The black bear and the grizzly bear are present in parts of the Rocky Mountains, with the black bear's range far more extensive than the threatened grizzly. While black bears can be found up and down the Rockies, the grizzly is mostly confined to the northern range of these peaks, with many more present in Canada than in the U.S. Black bears are smaller, weighing an average of between 150 and 300 pounds while the grizzly can be as large as half a ton and stand 10 feet tall on its hind legs. Both of these species are omnivorous, meaning they will dine on almost anything. Bear attacks have been well documented over the years, with several resulting in fatalities. Bears are especially dangerous when protecting a recent kill of their own and when a female has cubs.
North America's largest cat, the cougar, can weigh as much as 200 pounds. These cats at one time were found all across the U.S., but now are relegated mostly to the western states, with the Rocky Mountains as one of their few strongholds. Skillful hunters, there have been several instances where cougars actually stalked and killed human beings. Anyone who is venturing into areas of the Rocky Mountains that cougars frequent needs to be on the alert for these animals. Since 1900, there have been well over 100 cougar attacks on people in the U.S. and Canada, with a quarter of these resulting in deaths.
While most people do not associate different members of the deer family with danger, the potential always exists for a bad encounter with moose, elk, mule deer and white-tail deer--all inhabitants of the Rocky Mountains. Deer can be dangerous during the mating season and are also hazardous if they feel cornered or are surprised. Antlers and hooves can be formidable weapons against human beings, and a huge bull moose that is in the middle of the rutting period is not an animal that should be approached under any circumstances. Bison, which can exceed 2,000 lbs., can be found in places such as Yellowstone National Park in the Rockies. Bison account for more injuries to visitors in the park than all the rest of the animal species that live there combined. Thinking the bison is harmless, people foolishly approach them and put themselves at risk of being trampled or gored, especially if a young calf is in the area and the bison feels threatened.
There are rattlesnakes that live in parts of the Rocky Mountains. These stocky snakes are capable of causing great harm with their venomous bite. While the venom of a rattlesnake is not always injected into a bite when the snake strikes, if enough does get into a person's system, he may die without prompt medical attention. Rattlesnakes like to sun themselves on rocky ledges and trails, which make them a potential threat to mountain bikers that may come across them quickly and frighten them into striking.
Coyotes exist in large numbers throughout the Rockies, while their much larger cousin, the gray wolf, is present on a very limited basis. Both are clever predators that can be dangerous if confronted or if someone is out in the wilderness alone, with the wolf much more of a risk than the coyote since it lives in groups called packs. The bobcat, lynx, and wolverine also live in the Rocky Mountains, and while these three species are rarely seen and avoid humans whenever possible, they are able to inflict damage with sharp teeth and claws if provoked or threatened.