Black Bears

Bear’s Quest for Calories

Posted: by wgardner


Living around humans, bears have developed a taste for people’s garbage because it is often higher in calories than their natural food sources. Below, common types of human foods are contrasted with how many acorns a bear would have to eat to get the same amount of calories.

A dozen eggs is 888 calories. That is equql to 234 acorns.

A pound of hot dogs is 1,456 calories. That is equal to 384 acorns.

A McDonald’s double cheeseburger combo is 1,620 calories. That is equal to 427 acorns.

A pound of Black oil sunflower seeds is 1,740 calories. That is equal to 458 acorns.

A dozen Jelly donuts is 2,640 calories. That is equal to 695 acorns.

A large Pepperoni Pizza is 17,352 calories. That is equal to 4,566 acorns.

Compare that to 25 pounds of Purina dog chow. That is 42,425 calories. That is equal to 11,165 acorns.

I think that now you are getting the picture why bears prefer human food over acrons. Plus acrons don’t taste that good!

Bear Vocalizations: What Do They Mean?

Posted: by wgardner

Being a zoo keeper I get asked a lot of questions about the animals I work with and one question that comes up a lot is: what type of vocalizations do animals make and what do they mean?

Bears have several types of vocalizations. Some species vocalize more than others. Knowing what these sounds mean can help us understand bear behavior and help with their care.

Photo of brown bear yearlings play-fighting and vocalizing in Alaska. photo credit: Chris Morgan.

Giant pandas have some unique vocalizations. They bleat which is a friendly greeting, honk when anxious or distressed and during the breeding season a receptive female will chirp when meeting a male. Sloth bears make a huffing sound when sucking up food, which sounds like a vacuum.

Most bear species make vocalizations that sound like a huff, chomp, woof, growl, and/or bark which mean the bear is agitated, angry or annoyed. A bawl, bellow, squeal or whimper indicates pain. A mumble, hum, or purr indicates contentment.

In many cases vocalizations are done along with some type of body posturing. These are visual clues as to how the bear is feeling. Depending on how the bear is standing, holding its head, the ear placement and how they move can tell a lot about what the bear is thinking and whether it is a dominant or subordinate animal. Bears would rather avoid a fight so using vocalizations and posturing can help eliminate serious conflicts and injuries and along with this, conserve energy they need to survive.

Vocalizations can be heard on the North American Bear Center’s website.

Wendy Gardner, GBOP team

Bear Vision

Posted: by wgardner

Bears can see almost as well as humans, they tend to be nearsighted but have good depth perception. They have a layer of tissue called the tapetum lucidum that lies behind the retina that reflects light and improves their night vision. All bears have round pupils except giant pandas which have slits. Polar bears have a transparent eyelid (nictitating membrane) to filter snow glare and help them see underwater.

http://members.tripod.com/panowl/id27.htm

Studies have shown that bears can see colors. In a study done with giant pandas at Zoo Atlanta, it was not determined whether they could differentiate between colors but they could tell the difference between colors and gray. Being able to see colors may help bears find and distinguish ripe foods like berries, or fresh bamboo in the case of giant pandas.

For year’s people thought bears were colorblind and could not see well but research is showing this is not the case. We still have so much to learn about bears, it will be interesting to see what new things we learn in the future.

Giant Panda color vision study
Black bear and polar bear color vision study

Wendy Gardner, GBOP field specialist

Winter Bear Idiosyncrasies

Posted: by cmorgan

Bears have some fascinating physiological traits, several of which are manifested during their winter denning period. These include: delayed implantation of the embryo for 3-4 months following the summer breeding season, and maintenance of energy and water balance during the 3-5 month denning period.

Energy and Water Balance During Winter Denning

During winter denning, which varies in length from 3-5 months, black and grizzly bears derive all of their sustenance from their own bodies. During this denning period they do not eat, drink, urinate, defecate or exercise.

Bears break down fat tissue to create water and up to 4,000 calories per day. They break down muscle and organ tissues to create protein.

Even though bears drink no water during denning, they do not become dehydrated. In a study published in the American Journal of Physiology, researchers at the Mayo Clinic found that bears were in “almost perfect water balance” after 100 days of hibernation. The metabolism of bears is of interest to researchers because a greater understanding may yield information that helps people suffering from chronic kidney failure and other health issues.

Another unique strategy is that bears are able to take urea – a primary component of urine – and use it to build new protein. Consequently bears are able use newly created protein to restore muscle and organ tissue even when they are not eating and are losing weight, something that humans most definitely cannot do!

