The information listed here should help you understand some of the terms that you may see on the black bear and grizzly fact sheets and the bear cart talking points. 1
Bears are a dog-like form of the Order Carnivora. The dog-like forms typically possess a long snout and non-retractile claws. The Carnivora Order split early in the evolution process into the dog-like and cat-like forms about 50 million years ago. The split began with a change in dentition. The Kodiak bear (Ursus arctos middendorffi) and the Grizzly bear (Ursus arctos horribilis) are subspecies of the Brown bear (Ursus arctos) 2
All bears are omnivores, but each species has a unique diet their teeth tell the story. Omnivores have molars in between carnivores and herbivores, with more peaks and valleys due to the varied diet; cheek teeth are wide with low bumpy surfaces. Omnivore s teeth are less specialized than most mammals. Polar bears are the most carnivorous of the bears and use sharp canines to rip out chunks of meat, usually seals. They tend to swallow these chunks without much chewing, so their molars are reduced in size. The grizzly bear who fills 90% of diet with vegetation has more flat grinding molars. The black bears are very opportunistic eaters. Most of their diet consists of grasses, roots, berries and insects. They will also eat fish and mammals, including carrion. 3
The relative size of the nasal passage on a skull is an indication of the animal s sense of smell. Bears hunt by scent and their long noses contain millions of scent receptors. The thin bony structures inside the nasal passage, the turbinates, provide the framework for membranes which sense odor in vertebrates. Turbinate bones increase the surface area of the inside of the nose and heighten the sense of smell. They also function to filtrate, heat, and humidify air inhaled through the nose. Humans have a poor sense of smell compared to most animals. 4
Most bears exhibit sexual dimorphism, with males reaching an average size roughly 2 times larger than females. Polar bears are the largest of the terrestrial carnivores. Male polar bears are often twice--even three times--as heavy as females, which typically weigh 400 to 700 pounds (making them still larger than most other terrestrial carnivores). Brown bears are the second largest bear, specifically the subspecies the Kodiak bear. Black bears are the smallest of the three bear species found in North America. The male black bears tend to be anywhere from 20-60% larger than the females. Sexual dimorphism in a species makes it easier for animals to attract, find or fight for mates. 5
Mammals characteristically have two layers of hair forming the pelage (fur). There is a dense and soft undercoat, which traps a layer of air, providing insulation; the insulation provided by fur comes not from the hair itself, but largely from the layer of air trapped within the fur. Long, coarse hairs form the protective outer guard coat. These coarse hairs protect against wear and also provide coloration of the pelt. Fur is dead and made of keratin. Insulation is improved by fluffing up these hairs. This same action of raising one s hair is used in aggressive or defensive behavior to make oneself appear larger and scare the enemy away. Thick fur such as that of the grizzly bear offer some protection from physical damages such as bites and scratches. Many plants rely on animals for seed dispersal of their seed; the barbs of seeds attach to fur and feathers or human clothing and hitchhike to another area before they fall or are brushed off. A bear s pelt is a great place for a seed to catch a ride. 6
Polar and grizzly bears exhibit delayed implantation, which is when the embryo does not immediately implant in the uterus, but it is maintained in a state or dormancy. The phenomenon of delayed implantation is of the greatest importance to species in which the sexes meet only for a limited time each year or if births must be carefully timed to meet the season when food is most abundant. Bears usually mate when they first come out of their dens in the spring and the egg will implant if the mother has found sufficient food before she dens up in the late fall. In this way, she times her emergence from the den with the weaning of the cubs and the abundance of food. Another benefit of this adaptation is that no matter when mating occurs, the majority of the young are born around the same time. Bears are thought to be induced ovulators. Induced ovulation is when the females release an egg during or shortly after copulation. This is an advantage for species that lead solitary lives and may not come across a male that frequently. Induced ovulation means that fertilization may occur at any point the female comes across a male and is not restricted to certain cycles or times of year. 7
Hibernation is a period of dormancy or inactivity, varying in length depending on the organism and occurring in cold seasons; metabolic processes are greatly slowed and, in mammals, body temperature may drop. Hibernation is used by some animals to conserve energy and cope with food shortages that occur in the winter. During hibernation, stored body fat is used up at a relatively slow rate. A bear s metabolic rate is significantly less depressed and its body temperature is reduced only a little from a true hibernator. For example, a ground squirrel s body temperature during hibernation is reduced to near freezing. Alternatively, bears reduce their body temperatures by about only 10 degrees or so. Moreover, ground squirrels have to awaken about every week for about a day, eat stored food, pass waste, and then return to hibernation. They continue this cycle all winter. Bears don t need to do this. Bears can go for more than 100 days without eating, drinking, or passing waste. A bear s fat cells break down and supply water and calories, while muscle and organ tissues break down and supply protein. Also, true hibernators awaken slowly, as their body temperature rises. Bears, however, can awaken very easily during their denning period. This allows bears to tend to their cubs quickly when they are crying out. 8
