HYBRID EQUINES

Equid (horse, donkey, zebra) hybrids are well known and some are bred commercially. The generic term for a zebra hybrid with a horse, pony, donkey or ass is a zebroid. The generic term for a hybrid of a zebra with any type of donkey or ass is a zebrass. The usual naming convention for hybrids is a "portmanteau word" comprising first part of male parent's name + second part of female parent's name

Father Mother Offspring Donkey (jack) Horse (mare) Mule (male), John (male), Molly (female) Horse Donkey (jenny/jennet) Hinny Zebra Donkey (jenny/jennet) Zebrass, Zedonk, Zebronkey, Zonkey, Zebadonk, Zebryde, Zenkey (Japan), Hamzab (Israel) Zebra Horse Zorse, Golden zebra, Zebra mule, Zebrule Zebra Pony Zony Zebra Shetland Pony Zetland Donkey (jack) Zebra Zebret, Donkra Horse Zebra Hebra

A horse/zebra hybrid foal at the Rothschild Zoological Museum, Tring, England.

Zebras that are hand-reared or reared with domestic horses or donkeys can become tame enough to be led, ridden or used as draught animals. Those raised with horses or donkeys may prefer to mate with horses or donkeys rather than with zebras.

MULES, MOLLIES AND HINNIES

Mules (donkey stallion/horse mare) are bred as draught animals. Mules and hinnies are depicted in Egyptian art circa 1400 BC and were valued as draught animals by the Romans. Male mules are sterile, but fertile female mules (mollies) sometimes occur and can be mated to either a horse or donkey stallion. In France, the Poitou donkey is used almost exclusively for siring large, strong mules on Poitou horse mares. Jack donkeys are reportedly often reluctant to mate with horse mares and may have to be trained to do so. Miniature mules are produced using smaller breeds of donkey and pony. An article in The New York Times, Thursday Feb 22nd, 1968 entitled "Rare Type Of Mule Kicks Up Heels At Children's Zoo" detailed the birth of a foal to a Shetland pony fathered by a burro at New York's Central Park Zoo. Although sterile, mule stallions are generally castrated to make them tractable.

The hinny (horse stallion/donkey mare hybrid) is less common. The head of a hinny is more horse-like than the head of a mule. They are harder to produce than mules as stallion/jenny matings are less likely to result in pregnancy. Hinnies are smaller and finer boned than mules. This was believed to be due to the donkey mare having a less roomy womb, but the difficulty in impregnation suggests it is largely genetic. Donkeys have 62 chromosomes while horses have 64 chromosomes; hybrids are less likely where the male has more chromosomes than the female.

According to the “Illustrated Natural History” by the Rev JG Wood (1853, 1874): The cross-breed between the horse and the ass, which is commonly known by name of the Mule, is a very valuable animal for certain purposes, possessing the strength and power of the horse, with the hardiness and sure foot of the ass. The largest most useful Mules are those which are produced by a male ass and a mare, the large Spanish Ass being the best for this purpose. In Spain and in many eastern countries the Mule is an animal of some importance, the parents being selected as carefully as those of the horse itself. The chief drawback in the rearing of this animal is that it is unproductive, and is incapable of continuing its species, so that there can be no definite breed of Mules, as of horses and asses.

In "The Variation Of Animals And Plants Under Domestication" Darwin wrote: "The ass has a prepotent power over the horse, so that both the mule and the hinny more resemble the ass than the horse; but that the prepotency runs more strongly in the male-ass than in the female, so that the mule, which is the offspring of the male-ass and mare, is more like an ass, than is the hinny, which is the offspring of the female-ass and stallion." In "The Variation Of Animals And Plants Under Domestication" Darwin elaborated: "Colin, who has given in his 'Traite Phys. Comp.' tome 2 pages 537-539, [...] is strongly of opinion that the ass preponderates in both crosses, but in an unequal degree. This is likewise the conclusion of Flourens, and of Bechstein in his 'Naturgeschichte Deutschlands' b. 1 s. 294. The tail of the hinny is much more like that of the horse than is the tail of the mule, and this is generally accounted for by the males of both species transmitting with greater power this part of their structure; but a compound hybrid which I saw in the Zoological Gardens, from a mare by a hybrid ass-zebra, closely resembled its mother in its tail."

THE KIANG (The Field, 29th April 1893) Major Hay states that in Tibet the kiang breeds with the horse, and that their produce is highly valued; and he adds, but not on his own knowledge, that the hybrids are regarded as fertile, which is in the highest degree improbable.

Professor Cossart Ewart crossed kiangs (a type of wild ass) to ponies to test the theory that the then newly discovered Przewalski horse was a hybrid rather than a distinct species. This summary appeared in the Western Times (among others) on 30th June, 1903: THE WILD HORSE. INTERESTING DISCUSSION OF NEW BREED. The paper by Professor Ewart on the wild horse laid on the table at the recent meeting the Royal Society Edinburgh has now been printed and circulated. The writer states that decided to breed a number of kiang-horse hybrids to test the view hold by many zoologists that the horse discovered by the celebrated Russian traveller Przewalsky, said to the true wild horse, was not entitled to rank as distinct species, but was merely a hybrid between the kiang and a Mongolian or other Eastern pony. With the help of Lord Arthur Cecil he succeeded early in 1902 in securing a male wild Asiatic ass and a couple of Mongolian pony mares - one a yellow dun the other a chesnut. Jacob, the wild ass, was mated with the dun Mongol mare, with a brownish-yellow Exmoor pony, and with a bay Shetland-Welsh pony. The chesnut Mongol pony was put to a light grey Connemara stallion. Of the four mares referred to three had already foaled, viz., the Exmoor and the two Mongolian ponies. Comparison showed that the kiang horse hybrid differed from Przewalsky's horse in having at the most the merest hock callosities, in not neighing like a horse, in having finer limbs and joints and less specialised hoofs, in the form of the head, in the lips muzzle, and ears, in the dorsal band, and in the absence even at birth of any suggestion of shoulder stripes or of bars on the legs. Professor Cossar Ewart proceeds:

While most the zoologists who hesitated to regard Przewalsky's horse as representing a distinct and primitive type favoured the view that it was a mule; some asserted it in no way essentially differed from an ordinary horse. The colts brought from Central Asia, they said, were the offspring of escaped Mongol ponies. Others affirmed that they failed to discover any difference between the young wild horses in the London Zoological Gardens and Iceland ponies of a like age. To test the first of these assertions, I, as already mentioned, mated a chestnut Mongol pony with a young Connemara stallion; to test the second, I purchased last autumn a recently imported yellow dun Iceland mare in foal to an Iceland stallion. As I anticipated, the chestnut Mongol mare produced a foal the image of herself. This foal it is hardly necessary to say, decidedly differs from the Przewaisky colts recently imported from Central Asia by Mr. Hagenbeck, and it decidedly differs from the kiang hybrid. The Iceland foal, notwithstanding the upright mane and the woolly coat, for a time of a nearly uniform white colour, could never be mistaken for a wild horse, and the older it gets the differences will become accentuated. Przewalsky's horse is neither a pony mule nor a feral Mongolian pony, and if, moreover, it is fertile (and its fertility can hardly be questioned), I fail to see how we can escape from the conclusion that it is as deserving as, say, the kiang to be regarded as a distinct species.

FERTILE MULES AND HULES

FERTILITY OF HYBRIDS. (The Field, 25th September 1897) I have noticed some correspondence in your columns concerning the fertility of hybrids and think that the following may be of interest, and at all events it will give an opportunity to some of your readers of thorough investigation. Some years ago I was driving up from Perarolo to Cortina d'Ampezzo, and noticed several very peculiar looking animals, which to my eye were neither mules nor hinnys. My driver, a very intelligent man, one of the Apollonio family of Cortina, at once gave me their history, pointing out that this one was by a male mule out of a female hinny, and that one by a male hinny out of a female mule. He was perfectly familiar with the appearance of each breed, and declared that all these crosses were fertile. Ile told me what, indeed, I could see for myself, that these crosses, or descendants of crosses, were quite common in that part ; but added that he did not think that they had any good points about them. As to mules, he disliked them on account of their character, but admired their capacity for work. If he had to go over the e ground every day, then he would have a mule or mules; but as they dislike being put out of their groove, and resent it, horses suited him better. The mule, he said, is sly, and one must be always on one's guard with him. - M. D.