Delayed Embryo Implantation as an Advantageous Evolutionary Feature

Delayed implantation, or embryonic diapause, is a reproductive strategy used by nearly 100 mammals including: armadillos, bats, bears, otters and badgers, seals, walrus and kangaroos. Delayed implantation results in the embryo not immediately implanting itself in the uterus following fertilization, and instead being maintained in a state of dormancy for a period of time. As a result, the normal gestation period is extended, sometimes for many months. Because delayed implantation is found in diverse species of mammals, it is likely the result of separate evolutionary processes in response to different selective pressures.

In the case of bears, it allows the female to time the delivery of cubs so that they are born during favorable environmental conditions – so that they do not arrive too early nor too late. It also protects the mother if food is scarce, as the embryo will spontaneously abort if the mother goes into the den with inadequate food stores to carry out gestation and lactation.

Bear Haiku:

Tiny twin bear cubs
Birthed into winter’s darkness
Bellies full of milk

Brown bear sleeps soundly
Winter shifts to spring’s great thaw
And life starts anew

Nan Laney, GBOP field coordinator

Intestines, the Bear Facts

Posted: by wgardner

Many people have seen bear scat; whether it is in pictures, at a zoo or in the wild, it is usually very apparent what the bear had been eating. So how does the food get from one end of the bear to the other?


The teeth start the breakdown process of the food the bear eats. They use their teeth to hold, tear and grind food before swallowing it.

Bears have 42 teeth, except for the sloth bear that only has 40. Humans have 32 teeth.

The dental formula is:
I=3/3, C=1/1, P=3/3,M=1/2 total teeth =42
(Incisors-canines-premolars-molars)

Bears are omnivores that have relatively unspecialized digestive systems similar to those of carnivores. The primary difference is that bears have an elongated digestive tract; an adaptation that allows bears more efficient digestion of vegetation than other carnivores (Herrero 1985). Unlike ruminants, bears do not have a cecum and can only poorly digest the structural components of plants (Mealey 1975). To compensate for inefficient digestion of cellulose, bears maximize the quality of vegetal food items ingested, typically foraging for plants in phenological stages of highest nutrient availability and digestibility (Herrero 1985).

It is thought that the barrel shape of the bear’s body is an indication of a long intestine. Brown bears do have a longer intestinal length than that of a black bear.


Different foods take varying amounts of time to pass through the body. Meat takes about 13 hours while clover takes about 7 hours (Pritchard and Robbins, 1990). Berry seeds pass through unbroken and are able to geminate making bear’s great seed dispersers. Nutrients are also put back into the environment as the feces break down.

These are just two reasons bears are very important to the health of the environment.

Wendy Gardner, GBOP Bear Specialist
photo credit: Dennis Ryan, person belonging to the hat was not eaten
graphic credit:(Clemens 1980; Stevens & Hume 1995)

“Bears move to town” follow up comments

Posted: by dryan

Related to the previous BLOG entry I found the following graphic in the most recent issue of High Country News interesting. This graphic is based on data from the Wildlife Conservation Society and Nevada Department of Wildlife.


Click on the above image to enlarge.

Of particular interest were the facts that bears weigh more in urban areas, and that their density per square mile is greater. For instance the density of bears in the wild is 3 per 38 square miles, but in urban areas their density was documented as 120 bears per 38 square miles. Also noted is a decrease in denning period from 100-150 days per year to 50-100 days per year in urban areas, which means that bears are out and about searching for food more of the year. Finally, the age that females first reproduce is reduced, and the numbers of cubs per birthing cycle is increased in urban areas. This increase in reproductive rate is a natural outcome of an abundant food supply – most wildlife will increase their reproductive rate when food supplies are good and reduce their reproductive rate during harder times.

This data points out a positive feedback loop that certainly we humans don’t want to promote. The fact that bears can access an abundant and easy food supply in and around residences not only contributes to challenging bear behaviors, but also increases their reproductive rate and densities. All of this is another indicator of the need to educate citizens, businesses, schools and governmental organizations to make bear attractants inaccessible.

Unfortunately, however, it only takes a few people to contribute significantly to the food conditioning of bears, and not infrequently those that contribute most to the problem are least inclined to change their behavior. Even in parts of Canada where Conservation Officers can fine people who leave non-natural foods accessible to wildlife, large numbers of bears are euthanized each year. So there is no easy answer, but certainly continued education about this issue is warranted.

Nan Laney
Skagit, Whatcom and Northern Snohomish Coordinator
Grizzly Bear Outreach Project (GBOP)

Bears abandon wilderness and move to the city

Posted: by dryan


Bears are deserting traditional mountain and forest ranges and moving into towns where they scavenge for food. This attraction to ‘fast food’ in urban areas is luring black bears in North America to an early death, scientists have found.

Why? So many young bears are killed in traffic accidents that it is threatening the viability of wild populations.

