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What Do Bears Eat? From Salmon to Termites
At the right Alaskan waterfall in late summer, you can count sixty to eighty brown bears without turning your head. The biggest animals claim the ledge at the lip of the falls and pluck salmon out of the air mid-leap. Lower-ranking bears work the banks and the white water below. Young bears hang back and watch how it is done.
It looks like the definitive picture of what bears eat. It is one week of one diet in one place, and a few months later the same bears may be living on berries.
The short answer
Most bears eat mainly plants, and almost all of them eat whatever the season offers. Brown bears switch from moose in spring to berries in late summer and ground squirrels in autumn, and inland populations get 80 to 90 percent of their food from vegetation. Coastal brown bears gorge on salmon. Sun bears and sloth bears specialise in insects, the spectacled bear and the giant panda live almost entirely on plants, and only the polar bear is a true meat specialist, built to hunt seals.
A menu that changes every month
The single best predictor of a bear's dinner is the calendar. A brown bear that takes down a moose in May can spend August stripping thousands of berries off the bushes and September digging ground squirrels out of their burrows. Habitat, individual habit, and the luck of a given year all shift the mix. Across its huge range, a brown bear's diet is essentially a map of whatever the local ecosystem produces, coast to interior.
Why salmon bears eat the skin and brains first
On the coasts of Alaska and British Columbia, the salmon runs pull bears to the most productive water. In a strong year a big coastal brown bear may catch thirty salmon in a single day on a productive stream, and with that many on offer it becomes picky in a very precise way. It ranks each fish by energy density.
The fat-rich parts go first: skin, brain, eggs, and belly. Those are the tissues that build the autumn fat reserve fastest. The lean muscle, which most people would consider the best part of a salmon, is often abandoned for the eagles, ravens, and wolves waiting their turn along the same stream.
Inland bears live on plants
Far from the salmon coasts, brown bears lean heavily on vegetation, which supplies 80 to 90 percent of what they eat for much of the year. Roots, grasses, forbs (soft, leafy flowering plants), berries, pine nuts, and fungi make up the bulk. Insects fill in, especially ant larvae and ground-nesting bee colonies, along with small mammals caught when the chance comes.
The catch is that plant food is thin fuel. Meat and fish pack far more energy per mouthful, so a bear that size living on plants has to eat almost constantly while it is awake. For an inland bear, most of the active season is one long feeding shift from dawn to dusk.
The insect specialists: sun bears and sloth bears
Sun bear
The sun bear of Southeast Asia depends on insects more than any other bear. It carries the longest tongue for its body size in the family, up to 25 centimetres, roughly as long as a person's forearm. It reaches deep into bee and wasp nests for honey and larvae, while short, powerful claws rip open rotting logs and bark to get at the colonies inside. Fruit, plus the crowded insides of termite and ant nests, rounds out a high-energy diet.
Sloth bear
The sloth bear of India and Sri Lanka takes insect eating further, into its anatomy. Its whole skull is organised around termites. The two front upper teeth are missing, leaving a gap that works as an air channel. The lips push far forward against a mound wall, and the nostrils close on command to keep dust out of the lungs.
The bear smashes open a termite mound, jams its muzzle inside, blows the dust out with a hard exhale, and then sucks the termites in like a vacuum hose. The honking, snuffling noise of a sloth bear at work can carry a hundred metres through dry scrub.
The plant specialists: spectacled bears and giant pandas
Spectacled bear
The Andean spectacled bear is one of the two most plant-dependent bears alive. It tears bromeliads, tough leafy plants that store water in their crowns, out of trees and off the ground to reach their soft hearts. It strips palm fronds and climbs into the canopy for fruit. In some populations, vegetation supplies nine tenths of its calories.
Giant panda
The other plant specialist is the giant panda, and it has the narrowest diet in the bear family. Bamboo is poor food for a large mammal. Its bulk is cellulose, the rigid fibre in plant cell walls, and most mammals can extract almost no usable energy from it. Long ago, pressure from competing carnivores drove the panda into a way of life that no other large mammal occupied.
Evolution equipped it just well enough to survive there. An enlarged wrist bone, the radial sesamoid, works as a false thumb for gripping stalks. The gut is moderately enlarged, and pandas pick out the most nutritious parts of the plant. Even so, most of the bamboo passes through barely digested, so a panda has to feed for about fourteen hours a day, always close to the edge of its energy budget.
How bears save a kill for later
When a brown bear finds or makes a large kill, it rarely eats the whole carcass at once. It drags the body into cover, buries it under branches, soil, and forest litter, and comes back to feed over several days. Some bears bed down on top of the cache or right beside it guarding it from wolves and rival bears. The forelimbs that flip boulders turn into the lock on a private larder that can last a week.
Bear diets at a glance
| Bear | Main foods | Signature tool or habit |
|---|---|---|
| Coastal brown bear | Salmon in season, plus plants and prey | Eats the fattiest parts of each fish first |
| Inland brown bear | Roots, grasses, berries, nuts, fungi, insects, small mammals | Near-constant feeding; plants make up 80 to 90 percent |
| Sun bear | Honey, bee larvae, termites, ants, fruit | Tongue up to 25 centimetres long |
| Sloth bear | Termites | Missing front teeth, closable nostrils, suction feeding |
| Spectacled bear | Bromeliads, palm fronds, fruit | Up to nine tenths of calories from plants |
| Giant panda | Bamboo | False thumb from an enlarged wrist bone; about 14 hours of feeding a day |
| Polar bear | Seals | A dedicated hunter on the sea ice |
Across every species the rule is the same: match appetite to opportunity, put in the hours, and bank the surplus as fat for winter. The polar bear is the one bear that bet everything on a single food and a single frozen habitat.
Key terms
- Omnivore
- An animal that eats both plants and animals, which describes most bears.
- Forbs
- Soft-stemmed flowering plants that are not grasses, a staple for inland brown bears.
- Bromeliad
- A tough, leafy plant that holds water in its central crown; the spectacled bear eats the soft heart.
- Cellulose
- The rigid fibre in plant cell walls. Most mammals get very little energy from it, which is why bamboo is such poor food.
- Radial sesamoid
- An enlarged wrist bone in the giant panda that works as a false thumb for gripping bamboo.
- Cache
- A hidden store of food. Brown bears bury carcasses under soil and branches and return to them over several days.
Related field notes
For how bears turn all that food into a winter fat reserve, and what the one meat-specialist bear does on the sea ice, browse more Bears Decoded field notes.
This article is adapted from "What Bears Eat," chapter 3 of Bears Decoded, which follows the bear family's diets from Alaskan salmon falls to Indian termite mounds and Chinese bamboo forests.