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H. Wiesner and B. Rau


Keeping and breeding Przewalski horses have a long tradition in Hellebrunn, going back to the year 1932 when the first 3 animals arrived. From this time up to the year 1984 a total of 98 Przewalski horses were born. No doubt, keeping such a rare animal as the Przewalski horse over several generations signifies a great obligation for a zoo and the main measure of the success of the management of this ancestor of our domestic horse is correlated with the breeding success of the herd.

If we compare the different stages of breeding results in Hellabrunn we will see that these results vary considerably, especially during the last two decades, when we bred only 15 foals from 1965–75 and 28 foals from the years 1975–85. Such results give some idea about the sterility control programme of our group.


For the individual care of these precious horses, we keep the animals in an open stable system, protected against wind and rain, which makes it possible to get the horses alone or together in small groups. During the day in the zoo, the horses have access to a large open enclosure of 4400 m2 (Wiesner and Bostedt 1979).

In the years 1979 and 1983, we got two additional paddocks with 2 ha each 30 km outside Munich, that can be used to raise the yearlings under optimal paddock conditions or to establish another stallion group. In these enclosures a separation of the horses is not possible.

In this case we experienced that selective food preference by the stallion and the mares is greater than that of younger ones and leads to uncontrolled feeding. Therefore the stallion and the older mares are inclined to become too fat and the females may become sterile due to this overfeeding.

We have to point out that in any case for adequate housing and management of the mares and the foals the separation possibility during the night is essential. This gives the only possibility to feed each animal individually and also to check and control the health daily.

We assume that this kind of housing also should be recommended during at least the first two years of the reintroduction, then we would suggest to release the animals in a larger enclosure and finally, step by step to the wild. Only by this controlled possibility, especially with possible predators like wolves in the background, unnecessary losses can be avoided, until the animals are well adapted to the climate.


The food consists of 1–1.5 kg pellets (rawprotein 15%; StE 480; rawfiber 22% ca. 1,3%; P 0.5%; 12 500 I.U. Vitamin A; 2000 I.U. Vitamin D3 ; 250 mg Vitamin E per kg), 500 g - 1 kg crushed oats and depending on the time of the year, fresh lucerne clover hay and lucerne crops.

Two years ago we also started with corn silage with an additional dosage of 300 mg Vitamin E per day. We stopped this type of feeding in the last year, when we got the impression that our animals became too fat, especially in the paddock where individual feeding is not possible.

By the way, we say in our herd of dama dama the same problem and they interrupted their usual breeding for one season when fed with corn silage. Przewalski horses seem to be sensitive to white muscle disease. We provided the animals with 100–150 g of a Selenium containing vitamin - mineral mixture (500 000 I.U. Vitamin A; 40 000 I.U. Vitamin D3; 5000 mg Vitamin E per kg and 10 ppm Selenium). Sine this prophylactic measure we had no more cases of selenium deficiencies in the horses (Wiesner and Bostedt 1979; 1984).


According to our general schedule for the prophylaxis of wild animals, we also vaccinate our Przewalski horses but only against such diseases that have already occurred in our herd. All animals are routinely vaccinated via the blow pipe method against virus abortion and tetanus.

The animals in the outside paddocks are also protected once a year against rabies, which occurs in the fox population of this area. There is no special vaccination or serum treatment of the foals against the lameness infections caused by -harmolytic Streptococci and Staphylococco. The normal youngster prophylaxis consists of 10 ml SelepherolR s.c. on the second day of the birth (1 ml Selepherol contains 0.2 mg Na-Selenit, Vitamin E-acetat 0.04 g; Vitamin D3 5000 I.E.; Cogluconat 0.02 g; Cu-gluconat 0.02 mg; B12-Komplex 0.13 mg). No anitbiotics or sulphonamides are given to the foals for controlling any hypothetical new born diseases. In the last 10 years, we did not lose a single foal by infections or any other disease.

During the first year, the foals are checked for parasites by regular faeces control and treatment. We also deworm our foals with mebendazol (10 mg/kg 3 days) or fenbendazole (5 mg/kg 3 days) every two months, even when the faeces control has a negative result.

Since 1985 we also use Ivermectin by blowpipe darts with good results. The dosage is 1 ml/100 kg, i.e. 0.2 mg Ivermectin/kg body weight. This therapy is efficient and simple if a singular animal or the foals are standing with their mothers instead of treating them alone. No side-effects like muscle swelling or other incompatability reactions have been observed.

Periodically, perhaps every 2–4 years, we have had infestations by Mallophagae (Damalinia equi), which we treat by a distance therapy with a motor syringe with 0.2% Hexachlorcyclohexan solution. This should be done once a week for six consecutive weeks, to be sure that all parasites are definitely killed, as all the larval stages like the nymphae do not respond to the HCH treatment. Generally we can conclude that we do not have many infectious diseases in our experience to contend with in the re-establishment of the wild horses in the native habitat.

This corresponds with the results of post mortems from 210 captive Przewalski horses which died from 1943–1980 (Ashton 1984).

It may be that Malleomuces mallei could play a negative role in this matter. Of course, the conditions sine qua non for the reestablishment, besides top condition, would be for parasite free animals, checked monthly by several faeces samples during 6 months before their transport and given an adequate worm cure in positive cases.


Since the good breeding results we have had after the control and treatment of our mares in the years 1976/77, we check all the mares regularly, which fail to become pregnant after a 3–4 time covering rate. The gynaecological examination is performed after an appropriate immobilization. During this examination functioning of ovaries and uteri are rectally investigated and the organs are checked for pathological conditions. For the first several examinations in the lying down position of the skilled operator in rectalizing wild horses some experience of this unusual position is necessary. Therefore we also recommend training on other wild equidae like zebra, kilans e.a. Then in addition to this, due attention should be given to hygiene, the vagina should be examined by palpation and visual inspection in order to obtain a complete clinical picture. Samples from the cervix and uterus can be taken, followed by bacteriological and histological investigation, in order to enable comprehensive judgements of the state of fertility.

For the technical performance a Polanski-speculum with a light source as well as an instrument for taking samples like a knudsen katheder should be used to collect bacteriological and histological material for investigation. All these inflexible instruments can of course only be used on a well fixed animal that has been properly immobilized.

In positive cases, for example, an infection with β-haemolytic streptococci, a treatment with antibiotics is indicated. Also the stallion has to be medicated in a similar way.

According to the International Studbook, only 5 mares from the imported 20.19 Przewalski horses by Hagenback in the years 1901–1902 had become pregnant, the other 14 of them were sterile. Only one other mare “Lori”, born 13.7.31, studbook-nr. 198, imported from Askania Nova in the year 1932 had a further influence on the Hellabrunn Line. If we compare the old pictures of these imports with a healthy yearling of today there is no doubt in the mind of a clinically experienced wild horse breeder, that all these animals were in a bad condition probably due to the long stressful transport and due to severe malnutrition. With such animals, you can rarely achieve breeding success and we can be glad that some of these animals have become proven breeders. But on the return trail we want to assure the re-establishment of these wild horses in their native habitat, and we should avoid making similar mistakes like those of 70 years ago.