A 10-year study in the Sierra Nevada Mountains looked at the effects a landscape changed by human activity was having on the black bear (Ursus americanus). Led by the Wildlife Conservation Society (WCS) it looked particularly at whether exposure to humans and new food resources in the form of rubbish was affecting bear life history patterns.

Scientists followed 12 female bears in an urban environment and 10 females in wild land habitats from 1997-2006. All 22 bears were sexually immature females who could be followed through their life cycle.

The study, published in the Autumn 2008 issue of the journal Human-Wildlife Conflicts, had to be limited to 10 years because by then all the urban bears had been killed in traffic accidents while six of the bears still living in the wild survived. During the study the team handled a total of 43 female bear cubs and of those 28 (65 per cent) were dead before they reached 15 months of age.

Despite the bear being a protected species in Nevada, 89 bears were killed by vehicles, 27 by agency management actions for public safety, 17 for attacks on livestock, two due to illegal killing, and 16 due to other causes – such as being humanely put down because of their poor condition.

The study found that bears who lived in urban areas weighed an average of 30 per cent more than bears in wild areas due to a diet heavily supplemented by scavenged rubbish. As a result female bears give birth at a much earlier age – on average between four and five years old, compared with seven to eight years for bears in wild areas. Some urban bears around the Lake Tahoe area even produced young as early as two to three years of age.

The scientists concluded there had been a dramatic and rapid ecological shift of bears from the wild to urban areas in only 10 years to the extent that they found only one wild bear in the Carson Range outside the state capital of Carson City where historically they had always existed.

WCS researcher Jon Beckmann, the study’s lead author, said: “Urban areas are becoming the ultimate bear traps. Because of an abundant food source – namely garbage – bears are being drawn in from backcountry areas into urbanised landscapes where they meet their demise.”

The WCS is studying the effects of urban sprawl on a variety of wildlife and habitats in north America and is working with local authorities to increase the use of bear-proof rubbish containers and improve education efforts to reduce human-bear conflicts.

First published in the Telegraph. Read the full story.

Poor Huckleberry Crop May Lead to Fewer Bear Cubs Next Spring

Posted: by cmorgan

I’ve noticed while hiking in the high country this late summer and fall that something is notably missing – huckleberries. I’ve done a fair amount of hiking this year – on the PCT between Rainy Pass and the Canadian border, and closer to home on the northern and southern slopes of Mount Baker. Consistently I’ve seen small huckleberry crops in the alpine areas. I know the trails on the slopes of Mount Baker well, and my estimate is that the huckleberry crops there are 5-10% of a normal fall crop, depending on location. Aspect, shade / sun and soil are influencing factors in berry yields, but mostly the poor berry crop is a reflection of the late-arriving summer and unusual weather this year.

The fact that we are having a poor berry crop this year is contributing to increased human-bear conflicts in some instances. Bears are involved in something called “hyperphagia” in the late summer and fall. Hyperphagia is essentially a feeding frenzy to put on weight for the winter denning period. When food crops are scarce, such as they have been this year, bears can find human garbage, bird feeders, orchards and compost even more attractive than when there are good natural food supplies. In my experience the years with the most human-bear conflicts are the years when natural food supplies for bears are most limited.

A poor berry crop this year will result in some bears going into their dens under their ideal weight. For females who have been bred this summer who are underweight this may mean that they will come out of the den next spring without cubs. Bears have developed an evolutionary survival strategy called “delayed implantation.” What this means is that while breeding season is May through July, the fertilized egg is not implanted until the female goes into the den in October or November. If a bred female goes into the den in poor physical condition the fertilized egg(s) will not be implanted, but will instead by sloughed off, and she will come out of the den the following spring without cubs.

Polar bears will likely suffer the same fate as receding sea ice due to global warming inhibits their ability to hunt seals. This is their primary food source and will result in decreased denning wieghts.

Interestingly I’m taking a class at the Whale Museum in Friday Harbor to meet the continuing education requirements for my teaching certificate. Last week we had a guest speaker, Dr Joe Gaydos, a veterinarian who works for SeaDoc Society, come share information with us about Mustelids. (Mustilids are the largest family of carnivores and include river otter, sea otter, mink and about 60 other species.) I was fascinated to learn that many (maybe all) Mustelids also have delayed implantation. In the case of mink, fertilized eggs are not typically implanted until 30 days after breeding, and gestation is 27-33 days. Delayed implantation obviously has survival advantages or it would not have evolved, and I find it fascinating, amazing really.

Nan Laney, GBOP field coordinator

You make the call- Grizzly? or Black Bear?

