) reported that mule deer ( Odocoileus hemionus columbianus ) 
moved away when horses grazed too close to them. Both Blakeslee 
(1974) and Tyler (1972) wrote that free-roaming appaloosas and 
semi-wild ponies, respectively, dominated cattle. Tyler ob- 
served a yearling pony threaten a fallow deer doe ( Dama dama ) 
that was grazing near it. 

McKnight (1959) wrote that many of the respondents to his 
questionnaire stated that wild horses abused livestock, some- 
times killing or crippling them and sometimes excluding them 
from watering places. 

Wild Horse Management 

(The following sections on Population Management and Population 
Control were contributed by Milton Frei of the Bureau of Land 
Management, Denver, Colorado.) 

Population management . The management of wild horses 
presents a new challenge to public land administration agencies 
such as the Bureau of Land Management and the U. S. Forest 
Service. Heretofore management responsibilities of these 
agencies have been limited to animal habitat rather than the 
animals themselves. 

Although the concept of wild horse population management is a 
relatively new one, the principles of animal population manage- 
ment are well documented and can be applied directly to wild 

The first step in managing wild horse populations is to deter- 
mine the number of animals to manage in any particular area. 
The determination of this number must be based on available 
habitat and consideration of other animal species or resource 

Once the number of wild horses to be retained for management 
has been determined, the next step is to analyze those factors 
which have molded the population into what it is today. It 
must be true that over the long run, as many wild horses die 


as are born. This is the same scheme that nature has built 
into all of her animal species. Therefore, before management 
of wild horse populations can begin, the factors of population 
dynamics (productivity, mortality, sex ratio and age structure) 
must be collected and understood. These factors can then be 
analyzed to determine the forces which have shaped the popula- 
tion and to predict the numerical abundance of wild horses in 
the future. 

The first step in a wild horse population analysis is to deter- 
mine if the population is stable, increasing or decreasing. 
The following formula represents one method for determining 
the stability of a wild horse population: 

A = Estimated number of adults in population (1 year and older) 

B = Foal/100 adults (percent) 

F = Number of foals 
Zf = Mortality of foals (percent) 
Nf = Mortality of foals (number) 
Za = Mortality of adults (percent) 
Na = Mortality of adults (number) 

Y = Total population estimate (adults and foals) 

P = Projected population 

I = Population increase or decrease 

(A) (B) = F 
(F) (Zf) = Nf 
(A) (Za) = Na 

A + F = Y 

Y - (Nf + Na) = P 

P - A = I (increase or decrease). If P is less 

than A, reverse P and A in formula. Values 
will then be decrease in population. 

I = Population increase where P> A 

I = Population decrease where P< A 

Once the stability of a wild horse population has been deter- 
mined, it is necessary to analyze other population data prior 
to actual manipulation of the population. For example, if the 
population is determined to be increasing in total numbers and 
it is desirable to decrease total numbers, an analysis can be 
made as to the ratio of male animals to female animals in the 
total population. It may be possible to decrease the produc- 
tivity of wild horses by increasing the number of male animals 
in relation to the number of female animals. 


In another example, if the population is determined to be stable, 
it is important to understand the reasons why. It may be that 
births are equalling deaths or that the population is on the 
brink of disaster. In this example, an analysis can be made 
as to the age structure of the population. If the age structure 
is balanced (i.e. all age classes adequately represented), 
nothing more in the way of management need be done. However, 
if one or more age classes are lacking or totally missing, it 
may indicate that the missing age classes must be restored if 
the population is to survive. 

Population control. Control of wild horse populations 
differs from control of big game populations in that they are 
not a huntable or game species. Shooting of wild horses by 
persons other than officials of the Bureau of Land Management 
or U. S. Forest Service is prohibited by federal law and is 
socially unacceptable. 

Control of wild horses is also restricted in that it is a 
violation of federal law to use aircraft or motorized vehicles 
to capture or kill a wild horse. As a result, the only tech- 
niques available to capture the animals alive involve time- 
consuming techniques such as water trapping, dry trapping, 
roping and immobilizing. This is complicated by the fact that 
many areas are too rough or have too many water sources for 
these techniques to be effective. 