Therefore only gynaecological and andrological checked animals should be allowed to participate in this project. Maybe the actual inbreeding coefficient in the Przewalski horses of the Hellabrunn Line is quite high, as all our living horses definitely go back to 6.3 individuals (stallions Pascha, Neville, Severin, Sidor, Simon, Sindbad, mares: Lori, Roma Sidney).

That is by the way the reason we exchanged the Prague stallion “Bars” with our “Simon” in the year 1984, to get in the blood of Orlitza III! Further we have to consider that all the living ca. 600 Przewalski horses in the world go back to 5.8 animals, including the Mongolian domestic mare. This fact also results in a high inbreeding coefficient. But before we discuss deleterious genes, first of all we have to check the animals according to the best and most modern clinical methods we have available. Malnutrition, Vitamin or trace element deficiencies, mismanagement, like small enclosures, stress etc. can lead to multi-follicular activity of the ovaries: an untreated mare would be lost for breeding forever, and this we cannot afford. Nobody will refuse biological manipulation to avoid losses in the foals through parasites. Thanks to a problemless immobilization and the progress in sterility control we are able nowadays to avoid the loss of potential genetic material of a single mare suffering from β-haemolytic streptococci infection of the uterus.

According to our good results in Münchener Tierpark Hellabrunn we can demonstrate the effectiveness of this sterility control with 3 females in our herd. The mare “Rocette”, born 1965 (studbook-nr. 338), has regularly given birth from 1974–76, but did not foal in 1977. The sterility control showed a disturbance of the ovulation in the sense of multi follicular activity. The vaginalscopy view and the uterine mucus sample pointed to an additional endometritis, caused by β-haemolytic streptococci infection.

The animal was treated and gave birth to a female foal in May 1978. Since this date up to 1984, she has given birth to a foal every year without any more treatment and is highly pregnant at the moment, covered by the Prague stallion “Bars”.

The second mare “Silka”, born 1965 (studbook-nr. 340), showed at the examination small, almost strophic ovaries. Until the time of examination no one had ever seen her in heat, she had no offspring. After adequate treatment, she foaled regularly from 1977 to 1984 every year except 1981. Her first male offspring “Sindbad”, born 10.6.78 (studbook-nr. 777 Hell 77) successfully sired the mare “Siena”, born 18.6.79 (studbook-nr. 848) and the female foal “Sierra”, born 4.5.83 (studbook-nr. 1115) was born. Also her daughter “Simona”, born 8.5.77 (studbook-nr. 703 Hell 74) was successfully covered by “Simon” (stud-book-nr. 411) and gave birth on 27.4.82 to “Sikkim: (studbook-nr. 1037), which is now in Leipzig zoo. This proves a normal physiological condition of the reproduction organs in both sexes of the Fl generation of the treated animals.

Even in older mares sterility control can be helpful. In the year 1977 we also treated “Sira”, born 1957 (studbook-nr. 173), because of disturbances of her ovarian activity. This 20 year old mare corresponded well to the therapy and gave birth for 3 consecutive years to three healthy foals “Silvio”, born 20.7.78 (studbook-nr. 787), “Sigurd”, born 4.7.79 (studbook-nr. 853) and “Sitka”, born 8.7.80 (studbook-nr. 932) and we are sure that we owe her last three foals only to our sterility control. We can be sure that also in the former breeding decades of Hellabrunn, sterilities caused by multi-follicular activity occurred but have not been reported for lack of an exact autopsy. Only since 1972 regular post mortems have been done. The mare “Sinella” (born 10.6.67, studbook-nr. 378), which died 3.5.73, showed also cysts on her ovaries and had never foaled in her life. No doubt this sterility is a severe problem in Przewalski horses.

In two other mares, “Koketta”, born 1963 (studbook-nr. 297) and “Kolette”, born 1962 (studbook-nr. 274), which we took over from Copenhagen zoo in the year 1979, the prognosis for a successful treatment has been dubious so far as both mares have never been successfully covered in their lives. There is no doubt that such a therapy for wild horses aged over 15 years is similar to domestic horses, and is quite problematic, but should be performed in any case to utilize the smallest chance in breeding Przewalski horses to keep their gene pool as big as possible.

Therefore, all the mares between 5 and 20 years which show some disturbances or irregularities in fertility, should undergo such a sterility controlled programme.

To conclude our experiences in the sterility control of Przewalski horses with regard to starting a re-establishment programme in their native habitat, we would like to recommend:

  1. All the fertile mares which will be used for the re-establishment programme should submit to a sterility control described by an experienced operator.

  2. The younger females, which are still not fertile, should be checked in the 5th-6th year of their lives, in case they have not been successful in breeding.

  3. Only stallions should be used which are from a β-haemolytic streptococci free breeding.

  4. The first and the second pregnancy should be under enclosure conditions, which enable a post parture sterility control.

  5. Only mares should be released totally in the wild which are proven breeders.

  6. Only stallions over 6 years of age and proven breeders should be re-established in their native habitat.


Ashton D. 1984 A survey of diseases of the Przewalski Horse. Equus 2, Heft 2, 179–188.

Wiesner H. and Bostedt H. 1979 Zur Sterilitätsbehandlung beim Przewalski-Pferd, Zschr. Kölner Zoo, 22 Jahrg. 2:55–58.

Wiesner H. and Bostedt H. 1984 Further investigations on the sterility of Przewalski Horses. Equus 2, Heft 2, S. 150–154.


V.V. Klimov


The ethological structure of the band of Przewalski horses includes hierarchic ranks of horses which determine their social roles in the band. Besides the age ranks, the wild horses are characterized by the formation of harem groups, a “leading” group of females, a group of bachelor stallions, groups by relations, etc. The ethological structure determines the spatial one which is the form of distribution of horses over the territory, its assimilation and transformation into a system of informative-spatial units. Under the influence of “internal” and “external” stimuli, the intragroup regulatory mechanisms (social adaptations) manifest themselves allowing the band to function in the complicated situation of the reserve and man to control the band while using these mechanisms. There are grounds to believe that, given the balanced ethological structure of groups, wild horses will be able to become successfully acclimatized in natural biotopes.

The necessity to preserve genetic pools of rare animal species calls for careful studies of their biology and interaction with the environment. This also holds true in the case of the Przewalski horse (Equus przewalskii Poljakov 1881) - the last wild representative of the Equus subgenus already vanished from nature. Wild horses preserved and bred in captivity in isolated groups are being prepared for reintroduction into natural biotopes which accounts for the special interest in the least-studied aspects of their vital activity, i.e. the socio-demographic and spatial forms of population organization, as well as mechanisms of population homeostasis in contacts with the changing environment. Especially important are studies into the action of these mechanisms in captivity - that is in zoos and reserves having a specific impact on behaviour, reproduction cycle and morphology of wild horses (klimov and Orlov 1982).

