An ursid hybrid is an animal with parents from two different
species or
subspecies of the
bearfamily (Ursidae). Species and subspecies of bear known to have produced offspring with another bear species or subspecies include
American black bears,
grizzly bears, and
polar bears, all of which are members of the
genusUrsus. Bears not included in Ursus, such as the
giant panda, are expected to be unable to produce
hybrids with other bears. The giant panda bear belongs to the genus Ailuropoda.
Note all of the confirmed hybrids listed here have been in captivity (except grizzly × polar bear), but suspected hybrids have been found in the wild.[citation needed]
A recent study found genetic evidence of multiple instances and species combinations where genetic material has passed the species boundary in bears (a process called
introgression by geneticists).[1] Specifically, species with evidence of past intermingling were (1) brown bear and
American black bear, (2) brown bear and polar bear,[2] (3) American black bear and
Asian black bear. Overall, this study shows that evolution in the bear family (Ursidae) has not been strictly
bifurcating, but instead showed complex evolutionary relationships.
In the nine-year Report it is stated that the bears had been seen in the Zoological Gardens to couple freely, but previously to 1848 most had rarely conceived. In the Reports published since this date three species have produced young (hybrids in one case), ...[3]
A bear shot in autumn 1986 in
Alaska was thought by some to be a
grizzly × black bear hybrid, due to its unusually large size and its proportionately larger braincase and skull. DNA testing was unable to determine whether it was a large American black bear or a grizzly bear.[4]
Intercontinental brown bear hybrids
Although Eurasian brown bears and North American Brown bears are isolated, they are listed as a single species, so technically mating between the two sub-species is not hybridization, even though it cannot possibly occur in the wild. However, cross-breeding between the European brown bear and the North American grizzly bear has occurred in
Cologne, Germany.[citation needed]
Brown × polar bear hybrids
Since 1874, at
Halle, a series of successful matings of polar and brown bears were made. Some of the hybrid
offspring were exhibited by the
London Zoological Society. The Halle hybrid bears proved to be fertile, both with one of the parent species and with one another. Polar × brown bear hybrids are white at birth but later turn blue-brown or yellow-white.[citation needed]
An adult polar × brown bear hybrid bred in the 19th century is now displayed at the Rothschild Zoological Museum, Tring, England
Crandall reported the first polar × brown bear crosses as occurring at a small zoo in
Stuttgart,
Germany in 1876 rather than Halle in 1874. A female European brown bear mated with a male polar bear resulting in twin cubs in 1876. Three further births were recorded. The young were fertile among themselves and when mated back to European brown bears and to polar bears.[citation needed]
DNA studies indicate that the
ABC Islands bears have mixed brown and polar bear ancestry.[5]
Kodiak × polar bear hybrids
"Kodiak" or "Kodiak brown" is a term now applied to brown bears found in coastal regions of North America. In the far north, these bears feed on salmon and often attain especially large size. "Alaskan brown" is sometimes used for
Alaskan bears, but the main distinction is how far the bear is found from the coast. "Grizzly bear" is the term used for the brown bear of the North American interior.
In 1936, a male polar bear accidentally got into an enclosure with a female
Kodiak (Alaskan brown) bear at the U.S. National Zoo, resulting in three hybrid offspring. The hybrid offspring were fertile and able to breed successfully with each other, indicating that the two species of bear are closely related. The Kodiak is also considered by many to be a variant or subspecies of the basic Arctic brown bear.
In 1943, Clara Helgason described a bear shot by hunters during her childhood. This was a large, off-white bear with hair all over his paws. The presence of hair on the bottom of the feet suggests it was not an unusually colored Kodiak brown bear, but a natural hybrid with a polar bear.[citation needed]
In a 1970
National Geographic article[6] Elizabeth C. Reed mentions being foster mother to 4 hybrid bear cubs from the National Zoological Park in Washington, where her husband was director.