[There can be no doubt that there is some error in the account. In the Poitou district, where very large numbers of mules are bred annually, a fertile mule is unknown ; and M. Ayrault, in his valuable work, "De l'lndustrie Mulassiere," gives statements that are quoted in their work on "Horses, Mules, &c." by Messrs Tegetmeier and Sutherland, showing that the mules there are in the most favourable conditions for breeding , but are never fertile. The sterility of equine mules is fully discussed in this work.—ED.]

Mules are generally sterile, but several female mules have produced offspring when mated to a purebred horse or ass. This is so rare that the Romans had a saying, "cum mula peperit," meaning "when a mule foals" - the equivalent of "when hell freezes over." When a mule gave birth in Albania in 1994, it was thought to have unleashed the spawn of the devil on a small village. When a mule gave birth in 2002 in Morocco five years ago, locals feared it signalled the end of the world.

Donkeys have 62 chromosomes while horses have 64 chromosomes. As well as different numbers, the chromosomes have different structures. Mules and hinnies have 63 chromosomes that are a mixture of one from each parent. The different structure and number usually prevents the chromosomes from pairing up properly and creating successful embryos. Since 1527 there have been more than 60 foals born to female mules around the world and probably additional unreported ones. However, mollies have a strong maternal drive and will kidnap foals of horses and donkeys sharing the same paddock.

From The Royal Natural History, edited by Richard Lydekker and published 1894: There appear to be no authenticated instances of mules breeding among themselves; although the female mule will occasionally produce offspring with the male horse or ass. And it is somewhat remarkable that it does not appear that the hybrids between any other members of the Equine family are mutually fertile.

However, Cornevin and Lesbre stated that in 1873 an Arab mule was fertilized in Africa by a horse stallion, and produced female offspring. Both parents and the offspring were taken to the Jardin d'Acclimatation in Paris where the mule had a second female colt sired by the same stallion and then two male colts, one sired by an ass and the other by a horse stallion. The female progeny were fertile, but their offspring were feeble and died at birth. Cossar Ewart gives an account of a recent Indian case in which a female mule gave birth to a male colt. The best documented fertile mule mare was "Krause" who had 2 male offspring, both sired by her own sire. It is now known that in most fertile mule mares, the mare passes on a complete set of her maternal genes (i.e. from her horse/pony mother) to the foal rather than a mixture of chromosomes. A female mule bred to a horse will therefore produce a 100% horse foal.

In 1898, an Indian pack-mule produce a pony-like foal. In the 1920s, a mule mare called "Old Beck" (Texas A&M) produced a mule daughter called "Kit". When Old Beck was bred to a horse stallion she produced a horse son (he sired horse foals). When bred to a donkey, she produced mule offspring. Likewise, a mare mule in Brazil has produced two 100% horse sons sired by a horse stallion. There is an unverified case of a mare mule that produced a mule daughter (this may be another account Old Beck). The daughter was also fertile and produced a horse-like foal with some mule traits; this was dubbed a "hule". There are no reports as to whether the hule was fertile; it may have been castrated in the same way as a mule stallion.

After "Old Beck's" case came to light, several others were reported but no definite proof was available concerning most of those.

According to “AMERICA MAKES SOME NEW ANIMALS” by Frank Thone (Miami Daily News Record, 7th March, 1929):-

THE old dictum that hybrids are all sterile and can’t reproduce has, of course, been handled pretty roughly in all these experiments. In some cases it holds, in others it doesn’t.Anyhow, the doctrine seems to have been established originally by reference to the most familiar of domestic hybrids, the mule. Mules as a rule do not breed, yet in the recent past two undoubted cases of mule mares giving birth to healthy foals have come to light. Erasmus Haworth of Lawrence, Kansas, reports the case of a mule mare that produced a foal sired by a jack. And rare as such cases are, this same mule is now believed to be with foal for a second time. “Old Beck" is only an ancient Texas "cotton mule” mare who has been on this planet long enough to vote, but she has done her bit toward breaking the age-old reproach of sterility leveled at her hybrid race. For she has not only borne offspring — two lusty colts — but now has a grandchild. This grandchild is a horse in appearance, although one-quarter mule. For a mule to have a foal is an almost miraculous rarity, but for one of these to propagate is practically unheard of. Yet this is the record of “Old Beck," as reported by A. H. Groth of Texas A. and M. College. Her first offspring was a daughter, sired by a jack, and foaled in 1920. This feat brought her to the attention of the college authorities, and she was soon given a home on the campus. Subsequent matings with other jacks failed to produce another colt, but a noted stallion of the college stud sired a foal that has grown up to look quite like a horse — and a fine horse at that. "Old Beck’s” mule daughter has remained without issue, in spite of several attempts to breed her, but the horse-like colt, a stallion, has sired one healthy colt, now over a year old.

A molly gave birth to 2 foals in Nebraska in the mid-1980s. The event prompted the first genetic testing of a mule's offspring. Tests showed no evidence the mother passed along any genetic markers from her donkey father, who was also the father of the foals. This is called "hemiclonal transmission". She passes on only her horse DNA with no shuffling of horse and donkey genetic material.

In April 2007, a 7 year old black molly, “Kate”, owned by ranchers Larry and Laura Amos gave birth at a Grand Mesa ranch near to Colbran. Kate was one of 10 mules purchased from Pleasant Plains, Arkansas and would already have been pregnant. Genetic testing at the University of Kentucky and the University of California at Davis confirm that Kate is a mule and that the foal is her offspring. This rules out stolen foals that were donkeys or mulish-looking horses. Her son has a donkey-like appearance suggesting the father was a donkey and, because female mules usually only pass on their maternal horse DNA, that he is a mule.

A fertile hinny in China is believed to be a unique case. Her offspring was sired by a donkey. Named "Dragon Foal", one would have expected a donkey foal if the mother had passed on her maternal chromosomes in the same way as a mule. However, Dragon Foal appears to be a strange donkey with some mule-like features. Her chromosomes and DNA tests confirm she is a previously undocumented combination. In Morocco, a mare mule produced a male foal that is 75% donkey and 25% horse i.e. she passed on a mixture of genes instead of passing on her maternal chromosomes. There are no recorded cases of fertile mule stallions.

Asses have 62 chromosomes, horses have 64 so the hybrids have 63. When there's an odd number of chromosomes, meiosis (cell division to form gametes (egg or sperm cells)) doesn't work correctly. This causes hybrid sterility. Nature has a way round this called meiotic drive. Genes from each parent become tightly linked instead of independently assorted. The genes from one parent - usually the mother - will be over-represented in the gametes produced by the hybrid offspring. Normally when cells divide to form gametes, a random mix of maternal/paternal alleles ends up in each gamete. With meiotic drive, there is distinct segregation of maternal and paternal alleles: all the horse genes end up on one side of the cell and all the donkey genes end up on the other. The cell then splits unevenly. Only one of those daughter cells will get the necessary machinery for life (genes from the mother, mitochondria, cytoplasm etc) while the other cell is discarded along with all the genes from the father! In fertile mule mares, the mare passes on a complete set of her maternal genes (i.e. from her horse/pony mother) to the foal. A female mule bred to a horse will therefore produce a 100% horse foal (which is fertile) while a female mule bred to an ass will produce another mule. It seems to be nature's way of letting a female mate with a related species, but preserving the genes from the female side of the family so the hybrid descendent can produce a purebred offspring.