Rather fragmentary and incomplete data available on the ecology of Przewalski horses in nature can be summarized as follows. Until their migration regime had been disturbed by man, wild horses moved freely across central areas of Asia following precipitation which increased vegetation. In winter, they went to the northern mountainous areas of the Mongolian Altai and in summer they came down to the valleys, choosing foothill steppes, pebble and sand deserts of Jungaria that were most rarely visited by man (Grum-Grzhimailo 1896; Klements 1903). The horses keep in harem groups of 15–20 animals but may also form large herds of 100 and more. Stallions banished from bands form bachelor groups. In the daytime, horses stand waiting for the heat to subside and at dusk and night they begin foraging and watering. Their presence is clearly manifested by noticeable pathways and heaps of excrement (Grum-Grzhimailo 1896). Of considerable interest is the behaviour of stallions, who display force and courage not only in fights among themselves but also attack predators and man being able to find their bearings in complex and continuously changing situations while defending the band and directing it (Grum-Grzhimailo 1896; Klements 1903).

Note: References in this paper are found in the list of papers at the end of this publication.

Despite the 80 years of captivity there is a relatively small number of published papers on wild horses' biology and behaviour.

In the Askania Nova reserve, a band of Przewalski horses is kept in a corral surrounded by a 2 m high wire-net fence with a total area of 2660 hectares. The band comprises 40–43 animals, including 3–4 adult males, 2–4 semi-adult (2.5–3.5 year old) males, 3–4 two year olds, 3–4 yearlings and 3–4 newborn males; 14–15 adult females, 3–4 semi-adult and 3–4 two year old females, 4–5 yearling females and 4–6 newborn females.

Permanent observations of activities of the band of wild animals that provided material for the present paper were carried out in 1980–82.

The type of foraging activity and the nature of the use of the reserve's territory by horses depend on a number of factors sub-divided by us into two categories. The internal factors include the requirement of horses in forage and the socio-demographic structure of the group. The external factors comprise biotic (neighbouring groups of horses, gnats, the type of rangeland, the stage of vegetation development, etc.), abiotic (climatic conditions, relief features, configuration of the corral) and man-related factors (man's activities, machines and other equipment).

The social or ethological structure of the band is one of the main factors that unite horses into a system of structurally interdependent units, and accounts for their use of land spaces and their functioning in a hostile environment. It consists of a number of structural units, such as age and rank groups, certain temporary and permanent units and modifications thereof. The rank stages, which every animal enters successively over its whole life-period, are determined, largely, by the morpho-physiological and psychic status of each animal. A combination of these factors determines the position of each animal in the system, its rank and the social role in the band.

The present paper does not aim at an individual identification of each animal within the band with its general or situational rank but gives only a general description of the social structure because each newly-formed group of horses has its own hierarchy depending on age and hence on the individual qualities of the animal, its life aims and strategies.

Of great importance in the hierarchy of rank is the age of animals. Newborns stay together with their mothers and automatically stand beside them in the heirarchy. The more they grow up and start grazing, the more often they leave their mothers, and by two months they may be already included in a separate juvenile rank group - the lowest in the hierarchy. They are followed by yearlings, two-year old animals, semi-adults and adults. This is, so to say, the formal age-based rank structure underlying the hierarchic structure of the band. While animals of junior age groups may be easily identified due to considerable external differences, adult animals show almost no differences in size. However, observations show that each adult animal occupies its own place in the general hierarchy of the band.

At the top of the whole social structure of the band is the band stallion also known as the “leader”. For a number of years, the band stallion in the Askania Nova band of wild horses has been Pegasus - the oldest in all the group. It is in the actions of this stallion that all behaviour forms characteristic of males of the Equus subgenus find their complete embodiment, their functional and evolution significance. All his actions are subdivided by us into: 1 - methods and techniques for establishing domination; 2 - methods and techniques of guiding the band and defending it; 3 - reproductive function being both the result and means of domination.

The first group of actions comprises mainly aggressive forms and their ritual demonstrations. The methods of guiding the group include the stallion's actions to find the optimum locations for the band, the best pathways, to choose the timing for changing activities and the time for watering. The stallion banishes other males, breaks up fighting ones, keeps order in the band and takes care of females and younglings. He pays especial attention to external stimuli, viz. intrusion of other stallions, animals of other species (saddled horses, carts and motor vehicles). The stallion never attacks a man without a horse or car, and only demonstrates the aggressive ritual and marks the area with excrement. It immediately attacks domestic horses, either harnessed or saddled, and its victim may be saved only by the interference of man. There were cases in zoos, when a stallion attacked a mounted man, grasped him with his teeth and pulled him to the ground. Evidently in such cases, the stallion took the man and horse as one. However, a dismounted man attacking the stallion makes it retreat.

Among adult mares a leading group or “nucleus” may be isolated consisting of (3–5) dominating mares that form the principal structural and functional unit of the band. It is the mares of the “nucleus” that determine the direction of movement in foraging, in passages and in evading threats. In extreme situations, leadership is usually assumed by Volga - the oldest and most experienced mare of the band.

Another factor influencing the hierarchy of horses in the band along with individual qualities of animals is their relations by blood. The lowest kinship unit is the mother with the foal. If a mother has a yearling or a two-year old foal (which is a rare case) we may speak about a family cell within the band or within the general family group in our case-because almost all the members of the band are related through inbreeding. Despite their independent life, young animals do not forget their mothers and one may not seldom observe a mother being sucked by two foals - one new born and the other one either a one- or two-year old foal. Within this group of relations are relations between brothers and sisters. An example of such relations is the relation between Pegasus and Volga, both being children of the progenitors of the line. They spend long hours together standing either “nose to nose” or “muzzle to withers”. The mare also accompanies the stallion while patrolling the range. Due to this relation Volga occupies one of the highest positions in the hierarchic system of the band.

Along with the main structural units, there exist more or less permanent or temporary formations that change the social structure of the band depending on the season, the corral occupied by the band, the ecological situation, the demographic composition of the herd or the physiological state of individual animals. Their permanent formations are the following:

  1. Harem groups. When Pegasus is in the band all the mares are members of his harem. When adult stallions previously kept in isolation are introduced into the band in the absence of Pegasus, one of them takes the mares and banishes all the others; if the stallions are of equal strength they divide the band into two parts, which was observed in the spring of 1982 when stallion No. 6 and stallion No. 13 divided the herd into two groups (comprising 17 and 23 animals, respectively). In another case when the first of these stallions had been isolated he jumped to the neighbouring corral and drove away the mares of a Shetland pony. Having joined a Polesskaya domestic mare with a foal to his interspecies harem, he kept that harem over the whole season.

  2. Groups of bachelor stallions and solitary stallions. This is observed when the leader-stallion banishes other semi-adult and adult males that forage some distance away from the band. Sometimes they are on the territory of the band but never mix with it and even without any action of the leader keep in an isolated group. The isolation mechanisms of these two groups were clearly evident when on more than one occasion we tried to join the stallions with the band artificially. Even as far as 100–150 m away from the band they refused to go forward and tried to turn back or to bypass the band. At a distance of 30–50 m, the band stallion sprang into action. It banished the stallions by attacking the oldest and most powerful one ignoring younger animals. Longer-term observations of the bachelor groups show that without reason for rivalry stallions do not fight with each other and form a “community of equals”. With a stimulus for competition, age appears to be the decisive factor in rivalry. The older animal, as a rule, wins.