Posted: by dryan

Each year a fair number of people report seeing a grizzly bear in the North Cascades. Some even take photos. Field biologists from the various agencies and non-profits examine these photos to try and determine if indeed they are grizzly bears or just large brown black bears.

You be the referree. These photos were all recently submitted with sighting reports.





So, what features make a big brown bear a grizzly? Black bears and grizzlies overlap in both size and color.

Grizzlies have a large, defined shoulder hump. A big block head with small looking ears. Large claws, very large indeed. A face profile that is dished.

Black bears have a small or no defined hump. Large ears compared to their head size. A long snout that has a face profile that is straight. Claws that are rather small.

Most folks do not want to go up to the bear and examine it’s claws. However a good track will tell you if the bear was a black bear or a grizzly.

Learn more at the GBOP website about identifying bears.

If you see a grizz, call 1.800.WOLFBEAR or report the sighting at the GBOP website.

Alas, none of these photos can be classified as a grizzly. Therefore, they are most likely large brown black bears.

Dogs and People working Together to Save Bears

Posted: by wgardner


The Wind River Bear Institute (WRBI), together with its Partners-In-Life Program®, is an innovative program that is saving the lives of bears by changing the way they are managed and viewed by wildlife agencies and the public. The goal of this program is to reduce conflicts between humans and bears so the two can coexist in an ever shrinking world.

The WRBI uses knowledge of bear ecology and behavior to find solutions to human-bear conflicts and develop ways to prevent problems in the future. Most conflicts arise from bears getting human foods as well as pet food, livestock feed, bird seed and fruits from orchards. Bears that are habituated to people or are food conditioned are bears that have in most cases lost their fear of people; most attacks on humans have involved bears that were habituated or food conditioned.

Many people feel that “problem” bears should either be relocated or destroyed, but neither of these is a long term solution and both can be expensive and time consuming. Many “problem” bears that have been relocated return to where they were causing problems and end up being killed because the true problem, habituation and/or food conditioning, is not resolved.

Carrie Hunt, Director of the Wind River Bear Institute, developed and implemented what she calls Bear Shepherding®. This bear management technique uses Karelian Bear Dogs to teach bears how to recognize and avoid human boundaries.

Karelian Bear Dogs (KBD) originated in Finland where they were used mainly for hunting. They are extremely intelligent, fearless and have enormous energy making them a perfect match for the Partner’s In Life Program and for bear shepherding. KBD’s are a medium sized black and white dog that is very strong and muscular. They range in weight from 40-70 pounds and are 19-24 inches tall.

“The key components of the WRBI’s “Partners In Life Program” are that it emphasizes concurrent work on-site to teach people correct behaviors to reduce conflicts when living or recreating in bear country AND to rehabilitate and teach ”problem” bears correct behaviors on-site as well, through a non-lethal technique called Bear Shepherding®. This technique utilizes a strict protocol developed by WRBI to condition bears in the wild to modify undesirable behaviors that will lead to the eventual need to euthanize the bear, and as such, is the first of its kind. Bear Shepherding utilizes operant conditioning techniques where the bear learns to associate a human voice yelling “Get Out of Here Bear” with a painful or scary aversive stimulus causing it to leave or fade into cover as a wild bear should…. which teaches bears with problem behaviors to recognize and avoid human boundaries and developed sites. The Shepherding techniques teach the bears to control what happens by making correct choices. For example, when the KBDs “shepherd” a bear into appropriate cover or the bear otherwise leaves an area where it should not be, the Partners-In-Life team removes the “pressure” on the bear by recalling the KBDs. Bears may experience this training at the site of conflict or within areas they naturally inhabit, called their “home range.” This positive approach builds on the way bears operate and learn in the wild and uses their natural recognition of personal space and dominance hierarchies.

Since the Program began in 1996, several hundred bears and other wildlife conflicts have been handled annually by the Programs teams and extended Program “Family” of KBD/Handler teams. There have been no injuries to dogs, bears or handlers; a true testament to the commitment and training of both the WRBI teams and the dogs they work with.

The WRBI placed 2 of their KBD pups for use as Wildlife Service Dogs in Washington State. All dogs and owners are cared for, trained and handled, according to strict WRBI Program protocols to ensure safety and effectiveness for the Service Dog/Handler teams. The two Karelian Bear Dogs working in Washington State are both with Washington Department of Fish and Wildlife employees. “Mishka” works with Bruce Richards, Wildlife Law Enforcement Officer, and “Cash” works with Rich Beausoleil, Cougar and Bear Specialist.


Wind River Bear Institute is a 501(c) (3) non-profit corporation that relies on the generous support of private donors who believe in the value of their work.

Posted by Wendy Gardner; GBOP Bear Specialist, Woodland Park Zoo keeper