American black bear

The American black bear, known scientifically as Ursus americanus, is a medium-sized mammal native to North America.

It is the smallest and most widely distributed bear species on the continent. These bears are omnivores, meaning they eat a variety of both plants and animals. Their specific diet changes depending on the season and their geographic location. Most black bears prefer living in heavily forested areas with thick vegetation.

However, they may leave these forests to find food or enter human communities if food is easily available.

To understand how they survive, we can look at their generalist behavior. This means they are able to use many different types of food sources. This flexibility is a major reason why they survived the last Ice Age. Other large North American bears, like the giant short-faced bear and the lesser short-faced bear, became extinct.

Those extinct species were more specialized predators. The American black bear remained an arboreal omnivore, which means it can climb trees and eat many things. This ability to adapt to changing climates and plants allowed them to thrive while other species disappeared.

Evolutionary history shows a complex path for these bears. Genetic studies indicate that American black bears split from a common ancestor with brown bears and polar bears 5.05 million years ago (mya). They are more closely related to Asian black bears, which are considered sister taxa.

The ancestors of both black bear species diverged from sun bears 4.58 mya. Later, the American and Asian lineages split from each other 4.08 mya. Fossils of a primitive bear called Protarctos abstrusus from 4.95 mya may be a direct ancestor. Early fossils found in Pennsylvania resembled Asian species, though some later specimens grew as large as grizzly bears.

There are sixteen traditionally recognized subspecies of the American black bear.

These subspecies are often defined by their color or where they live. For example, the cinnamon bear has reddish-brown fur. The glacier bear in southeastern Alaska has silvery-gray fur with a blue luster.

In British Columbia, the Kermode bear, or spirit bear, has white or cream-colored coats due to a recessive gene. Other subspecies include the Olympic black bear and the Florida black bear, which often has a white blaze on its chest.

While many subspecies are well-known, a 2015 genetic study disputed some classifications.

Black bears are highly successful in terms of population numbers. The International Union for Conservation of Nature (IUCN) lists them as a "least-concern" species. This is because their population is estimated to be twice as large as all other bear species combined.

In the United States, populations are often stable or increasing. In 2011, the U.S. population was estimated between 339,000 and 465,000. In Great Smoky Mountains National Park, there were about 1,500 bears in 2020. In western North Carolina, the population grew from 3,000 in the early 2000s to over 8,000 in the 2020s. In contrast, the species is considered endangered in Mexico.

Sometimes, different bear species can produce hybrid offspring because they are reproductively compatible.

In 1859, a black bear and a Eurasian brown bear were bred at the London Zoo, but the cubs died before reaching maturity. In 1986, a bear in Michigan was thought to be a hybrid due to its large size and skull shape. However, DNA testing could not confirm if it was a hybrid or just a large black bear. Another case involved a bear in Florida thought to be a hybrid between an escaped Asian black bear and a male American black bear.

Today, black bears inhabit many different environments across the continent. They are found in the Appalachian Mountains, the Rocky Mountains, and along the West Coast.

They also live in much of their original Canadian range, though they are rarely found in the southern farmlands of Alberta or Saskatchewan. They have even been documented living year-round in Iowa, which was a rare occurrence for the state. Their habitat usually includes inaccessible terrain and thick understory vegetation. This environment provides them with plenty of edible materials, such as masts, to eat.