With the recent sightings of a little black bear in town, it seemed like bears would be an appropriate topic for today's Wild column. Colorado is home to only one bear species, the black bear. Although grizzlies used to live in Colorado, they have been considered extinct here since 1951, according to the Denver Museum of Nature and Science. The American black bear outnumbers all the other species of bears in the world combined.
It might surprise you to learn black bears are not always black in color. The bears are usually black with a brown muzzle, according to the International Association for Bear Research and Management. However, they also may appear chocolate, cinnamon brown or even blonde. Many black bears also have a white patch on the chest.
Black bears lack the shoulder hump of a grizzly bear. Their faces appear convex, or curved inward, as opposed to the facial profile of a brown bear, which is more concave.
The claws of a black bear are 1 to 2 inches long, very strong and curved. They are designed for climbing, according to the Western Wildlife Outreach. The rump is higher than the bear’s shoulders.
Males are 50 to 75 inches long and weigh 130 to 660 pounds. Although females also are 50 to 75 inches in length, they weigh less at 90 to 175 pounds. Males can be anywhere from 20% to 60% larger than females.
The home range for a female bear is smaller than that of a male. Females have home ranges of 2.5 to 10 square miles, whereas, males have home ranges of 10 to 59 square miles. A home range is the area in which a particular bear spends most of its time. Females usually do not tolerate other females in their territory, but their home range may overlap with several males.
Contrary to a myth that says bears can’t run down hills well, they can run both up and downhill quite well. Bears are capable of running up to 35 mph.
They have good eyesight, but do not pick up the yellow-red-orange spectrum of colors as well as humans. Their hearing is excellent, but their ability to smell is really exceptional. They can smell things seven times better than dogs, particularly when food is involved.
In the fall, bears are trying to put weight on for hibernation, gaining up to 35% of their body weight. Because of this, they will start to eat excessively, a period known as “hyperphagia.” Bears have good memories when it comes to food sources and will move seasonally depending on food availability.
Black bears eat both plant and animal matter, with plant matter making up 80% to 85% of their diet. They are opportunistic feeders and will eat carrion in addition to killing their own prey. The diet changes depending on what is available in a particular season.
In the spring, newly emerging shoots are nutritious and bears seek them out. They also may scrape off the sugar-rich layer inside bark. In the summer, their food sources change to maturing berries and meat. Black bears will switch to nuts, such as acorns and pine nuts, in the fall.
Black bears do hibernate, but may come out of their dens for short periods of time in the winter. They tend to choose dens for hibernation under large boulders, in tree cavities, under logs or buildings or even simple depressions under bushes.
Black bears normally have a heartbeat of 40 to 50 beats per minute, but this drops dramatically during hibernation to around 8 beats per minute. Their body temperature does not drop much. Because they don’t need to bring their body temperatures up like other bears, black bears can emerge quickly from their dens, which helps them defend their cubs and themselves.
Black bears metabolize fat when in hibernation, which is converted to energy and water. The bladder reabsorbs the urine, which gets converted to carbon dioxide, water and ammonia. Black bears do not defecate while in hibernation.
Females don’t reproduce until they are between 3 and 5 years old, but may be as old as 7 before reproducing. They will typically only breed every other year and have two cubs on average, but may have up to five.
Fifty percent of all cubs die during their first year. Females breed in the summer and gestation lasts around seven months. Black bears have an adaptation called delayed implantation, which means that the embryo does not actually start to develop until November or December even though the female conceived in the summer. Because females don’t breed while rearing their young, they may only produce six litters in their lifetime. The average lifespan of a black bear is 18 years.
Although rare, you may encounter a black bear while hiking and it is important to know what to do. Black bears have a couple types of communication of which hikers should be aware.
They may perform what is known as a bluff charge, when the bear charges the hiker but breaks off the attack a few feet away, sometimes accompanied by stamping its feet on the ground. Bluff charges are meant to scare you away and they are much more common than actual attacks.
The other behavior you may observe is the bear standing on its hind legs. In this case, the bear is likely just trying to get a better look at you.
If you do meet a bear, there are several things you need to do according to the city of Boulder. The first is to stay as calm as possible and do not run because this can cause a bear to chase you. Back away slowly and avoid direct eye contact. Talk to the bear so it is aware of your presence, but do not approach it or bear cubs. Do not throw food to distract the bear because this can teach the bear that people mean food. If attacked, fight back.
You can lessen your chances of running into a bear by heeding any warning signs that are posted, keeping dogs on leashes and making noise while hiking. If you see a bear in your backyard, stay away from it. You may be able to scare it by banging pots together or making other loud noises. If you feel threatened, call 911. Showing respect for bears will decrease the chances of an unpleasant encounter.