ZEBRA/DONKEY (ZEBRA/ASS) HYBRIDS

Zedonks (zebronkeys, zonkeys, zebadonks, zebrydes) are zebra stallion/donkey hybrids. Zebrets are donkey stallion/zebra mare hybrids and are rare. Other names have been used: zenkey (Japan) and hamzab (Israel). Generic terms are zebrass, zebra mule and zebra hinny. Zebrasses resemble donkeys with a striped pattern overlaided on the donkey's background colour. Usually there is clear striping on the legs, a dorsal stripe. There may be facial stripes and indistinct stripes on the body. According to Dorcas McClintock in "A Natural History Of Zebras," a hybrid foal from a Somali wild ass bred to a mountain zebra mare had 2 transverse shoulder stripes, leg bands and zebra-like ear stripes. Piebald zebrasses are produced when a zebra is crossed to a piebald donkey.

Zebra/ass hybrids have been recorded since at least the 1850s. According to the “Illustrated Natural History” by the Rev JG Wood (1853, 1874): Between the zebras and the domestic ass several curious Mules have been produced, and may be seen in the collection of the British Museum. It is worthy of notice that wherever a cross breed has taken place, the influence of the male parent seems to be permanently impressed on the mother, who in her subsequent offspring imprints upon them some characteristics of the interloper. In his "The Variation Of Animals And Plants Under Domestication", Darwin wrote: "I have seen, in the British Museum, a hybrid from the ass and zebra dappled on its hinder quarters. [...] Many years ago I saw in the Zoological Gardens a curious triple hybrid, from a bay mare, by a hybrid from a male ass and female zebra". Zebrass males are generally sterile in spite of Darwin's report of that horse mare x zebrass stallion hybrid (is it possible the stallion was a quagga rather than a hybrid?).



A zebrass foaled at Schoenbrunn in 1841.

German zebroid (1929)



Hybrid of Grevy's Zebra and Somali Ass (1929)

"Ass-zebra" ("Wonders of Animal Life" edited by J A Hammerton (1930)). Possibly one of the Sells-Floto Circus Hyneys.

Grevy's zebra/ass hybrid.

A Grevy’s zebra stallion was presented to USA by King Menelik of Abyssinia. President Roosevelt. It lived at the National Zoo from 1904 to 1919 and was loaned for a while to the US Dept of Agriculture for use in cross-breeding experiments with horses and asses. At least some of the hybrid offspring went to Sells-Floto circus. Sells-Floto Circus advertised one of the hybrids as:A New Member Of The Animal Kingdom. A strange beast came into being a short time ago, and naturally it was the Sells-Floto Circus which seized upon it as thing of interest to the public at large That beast was the ‘Hyney,’ a Government animal, now being exhibited with the Circus to show the wonderful results of the propagation and breeding of entirely different animals. For the parents of the Hyney were brought from widely separated parts of the earth. After years of experiments, in which attempts were made to cross the zebra with some other beast that might give it value as a domestic animal, the United States Government, through its division of husbandry and animal industry, decided that the burro was the proper animal. And so a Grevy Zebra, of the Galla district of Africa, the fiercest and wildest of all types of zebra, was crossed with a Rocky Mountain Burro, known as the slowest and dullest and most sluggard animal of the horse species. The result was a success. And thus it is that a new animal enters into being – the Hyney – with a burro for a mother and a zebra for a father. The combination is perfect. As fleet, as graceful as a horse, yet the Hyney has all the strength and working power of a mule. As intelligent as its zebra forebear, still it has the docility of its burro ancestors. Five of the animals are exhibited both in the menagerie and main performance of the Sells-Floto Circus, where the extent of their intelligence and their value as farm animals is well depicted.

Circa 1909. Zebra/ass hybrids bred at the National Zoo and shown performing in the circus. Two zebroids drawing a cart in 1915

An article from New York Times, June 16th, 1973, announced the birth of a zebra/donkey hybrid at the Jerusalem Zoo. They called it a "hamzab" from the Hebrew for donkey-zebra and erroneously claimed it to be the first of its kind born anywhere. A breeding programme at Colchester Zoo, England in 1975 produced three zedonk hybrids from Arabian Black Ass mares and A Chapman's Zebra stallions. In Christmas week of 1975 their third zedonk foal was born. Previous attempts at crossbreeding zebras with horses and donkeys had failed to produce surviving foals. The zoo's aim was to produce disease-resistant work-horses for Africa. Colchester Zoo experts believed their success was due to the use of an Arabian donkey (a variety not tried before in hybridization experiments) and had hoped that the hybrids would be viable and fertile. Their last surviving zedonk, Shadow, died in April 2009 aged 34. She shared an enclosure with zebras, but did not socialise with them. In latter years, the zoo tried to dissociate itself from the hybridisation programme by claiming the zedonks were the result of accidental matings, but contined to claim they'd bred the first ever zedonks, despite the hybrids being bred over 100 years earlier. The Chestatee Wildlife Preserve in Georgia, U.S. had its own zonkey on July 21, 2010. A donkey sanctuary in Shropshire has a zorse called Zulu, a zedonk called Zambi, and a zebra hinny called Zee (the latter results from a donkey stallion and zebra mare). The sanctuary does not condone breeding zebroids, but had rescued the three hybrids which had been bred in the USA where donkey/zebra and horse/zebra crosses are bred on several ranches as exotic riding or driving animals. Ippo the 'Zonkey' was born after a zebra stallion climbed out of his enclosure to mate with an endangered donkey at an animal reserve in Florence, Italy. The sire had been rescued from a failing zoo. The mother was a Donkey of Amiata, an endangered species, in a neighbouring field.



1970s zebra/donkey hybrid, photographed 2006 at Colchester Zoo, England.

Herbert Goodchild's painting of a zebrass in 1899

Usually a zebra stallion is paired with a horse mare or ass mare, but in 2005, a Burchell's zebra named Allison produced a zebrass (a zebret ) called Alex sired by a donkey at Highland plantation in St. Thomas parish, Barbados. In "Origin of Species" (1859) Charles Darwin mentioned four coloured drawings of hybrids between the ass and zebra. In his "The Variation Of Animals And Plants Under Domestication", he mentions an unusal zebra triple-hybrid: "I have seen, in the British Museum, a hybrid from the ass and zebra dappled on its hinder quarters. [...] Many years ago I saw in the Zoological Gardens a curious triple hybrid, from a bay mare, by a hybrid from a male ass and female zebra." and "a compound hybrid which I saw in the Zoological Gardens, from a mare by a hybrid ass-zebra, closely resembled its mother in its tail." If true, this is the only account of a fertile zebrass stallion. In "Darwinism An Exposition Of The Theory Of Natural Selection With Some Of Its Applications" (1889), Alfred Russel Wallace commented on the production and appearance of hybrids: "Crosses between the two species of zebra, or even between the zebra and the quagga, or the quagga and the ass, might have led to a very different result." THE ZEBRULA Although there is a much more detailed page about this specific hybrid and its uses, here is a summary. A widely circulated report, published in May 1903, writes: "That entirely new species of animals may be created is demonstrated by the latest achievements of the world’s greatest animal hunter, Carl Hagenbeck. On his animal ranch near Hamburg, Germany, Hagenbeck has for some time past been devoting himself to the creating of new species of animals and birds. He has obtained new varieties of deer and mules and wonderful crosses between the zebra and the horse. [. . .] Probably the furthest developed of the new species, of animals he is creating is the cross between the zebra and the horse. A number of these are at his depot in Hamburg, and it is not an uncommon sight to see him taking a drive behind two of these strange “horses.” The characteristic of these animals is that they possess the zebra’s body and the horse’s head, and are as large as mules. The aim has been to obtain a stronger and better blood than that possessed by the existing equine breeds. At present Hagenbeck has six zebra-horses broken to harness. He has found them possessed of greater endurance and strength than horses of their weight, and seemingly possessed of greater intelligence." According to the Croydon Chronicle and East Surrey Advertiser, 19th December 1903 (among many others): Scientific Cross-breedings. Carl Hagenbeck, of Hamburg, the well-known wild animal dealer, [. . .] is trying to introduce the zebrule, or hybrid horse and zebra into the German Army in place of mules. We know that the zebrules are being tried in the Indian Army. NEW DRAFT ANIMAL DOOMS ARMY MULE. CROSS BETWEEN HORSE AND ZEBRA IS SUPERIOR. DOES NOT CONTRACT DISEASE.