Disposing of wild horses which have been captured presents 
additional complications in population control. If animals are 
destroyed the problem arises as to what should be done with 
their carcasses. It is against federal law to convert the 
remains of wild horses into commercial use. If live animals 
are given away to private individuals for keeping under humane 
conditions, the problem arises as to transfer of title to the 
animal. It is not possible to transfer title to wild horses 
and as a result, many individuals are reluctant to keep a wild 
horse under those conditions. In addition, wild horses are 
just as their name suggests, "wild." Full-grown horses are 
very powerful animals and can be extremely dangerous when 
placed in the hands of unexperienced individuals. 

Methods of capture . Hall (1974) has prepared a paper on 
wild horse capture techniques based primarily on experience 
gained during the herd reduction program on the Pryor Mountain 
wild horse range. Rather than attempt to repeat, the reader 
is referred to this publication. The author states that many 
of the methods described will prove too costly in terms of 
manpower and money to capture large numbers of horses for 
population reductions. However, as far as is known, this is 
the only publication of its kind in existence. 


Other states, notably Wyoming, Nevada, and Oregon, have had 
experience in gathering wild horses. The Bureau of Land 
Management in Wyoming presented a paper to the National Advisory 
Board for wild, free-roaming horse and burros at their September 
1974 meeting in Reno, Nevada on the techniques and problems of 
wild horse capture. 

The methods used to capture wild horses after World War II and 
prior to the enactment of PL 92-195 have been described else- 
where. Methods of capture used by the early horse catchers 
included creasing, roping, snaring and running the animals into 
some type of corral or trap. Shooting a horse in the upper 
part of the neck close to the spinal column was termed creasing. 
The shock stunned the animal so that he was immobile until he 
could be tied. The method was more legend than truth. Old 
mustangers related that for every horse caught by this method 
fifty were killed. Horses were snared by attaching a loop of 
rope to a long pole. The rider rode alongside the horse and 
dropped the loop over his head. He then dismounted and choked 
the horse to the ground. Lassoing or roping did not become a 
common method of capture until late in the 19th century. Corrals 
or traps were of all types, depending upon the available material 
and the topography such as narrow canyons or ravines. Brush was 
often piled fan shaped as wings to guide the horses into the 
trap (Dobie, 1952). 

Hoyt (1886) describes wild horse capture techniques on the 
Texas panhandle. The horses were chased for 5 or 6 days by 
relays of saddle horses and riders until they were so exhausted 
they would mill rather than run when a rider approached. They 
were then roped and clog chains attached to their legs. Part 
of the clog was a free length of chain which wrapped itself 
around the forelegs if the horse attempted to run. All horses 
except yearlings and two-year-olds were clogged. The stallions 
were captured first and castrated at the time the clogs were 
attached. The horses were driven to water once a day and 
allowed to graze only at night so that they would spend the 
hours of darkness eating rather than attempting to escape. 

Ryden (1970) was told by old timers that early mustangers in 
the Wyoming Red Desert captured wild mares, tamed them, then 
sewed their nostrils together with rawhide until they could 
only partially breathe. The mares were then released to run 
with their old band. Since they could not run fast they slowed 
the whole band and the horses were easier to capture. Another 
method used was to bend a horseshoe around a captured mare's 
ankle and then release her. The horseshoe did not bother her 
when she walked but when she ran it banged against her other 
legs and slowed her. These mares were used over and over 


Both James and Catlin writing in 1823 and 1838, respectively, 
relate that the Comanches could tame and ride a wild horse 
within a day or so of capture. A small party of well-mounted 
Indians would hide in a narrow ravine or some other concealed 
area while the other members of the tribe would drive the horses 
into the ambush area. Each horse was captured with a lasso or 
noosed rope around the neck. They were then quickly thrown and 
their heels tied together. 