  3. Groups of animals showing personal likings to each other. Here for example, comes the relation between stallion No. 13 (Parade) and mare No. 14. When in June 1981 Pegasus drove Parade away from the band, he was followed by mare No. 14. After that she permanently stayed with Parade and when Pegasus jumped over the fence to their corral and tried to bring the mare back to the band, she refused to do it and again joined with her stallion. The next year the female met with the leader (Pegasus) in the band, and almost the whole season Pegasus was chasing her trying to drive her away from the band. Such relations may also arise between animals of different species. Thus, when the herd was kept in a large corral with Pegasus absent and Parade the leader, Volga together with three young horses and a Polesskaya domestic mare with a foal formed their own mini-band. The non-accidental character of this group is manifested by the fact that in subsequent years the group did not change its composition. The leading element of this group was Volga, whereas all the rest including males were subordinate.

    The temporary formations are:

  1. Groups of animals that are formed around females in oestrus. Two variants are possible here: first, when a female is followed by a “train” of stallions trying to fecundate her and second, when a female tries to approach a stallion. It was noticed that mares were attracted by “bright” objects such as the band stallion or even a domestic gelding who was an inadequate object for wild horses, when “dressed” in harness and accompanied by man.

  2. After mother-mares give birth to foals their temper, behaviour and rank change sharply. They become the most alert and aggressive animals of the band, and having a common desire to preserve their offspring, they have to resort to concerted actions against a threat, another stallion, etc. Their actions are characterized with especial ferocity and perfection of reactions directed against the enemy. Such behaviour ranks them second in the hierarchy after the band stallion who also prefers avoiding conflicts with them.

The age status and the rank of each animal of the population are in a sort of equilibrium. However, a time may come when the limits of its rank become too narrow for the animal and it breaks through these limits by conflicting with animals of the same or a higher rank. Thus, the rank status of each animal is established and maintained by its personal qualities, by animals of the nearby ranks, by high-rank horses and the band stallion. Changes in the psycho-physical status or rank of individual horses are brought about by their physiological conditions (traumas, illness). These internal causes together with external ones, such as climatic and seasonal factors, appearance of new members in the band or disappearance of old ones, change the ranks of a considerable number of animals, thus disturbing the whole social structure of the band. Such changes take a rather painful course in the presence of increased excitement levels, stresses, etc. The number of aggressions sharply increases - up to 40–50 per 5 minutes. The number of activity changes during the day-time increases from 27–30 to 68–70. The time for foraging and resting decreases (to 46 and 34 percent, respectively), whereas the time for movement increases up to 20 percent (as compared to normally from 8 to 12 percent). After 1–3 days, depending on the factors that had caused the change in the social structure, an equilibrium is established. Each animal occupies its own cell in the social organization which remains stabilized until a new “cataclysm”.

Relations within the group are regulated by means of demonstrative and agonistic behavioural forms. At first, the contact between two adult stallions is based on visual stimuli and ritual motions corresponding to their rank, motivation and pretentions. If, at this stage, the interest of males remains non-realized, the contact between them continues with growing excitement. The animals come closer to each other, rear up, bite and kick each other with the fore and hind legs. Fights between wild stallions lead to serious traumas and even the death of one of the rivals. Mares usually do not use rituals and immediately begin aggressive actions (bites and kicks).

The band's type of vital activity and spatial distribution depend on the corral: its area, relief features, configuration of the fenced territory, the availability and location of water bodies, shelters and solonetz patches. Depending on these factors the group forms its spatial structure that comprises the “core” and “marginal” (peripheral) zones, patrolling areas, sites for marking, resting, comfort activities, “toilets”, etc. The main territory occupied by horses during the reproductive period (from May to September) is corral No. 3. This is a tract of virgin steppe with an area of 45 hectares situated in the southwestern part of the corral system of the zoo (Fig. 1). The vital activity of horses in this corral has been thoroughly studied and presents a model of how a space may be used by horses (see Fig. 2). It should be noted that corral No. 7 with an area of 1550 hectares is the most appropriate place for horses. However, because of the high aggressiveness of Pegasus it is impossible to keep the band in that corral round the year and the horses are placed there after the end of the active reproduction season without the stallion.

The “core” zone located in the western part of the corral is a hoof-beaten dust patch having 9 m in diameter. This is a so-called “tyrlo” where the horses spend most of the day. This is also a resting and a comfort-activity site. This zone is surrounded by additional sites of comfort activity - dust “baths” with an area of 12–15 m2 and group “toilets” - constantly replenished piles of excrement. The “toilets” are of no small importance in the system of communicative and hierarchic relations of horses. They also play a role in establishing and maintaining the territorial distribution of the group. Additional “toilets” and comfort sites are situated in the most frequently visited parts of the corral (Fig. 2). Fifty metres away from the “core” zone there is another “tyrlo” - a peripheral one with an 8 m radius which is far less frequently used by horses. Both places are trampled out and barren. The “post-watering resting” site is situated close to the watering place and is used by the group, mainly in the evening, and also in day-time when the weather is cloudy. The site has an area of about 140 m2 and comprises several dust baths and 3–4 “toilets” located along the perimeter. The watering place is the beginning of horse pathways which go through the whole corral and end either in the “core” zone or at foraging sites. Observations show that pathways are renewed every spring from year to year and then are used during the whole season. We distinguish between “main” pathways connecting by the shortest way the watering place and the “core” zone that are trampled 3–4 cm below the general soil level, and peripheral pathways that spread over the whole corral and are hardly visible in dense grass. In any case, if an animal is not foraging and is moving either alone or within a group of animals, it prefers to follow a pathway. It is especially clearly seen when horses move in a group and in chains that glide noiselessly across the corral, winding, linking and spreading like ribbons. Movement in chains may be caused by resistance of the grass cover to animal legs when they go through “virgin land” or by the desire to “conceal” the true number of horses in the pathway. Along the pathways, especially along the main ones, there are “toilets” situated 15–20 m apart.