More Lively Than the Animal That Provokes Cussing and Cannot Be Less Intelligent. (Various, August 1903)

The days of the mule are numbered. Within the next few centuries his melodious voice will have been stilled forever. This is the prophecy of United States Consul General Richard Guenther, at Frankfort, Germany, who sends a report to the state department on the chances of the zebrula, a cross between the horse and zebra, superceding the mule. He says of the qualifications of the zebrula: “German papers contend that it has been demonstrated that the mule, the cross between the horse and donkey, is inferior to the cross between horse and zebra. Formerly the opinion prevailed that the zebra was almost extinct. The opening up of Africa, particularly the eastern part, reveals these fine animals in large numbers. Compared with horses and cattle, they possess peculiar advantages, as they are immune against the very dangerous horse disease of Africa, and also against the deadly “tztze.” The question was therefore raised whether the zebra could not take the place of the mule, commonly used in the tropics. The greatest credit with reference to the solution of this problem is due to Professor Cossar Ewart, who has been trying since 1895 to produce crosses between horses and zebras, with a view to developing an animal superior in every respect to the mule. Professor Ewart produced crosses from mares of different breeds and zebra stallions of the burchell kind. The offspring is called zebrula, and on account of its form and general bodily condition, especially the hardness of the hoofs, is specially adapted for all transport work heretofore performed by mules. The zebrula is much livelier than the mule and at least as intelligent. The zebra stripes are often well preserved, while the undertone of the skin is generally that of the mother. A full grown zebrula is fourteen hands high and the girdle circumference about 160 centimeters (sixty-three inches). The experiments so far have been so successful that it is predicted that the zebrula during the present century will completely supercede the mule.” Other newspapers of the time wrote "The days of the mule are numbered, comes the word from Germany, where a new animal, the Zebrula, has been evolved to take the place of the gentle-eyed, melodious-voiced and hard- hoofed little animal. The new animat1 is the result of a cross between the horse and a zebra. The nomenclature of horseology would indicate that a better name for the new quadruped would-be the zehorska." “A report from the November 25th, 1904 edition of the Olsburg Gazette mentions the zebrulas at the World’s Fair: “The Zebrula. A new breed of horseflesh has come into public notice, namely, the Zebrula. Some of these animals are being shown at the World’s Fair. They originated in Africa from a cross of the Zebra stallion and the horse mare. They are said to be highly regarded in South Africa, where they are valuable on account of not being affected by the bite of the tsetse fly, which is sure death to the horse or donkey. Breeders in South Russia, in England and Germany have taken up the breeding of these animals. They are said to be hardier than the mule or horse. The Zebra is known to be a very wild and swift animal and for a long time it was found impossible to make him useful to man on account of his wildness. The crossing has taken some of the wildness out of his progeny. The name given to the progeny is Zebrula. It is likely that we will soon have a good many varieties of the Zebrula, as there are two species of zebras, those inhabiting the mountains and those inhabiting the plains, and the crossing of these in various ways should give a great variety of markings and other conformations.” On January 27th, 1905, The Times Dispatched asked “Will Zebrulas Come Here? [American] Government May Experiment With New Zebra Horse Cross. It is understood that the government has under consideration the importance of zebras for the purpose of experimental breeding with the horse. The Agricultural Department has been asked to take up this work, but as Uncle James Wilson Is pretty well acquainted with the American mule and his good qualities, it is not sure that he will spend much time or money on the new breed. The hybrid between the horse and the zebra is a striped animal with great speed and endurance. Germany has been experimenting with this cross. for several years and has tested its value in war with results that were very encouraging. It is said of the zebrula that it is as gentle as a horse, in this respect differing very much from the zebra. It is stronger than a mule and entirely immune from certain diseases which are pretty certain to attack horses and frequently with fata) results when imported into certain parts of Africa. As soon as the German Government were satisfied with the success of this line of crossing, it at once established a breeding station in its African possessions. At this station much attention in being given to the breeding of zebrulas, and these are now regularly used in handling heavy ordnance, as, for instance, mountain batteries of the colonial service. They are also being used as mounts for officers and men, and for draught ' purposes in various ways. Later on, The Cincinnati Enquirer of May 1st, 1905 wrote: “Three Zebrulas Added To the Curiosities of the Cincinnati Zoological Garden. Three zebrulas have been received at the zoo from the Hagenbeck Company at Hamburg, Germany. The animals have been in this country for some time, and were a part of the big collection of wild animals which was exhibited at the St. Louis World’s Fair by Hagenbeck. The zebrula is a hybrid animai, which is secured by crossing the zebra with either a donkey or a horse. One of the zebrulas received here is a cross with a horse, and the other two are crossed with donkeys. The zebrulas are bred by the German army for experimental purposes for use in Africa. The zebra has a hide which can resist the insects and flies, and by crossing them with horses the Germans hoped to produce an animal which had the endurance of the horse and those qualities of a zebra which would allow it to be used for domestic purposes in Africa. The hybrid was called the zebrula as it is purely an artificial animal." Ultimately, the zebrula was to become a circus curiosity as this cutting from The Kingsport Times of August 20, 1925 indicates: "ZEBRAS AND ZEBRULAS DO TRICKS AT WILL OF CHRISTY'S TRAINERS. For the first time in the history of wild animal training zebras and zebrulas have been taught to perform tricks and obey the will of their trainer. Some fine specimens of these animals are with Christy Bros, trained wild animal show, which will exhibit in Kingsport on Monday, September 14. The striped equine has always been the stumbling block in the paths of educators and trainers of beasts and animals. Many of them after herculean and patient endeavor have given up in disgust and consigned the convict coated animal to a remote and disagreeable locality, acknowledging that he was beyond all human understanding. Christy Bros, trainers for many years concurred in this belief, but heroic perseverance was finally and justly rewarded. These circus kings now have with their great show zebras that give performances which include everything done by the best trick horses. Interesting in this connection is the appearance and presentation at the same time of several zebrulas, or equine hybrids, the only ones of their kind, produced by scientific crossing of full blooded zebras and Kentucky thoroughbred horses." Here we have an account of the hybrid from The Elyria Reporter on August 22nd, 1905: “ To experiment With Zebrula. Zebrula, .a newly coined word. Is applied lo a peculiar appearing animal. The zebrula is a cross between a full-blooded, vicious zebra and an American horse. The zebra, as students of natural history are informed, is the hardest of all four-footed, hay-eating animals to handle. It is more treacherous than either the lion or tiger, and is ten times more lively, when it comes to kicking, than the well-known Missouri mule. The zebrula does not Inherit these bad qualities from his sire’s side. He looks like a zebra about the head and has dull brown stripes that show indistinctly int [sic] he still duller brown of the hair, which is very soft and silky. A full-blood zebra possesses bright, black and white stripes in conformation the zebrula follows the type of the American horse, and from the infusion of the latter’s blood. Its temper is normal, as it were, and it displays the many good traits of the horse. English army officers have become greatly interested in the zebrula and have induced the government to request Mr. Hagenbeck to breed at least a dozen of them and send them to South Africa, for experimental purposes. The officers believe the zebrula will stand the South African climate better and do considerably more work than either the full-blooded mule or horse. From The evening News, September 7th, 1922: “Science is just now Interested In hybrids of the zebra stock. There is a flecky-built faintly-striped zebrula at the Zoo, a cross between a zebra and a Shetland pony. In Southern Indiana the zebra has been successfully mated with Arabia mares, producing the zebroid, a tough but docile beast of burden. One advantage expected of this cross Is the longevity that the sire may be able to confer on his progeny. In his native Africa he sometimes reaches 75 years, and if his hybrid American offspring can carry their vigor into fifty years, this would be more than double the horse’s expectancy of life. “ (The claim of such longevity in zebras was incorrect) The Daily Courier of December 7th, 1936, mentioned the zebrula in brief: “Mule, Jennet and Zebrula. Of animals which owe their existence to man the mule and the jennet are the oldest examples, and no one can deny that the mule is a most useful creature Hardy as a donkey, strong as a horse, surefooted and tireless, there is nothing like it for rough country traveling Its success caused the production of the zebrula which is a cross between the horse and zebra. The zebrula is as strong as a mule, but livelier and even less liable to disease. ZEBRA/HORSE, ZEBRA/PONY HYBRIDS Zebras will hybridize in the wild with feral horses in South Africa and with wild asses in northeast Africa. When I was a child, I had some of Time Life books. If memory serves, one contained a photo of a mixed herd of zebra, wild horses and zebroids where the aggressive zebra stallions stole the horse mares from the feral herds in parts of South Africa. The horses arrived in the region with settlers and with the British and German armies. Some escaped and others were abandoned (due to the cost of returning them to Europe); being herd animals, they would have been attracted to zebra herds. Others fell prey to lions as they lacked the zebra’s camouflage. The zebroid offspring, although they grew to adulthood and remained with zebra herds, were also vulnerable to predators and, being generally sterile, did not produce offspring of their own. Zorses or zebrules are zebra stallion/horse hybrids and zonies are zebra stallion/pony hybrids. Zorses are sometimes called golden zebras due to dark stripes overlaying a chestnut background, though the colour depends on the colour of the horse parent. The zetland is a one off accidental zebra/Shetland pony hybrid. Zebroid is a blanket term for zebra/horse hybrids. Any of the zebra species can be used in breeding zebroids; the colour depends on the colour of the horse; usually there is clear striping on the legs, a dorsal stripe, striped face and less distinct stripes on the body; the somewhat donkey-like attributes of zebras result in a dorsal stripe, upright mane without a forelock and large ears. Another term for zebra hybrids is zebra mule since zebra stallions (which are hand-raised or fostered on a horse mare) are used in preference to zebra mares. Zebra hinnies are rarely found. Zebroid and zebrass males are generally sterile. Although wild animals, zebras which are hand-reared or reared with domestic horses can become tame enough to be led, ridden or used as draught animals. Piebald zorses are produced when a zebra is crossed to a piebald horse. Stripes are visible on the colored areas of the coat. The white patches form a startling contrast with these striped patches. A hybrid called "Eclyse" was bred in Germany in 2007 from a zebra mare and piebald or skewbald horse stallion (piebald = black-and-white, skewbald = any-other -colour-and-white e.g. brown/bay/chestnut with white). Pied zorses are not commonly bred. In "Origin of Species" (1859) Charles Darwin wrote: "In Lord Moreton's famous hybrid from a chestnut mare and male quagga, the hybrid, and even the pure offspring subsequently produced from the mare by a black Arabian sire, were much more plainly barred across the legs than is even the pure quagga.. In his "The Variation Of Animals And Plants Under Domestication", Darwin wrote: "I have seen, in the British Museum, a hybrid from the ass and zebra dappled on its hinder quarters. [...] Many years ago I saw in the Zoological Gardens a curious triple hybrid, from a bay mare, by a hybrid from a male ass and female zebra". and further described Moreton's hybrid; In the famous hybrid bred by Lord Morton ('Philosoph. Transact.' 1821 page 20.) from a chestnut, nearly purely-bred, Arabian mare, by a male quagga, the stripes were "more strongly defined and darker than those on the legs of "the quagga." The mare was subsequently put to a black Arabian horse, and bore two colts, both [...] plainly striped on the legs, and one of them likewise had stripes on the neck and body. In "Darwinism An Exposition Of The Theory Of Natural Selection With Some Of Its Applications" (1889), Alfred Russel Wallace commented: "Crosses between the two species of zebra, or even between the zebra and the quagga, or the quagga and the ass, might have led to a very different result." Raymond Hook of Nanyuki, Kenya, is claimed to have bred the first zebroids by crossing a Grevy's zebra stallion with domestic mares (date unknown?). The hybrids had Grevy-like narrow stripes and a tufted tail, but were more horselike in conformation and color. The strong, sure-footed, docile and mulelike zebroids were used as pack animals by climbers on Mount Kenya's lower slopes. Grevy's zebra has also been crossed with donkey mares. Carl Hagenbeck produced zebrules (zebra/pony hybrids) at his Tierpark in Hamburg. These had dark bodies and faintly visible stripes.