Wild horse management plans . Both the U. S. Forest Service 
and the Bureau of Land Management have developed plans for pro- 
tection, management and control of wild horses. Both agencies 
have land use planning systems that evaluate the resource and 
then develop integrated planning and management for all the 
multiple uses of the land area under consideration. These 
include the vegetative and watershed conditions, wildlife needs, 
livestock use, recreational use, and other legitimate demands. 

Current problems . From various reports these include: 
rapidly expanding populations that, due to the restrictions of 
PL 92-195, will demand costly and inefficient means of control; 
lack of biological data on wild horses; lack of valid censusing 
and population data; lack of funds and manpower needed for 
intense management; competition between livestock, elk, deer, 
and antelope for forage and habitat; problems of disposing of 
excess horses; management and control of horses on intermingled 
lands (federal, private, state or other ownership); stallions 
stealing privately owned mares; highway hazards (Wyoming Bureau 
of Land Management reports that at least 10 horses were killed 
by cars in 1974); and recreationists have complained of being 
chased by wild horses. 

Cook (1975) concluded that the Wild Horse and Burro Act was 
short sighted. The bill essentially has no control measures 
and as a result wild horses will continue to increase to the 
detriment of the resource; the bill should be amended to permit 
the use of aircraft by the agencies for roundups and control; 
the excess horses cannot be sold or given away; and there is 
no provision to permit complete removal of horses from some 
areas of unsuitable year-round habitat. 

Advantages of wild horses . There are certain advantages 
to having wild horses on the range. Due to their inefficient 
digestive system they aid in spreading plants by the distribu- 
tion of feces that contain viable seeds. Their feces distri- 
bution also fertilizes the soil and aids germination of seeds. 
Horses aid livestock and other herbivores by breaking ice 
covering water holes in the winter and help all animals by 
breaking trails through snow. They provide an esthetic value 
to the western range that has never been exceeded by any other 
animal (Dobie, 1952; McKnight, 1959; Ryden, 1970). Horses 


graze very selectively and can utilize grasses too coarse for 
most other domestic animals (Stoddart e_t ajL, 1975). The removal 
of coarse forage material exposes finer, more succulent feed for 
other herbivores. Frei (1975) claims that wild horses use 
range lands more efficiently than cattle. They travel much 
greater distances in search of forage and do not excessively 
utilize vegetation near water because they do not remain near 
watering sources for long periods like cattle. 

Disadvantages of wild horses . McKnight (1959) listed 
about a dozen problems associated with wild horse from respond- 
ents to his questionnaire. Heading the list was competition 
with livestock for forage and water. Other problems were com- 
petition with big game, overgrazing, trampling, heavy grazing 
during the spring, leading tame horses into the wilds, destroy- 
ing range improvements, tearing down fences, excluding other 
animals from water, molesting livestock, roiling or dirtying 
water holes, and breaking into cropland and grazing. Stoddart 
et al (1975) states that horses constantly seek fresh feed and 
are capable of cropping forage very closely because they have 
both upper and lower incisor teeth. When horses are confined 
in small pastures no other animal can match their impact. 

Research needs . All aspects of wild horse ecology need 
research, and so it is difficult to assign priorities. However, 
if management of wild horses is to be meaningful to the land 
managers in the near future, it would appear that research into 
year-round habitat requirements would assume great importance. 
Also desperately needed are data on population dynamics and 
competition with other animals. 

Current research . At present neither the Department of 
Agriculture nor of the Interior are funding any research on 
wild horses. Eastern Montana College at Billings, Montana, 
and Colorado State University at Fort Collins, Colorado, are 
presently engaged in wild horse research that is privately 
funded. Results have not as yet been published. 

Designated wild horse ranges . In 1962 the Secretary of 
the Interior established a 435,000-acre refuge for wild horses 
in southern Nevada. The area is northwest of Las Vegas in the 
northeast corner of Nellis Air Force Base. 

In 1968 the Secretary of the Interior established a 31,000-acre 
wild horse range in the Pryor Mountains of south-central 
Montana. The area adjoins the Wyoming state line and the 
Bighorn Canyon National Recreation Area. 


