The black bear (Ursus americanus) is the most common and widely distributed bear species in North America. However, the Greater Yellowstone Ecosystem is one of the few areas south of Canada where black bears coexist with the grizzly bears. From 1910 to the 1960s, park managers allowed visitors to feed black bears along park roads, although the National Park Service officially frowned on this activity. During this time, along with Old Faithful, black bears became the symbol of Yellowstone for many people, and are still what some people think of when Yellowstone bears are mentioned. Since 1960, park staff have sought to deter bears from becoming conditioned to human foods.
Little is known about the black bear population in Yellowstone or whether it has been affected by the increase in grizzly bear numbers and distribution since the 1970s. Black bears are commonly observed in the park, especially on the northern range and in the Bechler area of the park. Black bears have few natural predators, although both cubs and adults are occasionally killed by their own kind or by the other large carnivores with which they compete for food—wolves, cougars, and grizzly bears. Vehicle collisions (average = 1 per year) and removals of nuisance bears (average = 1 every 5 years) are not common either. Most black bear mortality in the park is likely attributed to old age or other natural causes. Outside the park, some black bears are killed during state regulated hunting seasons. As their access to human foods has been reduced, human injuries from black bears in the park have decreased from an average of 45 per year during the 1930s–1960s to approximately one injury every five years since 1980. Black bears are occasionally radio-collared for management and scientific reasons, with the latter focusing on research on habitat selection and multi-carnivore interactions.
In Yellowstone, about 50% of black bears are black in color; others are brown, blond, and cinnamon. Black bears eat almost anything, including grass, fruits, tree cambium, eggs, insects, fish, elk calves, and carrion. Their short, curved claws enable them to climb trees but do not allow them to dig for roots or ants as well as a grizzly bear can.
The life cycle of black bears is similar to grizzly bears. Like grizzly bears, black bears spend most of their time during fall and early winter feeding during hyperphagia. In November, they locate or excavate a den on north-facing slopes between 5,800–8,600 feet (1,768–2,621 m), where they hibernate until late March.
Males and females without cubs are solitary, except during the mating season, May to early July. They may mate with a number of individuals, but occasionally a pair stays together for the entire period. Both genders usually begin breeding at age four. Like grizzly bears, black bears also experience delayed implantation. Total gestation time is 200 to 220 days, but only during the last half of this period does fetal development occur.
Birth occurs in mid-January to early February; the female becomes semiconscious during delivery. Usually two cubs are born. At birth, the cubs are blind, toothless, and almost hairless. After delivery the mother continues to sleep for another two months while the cubs nurse and sleep.
The Greater Yellowstone Ecosystem is one of the few areas south of Canada where black bears coexist with grizzly bears. Although grizzly bears in Yellowstone have been studied continuously for more than 50 years, little research has been conducted on the park’s black bears since the 1960s. However, a series of black bear studies starting in the early 2000s have provided new insights on black bears, demonstrating their population has also been impacted by changes in the ecosystem, whether it be the changes in the grizzly bear population to changes in resource availability.
Recently, research studies that have utilized GPS tracking collars and non-invasive DNA samples from hair snares have helped biologists learn more about the black bear population size and density, predatory rates on elk, home range sizes, movements, food habits, and habitat use.
Results have shown that black bears in the northern portion of Yellowstone occur at some of the highest densities found in the GYE, which could have implications for other wildlife populations in the region. In addition, collar data has shown that the quality of spring forage influences how black bears navigate around the landscape and annual movement data found that male black bears range farther than previously thought. The results from these studies demonstrate the need to continue studying black bears in YNP as they continue to play an important role in the region.
Best practices for traveling safely in bear country.
Learn about the biology of this top predator.
Bear management has evolved since the park was established.
Bear Management Areas
Restrictions to reduce encounters between humans and bears.
Grizzly Bears & Endangered Species Act
The Yellowstone population of grizzly bears was designated as threatened with extinction in 1975.
All of the park's hoofed mammals migrate across the park to find the best plant growth.
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Last updated: April 24, 2023