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Black Bears in Alaska

Picture
BLACK BEAR
Black bears (Ursus americanas) are classified in the order Carnivora along with wolves, wolverine and lynx. However, bears are not carnivores; they are omnivores, eating both plants and animals. Some people erroneously believe that bears are closely related to pigs, partially because both species are omnivores. Female bears and pigs are called sows, male bears and pigs are called boars, and both species harbor the parasite that causes trichinosis. From an evolutionary standpoint, bears and pigs are not related. Pigs are classified in the order Artiodactyla, along with deer, goats, sheep and giraffes, because they have hooves, not paws and claws, like bears. Furthermore, a bear’s teeth and leg bones, characteristics used to classify animals, are not like those found in pigs.

SIZE: Male black bears are larger than the females. The average Alaska male black bear is about 2½–3 feet (0.7–1.0 m) tall at the shoulder and five feet (1.5 m) long: add a few inches (8 cm) for the tail. Black bears may weigh 40 percent less in the spring after emerging from their winter dormancy, a period during which they do not eat. The average spring weight of a female black bear is 100–150 pounds (45–60 kg), and the average adult male spring weight is 170–200
pounds (77–90 kg). Spring males weighing nearly 400 pounds (180 kg) have been reported in Alaska. Fall male black bears can weigh over 500 pounds (227 kg).

COLOR: Black bears are usually black, but additional color variations include cinnamon, gray or blue (see the image upper left with a cinnamon mother and cub with a black cub in the same litter). The gray or blue-colored black bear is often referred to as a “glacier bear.” A white color phase occurs in British Columbia but has not been reported in Alaska. Any color sow can give birth to cinnamon, black or glacier colored cubs. More than one color phase may occur in the same litter. Black bears often have a white patch on the front of their chests.

SPEED: Black bears can reach speeds of 30 miles per hour (48 km/hr).

LONGEVITY: The life span for black bear is approximately 20 years in the wild.

REPRODUCTION: During spring, boars will approach sows cautiously, moving in a non-threatening manner making sure their body language does not frighten the sow. Boars tend to be submissive and playful around the sows at this time of the year. Once the female becomes comfortable with the boar, mating may occur several times a day for several days. After this time they go their separate ways in search of food or other mates. Boars attempt to mate with as many sows as possible. The sow may mate with more than one boar.

Fertilized eggs stay in a suspended state until fall,then implant in the uterus if the sow is healthy enough to support herself and the cubs through the winter. This is referred to as “delayed implantation.” After implantation the embryos will develop for seven months. Cubs are born in the winter den when the female is in winter dormancy. She may give birth to
one to four cubs, small, less than one pound (0.5 kg), blind and nearly hairless. Cubs begin suckling right away and grow quickly.

Cubs weigh about five pounds (2.3 kg) when they emerge from the winter den, covered with a fine thick coat. The youngsters must learn how to locate food and avoid predators and other dangers. They remain with the sow for that summer, fall and another winter, taking survival lessons from their mother. When the sow breeds again the following summer, the cubs are usually on their own. In the more northern regions of Alaska, where the conditions are more difficult, cubs stay an additional year with the sow, and she may only breed every three years. Black bears become sexually mature when they are between three and six years old.

SOCIAL STRUCTURE: Black bears are usually solitary except for sows with cubs and during mating season in June and July. Sows with cubs are cautious around boars and avoid them. Boars kill cubs if given the chance. Since these sows would then soon come into heat again, it allows the boar an evolutionary advantage for him to pass on his genes to the next generation.

Bears may gather at abundant food sources such as salmon spawning streams. A hierarchy is established at the site, with the dominant animals controlling the best fishing spots. The most dominant animals are the large boars followed by sows with older cubs, then sows with younger cubs and then other younger bears. Body language is used to establish and maintain rank, which reduces the number of physical confrontations.