Legislation concerning wild horses and burros . Congress 
has passed two Federal laws to protect wild horses. Public Law 
86-234, passed in 1959, makes it illegal to use aircraft or 
motorized vehicles to capture or kill wild horses. Public Law 
92-195, passed in 1971, places wild horses and burros roaming 
on national resource lands under the jurisdiction of the Secre- 
taries of the Interior and of Agriculture Departments for pro- 
tection, management and control. It provides a penalty for 
harassing, capturing, killing, or selling wild horses, and 
prohibits the processing of wild horses into any commercial 
product. The maximum penalty consists of a fine of $2,000 and 
imprisonment for one year. The Act of 1971 provides for the 
establishment of an advisory board to make recommendations on 
the management and protection of wild horses and burros. 

Under the laws of the various states, wild horses are not 
recognized as game animals or wildlife. They are considered 
as "estrays" or abandoned animals and are not included under 
the provisions of the Taylor Grazing Act. 

Cooperative agreements for the protection and management of 
wild horses and burros are authorized between the Secretaries 
of Interior or Agriculture and state and local government 
agencies and with other landowners. 

Organizations concerned with the welfare of wild horses . The 
inclusion of all the people, groups, animal welfare organizations 
or others that have aided and supported the wild horse cause would 
be extremely lengthy. Therefore, the organizations listed below 
include only those that are directly and exclusively concerned 
with the preservation and welfare of the wild horse. 

1. American Horse Protection Association 
Washington, D. C. 20007 

2. American Mustang Association 
Phoenix, Arizona 

3. Canadian Wildhorse Society 
Richmond, British Columbia 

4. International Society for the Protection of Mustangs 

and Burros 
Reno , Nevada 

5. National Mustang Association 
Newcastle, Utah 84756 


6. Spanish Barb Wild Horse Research Farm 
248 N. Main Street 

Porterville, California 93257 

7. The Spanish Mustang Registry 
Oshoto, Wyoming 

8. Wild Horse Organized Assistance 
Reno , Nevada 

Glossary . All modern horse breeds are called either hot, 
cold, or warm bloods. The hot bloods, small, swift and tempera- 
mental developed from the Arab horse. The cold blood, larger, 
more placid, developed in northern Europe during the middle 
ages to carry armored knights. The warm bloods are a mixture 
of the two (Ryden, 1970). 

Hand - the system of measuring a horse's height. A hand is 
four inches or the width of an adult man's hand across the 
thumb. The term dates back to ancient times (Howard, 1965). 

Mustang - a corruption of the Spanish word Mesteno, which refers 
to an animal that belongs to everyone and not to any particular 
person. The term was first applied to horses that had escaped 
and became wild in the Southwest. In a short time all feral 
and semi- feral horses were referred to as mustangs. The name 
was also applied to certain domesticated horses. When feral 
horses were caught and broken, the word also came to mean cow 
pony (McKnight, 1959). 

Cayuse - the term applied to any horses that resembled Indian 
stock or to cow ponies that were wild. The name originated 
from the Cayuse Indians of Idaho (a tribe now extinct) who 
were known for the numbers of horses they possessed (Dobie, 

Estray - "any steer, heifer, bull, stag, cow, calf, horse, mare, 
gelding, or colt not wearing a brand (Ryden, 1970). 


Labeled Points or Parts of a Horse 












/ o 















Three Types of Lumbar Vertebrae Found in Horses 

'. O 











Coat Colors in Horses 

Adapted from Gremmel, 1939 

A. Basic Colors 

I. Black - body color is true black (disregarding weathering) 

1. Black - true black without light areas 

2. Seal brown - black with light areas to include 
muzzle, under eyes, flank, and inside of upper legs, 
termed "light points." 

II. Bay - shades from tan to brown, with black mane and 
tail and often with black lower legs: 

1. Mahogany bay - the brown shades of bay, often 
called brown 

2. Blood bay - the red shades of bay 

3. Sandy bay - the light shades of bay 

III. Chestnut - shades from yellow gold to dark brown, mane 
and tail not black but approximately the color of 
the body: 

1. Liver chestnut - the dark shades, some appearing 
dark brown with an auburn hue 

2. Sorrel - the red shades; sometimes in the lighter 
shades the mane and tail are of the color described 
as "crushed strawberry." 