Fig. 1

Fig. 1     The layout of corrals in the Askania Nova Reserve:
a - buildings, barns; b - corral numbers; c - roads;
d - fences (wire net); e - water body; f - canals;
g - zoo; h - park

Fig. 2

Fig. 2     Layout of Corral No. 3 and its spatial use by Przewalski horses (1–10 - topographic symbols designating terrain features; 11–18 - parts of the corral territory used by horses): 1 - agricultural animal farms; 2 - fields; 3 - fencing (wire net) with gates; 4 - road; 5 - route taken by horsemen; 6 - water body; 7 - canals; 8 - trampled out places; 9 - solonetz patches; 10 - zones occupied by animals of other species; 11 - the core zone; 12 - the post-watering resting place; 13 - main pathways; 14 - peripheral pathways; 15 - dust baths; 16 - patrol pathways; 17 - marking sites; 18 - toilets

Along the perimeter of the corral lies the area of patrolling. It is especially clearly visible along the northern and eastern fences separating horses from animals of other species. The patrolling area is a pathway duplicating all the curves of the fence half a metre away from the wire net. The patrolling pathway both bypasses the water body and crosses it (Fig. 2). Being calm, the patrolling stallion goes around the water body. When excited by an external stimulus across the fence (another stallion or horsemen) he fords the water body. Marking sites are located near each of the gates, in the northeastern corner of the corral, around the geodesic signpost and at several places of the patrolling pathway. They are small (1–1.5 m2) sites filled with excrement constantly renewed by the band stallion. The stallion marks the sites only in the presence of a possible threat from the neighbouring corrals (wild animals, domestic horses, horsemen). In a peaceful situation without any external factors, he may only smell these sites and go away, since there are no other stallions in the band who could have marked the sites and no mares ever come to peripheral areas which are the areas of action of the stallion.

The southwestern part of the corral bordering on agricultural farms is less frequently visited by the stallion, and there are no clearly-seen patrolling pathways. This may be explained by the fact that disturbing factors present are inadequate and man-related. Different sounds come from the “Krugloye” cattle farm, and tractors, vehicles, bicycles, etc. passing by. All these factors may disturb the band but never influence its social structure and do not come within the range of hierarchic and agonistic reactions of the stallion.

Foraging is one of the main types of activity of horses. Resting areas, standing areas and “toilets” do not come within the domain of their trophic interests, probably because of excrement. Foraging usually starts after the day or night rest and also when externally-caused excitement that consolidates the group calms down. Gradually becoming calm the horses begin foraging. While foraging every animal tries to keep an appropriate distance between itself and its neighbours depending on the rank of the animal. Distribution of the group over a rangeland is by no means random and has a certain spatial structure and configuration (Fig. 3). Without external factors the horses disperse radially from the centre of the group outwards. This is a so-called “circle”. Under the impact of both external and internal factors a group of domestic horses may spread over a pasture in a “horseshoe”, an “arc”, a “double arc”, a “ribbon”. etc. (Baskin 1975, 1976). We have registered another type of pasture use when studying Mongolian domestic horses (Mongolia) which may be called formation in “tongues” or “wedges”. This formation is explained by foraging in mountains when horses spread along slopes in small “tongues” or “wedges” following one another.

Fig. 3

Fig. 3     Socio-spatial formations of Przewalski horses in foraging (1–6), in moving (7), in resting (8–11), being chased (12–16): 1 - circle; 2 - horseshoe; 3 - wedge; 4 - arc; 5 - ribbon; 6 - file; 7 - chain; 8 - variants of “tail-to-head” pairs; 9 - “tail-to-head” file; 10 - random group; 11 - consolidated formation against a threat; 12 - compact group; 13 - wedge; 14 - shuttle manoeuvring; 15 - break-through by one animal; 16 - breakthrough by the whole band; a - horse, b - band stallion, c - horseman

The internal factors determining the direction of a band of wild horses are the actions of mares of the “head group” and the stallion who in their turn are guided by external stimuli and the nature of the intergroup hierarchy. The leading group determines the general direction and, with individual distances set, it moves slowly forward. Other animals find their places in vacant spaces and trying to keep with the group they form a “wedge” or a “horseshoe”. This formation expands to a certain extent while the animals spread apart setting individual distances (5–7 m). Now that the distances are established the spatial formation of the group stays unchanged for some time. Given a large space (corral No. 7) a “wedge” or a “horse-shoe” may transform into an “arc”, a “file” or a “ribbon” (Fig. 3). A “double arc” was never observed. Sometimes, a “circle”, a “horseshoe” or a “wedge” begin to narrow. This occurs when the animals come to a standstill or begin to turn backward. In this case they graze on the same area which they have already passed. Usually, the group is very compact and never spreads over a distance exceeding 100–150 m. In a large corral (No. 7) a dispersion over a distance of up to 600 m was observed, but in that case the band was without the leader-stallion.

Climate is a factor of no small importance in the life of the band. During the grazing season and especially during the hottest period of summer, animals wait for the day heat to subside on a “tyrlo”. In this period (from 11 to 18 hours) short (0.5–1 hour) periods of foraging are possible, but usually the animals rest. Prolonged foraging during that period may be considered as a sign of undernourishment and should cause concern. When standing still in the daytime the horses are affected by sun radiation which influences the activity of insects. Domestic horses have been registered to show collective forms of protection against gnats. They are “compact crowd”, “tortoise”, “tail-to-head” formations. According to our observations more typical for Przewalski horses are different variants of a formation when two horses stand “tail-to-head” and a “double-file” formation (Fig. 3). Compact crowds oriented inside the group are very rare for wild horses. Animals often stand in “random” groups, horses being oriented to different directions. An advantage of such a formation is a better view of the terrain. The lack of clearly observed social adaptations to gnats that are so common with domestic horses may be explained by a higher individual protection and stability against adverse impacts of the environment. The high protection results from a higher skin thickness and the density and the greater thickness and length of hairs.

The external stimuli that determine the direction of movement of the group are: obstacles, adverse parts of rangeland (silty trampled areas), herds of other animals, man, rainfall, snow and wind.

In low and temperate winds, animals both moving and standing are oriented independently of the wind direction. When the wind rises up to 12–15 m/s spatial distribution of horses changes. In this case the formation of horses is oriented and moves “against the wind”. When approaching a fence from the leeward side the group slows down the movement well in advance and forages almost at the same place. In the immediate vicinity of the fence (100–200 m) the group may either move along the fence or stay at the same place until the time for watering comes or any external stimuli appear.

Unlike domestic horses that are greatly influenced by wind, Przewalski horses do not change their activity under the impact of wind. As a rule, when it starts raining domestic horses moving “against the wind” turn “leeward” holding their backs and croups to the rain whereas wild horses move in the same direction “against the wind and rain”. Even foals do not hide under mothers or within the group. Only a sharp increase in foraging activity of wild horses was observed which could be related to a better assimilation of moist grass and an instinctive desire of a desert animal to accumulate moisture. Such differences in reactions of wild and domestic horses demonstrate the better stability and adaptation of the former.

In winter, horses find forage under snow, but in the severe conditions of Central Asia (snow storms, ice crusts), domesticated Mongolian horses died by the thousands. For example, in the winter of 1910, 10 million horses died in Mongolia. But Przewalski horses managed to survive even under such severe conditions. In Askania Nova, snow is seldom deep and seldom stays for a very long time. It usually lasts for 1–2 months. The horses that have not lived in the wild and have no experience in winter foraging, make, nevertheless, scratching “caballoidal” movements with the forelegs pushing the snow apart, digging into it with the muzzle and getting wisps of plants.

The same internal and external stimuli influence the distances covered by the band during different time periods. Thus, in an undisturbed state the group covers 4–7 km in the large corral with a sharp decrease in activity during the hot period of the year. During autumn roundups the resistance of the band decreases sharply after some 10–15 km. This clearly testifies to the lack of movement in their life, since cases were registered when wild horses were chased for 2–3 days by horsemen who had tired out several relay horses only to capture foals (Klements 1903).

