I am obliged to report that which is reported, but not to believe it.
The History, VII, 152
Black bear, Ursus americanus|
This cross, which is interfamilial (Canidae × Ursidae), is listed in various older works. However, it is doubtful whether such a hybrid has ever been produced. The disparity of the cross and the old and unreliable nature of the documenting sources raise many questions, for example, the following article, quoted in its brief entirety from the American Veterinary Review (1905-6, vol. 29, p. 408), seems to be the only scientific paper ever reporting such a hybrid:
As has already been mentioned, this scanty account seems to be the only instance of a bear-dog hybrid having been reported in a scientific journal. And yet, even here, there is no documenting specimen. So the evidence for this cross is dubious at best.
Woodcut illustration of an alleged bear-dog hybrid (Boaistuau 1591, p. 206).|
17th-century depiction of a mastiff.|
Elizabethan bear baiting|
Fossils demonstrate the former existence of animals known as bear-dogs (Family Amphicyonidae, 46.2-1.8 mya) and dog-bears (Family Hemicyonidae, 33.9–5.3 mya). These creatures were so named because they had both bear- and dog-like traits. An example of the bear-dog Amphicyon, is shown above and an artist's reconstruction of the dog-bear Hemicyon appears below.
Of course, old reports of this cross occurring in captivity do exist as well, but they are not particularly convincing. 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 bear-dog 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:
Boaistuau then turns to a discussion of other types of hybrids, but eventually returns to his description of the bear-dog:
|Brown bear, Ursus arctos|
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:
Scherren (1907, pp. 432-433) provides a brief review of reports alleging the occurrence of this cross.
Of course, nowadays dogs and bears are very rarely kept caged together, and it seems no one has tried 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.
The gestation periods of dogs and bears differ widely (a little over two months in the former versus 7 months in the latter).
The chromosome counts of dogs and bears are fairly similar (in dogs, 2n=78, in both black and brown bears, 2n=74).
The following is a list of dog crosses discussed on this site. Some of these crosses are much better documented than others (as indicated by the reliability arrow). Moreover, some are extremely disparate, and so must be taken with a large grain of salt, but all have been reported at least once.
By the same author: Handbook of Avian Hybrids of the World, Oxford University Press (2006).
An account of Elizabethan bull and bear baiting
“There is still another place, built in the form of a theatre, which serves for the baiting of bulls and bears they are fastened behind and then worried by great English bull-dogs but not without great risk to the dogs from the horns of the one and the teeth of the other; and it sometimes happens that they are killed upon the spot, fresh ones are immediately supplied in the places of those that are wounded or tired.” (from Travels in England During the Reign of Queen Elizabeth by Paul Hentzner and Sir Robert Naunton)
On bear baiting
(from Chambers 1864)
“In the twelfth century, the baiting of bulls and bears was the favourite holiday pastime of Londoners; and although it was included in a proclamation of Edward III, among ‘dishonest, trivial, and useless games,’ the sport increased in popularity with all classes. Erasmus, who visited England in the reign of Henry VIII, speaks of ‘many herds’ of bears regularly trained for the arena; the rich nobles had their bearwards, and the royal establishment its ‘master of the king’s bears.’ For the better accommodation of the lovers of the rude amusement, the Paris Garden Theatre was erected at Bankside, the public being admitted at the charge of a penny at the gate, a penny at the entry of the scaffold, and a penny for quiet standing. When Queen Mary visited her sister during her confinement at Hatfield House, the royal ladies were entertained with a grand baiting of bulls and bears, with which they declared themselves ‘right well contented.’ Elizabeth took especial delight in seeing the courage of her English mastiffs pitted against the cunning of Ursa and the strength of Taurus. On the 25th of May 1559, the French ambassadors ‘were brought to court with music to dinner, and after a splendid dinner, were entertained with the baiting of bears and bulls with English dogs. The queen’s grace herself, and the ambassadors, stood in the gallery looking on the pastime till six at night.’ The diplomatists were so gratified that her majesty never failed to provide a similar show for any foreign visitors she wished to honour.”
|The Paris Garden Theatre, Bankside, the primary venue for bear baitings in old London (engraving from Chambers 1864, vol. II, p. 57)|
Most shared on Macroevolution.net:
Bear-dog Hybrids - © Macroevolution.net