1899 zebra/horse hybrid

1899 zebra/horse hybrid

1904 zebra/horse hybrid

In "Anomalies and Curiosities of Medicine" by George M Gould and Walter L Pyle (1896) wrote: The influence of the paternal seed on the physical and mental constitution of the child is well known. To designate this condition, Telegony is the Word that was coined by Weismann in his "Das Keimplasma," and he defines it as "Infection of the Germ," and, at another time, as " Those doubtful instances in which the offspring is said to resemble, not the father, but an early mate of the mother," - or, in other words, the alleged influence of a previous sire on the progeny produced by a subsequent one from the same mother. In a systematic discussion of telegony before the Royal Medical Society, Edinburgh, on March 1, 1895, Brunton Blaikie, as a means of making the definition of telegony plainer by practical example, prefaced his remarks by citing the classic example which first drew the attention of the modern scientific world to this phenomenon. The facts of this case were communicated in a letter from the Earl of Morton to the President of the Royal Society in 1821, and were as follows: In the year 1815 Lord Morton put a male quagga [a type of zebra] to a young chestnut mare of seven eighths Arabian blood, which had never before been bred from. The result was a female hybrid which resembled both parents. He now sold the mare to Sir Gore Ousley, who two years after she bore the hybrid put her to a black Arabian horse. During the two following years she had two foals which Lord Morton thus describes: " They have the character of the Arabian breed as decidedly as can be expected when fifteen sixteenths of the blood are Arabian, and they are fine specimens of the breed; but both in their color and in the hair of their manes they have a striking resemblance to the quagga. Their color is bay, marked more or less like the quagga in a darker tint. Both are distinguished by the dark line along the ridge of the back, the dark stripes across the forehand and the dark bars across the back part of the legs." The President of the Royal Society saw the foals and verified Lord Morton's statement. Cossar Ewart, Professor of Natural History at Edinburgh (1882-1927) and a keen geneticist, crossed a zebra stallion with pony mares in order to disprove telegony, or paternal impression, a common theory of inheritance at the time. Cossar Ewart found that zebra-horse hybrids were brown with faint stripes. When the same mares were subsequently mated with a pony, the resulting foals showed none of the markings or temperamental characteristics of a zebra. He completely undermined Lord Morton's case by pointing out that similar bandings occur naturally, without crossing, in certain breeds of horses, notably a Norwegian breed; and by breeding many zebra hybrids — the progeny of a great variety of virgin horse and pony mares, followed by foals from the same mares by an Arab stallion — not one of which showed any marking or other characteristic which could be traced to the zebra! Cossar Ewart found that in male zebra-hybrids the sexual cells were immature and the sperm were abnormal, however the ovaries of female zebra-hybrids appeared similar to those of a normal mare or female zebra. As well as disproving paternal impression, he wanted to produce a more resilient draught animal for South Africa; one less subject to local diseases and more tractable than a mule. Gos de Voogt wrote, in “Our Domestic Animals, their habits, intelligence and usefulness” (translated from the French by Katherine P. Wormeley; edited for America by Charles William Burkett; Ginn and Co.; Boston; 1907): Lately a Scotch naturalist, J. C. Ewarts, who has made himself a name in this domain, mated a zebra stallion, named Matopes, with a mare from one of the Scotch islands. The product was a foal which received the name of Romulus, the new race being called zebrules,Sir John, a colt, and the fillies Bunda and Black Agnes, which were both sold to Hamburg ; the English government then bought them and sent them to India, where they were trained for service in a mountain battery. In shape the zebroids are a cross between the horse and the zebra. Romulus, born in 1896, derived from his father only very indistinct stripes, while Sir John has them more clearly defined. These zebroids are strong, manageable, and easy to train both for saddle and harness ; it is hoped that they have inherited the zebra's immunity from equine diseases.



