During spring and summer, people often encounter young animals in urban areas, the mountains and the plains. In all cases, the rule of thumb is: Leave them alone!
Deer, elk, and other mammals often leave their young while feeding, relying on the young animals' natural camouflage to protect them. Don't assume that just because you don't see the parents, the young have been abandoned.
In cases where newly hatched birds have fallen from their nest, return them to the nest if you can do so safely. Or, place them on a high branch to keep them away from pets.
Keep in mind that when young birds begin to fly, they often spend time on the ground before they perfect their flying skills. If this appears to be the case, leave them alone and let them learn. There are very few cases of 'abandoned' wildlife. If you are absolutely certain the parent animal is dead (hit by a car, for example), mark the location on a map or measure the mileage from a landmark and report it to the Colorado Parks and Wildlife.