IV. Ysabella - a color group having flax or silver manes 
and tails: 

1. Red ysabella - red sorrel-like; flax mane and 

2. Palomino - a golden yellow; silver mane and tail 

3. Pseudo-albino - very light cream to white; silver 
mane and tail; often have "glass" or blue eyes 

B. Color Patterns 

I. Gray - causes gradual displacement of colored hair by 
white hair as age advances: 

1. Iron or steel gray - usually a high percentage of 
colored hair, indicating a young animal 

2. Dapple gray - having the colored hair in such 
distribution as to give a dappled effect 

3. White - almost devoid of colored hair 


II. At certain ages gray, black roan, and gray roan are 
practically indistinguishable, but true genetic 
differences exist. Gray is foaled solid color; any 
roan is foaled roan; and gray roan whitens with age 
the same as does gray. 

Roan, a more or less uniform mixture of colored and 
white hairs, occurs in a number of combinations: 

1. Black roan - black and white hairs mixed, usually 
called "blue." 

2. Blue roan - usually described as black and white 
hairs mixed, but almost invariably having some 
red hairs. 

3. Bay or red roan - roaned bay. 

4. Chestnut or strawberry roan - roaned chestnut. 

5. Paint roan - roaning imposed on the colored areas 
of paint. 

6. Dun roan - roan in combination with the dun factor 

7. Gray roan - roan in combination with the gray 

III. Dun - always with dorsal stripe; often zebra stripes 
on legs and transverse stripe over withers and 
shoulders; coat appears diluted: 

1. Mouse dun - dun imposed on black, seal brown, 
dark mahogany bay, and dark liver chestnut, giving 
a smoky effect. 

2. Buckskin dun - dun imposed on blood and sandy bay. 

3. Claybank dun - dun imposed on sorrel. 

IV. Paint or pied - irregular colored and white areas: 

1. Piebald - white and black 

2. Skewbald - white and any color other than black 

Gray, roan, dun, and pied or paint may be in any 



Movement on Land 

Adapted from Tricker and Tricker, 1966 



Three Gaits of the Horse, Drawn from Cine Film 



Evolution of the Horse: Teeth, Skulls and Feet 

Adapted from World of Wildlife 











Br — a^cQ i 












Plant Species Comprising at Least 2% or More of the Diet 
of Wild Horses in the Southwest Desert Vegetation Types 
Adapted from Hansen, 1975 

Scientific Name 

Common Name 

Agropyron spp. 
Bouteloua spp. 
Hilaria mutica 
Koelaria cristata 
Leptochloa dubia 
Muhlenbergia spp. 
Setaria macrostachya 
Sporobolus spp. 
Atriplex spp. 
Prosopsis julif lora 
Salsola spp. 


grama grasses 

Tobosa grass 

prairie junegrass 

green spangletop grass 

muhly grass 

plains bristlegrass 

dropseed grass 



russian thistle 

Plant Species Comprising at Least 2% or More of the Diet 
of Wild Horses for the Foothills and Northern Desert Shrub 
Vegetation Types in Western States 

Agropyron spp. 
Bromus spp. 
Carex spp. 
Juncus spp. 
Elymus spp. 
Festuca spp. 
Koelaria cristata 
Oryzopsis hymenoides 
Poa spp. 
Stipa spp. 
Allium spp. 
Amelanchier spp. 
Artemisia frigida 
Artemisia spp. 
Cercocarpus spp. 
Chrysothamus spp. 
Eriogonum spp. 
Eurotia lanata 
Leptodactylon spp. 
Lupinus spp. 
Phlox spp. 


brome grass 



wildrye grass 

fescue grass 

prairie junegrass 

Indian ricegrass 


needle and thread grass 

wild onion 

service berry 

fringed sagewort 


mountain mahogany 




prickly phlox 





The Spread of the Horse to the Western World 

Adapted from Smith, 1969 

The spread of the horse 

5AM RAFfttl 




to the western world 



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