DISTRIBUTION: Black bears are found in most of Alaska’s forested areas. They are not found on the Seward Peninsula, north of the Brooks Range, or on many of the large islands of the Gulf of Alaska (including Kodiak, Montague,  Hinchinbrook, Admiralty, Baranof, Chichagof and Kruzof) where brown bears are abundant.

MOVEMENTS AND MIGRATION: Bears leave their winter dens in the mountains in spring, and by July most black bears are feeding on the lush vegetation found in meadows and avalanche chutes. Bears learn from their mothers and from their own experiences where and when to find food. This drives their annual wanderings. Bears depend upon the entire landscape for survival. The first emerging plants in spring are low in the valleys and along coastal shorelines. As spring moves up the hills and mountains, bears move up with it to eat nutritious emerging plants. By late summer many black bears are again at higher-elevation meadows feeding on the lush plants just released from winter’s grip.

Black bears will move to where salmon and other foods are available. This brings them back down the mountain to salmon streams and berry patches. Bears often use the same corridors, or paths, as they move through the forest. These well-used trails have worn footsteps, sometimes in solid rock, where many generations of bears have passed.
By late fall most black bears are again moving back up the mountain, feeding on the ripening berries. As snow begins to build up in the mountains in October, black bears start locating and preparing their winter dens. Most black bears will stay in their dens all winter, but some bears will come out for a brief trip and then return to stay in their dens until spring.

HABITAT: Black bears usually are associated with forested habitat; however, bears are creatures of landscape in that they use a wide variety of habitats including streams, forested valleys, beaches, meadows, muskegs, tundra and mountains. They are rarely seen on the open tundra, probably because there are no trees to climb to escape predation by grizzly bears.

PREY: Bears need to eat enough in a few months to provide energy to survive the long winter. Black bears are mostly vegetarians and may remind the human observer of cows as they are seen grazing on sedges and fern fiddleheads. However, black bears also will eat winter-killed animals and sometimes will kill and eat newborn moose calves and deer fawns. They have been seen digging and eating clams.

In August salmon are on the menu for most black bears that can access a salmon spawning stream. Salmon can be a boon for bears by supplying them with necessary nutrients and calories. The eggs, brains and skin of salmon are packed with calories, and it is calories that are needed to get black bears through the winter. Bears usually eat the entire fish early in the season but, as salmon spawning season progresses, bears become picky and may eat only the brains and eggs, discarding the muscle tissue completely. Bears often discard male salmon in favor of egg-laden females.

PREDATORS:Wolves or brown bears may kill black bears, especially those that are younger and smaller. Sometimes
male black bears will kill bear cubs, possibly for food. People hunt black bears for food and for their hides.

PREDATORY CHARACTERISTICS: Black bears occasionally prey on young moose, caribou, deer and other ungulates. They may happen upon these younger animals, but some black bears learn to hunt them. The bears’ sharp claws and long canine teeth are used to secure and kill their prey. Black bears sometimes stalk and kill people, although this is rare.

CURRENT STATUS: Black bear populations are healthy in Alaska, although bears often are driven away from human populated areas. In other urban areas, bears are attracted to human waste and garbage.

ECOLOGY/CONSERVATION: The next time you are in the Alaska woods and come across a large pile of bear feces, grab a stick and pick it apart. To some this may seem odd and disgusting, but to those interested in nature and in bears, poking and prodding a large pile of bear scat can be revealing and interesting. The salmon bones are easy to pick out, and you even may be able to determine if the bear has been eating chum or pink salmon by the size of the bones. Bones from mice, rabbits and other mammals can indicate a wider feed source. Most green vegetation is black after being digested, but the berries can be very interesting.

Blueberries can turn the feces dark purple to black, but many of the berries can pass through the bear unscathed. When bears eat berries they usually eat some of the leaves. These can be seen in the mix. Black and brown bears may eat high-bush cranberries or devil’s club berries. These red berries actually make a pile of bear scat rather attractive. Older piles of bear scat, from previous years, sprout mushrooms or seedlings of the berries the bear ate. That is how many
berry bushes get their start in life.

