Ursus sp. × Canis familiaris
EUGENE M. MCCARTHY, PHD Google+ Profile
This cross, which is interfamilial (Canidae × Ursidae), is listed in various older works. For example, the following is an article quoted in its entirety from the American Veterinary Review (1905-6, vol. 29, p. 408):
Ursus-Canis (Presumably [Ursus] Americanus). — Half bear half dog, a remarkable prodigy of nature, was brought to the city [Denver, Colorado] Wednesday morning from Nebraska by I. Pinter. It is the only known example of the crossing of the dog and bear families. “Teddy” is the name of the hybrid. His mother was a common stray dog of North Platte, Neb., a little bigger than a Scotch terrier and of the same general build and color. Father Bear has never been seen. The dam gave birth to a litter of five of the strange puppies, but four were born dead. The creature is now eleven months old and weighs about thirty-five pounds, but looks much heavier. At first sight the animal gives the impression of a peculiar kind of dog, although on closer examination the bear peculiarities are more evident. The ears are long and drooping, like those of a spaniel, the tail is also that of a spaniel. The eyes are large and have the mild, dog like expression. A bear has short upstanding ears, a stub tail never more than a couple of inches long and the eyes are small and quite different in expression and the manner they are set in the head. But the bear hump is very plain above the hindquarters. The legs are bear paws thick as a man’s arm and short, with pads, that will in time make an impression similar to the human foot, and the claws are long. Teddy has never been heard to bark, but will occasionally give a modest bear’s growl. In habits he is more like a bear than a dog, lying down on his side like bruin instead of upright as is the fashion in the canine world. He always lies down to eat. The animal shows very little intelligence and energy. He has not strength enough to walk upstairs and will refuse to go more than a mile at a time unless very slow progress is made.
The Denver hybrid was the alleged result of a serendipitous mating between a domestic dog and a wild bear, but there are old reports of this cross occurring in captivity as well.
Writing during the Elizabethan era, the French humanist Pierre Boaistuau, in his Histoires prodigieuses, says dogs and bears were intentionally mated in London and that sometimes a hybrid resulted. He includes an artist’s illustration of a supposed hybrid (shown at right). Bears and dogs, usually mastiffs, were kept to fight in the bear baitings so popular at the time and a favorite pastime of the Queen. An English translation of the passage in question (Boaistuau 1591, pp. 206-209) reads as follows:
This monstrous animal, which you see illustrated at the beginning of this chapter, was engendered by an English dog covered by a bear. As a result, it partakes of the nature of both, which doesn’t seem strange to those who have observed how in London dogs and bears are kept in small cages near each other. Their keepers cage a female bear and a male dog together when they are in heat, so that pressed by their natural urges, they convert their cruelty into love. From such conjunctions are sometimes born animals like this one, although it may be quite rarely. Among these I have seen two, which were given to his grace the Marquis de Trans. One of these he gave to my lord the Conte d’Alphestan, the Emperor’s ambassador. The other, he had taken to France, which I have had reproduced here. The illustrator has omitted nothing. [Translated by E. M. McCarthy. Original French.]
Boaistuau then turns to a discussion of other types of hybrids, but eventually returns to his description of the bear-dog:
But to return to the description of our animal, of which you can see the appearance is so monstrous, which resembles a small bear, and which is also in its movements, its voice, and manner of doing all things more like a bear than a dog. However, I can assure you that he is one of the most ferocious beasts that you will ever see, for there is no species of animal that he will not attack, be it a bear, a lion, or a bull, or others of a similar kind. And he is so ardent in these combats that once he has sunk his teeth into some beast, he would rather be dismembered than relinquish his grip, as I can attest after witnessing him in combat in London against a bear. [Translated by E. M. McCarthy. Original French.]
The exact identity of the bears involved in Elizabethan bear baitings is somewhat in doubt. But it does seem that the Brown Bear (Ursus arctos) is the animal in question. As Henry Reeks (1878) states in a scholarly article on mammals mentioned by Shakespeare, the brown bear (he refers to Ursus arctos and to its synonym Ursus isabellinus) “would probably be the bear with which Shakspeare [sic] would be most familiar. Bear baiting seems to have been a very popular amusement about that period and for many years subsequently.”
Though one might suppose that a brown bear would be far too large to mate with a dog, there is a very wide range of geographic variation in the adult size of these animals. Nowak (1999, pp. 685-686) states that while brown bears may weigh as much as 780 kg (1720 lbs) on the southern coast of Alaska, elsewhere they can be far smaller. For example, the average figure he gives for southern Europe is just 70 kg (154 lbs). It does seem, then, that some bears would be within the size range that would allow mating with a large dog.
