North American brown bears once thought to only be scavengers (before scientists use satellite telemetry to track movements).
Recent studies show a more carnivorous diet than more omnivorous American and Asiatic Black Bears, Sun Bears, and Andean Bears. (Sacco and Van Valkenburgh 2004)
- Prey: typically juvenile ungulates and small, burrowing rodents.
- Extreme size difference with prey - may be up to 100 times heavier than prey
- Use brute strength rather than specialized killing techniques to dispatch prey
- In Mt. McKinley National Park, bears ate voles, lemmings, mice, ground squirrel. (Murie 1985)
- On Tibetan Plateau, eat mainly meat; pika are the prey. (Xu et al 2006)
- Have the capacity to also take much larger prey such as moose, musk oxen, caribou, elk. pronghorn, deer, bison (Murie 1985) (Craighead 1995) (Mowat & Heard 2006)
- Calves are preferred but adults sometimes taken (Zager and Beecham 2006)
- Caribou in Arctic provide significant portion of terrestrial meat (not salmon) in diet
- Salmon important component of diet in Pacific coast of North America. (Mowat & Heard 2006) (Zager and Beecham 2006)
- In coastal areas, salmon provide the main source (greater than 50%) of nutrients for Brown Bears.
- Seasonal changes in metabolism (Hilderbrand et al 1999)
- In spring bears convert meat to lean body mass
- In fall, bears convert excess protein to fat
In addition to carnivorous habits, consume a wide variety of plant and animals, seasonally available (Craighead 1995) (Murie 1985) (White et al 1998)
- Berries, Whitebark Pine seeds in Yellowstone ecosystem (important for laying on stores of fat for winter)
- Sedges, grasses, horsetail (Equisetum)
- Dig and eat underground stores of roots and tubers cached by mice.
- Army cutworm moths (noctuids) sought on high mountain rocky slopes.
- In Yellowstone region, Whitebark Pine trees currently severely threatened by disease and a warming climate; major concern for grizzly well-being.(Mattson & Merrill 2002).
Search for food with a wide variety of techniques, using "intelligence, curiosity, determination, skills, memory and endurance" (Huber 2010)
- Turning over rocks
- Plucking rotten logs and anthills (for ants)
- Digging for tubers and invertebrates
- Catching for small mammals
- Stalking and capturing ungulates
After having eaten its fill, bear may cache remaining carcass by covering it with soil, sod, or rocks.
- Largest bears have priority when a carcass is discovered; subordinate bears wait