Colorado Parks and Wildlife said Thursday about 60 percent of the bears with tracking collars have left their dens. The agency says the bears that are still inside their dens are mostly sows with newborn cubs and should be out in the next few weeks.
An estimated 17,000 to 20,000 bears live in Colorado.
Wildlife officials advise hikers to travel in groups, make noise to avoid surprising bears and be alert for tracks, claw marks and other signs they might be near.
They say homeowners should avoid attracting hungry bears by keeping garbage secure, not leaving pet food outdoors and taking down birdfeeders. They say birds don't need to be fed in the summer.