The grizzly bear is now regarded by most taxonomists as a variety of brown bear, Ursus arctos horribilis. Clinton Hart Merriam, taxonomist of grizzly bears, described an animal killed in 1864 at Rendezvous Lake, Barren Grounds, Canada as "buffy whitish" with a golden brown muzzle. This is considered to be a natural hybrid between a grizzly bear and polar bear. On 16 April 2006, a polar bear of unusual appearance was shot by a sports hunter on Banks Island in the
Northwest Territories. DNA testing released 11 May 2006, proved the kill was a grizzly×polar bear hybrid. This is thought to be the first recorded case of interbreeding in the wild.[7] The bear was proven to have a polar mother and a grizzly father. The DNA testing also spared the hunter the C$1000 fine for killing a grizzly bear, as well as the risk of being imprisoned for up to a year. The hunter had bought a license to hunt polar bears; he did not have a license to hunt grizzly at that time.[8]
The animal had dark rings around its eyes, similar to a
panda's, but not as wide. It also had remarkably long claws, a slight hump on its back, brown spots in its white coat, and a slightly indented face — the nasal "stop" between the eyes which polar bears lack. The guide leading the hunt, Roger Kuptana of Sachs Harbour in the Northwest Territories, was the first to note the oddities.
Several names were suggested for this specimen. The Idaho hunter who killed it, Jim Martell, suggested "polargrizz". The biologists of the
Canadian Wildlife Service suggested "grolar" or "pizzly", as well as "nanulak", an elision of the
Inuitnanuk (polar bear) and aklak (grizzly or brown bear). Both "grolar" and "pizzly" were used by the Canadian Broadcasting Corporation in widely distributed stories. Presently, though the mating seasons overlap, the polar bears' season begins slightly earlier than the grizzly bears'. A blog columnist for the Seattle Post-Intelligencer suggested that more hybrids may be seen as
global warming progresses and alters normal mating periods. The Canadian Wildlife Service noted that grizzly-polar hybrids born of zoo matings have proven fertile.[citation needed]
Grizzly bears have been sighted in what is usually polar bear territory in the Western Arctic near the Beaufort Sea, Banks Island, Victoria Island, and Melville Island. A "light chocolate colored" bear, possibly a hybrid, is reported to have been seen with polar bears near Kugluktuk in western
Nunavut.[citation needed]
In 2005, a possible Asiatic black bear × sun bear hybrid cub was captured in the
Mekong River watershed of eastern Cambodia. The bear's mane was relatively slight, forming a crest on each side of the neck, as is typical in sun bears and some black bears. The appearance of its face was intermediate between that of a sun bear and a black bear, though its ears and large stout canines closely resembled those of the sun bear. Overall, the hybrid resembled an Asiatic black bear with an unusually glossy fur and an unusual head.[10]
^Hailer, Frank; Kutschera, Verena E.; Hallström, Björn M.; Klassert, Denise; Fain, Steven R.; Leonard, Jennifer A.; Arnason, Ulfur; Janke, Axel (2012). "Nuclear genomic sequences reveal that Polar Bears are an old and distinct bear lineage". Science. 336 (6079): 344–347.
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Martin, P.L. (1876–1877). "Ursus arctos and Ursus maritimus. On bastards between these species born in Nill's menagerie at Stuttgart". Zoologische Garten: 20–22, 135–136.
Stendell, W.; von Martens, E. (1876–1877). "[no title cited]". Zoologische Garten: 401–402.
Stendell, W.; von Martens, E. (1882). "On a hybrid between a male Ursus maritimus and a female Ursus arctos". Zoologische Garten: xxiii, 370.
Kowalska, Z. (1962). "Intergeneric crossbreed of the brown bear Ursus arctos L., and the polar bear Thalarctos maritimus (Phipps)". Przeglad Zoologiczny (in Polish and English). 6: 230.
Kowalska, Z. (1965). "Cross breeding between a female European brown bear and a male polar bear in Łódź Zoo". Przeglad Zoologiczny (in Polish and English). 9: 313–319.
Kowalska, Z. (1969). "A note on bear hybrids Thalarctos maritimus x Ursus arctos at Łódź zoo". International Zoo Yearbook. 9: 89.
doi:
10.1111/j.1748-1090.1969.tb02632.x.
Wurster-Hill, D.H.; Bush, M. (1980). "The interrelationship of chromosome banding patterns in the giant panda (Ailuropoda melanoleuca), hybrid bear (Ursus middendorfi × Thalarctos maritimus), and other carnivores". Cytogenet. Cell Genet. 27 (2–3): 147–154.
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