An experiment that disproved telegony. Left, a striped zebra-horse hybrid, produced by mating a mare with a zebra stallion. The same mare was then mated with a horse stallion, and produced the filly shown below, which bears no traces of any effect of the previous sire. The experiment was carried out by the US Government and reported in "Genetics in Relation to Agriculture" by E B Babcock and RE Clausen. ("The Science of Life" by H G Wells, J Huxley and GP Wells (c.1929))

In "The Science of Life" (c 1929) by H G Wells, J Huxley and GP Wells, the authors wrote "To-day it is possible to assert without any question that telegony is a mere fable, which could only have gained ground in the days when men were ignorant of the true mechanism of fertilization and reproduction. The supposed instances of telegony which are constantly being reported even to-day, invariably. Perhaps the most famous example is that of Lord Morton's mare. The mare, a pure Arabian, was mated with a zebra stallion, and produced a hybrid foal. On two later occasions, she was bred to a black Arab stallion, and gave birth to two further foals. These had legs which were striped even more definitely than those of the hybrid foal or the zebra sire himself, and one had some stripes on parts of the neck also. In addition, they had a stiff mane of very zebra-like appearance. Darwin himself accepted the evidence as sufficient proof of telegony. But when definitely planned and long-continued experiments were made, the proof escaped. Cossar Ewart, for instance, made a number of horse and zebra crosses to test the validity of the belief. When mares previously bred to zebras were afterwards mated with horse stallions, their colts were often without the least trace of zebra characters. In other cases, colts with some degree of striping were produced. But one mare gave birth to a striped colt as a result of her first mating, which was with a horse stallion ; while two later matings with other stallions, made after she had been successfully mated once and three times respectively with a zebra, gave unstriped offspring. In other cases, when striped colts were born to a mare and stallion after the mare had been previously mated to a zebra, Ewart took other mares, closely related to the first, bred them to the same Arabian stallion without having mated them previously with a zebra - and they, too, produced striped foals. In short, the production of striping (and also of erect mane) in foals is not a very uncommon occurrence in horses; it may appear whether previous impregnation by a zebra has taken place or not. The stripes of Lord Morton's foals were a mere coincidence, well illustrating the danger of drawing conclusions from single and therefore possibly exceptional cases, and the need for systematic and repeated experiments." Above: The King's Hybrid (1902). This is the animal that Hammerton later described in 1930. A REMARKABLE ZEBRA HYBRID. (The Sketch, 30th July 1902) The accompanying photograph of a remarkable zebra hybrid which Lord Kitchener brought home for presentation to the King is of peculiar interest. The animal (which, properly speaking, should be described as a “quagga," being a cross between a zebra and a pony) was bought as a yearling in South Africa by Captain A. C. Webb, of the Johannesburg Remount Depot, who, after training it to the saddle, sent it home by Lord Kitchener as a present to His Majesty. The quagga is an inch and a-quarter over thirteen hands the body-colour brown, lightening to bay on the head and legs, with very peculiar striping. The marks on the body and cheeks are almost vertical, the leg markings horizontal to the hocks, below which the colour is black, while the dorsal stripe tapers to the tail. The animal is very beautiful and shapely, strongly resembling a well-grown pony, with a quiet, easy temper. When first brought home by Lord Kitchener, it was quartered in the Royal Mews at Buckingham Palace, but, as the King has decided that so remarkable a hybrid specimen should find a place in the Zoological Gardens, it was taken to Regent's Park last week by two of the Royal grooms, who led it quietly through tire busy streets without attracting any attention. It occupies, for the present, a big loose-box in the Upper Yard in the “Zoo," where it has apparently made itself quite at home and comfortable. From a scientific point of view, the new-comer is said to be one of the most remarkable animals that have come into the possession of the Society for many years. The photograph was taken at the Remount Depot at Johannesburg. In "Animal Life and the World of Nature" (1902-1903), WP Dando (Fellow of the Zoological Society, London) writes: Much interest has been aroused at the Zoo by the presentation by His Majesty the King of a hybrid Zebra, a cross-breed between a stallion horse and a Burchell's zebra mare. This animal was sent over to England by Lord Kitchener, who discovered it among the remounts placed at his disposal in the Transvaal during the war. The zebra markings are fairly distinct on all four legs, also slightly across the loins and at the root of the tail, continuing a few inches up the centre of the buttocks. These markings (and the tail itself, which it will be noticed is more like a donkey's than a horse's) are the only characteristics of the zebra which are prominent, the animal lacking the erect mane and other distinguishing features. Since the animal has been in captivity he has become most ferocious and savage - no doubt from the want of proper exercise. By the courtesy of the Society's officials I was enabled to get my pictures in the yard adjoining the stables, the animal being securely held; and I took my position at a respectful distance."



In "Wonders of Animal Life" (1930), J A Hammerton, it noted that crosses were made between Chapman's zebras and a ponies during the South African War .