One characteristic feature of a band of wild horses is its permanent readiness to react to external stimuli using group adaptation forms. Those group adaptation forms have been acquired by social groups of animals in the severe environment of Central Asia and have been preserved by animals born and grown up in captivity.

In any type of vital activity - resting, foraging or movement, two or three animals are always surveying the surroundings. Thus surveying is facilitated by different spatial orientation of horses during foraging or resting. The band stallion always stays away from the group and spends the greater part of the day surveying the environment. Sometimes, he also makes patrol rounds of the territory.

The animal who happens to be the first to spot the appearance of an alien object sharply and loudly inhales and exhales and becomes alert. This signal is immediately spread throughout the band and all the horses scrutinize the intruder. As a rule, the stallion is the first to notice the threat and meets the intruder on the boundary of the corral - near the gate or the wire net. The reaction of the band depends upon the nature of the threat. If the object is fairly familiar, or vice versa, completely strange, it may cause curiosity instead of a defensive reaction. When the horses see an approaching observer, they may surround him at a distance of 20–30 m and study him by actively bringing the mares together and driving them away to a safe distance. If the intruder gives grounds for concern the herd after the first warning signals comes together in a compact group ready to follow their leaders. Mares with foals retreat to the rear of the group leaving in the forefront adult animals who assume responsibility for choosing the direction and one- and two-year olds who simply “stand in the way” having no experience in handling emergencies.

The leader usually positions himself between the intruder and the band demonstrating the aggressive ritual and marking the territory. In doing so he and the mares of the front group carefully study the intruder visually ready to react to the intruder's possible actions. If they are confronted by a horseman or a harnessed horse the stallion attacks the horse trying to bite it. If the stallion decides to lead the band away he gives a signal by assuming an indicative “hegoose” stance, lowering his head to the ground and turning it from side to side. The signal is usually received by one of the mares of the “nucleus” who assumes the leadership.

We should note joint and coordinated actions of horses when the band is escaping pursuit. When the band is chased by horsemen during interseasonal roundups the leader or the leading group may be clearly observed to make a coordinated “shuttle” manoeuvre in an effort to deviate from the direction forced on them. The animals make feints and seizing a good opportunity escape the control of horsemen in one rush. Such a breakthrough may be performed not only by members of the leading group but also by any other resolute animals. After even one animals escapes the whole band cannot be checked. At such moments the animals show no former fright for man and do not keep the usual distances (30–50 m). The horseman should bring the band together and start the rounding up from scratch.

This is an example of intergroup mechanisms in action that organize and coordinate the band. These mechanisms may be used for controlling the behaviour of animals and their distribution over the territory.

Here we should note that all the above actions of the group, both of a rangeland and in relation to external objects are characteristic only of a band with a complete social structure formed by a number of generations.

If an experienced band stallion is missing or is replaced by a young and inexperienced one, the perfectly organized and functioning system of the band is immediately transformed into a shapeless mass. Such a group spontaneously changes types of activity, does not develop the territory, shows no stable rotation patterns of daily activities and easily gets confused finding itself in a pessimal situation under the influence of external threats*.

Let us consider formation dynamics of principal adaptation forms of behaviour (or strategies) of different social groupings of the band when they reach the life and reproduction success under typical or close to typical ecological conditions, as these strategies are formed in ontogeny.

Newborns try to keep a constant visual, olefactory and tactile contact with their mothers. Their protection within and without the herd and their individual distances are the responsibility of their mothers. Infantile foals (up to 6–8 months old) continue to follow their mother and seek protection from them. Beginning from the age of 8–9 days they begin periodic foraging and beginning from the age of 10–14 days they establish personal contacts with foals of the same age group and later when they switch over to grazing and more often leave their mothers they begin to establish contacts with adult members of the band. In this case elements of rivalry with foals of the same age and of aggression from adult horses are added to conjunctive contacts. Towards the end of the period a hierarchy is established in the infant rank groups. Individual distances for younglings are determined by adult members of the band.

Juvenile animals (up to 1.5–2 years of age) become separated from their mothers but still maintain relations with them. Personalized contacts are developed through plays and tournaments. Some elements of the future reproduction-behavioural repertory are manifested in plays showing sex-related differences of each animal. Young animals try to keep individual distances.

* This may be the cause of such a quick disappearance of wild horses in Mongolia and China. It was the stallions whom Mongolian herdsmen tried to kill first because they prevented successful hunting of wild horses. Left without leadership mares could not withstand the environment pressure.

Two-three year old females automatically (together with their mothers) become members of the general harem or of one of the subordinate ones. Cases were observed when young females were banished from the band. In the harem there are personalized conjunctive contacts and in marriage-family relations - polygynic ones. Adult females may keep individual distances though not always selectively, in foraging, resting, movements and in extreme situations. They do not mark and do not guard the territory. Passive defensive reaction prevails in the presence of external stimuli. They do not drive other females to the band and guide the band passively (by leading it). Without the leading element (the leader stallion) females are incapable of purposefully coordinating the actions of the band and cannot withstand external conditions. Mothers with foals increase individual distances and the share of aggressive actions in their repertory. As they get older mares may obtain higher hierarchic standings and may enter the “nucleus”.

Two- and three-year old males develop personalized contacts in their rank group using plays and fights and establish a more clear-cut hierarchy than in the preceding age group. They try to court females, drive them to the band and demonstrate a reproduction repertory. They attract the attention of the band stallion who begins chasing them and eventually banishes them from the band. The banished stallions form a bachelor group with its own inner hierarchy characterized by stable and non-competitive relations (prior to the appearance of reproduction stimuli). Some stallions with the growth of their morpho-psychic status, try to seize females. Bachelors neither mark nor guard the territory. Young stallions are characterized by incomplete performance of individual chains of aggressive and reproductive behaviour due to insufficient development and the lack of certain constituent blocks. Their actions, therefore, do not attain the hierarchic supremacy over other males and females and hence, they cannot take possession of the latter. When the leader-stallion is absent from the band (or due to other reasons) the most dominant of the young stallions seize either a part of the females or the whole band, banish all other mature stallions and try to consolidate their new social and reproduction status. In the period of establishment of the social structure the relations in the band are mainly aggressive since the drive and pretentions of the stallion meet with resistance of dominant mares. After the social homeostasis of the group is stabilized such stallions play secondary roles after dominating mares. They do not mark or guard the territory and do not purposefully guide the band which affects its future. The stallion may acquire the dominating status in the group only after the age of 4–5 years having accumulated experience in possessing a harem (evidently, by the age of 10). Such a stallion is an unchallengeable dominating figure in the band. He patrols, marks and guards the territory occupied by the band. The fact that Pegasus guards the whole corral No. 3 cannot be extrapolated to conditions of the wild since horses are nomadic animals. Nevertheless, the size of the territory, the number of females and the amount of effort to keep them are directly dependent on male qualities and the social experience of the stallion. The band stallion with his potential for socially-adequate actions takes care of the band members, coordinates the activities of the band and withstands the environment thus promoting the flourishing of the population and continuation of his progeny.

