The American black bear, Ursus americanus, is an interesting creature. The smallest of the three bear species found in North America, a fully grown adult can be in excess of 300 pounds. They are among the largest and most successful predators on the continent and yet they have rather poor eyesight for a natural wild predator, though good by human standards. People might wonder, then, how they can be so successful. The answer hinges around the fact that they have good hearing and a great sense of smell.
It might seem strange to even consider the diet of this bear, when looking at their sense of smell, even more so as they are a predator. However, how well they detect a scent is important to their survival, in part because of what they eat.
While the bears are predators and do use the sense of smell to locate prey, they are also true omnivores. That is, they will eat plants, fruits, roots, freshly killed meat, fish and carrion. Like man, they require a balanced diet for optimum health. They are also quite fond of sweets. Natural sweets like honey and berries give them a burst of carbohydrates that can be converted to fat. This is important so they can survive through sometimes-harsh winters. Often, they find their food by smelling it first, sometimes from a surprising distance.
The sweets are often found due to the bear's sense of smell. How well they key in to the smell of sweet food is shown in an unofficial test conducted at Crater Lake National Park in the very early 1970s. The experiment was conducted after a park worker explained the major damage to his government issued truck by saying that a bear had appeared out of nowhere to rip the door off in order to get to a peanut butter and jelly sandwich in the seat.
A similar sandwich was made and set on a stump, in an area where employees were relatively certain there were no bears within several miles. Within 20 minutes, a bear showed up to devour the sandwich. Apparently, it smelled the sandwich from several miles away. As put by the chief ranger at the time, "I knew they [black bears] had a great sense of smell and this proved it. It also showed why bears often show up in campsites and picnic grounds."
It would be a mistake not to mention how the sense of smell sometimes relates to bear attacks. Bears tend to go after, and are often attracted by, anything that smells like food. This includes human food, but can also include things we wouldn't ordinarily eat, like suntan lotion, perfume, cologne, body lotions and even some kinds of soap.
Bears can identify their young by smell alone. They are protective of their cubs and the smell can give them an idea of where the cubs are, even if they aren't within sight. There is a case of a black bear at Yellowstone National Park, shown to be blind, that not only survived but also raised at least two litters of cubs. There is no doubt that the sense of hearing played into this, however the sense of smell was most likely more important.
An American black bear's sense of smell is excellent. It is a major reason the bear survives, and why its range is so great. The ability of the bear to smell what it perceives as food from miles away also helps explain many of the bear attacks. Wildlife departments and other agencies continue to explore just how fantastic and precise the bear's sense of smell is. Bears can still be startled by humans, but there is a good chance that they know a person is there, by smell, long before the person sees the bear.