All bears have good senses of sight and hearing. Their sense of smell is excellent. Alert bears can detect, with their eyesight alone, a moving human form from over a mile (1.6 km) away, and move off to avoid contact. Use this information to avoid dangerous encounters with bears. If you spend time in bear country you should:
• Look for signs of bears and make plenty of noise.
• Avoid surprising bears at a close range
• Avoid crowding bears; respect their “personal space.”
• Avoid attracting bears through improper handling of food or garbage.
• If confronted by a bear, plan ahead, stay calm, identify yourself (e.g., yell,”Hey, bear! Scram”) and don’t run.

In most cases bears are not a threat, but they do deserve your respect. More information about what to do and how to operate in bear country can be obtained from the Alaska Department of Fish and Game www.wildlife.alaska.gov/aawildlife/harmony.cfm.

Black bears usually avoid contact with humans. However, once black bears become habituated to humans and to their food they may become especially dangerous. These bears lose their fear of humans and associate humans with food. Each year many bears are killed in Alaska’s towns and cities because they become accustomed to feeding on garbage, and are considered unpredictable and dangerous to humans. Providing food for bears usually results in the bear being in conflict with humans. Capturing habituated or “garbage bears” and relocating them often does not work. Some bears
have returned over 100 miles (161 km), crossing major rivers, while other bears find another community and, in both cases, they resume their bad habits. Protect bears by eliminating garbage and other available food items from camps and residences.

Hibernation is something arctic ground squirrels do, when their body temperatures drop to just above freezing and the heart rate is a small fraction of normal. Black and brown bears go into winter dormancy, their body temperatures drop a few degrees, their metabolic rate is reduced, and they sleep for long periods. In the more southern ranges black bears occasionally will emerge from their dens during winter. In the northern part of their range bears may be dormant for
as long as seven or eight months. Females with cubs usually emerge from winter dormancy later than boars or sows without cubs.

Black bear dens in Alaska are often in rock cavities or caves, fallen hollow trees, or dug into dirt or clay banks. Most dens are in the mountains, but some bears use dens at lower elevations. Black bears may prefer to hibernate in the mountains and on north-facing slopes to avoid melt water flooding the den when warm, wet winter storms come in off the ocean. During winter dormancy bears don’t urinate, defecate or eat. They must survive off their fat reserves.

Salmon return from the sea, enter their natal rivers and streams, spawn and die. Were it not for the predators, such as bears, that eat them many of the nutrients found in the dead salmon would be washed back to sea. Black bears and other predators are important for moving the nutrients into the watershed. Their scat enhances the growth of trees and vegetation along the length of the streams where salmon spawn. The entire forest ecosystem is dependent upon bears and other predators for fertilizing the watersheds with nutrients from the salmon. Even the salmon benefit because the
fertilized watershed will produce more stream-shading vegetation and more insects used as food by young salmon. The productivity of salmon is enhanced in systems with bears.

Black bears are important food for humans in some parts of Alaska. Spring bears are lean and their flesh is usually very palatable. Late summer and fall bear meat may be less tasty, especially when they have been feeding on salmon. Sometimes fall bears that have fattened up on berries are harvested just for their fat, which is rendered and used in cooking. Good-quality bear fat looks just like white pig lard and is used for baking pies and donuts. Black bears can harbor the parasite that causes trichinosis. To prevent infection from this disease, wear protective gloves when handling bear meat, and cook the meat thoroughly before eating.

Reference: Wright, Bruce A., 2011. Alaska Predators, Their Ecology and Conservation. Hancock House Publishing. 119 pages. http://www.hancockhouse.com/products/alapre.htm

Other species:
Pacific sleeper sharks in Alaska
Salmon sharks in Alaska
Great white sharks in Alaska
Bald Eagle
Gyrfalcon
Great Horned Owl
Snowy Owl
Brown Bears
Polar Bears
Orcas
Wolves
Wolverine