First, always respect any closure sign that may be posted. These signs are posted for your safety and the benefit of the bears. If a bear detects your presence, it will usually leave the area immediately. However, if you surprise a bear, the chances of an attack are much greater. Never store food in your tent or close to where you will be sleeping.
Bears can smell food from miles away even if it is packaged or sealed in a container.
The sense of smell for bears ranks among the keenest in the animal world. A bear has been known to detect a human scent more than fourteen hours after the person passes along a trail. At any rate, bears have an extremely keen sense of smell and are always seeking food. In short, when in Yellowstone, obey the trail closure signs, follow the rules of bear country use, and exercise some common sense. The grizzly bear is one of the many awesome and beautiful animals that can be found in Yellowstone National Park.