The grizzly bear is the largest of North American terrestrial carnivores. Once they occurred throughout Colorado, and they apparently were fairly common in the western three-fifths of the state at least until the turn of the century. After 1900 populations declined rapidly. No grizzly was killed in the state from 1952 until 1979, when naturalists were surprised to learn that a grizzly was killed by a hunting guide in the San Juan Mountains, apparently in self-defense.
Grizzly bears are unmistakable, not only because of their large size (to 7 feet long, and weighing 500 pounds or more), but due to conspicuously humped shoulders, front legs longer than rear legs, a dished-in face, and front claws over 4 inches long. Color is mostly yellowish to reddish brown.
Grizzlies are too large and hungry to be picky eaters. They eat carrion (often of bison carrion once-upon-a-time), fruit, young vegetation shoots, roots, bulbs, fish, and larval and adult insects. They seldom chase down adult hoofed mammals, but do take elk calves and fawns they stumble upon. Sometimes they excavate burrows and tunnels of marmots and other rodents.
These bears breed in July. Embryo implantation is delayed, and after a gestation period totaling 26 weeks, the young (usually twins) are born to the hibernating sow in her winter den. Mother and cubs emerge from the den in April or May. The young are weaned in early autumn. Females first breed at 3 1/2 years and thereafter produce cubs every second or third winter.
The grizzly bear is classified as an endangered species in Colorado, but it probably is gone from the state. Some have argued that because grizzly bears are native to Colorado's wild lands they should be re-established here, but the Colorado Wildlife Commission is on record as opposing restoration.