Jakob Benjamin Fischer, too, in his Naturgeschichte von Livland (1791, p. 146), mentions a bear-dog hybrid that was supposedly fertile. He gives the cross in the same direction as in the account of the Denver hybrid (female dog/male bear), but in the opposite direction from that specified by Boaistuau:
One has the example of a bear mixing sexually with a dog. In Riga, a male bear mated with a bitch, which went on to produce offspring. Among these was a remarkable dog. He had a bear’s head and no tail. His voice was a dog’s bark mixed with the growling of a bear. They let this dog mate with a bitch, but no great caution was taken—she probably mated with other dogs—and at her expected time she gave birth to sixteen puppies (an unusual example of canine fertility) of which only six resembled the bear hybrid, with bear’s heads, shaggy coats, and no tails. One sees from this, that it is in fact possible for hybrid beasts to produce offspring. Translated by E. M. McCarthy.
Of course, nowadays dogs and bears are very rarely kept caged together, and there seem to have been no attempts to cross them by artificial insemination. Therefore, in the absence of experimentation, it must remain an open question whether the various early reports of this type of hybrid have any basis in fact.
Naturally, there are, as with many other types of hybrid crosses, those who say that such a hybrid is impossible. For example, the following is taken from the English Cyclopaedia (1866, p. 433):
We ought not perhaps to conclude this article without referring to those hybrids which were supposed to be the offspring between a dog and bear. Even at the present day there is an inclination to believe in the existence such animals, but we need hardly observe that it is extremely improbable, to use no stronger term, that two animals differing so widely in their dentition and general structure, in the periods of gestation and in their habits, should produce a mule.
The gestation periods of dogs and bears do differ widely (a little over two months in the former versus 7 months in the latter). However, we also need hardly observe that in every hybrid cross, the parents differ to some degree. And that difference is larger in some crosses than in others. Though much is believed and much has been said with regard to this matter, it is in fact unknown exactly how different two animals can be and still engender hybrids together. More specifically, it is still unknown just how different the gestation period lengths of two organisms can be if hybrids are to be produced. All we can say for sure is that hybrids between parents with differing gestation periods are known. Indeed, in any hybrid cross where the gestation periods (or, in birds, the incubation periods) differs in length between the parents, the typical finding is for the period in the hybrid to fall about halfway between. But the whole notion of gestational periods as a criterion of ability to hybridize seems to be established only by tradition (the idea dates back 2,000 years to Pliny and Aristotle) and scientific investigation of the issue has been next to nihil. Indeed, it is well known today that certain pairs of parents with markedly different gestational periods can hybridize. For example, bottle-nosed dolphins and false killer whales can cross, as documented in the following cross account taken from the dolphin hybrids page of this website (note, too, that the dentitions differ hugely here, as well):
Pseudorca crassidens [False Killer Whale]
× Tursiops truncatus (♂) [Common Bottle-nosed Dolphin] CHR(Japan and at Sea Life Park, Hawaii). NHR?? CON: Indian, Pacific, and Atlantic oceans. HPF(♀♀). Wolphins, as the hybrids are known, are intermediate in size (~3m long, ~270kg), color and shape. They have 66 teeth (a bottlenose has 88, a false killer whale, 44). A female wholphin produced two calves in backcrosses to T. truncatus (which look much like bottlenoses). At 6 months one was already the size of a year-old bottlenose. Herds of false killer whales and bottlenose dolphins associate in the wild and there are anecdotal reports of natural hybrids. False killer whales are about five times as large bottle-nosed dolphins. A female hybrid born in May 1985 at Sea World in Hawaii was still alive in 1998. This hybrid reaches a weight of about 800 lbs and a length of 12 feet. Bottle-nosed dolphins and false killer whales differ markedly in gestation period (12 months and 15.5 months, respectively). Breese 1992; Duffield 1999; International Zoo Yearbook 1990 (p. 453); Nishiwaki and Tobayama 1982, 1984; Odell and McClune 1999 (p. 230, 235); Ryan 1985; Sylvestre and Tasaka 1985. Internet Citations: HOTS†.
The chromosome counts of dogs and bears are fairly similar (in dogs, 2n=78, in both black and brown bears, 2n=74).
See also: Scherren (1907, pp. 432-433).
By the same author: Handbook of Avian Hybrids of the World, Oxford University Press (2006).
Bear-dog Hybrids - © Macroevolution.net