Thus, the socio-spatial phenotype of the band of Przewalski horses in Askania Nova may be regarded as an activity of a functional biologic system with a hierarchially-interdependent structure possessing a relatively large diversity of the composition and strategies of each of the social groupings functioning on a certain territory used and partially guarded by animals. These strategies united by cooperating and coordinating elements allow the system to respond resiliently to a changing environment and to adapt successfully to it in order to continue its existence. At the same time individual elements of the system in isolation cannot react adequately to external conditions and withstand them. This calls for a more purposeful establishment of introduced groups with due regard for all the elements of the band (population) and their importance for its future if wild horses are introduced into the natural biotopes of Asia.


The Species Survival Plan for the Asian Wild Horse in North America and Implications for Restoration of Przewalski's Horse to Mongolia

Oliver Ryder

A cooperative breeding programme was organized in 1979 following the World Conference III on Breeding Endangered Species in Captivity held in San Diego, California. An interim breeding plan was adopted taking into consideration the genetic background of the North American population (Ryder and Wedemeyer 1982). According to the plan, males with genetic input from the domestic mare are not incorporated into herds of mares for breeding; in this way the genetic contribution of the domestic mare is being diluted in those collections whose mares include genetic contribution from the domestic mare. Given the size of the population in North America (40.61) and the pedigree relationships of individuals, inbreeding coefficients of new-born foals within the SSP population have actually decreased under the management plan.

The significant exchange of animals that occurred between the Soviet Union and the United States in 1982 furthers the goals of the SSP programme through the introduction of three horses related to only wild-caught individuals #231 Orlica III, #17 Bijsk 7, #18 Bijsk 8, #39 Bijsk A, #40 Bijsk B, #211 Woburn 6, and #212 Woburn 7. Furthermore, the importation into the Soviet Union of three US-bred horses similarly is hoped to enhance the gene pool management of the species in the USSR. All three of the horses exported from Askania Nova to the United States have subsequently bred and as of 1 May 1985 4.4 offspring survive. The stallion, #606 Askania 22, Vulkan, was transferred from New Yrk to San Diego of 16 April 1985.

The breeding programme adopted by the Asian Wild Horse SSP reflects the opportunity for regional cooperation in management of the subset of the toal captive population. Whereas the goal of continued reduction in the genetic contribution of the domestic mare has not been formally adopted by other geographically organized breeding programmes the trend in worldwide reduction of the genetic contribution of the domestic mare to the species' gene pool is consistent with such a plan. In any event, some population subdivision may be useful for retention of genetic diversity. The designation of individuals for a restoration project could be based on differing criteria. As the very process of willfully choosing idividual animals for such a project amounts to selection, the issue reduces to a consideration of what selective criteria should be employed. In the case of the restoration of Przewalski's horses to Mongolia, an appropriate course of action would be to assemble representatives of the entire captive gene pool and provide opportunity for the horses themselves to interact in their new environment and allow selective forces to exert their influence on the variety of offspring produced. Consideration should be given to the relative founder contributions of individuals designated for restoration to Mongolia in comparison to the relative founder contributions of the worldwide captive population. Thus, the proportion of domestic horse genes present among individuals destined for restoration should be less than or equal to the current worldwide average.

The institutions participating in the Asian Wild Horse SSP have on three separate occasions ratified the concept of designation of individual horses for appropriate restoration projects. However, in consideration of the concern for the continued well-being of the captive population over time every effort must be made to ensure as much as possible that proper habitat, appropriate facilities and trained personnel for oversight of the restoration project are chosen. The comments of Studbookkeeper Dr. Volf concerning the desirability of soliciting the comments of breeders of Przewalski's horses concerning appropriate site and facilities should be heeded.


  1. The well-being of the captive population with respect to genetic composition and demographic stability must not be jeopardized in any sense by restoration projects. The rationale for this position is that, until there exist multiple, geographically isolated, free-living populations of Przewalski's horses having adapted to the local steppe conditions and having survived for generations in their new environment with ever-increasing numbers, the further existence of the species must be assumed to depend upon the captive population and the gene pool that it represents.

  2. The historical commitment of the captive breeders of Przewalski's horses has been to the ultimate restoration of the species to its former range, and specifically to Mongolia. Therefore restoration of Przewalski's horse to the Mongolian People's Republic should not be delayed once suitable facilities are created.

  3. The design of facilities and management should be coordinated by an international group of experts with authority for continued monitoring of the site and its facilities. These activities must occur in cooperation with local experts.

  4. Monitoring of the progress of the restoration project must include Mongolian experts and also involve the International studbookkeeper, captive breeders of Prewalski's horses, experts in feral horse biology and range management, as well as experts in disciplines such as veterinary medicine, genetics, comparative equid behaviour and pathology.

  5. Multiple acclimatizations are to be avoided. Multiple acclimatizations produce multiple genetic bottlenecks that can best be avoided by acclimatization in situ preceding release.

  6. Multiple reserve populations consisting of free-living individuals organized into appropriate social groupings are desirable for preservation of total species genetic diversity.

  7. The multiple reserve populations need not be as large as 500 genetically effective individuals. In fact, it is preferable to have multiple groups with effective population sizes in the range of 50–100.

  8. Maximal preservation of genetic variation as well as the exchange of previously existing and newly arisen adaptive genetic variation will occur if periodic migrations of small numbers of individuals between the multiple reserve populations are conducted. Similarly, continued bidirectional gene flow between the captive population and the reserve populations - achieved by periodic transfers of individuals (or their germplasm) - is highly desirable.


Pedigree Analysis

Due in large part to the excellent quality of the data in the International Studbook as well as to the relatively long history of captive breeding of Przewalski's horse, pedigree analyses intended to shed light on the inheritance of particular traits and determine the likelihood of loss of genetic variation are being undertaken utilizing the data in the volumes of the International Studbook. Blood typing and chromosomal studies continue and recently detailed studies of DNA have been conducted.

Vitamin E deficiency

Following the publication of case studies of Przewalski's horses with significant myelopathies reminiscent of vitamin E-deficient laboratory and domestic animals, a study of serum tocopherol levels was indicative of general deficiency. Most significantly, the horses exhibiting the lowest serum vitamin E levels were the same individuals most severely ataxic. Thus, the “genetic disease” of atxia must be reconsidered in light of this new evidence.

Embryo Transfer, Semen Collection and Storage

The first transfer of a Przewalski's horse embryo into a domestic pony mare leading to a successful birth took place last year in London. Several zoos in the United States are collecting semen and experimenting with freezing protocols as well as anaesthesia conditions and electroejaculation techniques. A programme to collect and transfer or freeze Przewalski's horse embryos is beginning utilizing Quarterhorse mares as recipients. The embryo donors are mares that are unable for medical reasons to be in with the rest of the herd.


