Species Guide: Brown Bear (Ursus arctos)
Family: Ursidae
The Brown Bear, scientifically named Ursus arctos, is one of the most widely distributed large mammals on Earth. Found across parts of North America, Europe, and Asia, this species demonstrates extraordinary ecological flexibility. It occupies diverse environments ranging from coastal temperate rainforests to arid deserts and high mountain habitats. The species is known for its impressive size, strength, and adaptability, making it one of the most recognizable members of the bear family, Ursidae.
Appearance
Male
Adult male Brown Bears are typically larger and more massive than females. Size varies regionally, with some coastal populations becoming among the largest bears known. Adult males often weigh significantly more than females and tend to have broader heads and more muscular shoulders. The fur color ranges from light brown to almost black, sometimes with lighter tips, giving a “grizzled” look in certain populations.
Female
Females are generally smaller and lighter in build than males. They exhibit the same range of coat colors but are more compact in body shape. Sexual size differences are common and are considered a result of reproductive and ecological pressures.
Juvenile
Juvenile Brown Bears are smaller versions of the adults, born blind and helpless with a sparse coat that darkens and thickens as they grow. Cubs often remain with their mother for two to three years, during which they gain strength, coordination, and survival skills.
Diet
Brown Bears are omnivores with one of the most diverse diets among large mammals. They feed on a combination of plant and animal foods, including berries, roots, grasses, nuts, insects, fish (especially salmon in regions where it is available), and small to moderately large mammals. Diet composition varies geographically and seasonally, with coastal bears consuming more protein-rich foods, such as fish, while inland bears rely more on vegetation.
Habitat
The adaptability of Brown Bears is reflected in their broad habitat range. They occupy forests, shrublands, grasslands, alpine meadows, tundra, and even desert oases where human disturbance is minimal. Brown Bears typically select habitats rich in food sources and with low human density.
Behavior
Brown Bears are primarily solitary except during mating or when a female is raising cubs. They exhibit flexible daily activity patterns that can be crepuscular, diurnal, or nocturnal, depending on season, food availability, and human presence.
Calls and Communication
Communication in brown bears primarily consists of body language and non-vocal signals. They may hiss, grunt, snort, huff, or growl during confrontations or when alarmed. Cubs may produce plaintive cries when separated from their mother.
Brown Bear Roar:
Life Cycle
Breeding occurs from late spring through early summer. Fertilization is followed by delayed implantation, where the embryo does not attach until later in the year, allowing the female’s body to assess whether adequate fat reserves have developed. Cubs are born during winter dormancy, usually in January or February, and remain with the mother for up to three years.
Biometrics
Brown Bears rank among the largest terrestrial carnivorans. Adults range widely in size depending on subspecies and habitat, with body lengths typically between one and nearly three meters, and weights from roughly 80 kilograms to more than 600 kilograms in some populations. Coastal populations with abundant food, like salmon, often reach larger sizes.
| Length | 1-3 m |
| Body Weight | 80-600 Kg |
| Longevity | 20 Years |
Natural Predators
Adult Brown Bears face few natural predators due to their size and strength. Predation pressure is usually limited to intraspecific conflicts (bears on bears) or scavenging by wolves in rare circumstances. Young cubs, however, are vulnerable to predation by wolves and other large carnivores in some regions. Human hunting is also a significant source of mortality.
Relationship to Humans
Humans have long interacted with Brown Bears across cultural and economic contexts. In many Indigenous cultures, the bear is a symbol of strength and spiritual significance. In folklore and fables throughout Europe and Asia, bears often appear as powerful characters reflecting human traits like courage or stubbornness. Historically, bears have also been viewed as threats to livestock or human safety, leading to conflict and persecution. Modern wildlife management strives to reduce conflict while promoting coexistence through education and habitat protection.
Conservation Status
At the species level, Brown Bears are classified as “least concern” by the International Union for Conservation of Nature due to their broad range and relatively large global population. However, local populations can be endangered or declining due to habitat loss, fragmentation, hunting, and human conflict. Conservation efforts vary regionally and often focus on habitat protection, conflict mitigation, and regulated management.
Global
Conservation Status
Subspecies of Ursus arctos
The Brown Bear species includes a number of recognized subspecies that display regional adaptations. While historically many populations were described as distinct subspecies based on morphology, modern genetic analyses have shown that many differences are superficial and reflect ecological influences more than deep genetic divergence. Recent genomic studies indicate distinct evolutionary lineages across geographic areas, though all share a common species identity as Ursus arctos.
Grizzly Bear (Ursus arctos horribilis)
Often referred to in North America as the grizzly, this population occupies inland regions. Differences from coastal brown bears mainly reflect diet and habitat rather than species-level separation. Inland bears tend to be smaller on average due to less abundant high-calorie foods.
Kodiak Bear (Ursus arctos middendorffi)
Exclusive to the Kodiak Archipelago of Alaska, this subspecies includes some of the largest individuals of the species. Geographic isolation has contributed to its recognition as a distinct subspecies, although its behavior and ecology largely align with those of other coastal Brown Bears.
Kamchatka Brown Bear (Ursus arctos beringianus)
Native to the Kamchatka Peninsula of Russia, this form is one of the largest brown bear populations in Eurasia. It shares coastal food resources and adaptations similar to other large brown bear groups.
Eurasian Brown Bear (Ursus arctos arctos)
Native to much of Europe and parts of Asia, this subspecies is variable in size and color. Some European populations are small and isolated, often endangered locally despite belonging to a broadly distributed subspecies.
Gobi Bear (Ursus arctos gobiensis)
The Gobi Bear is a critically endangered population found in Mongolia’s Gobi Desert. Genetic isolation and extremely low numbers distinguish this group, making it a priority for conservation.
Why These Groups Are All Ursus arctos
Modern genetic research shows that Brown Bear populations around the world share a common species-level genetic framework, with variation largely reflecting geographic separation and local ecological pressures. Genetic analyses identify multiple evolutionary lineages, but all remain part of Ursus arctos, capable of interbreeding where ranges overlap. Subspecies designations persist for management and descriptive purposes, but they do not imply separate species status under modern taxonomy.
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References
- Hertel, A.G. et al. (2025) “Human Footprint and Forest Disturbance Reduce Space Use of Brown Bears (Ursus arctos) Across Europe,” Global change biology, 31(1), pp. e70011-n/a. [Accessed 25/01/2026]
- Støen, O.-G. et al. (2015) “Physiological evidence for a human-induced landscape of fear in brown bears (Ursus arctos),” Physiology & behavior, 152(Pt A), pp. 244–248. [Accessed 25/01/2026]
- Penteriani, V. et al. (2018) “Evolutionary and ecological traps for brown bears Ursus arctos in human‐modified landscapes,” Mammal review, 48(3), pp. 180–193. [Accessed 25/01/2026]
- Stenhouse, G.B. et al. (2021) “Road visibility influences habitat selection by grizzly bears (Ursus arctos horribilis),” Canadian journal of zoology, 99(3), pp. 161–171. [Accessed 25/01/2026]
- STEYAERT, S.M.J.G. et al. (2012) “mating system of the brown bear Ursus arctos,” Mammal review, 42(1), pp. 12–34. [Accessed 25/01/2026]
- Stenset, N.E. et al. (2016) “Seasonal and annual variation in the diet of brown bears Ursus arctos in the boreal forest of southcentral Sweden,” Wildlife biology, 22(3), pp. 107–116. [Accessed 25/01/2026]
CITATIONS
- By IUCN Red List of Threatened Species, species assessors and the authors of the spatial data., CC BY-SA 3.0. [Accessed 25/01/2026] ↩︎
