One of the main reasons Kodiak bears grow so much larger than inland grizzly bears is due to the abundance of food on Kodiak. Not only can bears feast on protein-rich salmon in the summer, but the archipelago is loaded with nutritious vegetation and sugar-packed berries. A brown bear’s jaws have powerful muscles and teeth that have evolved to adapt to an omnivorous diet of both plants and animals. Kodiak bears are opportunistic feeders. They eat roots, berries, grasses, sedges, wildflowers, wild celery, and other plants, as well as rodents, insects, large mammals (including deer and mountain goats), fish, carrion, and yes, unfortunately, garbage and pet food.
Bears’ stomachs contract during hibernation, and when they first leave their dens, they aren’t hungry. They eat little at first, concentrating on emerging plants and their roots. As the spring progresses, Kodiak bears can be seen feeding in grassy meadows and look much like grazing cattle. Their diet switches to salmon in the summer months, when they chase and catch fish in shallow streams or on the tidal flats near the heads of the deep, narrow bays on Kodiak. Bears also consume dead salmon that have washed up on shore. When the salmonberries, elderberries, crowberries, blueberries and other berries begin to ripen on Kodiak in late July and August, most bears spend at least part of their day in berry thickets, pulling the berries from the bushes with their lips and mouths. Salmon provide bears with fat and protein, and berries are high in natural sugars, all of which are important for building up a fat reserve for hibernation. As fall progresses, bears increase their consumption of salmon and berries as they strive to build up their fat layer before entering the den for hibernation. A diet rich in berries has its downside, though. Bears are one of the few wild animals susceptible to tooth decay. Abscessed teeth are not uncommon, and rotten teeth may affect the bear’s ability to eat and may even lead to starvation.
One of the most enjoyable aspects of bear viewing is watching a bear chase and catch a salmon. Sows teach their cubs how to fish and will often corral a salmon toward the cub in shallow water and then encourage the cub to chase the fish. A sow with newborn cubs that are still nursing will only allow her cubs to eat a small part of her catch after she has had her fill because she needs the extra protein to produce the milk to nurse her cubs, and the cubs are receiving most of their nutrition from her. As the cubs age, they nurse less, and the sow shares more of her catch with them. Finally, when they are old enough, she encourages them to fish on their own, and by the time the cubs are two years old, they can usually chase and catch a few salmon without the help of their mother.
Fishing is a skill bears learn with much practice over time, so young bears are often clumsy fishermen. A sub-adult bear may gallop back and forth in a stream for thirty minutes without successfully landing a salmon, while an older bear walks slowly downstream and pounces on a passing salmon with little effort. A bear may also develop his own unique fishing technique. One bear may sit on a fallen log hanging low over a stream and attempt to grab fish as they swim past. A second bear may “submarine” by dunking his head under water to watch for fish, and a third may obtain his fish by chasing another bear and stealing that bear’s catch.