Ursid hybrid

An ursid hybrid is an animal born from parents of two different bear species or subspecies. These animals belong to the bear family, known as Ursidae. Most hybrids occur between bears within the genus Ursus. This genus includes the American black bear, the grizzly bear, and the polar bear.

However, not all bears can crossbreed. The giant panda belongs to a different genus called Ailuropoda. Scientists expect that pandas cannot produce hybrids with other bears.

Geneticists study a specific process called introgression. This occurs when genetic material passes across a species boundary. Recent studies have found evidence of this in several bear combinations. For example, brown bears and polar bears have intermingled in the past. There is also evidence of mixing between brown bears and American black bears. Additionally, American black bears and Asian black bears have shown signs of past intermingling. This suggests that bear evolution is not a simple, straight split. Instead, the evolutionary relationships within the Ursidae family are quite complex.

Humans have observed bear hybridization in zoos for many years. In 1859, a black bear and a European brown bear mated at the London Zoological Gardens. They produced three cubs, but the cubs did not reach maturity. Later, successful matings occurred between polar and brown bears in Halle starting in 1874. Some reports suggest these crosses actually began in Stuttgart, Germany, in 1876. These polar and brown bear hybrids were white at birth. As they grew, their fur turned blue-brown or yellow-white.

These hybrid bears were fertile. They could breed with their parent species and with each other. One adult hybrid from the 19th century is now at the Rothschild Zoological Museum in England.

Other hybrids involve the Kodiak bear, which is a brown bear found in North American coastal regions. In 1936, a male polar bear at the U.S. National Zoo mated with a female Kodiak bear. This resulted in three hybrid offspring. These cubs were fertile and could breed successfully. This proves that polar bears and Kodiak bears are closely related. In 1943, a woman named Clara Helgason described a large, off-white bear with hair on its paws. She believed it was a natural hybrid between a polar bear and a Kodiak bear.

One of the most famous cases of hybridization happened in the wild. On April 16, 2006, a hunter shot a polar bear of unusual appearance on Banks Island. The bear had dark rings around its eyes, long claws, and a slight hump on its back. It also had brown spots in its white coat. DNA testing released on May 11, 2006, proved the animal was a grizzly and polar bear hybrid. The bear had a polar bear mother and a grizzly bear father. This was likely the first recorded case of such interbreeding in the wild.

Many different names have been suggested for these grizzly-polar hybrids. A hunter named Jim Martell suggested the name "polargrizz." Biologists from the Canadian Wildlife Service suggested "grolar," "pizzly," or "nanulak." The term "nanulak" combines the Inuit words for polar bear and grizzly bear. Some people believe more hybrids may appear as global warming progresses. This may happen because warming alters normal mating periods. Currently, the mating season for polar bears begins slightly earlier than the season for grizzly bears.

Hybridization also occurs between other types of bears outside the Ursus genus. In 1975, a female Asian black bear and a spectacled bear produced hybrids in a Venezuelan zoo. In 2005, a possible hybrid between an Asiatic black bear and a sun bear was found in Cambodia. This cub had a face that looked like a mix of both species. In 2010, a male hybrid named Emma was rescued from a bile farm in China. Emma was a mix of an Asiatic black bear and a brown bear. Furthermore, hybrids between sloth bears and Asiatic black bears are known. Sloth bears have also produced hybrids with Malayan sun bears at the Tama Zoo in Tokyo.