They can smell one-thousand times better than humans. Bears use this sense of smell to detect food. When you combine the quest for food attitude of a bear, with their keen sense of smell, and then add humans into bear country with our perfumes and delicious food, one can quickly learn why bear encounters are so common. In North America there are black bears and brown bears. Black bears aren't always black, and brown bears aren't always brown.
Black bears can be brown, red, yellowish, and honey in color.
Brown bears, or grizzly bears can be black in color. Brown bears have a distinctive hump on their shoulder and shorter noses. Depending on your location and altitude, bears can be active from as early as late February through to November and December. For example in Yellowstone bears are dangerous from April through May as they are bulking up from the winter hibernation. Then in June and July bears are dangerous because it is calving season and they are after easy prey.