In "Wonders of Animal Life" (1930) edited by J A Hammerton, it notes: During the South African War, an attempt was made by the Boers to evolve a new animal to supplement the supply available for transport work. A cross was obtained between a Chapman's zebra and a pony and a specimen was captured by the British and presented to King Edward VII by Lord Kitchener. The animal was produced chiefly for hauling guns. It was photographed by W S Berridge. WP Dando FZS, in the 1902/03 encyclopedia "Animal Life and the World of Nature" described the same hybrid as a cross with a Burchell's zebra. McClintock noted that a Chapman's zebra stallion, kept by Friedrich von Falz-Fein at Askania-Nova in southern Russia actually preferred to mate with domestic mares rather than with a Chapman zebra mare. Eventually the stallion killed his zebra mate by biting her to death. In “Out of Africa”, the African memoirs of Baroness Karen Blixen (1885-1962) published in 1937, Blixen writes: ” It is a much debated question whether it is possible to cross domestic animals with the game: many people have tried to create a type of small horse fitted to the country, by breeding from zebra and horses, though I myself have never seen such cross-breeds.” Today, zorses and zonies are relatively common. Zebra hybrids are considered better suited (through better temperament and more horse-like/donkey-like conformation) than pure zebras to being ridden or used for draught. They are resistant to some of the diseases that afflict horses and donkeys, hence they have been used use in Africa for trekking and draught. In the USA they are bred as riding and show animals, because of their interesting appearance. in Manila Zoo in 2011, a domestic stallion that found itself isolated by other horses, made itself part of the zoos zebra herd where it fathered a “hebra”. ZORSE/ZONY COLOURS Zebras are normally bred to solid colour horses/ponies to produce offspring with striping over the whole body. The interaction of chestnut and zebra striping gives rise to the alternative name "golden zebra". The striping pattern depends on the type of zebra used. When bred to a piebald (black-and-white) horse (US: piebald pinto) or to a skewbald (brown/bay/chestnut-and-white) horse (US: skewbald pinto) or to particoloured USAnian breeds known as "Paint" and "Appaloosa", the offspring have a mix of striped coloured areas and unstriped white areas. Grey horses are not used as the offspring will be grey, becoming white with age, albeit having the conformation of a zorse/zony. DARWIN ON HYBRID EQUIDS In "Origin of Species" (1859) Charles Darwin mentioned four coloured drawings of hybrids between the ass and zebra. He noted "In Lord Moreton's famous hybrid from a chestnut mare and male quagga, the hybrid, and even the pure offspring subsequently produced from the mare by a black Arabian sire, were much more plainly barred across the legs than is even the pure quagga. Lastly, and this is another most remarkable case, a hybrid has been figured by Dr. Gray (and he informs me that he knows of a second case) from the ass and the hemionus." Darwin described the latter hybrid in "The Variation Of Animals And Plants Under Domestication": The Equus indicus [onager] a hybrid, raised at Knowsley ('Gleanings from the Knowsley Menageries' by Dr. J.E. Gray.) from a female of this species by a male domestic ass, had all four legs transversely and conspicuously striped, had three short stripes on each shoulder and had even some zebra-like stripes on its face! Dr. Gray informs me that he has seen a second hybrid of the same parentage, similarly striped. In his "The Variation Of Animals And Plants Under Domestication", Darwin wrote: "I have seen, in the British Museum, a hybrid from the ass and zebra dappled on its hinder quarters. [...] Many years ago I saw in the Zoological Gardens a curious triple hybrid, from a bay mare, by a hybrid from a male ass and female zebra. and further described Moreton's hybrid; In the famous hybrid bred by Lord Morton ('Philosoph. Transact.' 1821 page 20.) from a chestnut, nearly purely-bred, Arabian mare, by a male quagga, the stripes were "more strongly defined and darker than those on the legs of "the quagga." The mare was subsequently put to a black Arabian horse, and bore two colts, both [...] plainly striped on the legs, and one of them likewise had stripes on the neck and body. In that book, Darwin concluded: "The ass has a prepotent power over the horse, so that both the mule and the hinny more resemble the ass than the horse; but that the prepotency runs more strongly in the male-ass than in the female, so that the mule, which is the offspring of the male-ass and mare, is more like an ass, than is the hinny, which is the offspring of the female-ass and stallion." In "The Variation Of Animals And Plants Under Domestication" Darwin elaborated: "Colin, who has given in his 'Traite Phys. Comp.' tome 2 pages 537-539, [...] is strongly of opinion that the ass preponderates in both crosses, but in an unequal degree. This is likewise the conclusion of Flourens, and of Bechstein in his 'Naturgeschichte Deutschlands' b. 1 s. 294. The tail of the hinny is much more like that of the horse than is the tail of the mule, and this is generally accounted for by the males of both species transmitting with greater power this part of their structure; but a compound hybrid which I saw in the Zoological Gardens, from a mare by a hybrid ass-zebra, closely resembled its mother in its tail.)" In "Darwinism An Exposition Of The Theory Of Natural Selection With Some Of Its Applications" (1889), Alfred Russel Wallace commented: "Crosses between the two species of zebra, or even between the zebra and the quagga, or the quagga and the ass, might have led to a very different result." OTHER EQUID HYBRIDS, ZEBRA X ZEBRA HYBRIDS All equid species will hybridise to produce viable offspring, though the offspring are generally sterile with only a few exceptions. Hybrids between Equus africanus (wild African ass) x Equus asinus (domestic donkey) hybrids are fully fertile.. Hybrids between the Equus caballus (domestic horse) and Equus przewalskii (Przewalski horse), a primitve wild species, are fertile despite their differing chromosome numbers (66 for the Przewalski horse, 64 for the domestic horse). The onager (Equus hermionus) is an Asiatic ass or hermione. Ass/onager and horse/onager hybrids appear to have been bred in the ancient civilisations of western Asia, these having a similar role to modern mules. WILD ASS HYBRIDS. (The Field, 27th June 1903) Equus temoinus, Pallas, is usually known as the kiang. Blandford terms it the Asiatic wild ass [. . .] Capt. Sutherland and myself, says that it, breeds freely with the horse, and that the produce is highly valued. There can be, in fact, but little doubt that the mule bred by the kiang would be of the highest value. [. . .] As practical a man as Colonel Kinloch suggested that a cross between the kiang and the horse would prove a most valuable animal, possessing all the good qualities of the ordinary mule, with greater size and strength. [. . .] There were formerly several examples of the Syrian wild ass (Equus hemippus, St Hilaire) in the gardens [London Zoo], and in the catalogue of animals published in 1896 there is a record of a hybrid between this species and the Asiatic ass, which was bred in 1883. According to Dorcas McClintock in "A Natural History Of Zebras," Grevy's zebra has 46 chromosomes; plains zebras have 44 and mountain zebras have 32. The domestic horse has 64 chromosomes. Although all 3 zebra species have been crossed with domestic horses, the 2 dissimilar sets of chromosomes inherited by a zebra hybrid cannot mix because of differences in number, size and shape. As a result, almost all zebra hybrids are sterile. In captivity, plains zebras have been crossed with mountain zebras. The hybrid foals had no dewlap and, except for their larger ears and their hindquarters pattern, they resembled the plains zebra parent. Attempts to breed a Grevy's zebra stallion to mountain zebra mares resulted in a high rate of abortion. In the wild, zebra species don't interbreed even where their ranges overlap or they graze together. This was was also true when the quagga and Burchell's race of plains zebra shared the same area. A hybrid foal from a Somali wild ass bred to a mountain zebra mare had 2 transverse shoulder stripes, leg bands and zebra-like ear stripes. According to Crandall, some hybrids ("racial intergrades") were foaled by a Hartmann's mare and sired by a Cape stallion between 1924 and 1931; one of these was sent to London Zoological Gardens and figured by Antonius (1951:196). Crandall noted that Gray (1954) listed many crosses between zebras and both horses and asses, wild and domestic. In most cases the male hybrids seemed to be sterile, but there was some evidence indicating that females may sometimes be sterile. Several of these hybrids were figured by Antonius (1954). Additionally, Przewalski's horse interbreeds freely and fertilely with domestic horse and has produced hybrids, probably sterile, with zebras, but did not produce offspring when mated with donkeys (Gray 1954). Although Crandall did not state where these Przewalski hybrids were produced, they may have been at Hagenbeck's Tierpark. As a result, there may be a very low level of domesticated horse blood in some Przewalski's horses today. The herd at the National Zoo's breeding farm at Front Royal, Virginia is known to contain domesticated horse blood. There are three living species of zebras: the plains zebra Equus quagga, Grevy’s zebra E. grevyi (endangered) and the mountain zebra E. zebra (endangered). The plains zebra has five extant subspecies: Burchell’s zebra E. q. burchelli, Grant’s zebra E. q. boehmi, Selous’ zebra E. q. borensis, Chapman’s zebra E. q. chapmani and Crawshay’s zebra E. q. crawshayi. The mountain zebra has two subspecies: Cape mountain zebra E. z. zebra and Hartmann’s mountain zebra E. z. hartmannae. The plains zebra and the mountain zebra belong to the subgenus Hippotigris, but Grevy’s zebra is the sole species of subgenus Dolichohippus. Plains and mountain zebras live in stable harems consisting of one stallion, several mares, and their offspring; the harems are expanded by taking mares from the harem they were born into (this prevents inbreeding). Plains zebra groups gather into large herds which may contain sub-groups, but where the structure is more fluid. Grevy's zebra stallions establish large territories and monopolise mares that enter them; mares with young remain in the sire’s territory – if they wander into another territory the stallion will kill the foal in order to mate with its mother. In all species, excess males establish bachelor groups. Hybridization between Grevy’s zebra and Grant’s zebra, a sub-species of plains zebra has been reported in the wild, resulting in fertile F1 individuals. Hybrids were derived from natural matings between male Grevy’s zebra and female Grant’s zebra in Kenya, and the F1 hybrids remained with the Grant’s zebra group. [Cordingley, J. E. et al. Is the endangered Grevy’s zebra threatened by hybridization? Anim. Conserv. 12, 505–513, (2009)] Ito et al studied six populations comprised of two pure species (Grevy’s zebra and Grant’s zebra) and four hybridized populations of Grevy’s zebra x Grant’s zebra, including F1 x F1 hybrids (F2 hybrids) and F1 backcrossed to one or other parent species. The backcrossed individuals tended to have ranges overlapping with the backcross parent allowing introgression. The distribution of Grant’s zebra and Chapman’s zebra minimises the opportunities for hybridization in the wild, but they are commonly kept in captivity and are not managed by studbooks, so there is a risk that these sub-species might have hybridized in the past and that some zoo populations are mongrelised. [ Ito, H., Langenhorst, T., Ogden, R. et al. Population genetic diversity and hybrid detection in captive zebras. Sci Rep 5, 13171 (2015). ] Hybridisation has been recorded between the plains and mountain zebra, though it is possible that these are infertile due to the difference in chromosome numbers between the two species. [Giel, E.-M.; Bar-David, S.; Beja-Pereira, A.; Cothern, E. G.; Giulotto, E.; Hrabar, H.; Oyunsuren, T.; Pruvost, M. (2016). "Genetics and Paleogenetics of Equids". In Ransom, J. I.; Kaczensky, P. (eds.). Wild Equids: Ecology, Management, and Conservation. Johns Hopkins University Press. p. 99. ISBN 978-1-4214-1909-1.] HORSES, ASSES, ZEBRAS, MULES AND MULE BREEDING (1895)