During this time of denning up, the cubs are born; cubs are born altricial, meaning requiring nourishment. Altricial young are born helpless and require care for a specific amount of time; cubs are born relatively immobile and have closed eyes, they are not able to obtain food on their own, and must be cared for by adults. These cubs weigh about one pound or less. Denning up has allowed for a longer period of time for the parents to teach skills that are necessary for survival and to live through the winters when resources are not as readily available. By the time denning up has ended the cubs are bigger and full of energy. Bear cubs are really playful. Play fighting is very important for young bears because it teaches them to protect themselves and helps them get stronger. They are learning the skills that are necessary for survival. 9
Bears have a plantigrade gait; they walk on the sole of their foot with the heel touching the ground. Since bears are so large, having the whole foot on the ground provides better support and stability. This is in contrast to a digitigrade gait, where an animal walks on their toes with the heel and wrist permanently raised, as in a cat. Also the unguligrade gait, where an animal walks on the nail or nails of the toes (the hoof) with the heel/wrist and the digits permanently raised, as in a horse or zebra. The grizzly and the polar bear both have thick, curved, non-retractable claws. The grizzly uses his claws for digging for food and the polar bear s claws are used for grasping prey and traction on snow and ice. They grow back during the denning up period. 10
The bears are given a variety of enrichment. Providing ice gives the bears the ability to explore different temperatures and textures. Black bears: Climbing structures provide climbing opportunities and provide shade. Pools provide a natural environment and ability to cool down. Behavioral training enables staff to perform minor medical exams and procedures if needed. Grizzly Bears: Keepers add variety to their diet with edible browse, fish, edible wild berries and meat. They also provide foraging opportunities with live fish in their pool, burying foods in substrate, or by putting food in boxes. They also use peanut butter and honey for different textures and smells and a variety of olfactory enrichment is given, such as fennel. Various behavioral training enables staff to perform minor medical exams and procedures if needed. The bears are also trained to present their shoulder in case the need for an injection or a blood draw. This eliminates the need to anesthetize the bears for minor medical care. 11
The Hearst Grizzly Gulch provides a home for the two orphaned bears, Kachina and Kiona, whose names in Native American dialect mean sacred dancer and brown hills respectively. They were originally slated to be euthanized after they were considered problem animals for getting too close to developed areas and into a rancher s grain storage. In the fall of 2004, San Francisco Zoo Board Member Fred Carroll notified the Zoo of the bears dire situation. With the cooperation of the Montana Fish, Wildlife and Parks Department, the Zoo agreed to provide a home for the two grizzly sisters. Hearst Grizzly Gulch is one of the largest naturalistic environments dedicated to grizzly bears in any zoo; it is 1 acre. At the exhibit, you ll also learn the tale of Monarch, the grizzly bear that was the inspiration for the and whose image appears on the California state flag. Recognized as the California state mammal and the symbol of the California state flag, the grizzly bear is now extinct in the state. Between 1800 and 1975, the grizzly bear population in the lower 48 states decreased from 50,000 to less than 1,000. The decline can be attributed to human development, livestock depredation control, commercial trapping and unregulated hunting. 12
The motherless black bear cubs, one male and one female, were found emaciated and wandering alone in Alaska hundreds of miles apart in late spring 2017. The cubs were nursed back to health at the Alaska Zoo in Anchorage before they arrived in San Francisco in late July. 13
The Brown Bear is the most widely distributed ursid. It once ranged across a large portion of western North America, including northern Mexico. Although, as a whole, this species is secure with relatively large numbers and an expansive range, many small, isolated populations are threatened due to their low numbers and frequent contact with humans. The primary threat to the survival Grizzly is loss of habitat due to human encroachment, logging, energy and mineral exploration. Fewer than 2,000 grizzlies remaining in the continental U.S.. Grizzlies are classified as threatened in the lower 48 States since 1975. Conservation actions for Brown Bears vary greatly among nations and regions within nations. Large populations of this species (in Russia, Japan, Canada, Alaska, and parts of eastern and northern Europe) are legally hunted, and thus managed as a game animal. Most small populations are protected by national laws and international agreements, with varying degrees of enforcement. A grizzly bear named Monarch was the first animal in what would become the SF Zoo. Monarch was California's last captive grizzly, and he became an important symbol of the state's evolving relationship with vanishing wildlife. A looming concern, but not a widespread problem in North America, is the poaching of bears for their paws and gall bladders, which may be sold commercially. Those products, particularly bile from gall bladders, are highly valued by practitioners of Traditional Chinese Medicine. Several U.S. states and Canadian provinces allow the sale of bear parts taken legally by hunters. 14
Definition: Atricial: helpless at birth or hatching and requiring parental care for a period of time. Delayed implantation: delayed implantation the embryo does not immediately implant in the uterus, but it is maintained in a state or dormancy. Examples include rodents, bears, seals. Diurnal: of, relating to, or occurring in the daytime Hibernation: a period of dormancy and inactivity, varying in length depending on the organism and occurring in cold seasons; metabolic processes are greatly slowed and, in mammals, body temperature may drop. Induced ovulation: the act of breeding causes the female s ovaries to release eggs. Keratin: is a structural material of hair, fingernails, claws, horns, feathers and skin. Omnivore: an animal that eats both plants and animals. Plantigrade: walking with the entire sole of the foot on the ground, as humans, bears, raccoons, and rabbits Sexual dimorphism: the condition where the two sexes of the same species exhibit different characteristics beyond the differences in their sexual organs, such as in color, shape, size, and structure. 15