Ryder O.A. and Wedemeyer E.A. 1982 A cooperative breeding program for the Mongolian wild horse, Equus przewalskii, in the United States. Biol. Conserv. 22:259–272.


V. Klimov

As the ever-growing impact of man on ecosystems leads to their gradual depletion and destruction of historically established relationships that ensure biological balance and homeostasis of the system, a problem arises how to preserve both natural biotopes and relevant species of flora and fauna. Ecological conditions favourable for natural evolution and conservation of rare species are now vanishing at a higher rate. But these species can be maintained in reserves and zoos. In doing so, it is essential to define a direction in which a given species will evolve. Przewalski horses extinct from the wild served as a model that allowed some aspects of vertebrate preservation to be defined. Living captive wild horses trace their ancestry to eleven Przewalski horses (Equus przewalskii) and one domestic mare (Equus caballus). Though the current captive population exceeds 400 individuals, the observations of this species have shown reduced genetic variability, higher levels of homozygocity, decreased frequency and loss of particular alleles. Zoo management of the horses results in depression of their reproductive system, relevant processes, fertility and viability as well as juvenile mortality and neonatal abnormalities. Concurrently a variation in the phenotype and loss of species-typical status (both behavioural and morphological) occur. These processes have been caused by ecological and genetic problems. The former relate to inadequate conditions in the zoos and reserves while the latter concern progressive inbreeding due to a small number of founders and difficulties in handling the horses since they are distributed over 70 management centres. In addition, the gene pool of general population is affected by a genetic drift leading to allele loss in isolated minipopulations natural and directed breeding minimizing the number of individuals involved in reproduction and elimination of genes when certain lines vanish. As far as the Przewalski horse gene pool goes, microevolutional processes, therefore, influence the captive population in a negative way and are practically beyond our control.

Techniques used in the management and preservation of the Przewalski horses and their gene pool may be roughly divided into methods of genetic and ecological monitoring. The first are aimed at preservation and enrichment of the gene pool of the wild horses, avoiding the inbreeding, maximum genetic diversity and involvement of every available animal in reproduction:

  1. Total account of the recent horses.

  2. Identification of relations and genealogy of all the captive horses.

  3. Annual publication of International Studbook in Prague.

  4. Marking of horses where possible and necessary. In small populations animals can be detected by individual features. The Askania Nova zoo maintains 50 animals marked by not branding on the shoulder.

  5. Genetic marking and genetic monitoring of genealogy involving electrophoresis of serum proteins, isoelectric focusing, determination of blood groups, cytogenetic studies. The world's zoos consider such studies as a major method in registration of the horses, identification of genetic variability level and genealogy of groups and individuals, detection of phylogeny and taxonomy within Equides. The similar studies in Askania Nova have shown that 20% of horses bear 70% of genetic variability, with the herd's homozygocity constantly increasing. Homozygocity of each succceeding generation is much higher than that of the preceding one. Mean group heterozygocity makes 0.1071 ±0.0169.

  6. Selection of reproductive groups, pairs and individuals based on the above stated principles.

  7. Selection and reproductive culling. It is rather controversial whether selection should be employed at this stage since it minimizes the number of animals involved in reproduction and makes low heterozygocity of the lines even lower. But as (a) there is a domestic mare among the founders of the present captive population affecting the general gene pool, (b) inbreeding and inadequate environmental conditions result in abnormalities in the animals' development and phenotype, selection is necessary. This promotes consolidation of the wild horses' gene pool and phenotype. Due to a high value of the animals, reproductive rather than physical selection can be discussed which, in its turn, should be employed in extreme cases only. Wild-caught animals and first captive generations can serve as a standard of phenotype.

  8. Formation of intralinear groups with horses with differentiated gene pool and their breeding, with particular intralinear groups being able to form other lines in future.

  9. Intralinear replacements. They are made within independent intralinear groups to increase genetic variability and obtain new gene combinations.

  10. Exchange between lines. In 1982 horses were exchanged between USA (San Diego and Bronx) and USSR zoos (Askania Nova). Each side delivered a stallion and two mares that formed new reproductive groups in the zoos.

  11. Establishment of stallion pools, i.e. centres that concentrate and distribute stallions among other institutions for breeding purposes. Such pools of stallions unused in reproduction are being set up in the USA.

  12. Taking account of the animals incapable of reproduction, their prophylaxis and treatment.

  13. Cryoconservation of sperm, creation of gene banks, experiments on collection of sperm and artificial insemination of mares.

  14. Employment of computerized analysis in elaboration of breeding plans. It includes not only computation on inbreeding coefficients and heterozygocity indices but also salection of potential pairs and reproductive groups with lowest level of inbreeding, high fertility, vitality, etc. Combinations of particular groups can be established with the help of such analysis.

  15. If horses capable of reproduction are sufficient in number (over 50), it is possible to let them function on their own, thus making use of natural social processes (rotation of stallions, reproductive success of stronger individuals that are replaced by successors when exhausted, formation of several harems, rotation of mares between harems, etc.) to obtain genetic diversity.

The objective of the propagation of rare species, Equus przewalskii, in particular, is to promote natural evolution of the species and can only be attained under specific environmental conditions. A model set of these conditions is represented by methods of ecological monitoring. Since, in our opinion, a species can be properly preserved only with its specific historical biotope and ecological relationships being conserved, it is necessary to introduce the animals into their biotope or simulate this biotope. When there are no opportunities of preserving the entire biotope, species representatives can be maintained in captivity under the following conditions:

  1. Management of the species by a population rather than in singles or pairs that represents an organized system from spatial, social and genetic points of view and ensures preservation of the species' complete genetic information.

  2. The population should be placed under conditions similar to those of its original habitat - physical, geographic, climatic, landscape soil and trophic complex.

  3. The population can be productive and functional only when provided with a required area. Wild horses need 20 ha per animal.

  4. The animals should be isolated from allied taxons, domestic in particular, that may become sources of nonself genes, infections, invasions, etc.

  5. In restricted areas additional exercises are needed that consist in riding the horses. Time and pace of riding are determined for each animal (availability of lactating, brood mares, etc.).

  6. Intervention by man involving supplementary feeding, protection from weather, invasions, etc. should be minimized to let them function on their own. Only this approach can be followed to stabilize the population's functioning in the biotope.

In doing so, one should make use of models the size of which can provide the species with required ecological components and conditions and partially substitute for natural regulatory mechanisms. Establishment of the systems that make it possible to concentrate horses from the European and American zoos with a view to their primary acclimatization before the reintroduction is possible in the steppe reserve Askania Nova or Altai region. In due course the second and third generations of the horses can be reintroduced to Mongolia. Conditions and techniques of transit, distribution and management of the horses being introduced were defined by our expert group in Mongolia in 1980. Upon placement of a project order, Mongolian specialists in cooperation with the Soviet ones set up and equipped a reception station in the Bogdo-Una Reserve that will initially manage the horses. When the delivered animals get adjusted to climatic and environmental conditions, their offspring can be transferred to large reserves in the country's steppe zone, with their group dislocations being limited in optimal biotopes.

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