By W. B. TEGETMEIER, M.B.O.U., F.Z.S., AND C. L. SUTHERLAND, F.Z.S., CHAPTER X. HYBRID EQUIDAE. It would appear that all the different species of the genus Equus are capable of breeding together and producing hybrid offspring, some of which are perfectly sterile mules, whilst others are apparently fertile, either with one or other parent species if not inter se. Some of these hybrids are of great economic value, and it is deeply to be regretted that the opportunities that have presented themselves in our European zoological collections have not been utilised as they might have been, in introducing new species into the service of man, and in producing other useful hybrids beyond the common mule. In the present chapter I propose to enumerate, as far as practicable, the various equine hybrids that have been produced, and of which any definite account has been published, commencing with those of the horse. HORSE (E. CABALLUS) HYBRIDS.

It appears most probable, though it has not been absolutely proved, that the horse is capable of producing hybrids with every other species of the genus Equus. The hybrid between the horse and the ass is well known. When the ass is the male parent it is termed a mule ; on the other hand, if the horse is the sire the produce is termed a hinny, or in some places a jennet. The consideration of the breeding and practical utilisation of these two hybrids will be fully treated of in the concluding chapters. The horse has bred repeatedly with both the Mountain and Burchell's zebra. In the Jardin d'Acclimatation there is at the present time a hybrid between the horse and the Burchell’s zebra, of bright bay colour, with black legs and distinct dorsal stripe. Some years since I described some hybrids between the horse and the female Burchell which were in the park of Sir Henry Meux at Theobalds. The sire of one was an ordinary park pony, that of the other an American trotting pony. This latter hybrid was striped on the legs, neck, and haunches. Both of them, as might be expected, showed much of the equine character and form of the male parent; and from the relative sexes of the parents they necessarily partook more of the characters of the hinny than of the mule. Early in this century a pair of hybrids, bred between the horse and BurchelFs zebra, were driven about London in the service of the Zoological Society, but I have not been able to ascertain definitely the relative sex of the two parents, but believe they were hinnys from a zebra mare. The horse has also bred with the Asiatic ass {E. hemionus). In a private letter Lieutenant J. L. Harrington informs me of a male Hemione breeding with an Indian pony, and producing a hybrid that, with the exception of the tail, which was asinine, looked more like a pony than anything else. Two hybrids, between a Hemione and a mare, in the Jardin d'Acclimatation, were described by the late Mr. Jenner Weir. One of these is a very beautiful animal, possessing no shoulder stripes, and with very faint dorsal stripe. ASS {E. ASINUS) HYBRIDS.

The hybrids between both sexes of the ass and the horse have been spoken of under the last heading. The ass also hybridises freely with Burchell’s zebra ; a hybrid of this is now in the Jardin d^Acclimatation. It is rather sparely striped, but the three shoulder stripes are well marked. ASIATIC ASS (E. HEMIONUS) HYBRIDS.

The Asiatic Ass hybridises with the horse, as has been already stated. It has also been mated with Burchell’s zebra in the Jardin des Plantes, the produce being a faintly striped animal with a broad dorsal stripe, the hind quarters of which are not striped but dappled. The cross between the Asiatic ass and the mare has been already named. MOUNTAIN ZEBRA (E. ZEBRA) HYBRIDS.

Several of these were apparently recorded in the "Knowsley Menagerie," but sufficient care was not taken to distinguish between the two species, namely, the Mountain and Burchell’s zebras. BURCHELL'S ZEBRA (E. BURCHELLII) HYBRIDS.

Burchell’s zebra breeds most freely with several of the other species of Equus, and there is no doubt whatever that the hybrids of this most horse-like of the asses and zebras now existing would be exceedingly valuable to man if the animals were mated as carefully as is done in breeding heavy draught mules in Poitou, and pack mules for the military service in India. The Burchell is an animal much better adapted by its structure and form to the use of man than the other wild asses, and were it properly mated and utilised would no doubt produce most valuable hybrid offspring. The hybrids of the Burchell zebra with the horse have already been mentioned ; it also breeds freely with the common ass. In the Gardens of the Zoological Society at Melbourne there are some Burchell's zebras that were bred in Paris, for this most useful animal breeds freely in confinement. On September 6th, 1892, an experiment was made by crossing the zebra with a white so-called Siamese ass, which was obviously a variety of the domesticated Equus asinus. The foal was born on October 25th, 1893, showing that the period of gestation in Burchell's zebra resembles that of the ass in being considerably over twelve months. The young one is described as a strong, vigorous animal, galloping round the enclosure when a day old and evincing considerable speed. Its colour is somewhat remarkable, not resembling that of its white sire, but being very dark with pronounced shoulder and dorsal stripes, black tips to its ears, and bars on the legs, which are well marked, especially over the joints — the zebra from which it was bred being a true Burchell, not marked on the legs like the variety known as Chapman^ s zebra. The foal is described as being a compact and well-made little animal, showing splendid bone. As the progeny of the Burchell zebra are likely to attract much attention, I reproduce the photograph as it was published in the Australasian. In the Jardin d'Acclimatation there is another hybrid between a Burchell's zebra and a white Egyptian ass, which shows three distinct shoulder stripes, but otherwise is very faintly marked. A hybrid between a male Burchell’s zebra and the common ass was bred by the Earl of Derby and figured in the "Knowsley Menagerie." It was utilised by being driven in tandem, and the skin was afterwards deposited in the British Museum. The Hemione or Asiatic wild ass has also been bred with Burchell' s zebra. QUAGGA (E. QUAGGA) HYBRIDS.

In Colonel Hamilton Smith's unpublished volume he gives a portrait, drawn by himself, of a hybrid, the foal of a quagga and a brood mare. This was faintly striped on the fore-quarters. In the fine collection of plates known as the “Knowsley Menagerie” there are numerous illustrations of the wild Equidae, more especially of the striped species inhabiting Africa, namely, the Equus zebra, E. burchellii, and E. quagga. All these species interbreed, not only with each other, but with the wild unstriped asses of Asia. Dr. Gray figured in the “Knowsley Menagerie” a mule bred at Knowsley between a male Tibetan wild ass, or kiang, and the female zebra. In this the legs and neck are banded. There is also a figure of a mule between a Maltese male ass and zebra, in which the head, neck, and legs are well striped, the body less so, and the hind quarters profusely spotted. Should any of my readers refer to the plate in the folio they will find that the names of those two have been transposed, as is evident on referring to the text. There are also figured a mule between Burchell’s zebra and the common ass ; a second between the ass and the kiang, the titles of which are also transposed on the plate ; finally, we have a mule between the kiang and Burchell's zebra, and, what is very interesting, a representation of the offspring of a mule, of male ass and zebra parentage, with a bay pony mare. This strange animal may be described as iron-grey, with a short, narrow dark band on the withers, very faint indications of perpendicular stripes on the sides, distinct dark stripes on the hocks and knees, a horse-like tail, bushy from the base, and a heavy head with a grey hog mane. This creature, singular from its triple parentage, was eight hands high, and was regularly used in harness. Textual content is licensed under the GFDL.