Polar Bears

From Student M:

What is the average difference in weight between male and female polar bears?

Male polar bears average about 1100 pounds and females average quite a bit less at about 525 pounds. I’ll let you do the math!

What are the behavioral differences between polar bears in captivity, and those in the wild?

Because of the warmer conditions of most places where polar bears live in captivity, they do a lot more swimming in captivity to help stay cool. While they generally can’t hunt in captivity, their keepers provide them with various forms of enrichment that entice the bears to use behaviors that they would use while hunting. For instance, rather than just giving the bear a snack like a fish or lump of lard, the keepers may hide the snack so the bear must use its sense of smell to locate it or they might put it into a container of some sort that the bear needs to tear into like it would a seal carcass to get at the snack. Mating behaviors are fairly similar to those in the wild. Like wild females, Alaska, one of our female bears, dens up every fall and early winter after mating in spring. Unfortunately, she has never successfully produced cubs. Our male, Magnet, and two females, Alaska and Anoki, see a lot more of each other than males and females would in the wild. Adult polar bears are generally solitary. Of course, should one of our females have cubs, Magnet would be separated from them because male polar bears do nothing to help raise the cubs and will actually kill and eat any cubs that he happens upon. Fortunately, even though they are much smaller, female polar bears with cubs are very aggressive and can typically drive off threatening males.

What are some of the main causes of them going extinct?

Hopefully, polar bears will not go extinct. Right now, the International Union for the Conservation of Nature (IUCN) lists the polar bear as “Vulnerable”, which basically means there are concerns that, because of environmental conditions, polar bear populations could drop to dangerously low levels. However, they have not reached levels that would cause scientists to consider them as actually “Endangered” (populations low enough that they may become extinct) or worst of all “Critically Endangered” (real close to becoming extinct). The main cause for concern regarding polar bear populations is a situation, that you may have heard of, called “climate change”. In response to chemicals like carbon dioxide and methane that are released into the atmosphere by humans through the burning of petroleum, coal, trees and other industrial products. The theory is that these “greenhouse gases” let sunlight through but trap heat that is radiated from the earth’s surface — slowly making the earth warmer. Of course, for an animal that depends on sea ice (see below) for its survival, this is not a good situation. Less ice means less area for hunting. Also, in areas where young bears and denning females, come onto land (see below) in the summer, like Churchill, Manitoba, there is concern that bears may starve to death if the Hudson Bay ice pack starts freezing later in the fall and winter.

What parts of the world are most inhabited by polar bears?

Polar bears are uniquely adapted to the northern polar regions of the earth. Their large size (up to 1300 pounds), thick, hollow fur, 4.5 inch thick winter layer of blubber and relatively short extremities (tail, legs and ears) help polar bears remain active through some of the harshest winter conditions on earth. Known as the ice bear or sea bear, polar bears roam the arctic ice cap in search of ringed seals and other pinnepeds(seals and walruses). They are truly marine mammals because the arctic ice cap floats above the Arctic Ocean and, generally, most adult males and some females spend all of their time on the ice flows. With webbed front feet, they are also good swimmers, but, generally only do this to get from one flow to another and not to hunt. They often capture seals and, sometimes, small beluga whales at pull out and air holes. They also break into the nursery dens of seals under the ice to feed on the young seals. During summer, some young bears and denning females come to land in certain places, like Churchill, Manitoba where the ice seasonally recedes, food availability on the ice floes becomes limited and good denning sites abound. These bears essentially do not eat for the entire summer -living off the fat they accumulated during the winter hunting season. Polar bears are active all year long with the exception of denning females who give birth in their dens in the late fall – just as the ice begins to return and food supplies increase. Polar bears are not found with penguins at the south pole. They are purely a northern animal and penguins are purely found south of the equator. Polar bears are found all across the polar regions in Alaska, Canada, Greenland, Scandinavia and Russia.

What is the average amount of offspring the bears have annually?

Female polar bears usually give birth to two young. However, sometimes they only have one and, rarely, they have three. The young will stay with the female for up to three years although two years is more usual.

From Student NH:

What would you say are the five (or main) essentials that a polar bear must have in order to survive?

Food water shelter and space are essential for all species. Their main food (1) is ringed seals which they can’t out swim in the water so they need the ice pack(2) in order to catch the seals while they are resting on the ice or immerging from the water. Polar bears (or brown bears for that matter)are not capable of catching fish in open water (brown bears catch fish when they migrate up and are clumped together in streams)so although they will eat fish given the opportunity, they typically cannot catch them. The seal blubber is the preferred part of the seal. It is an important food source because it can be metabolized into blubber on the bear. The blubber (3) is extremely important for a polar bear. Blubber is b.e.s.t.! It provides buoyancy (b), energy (e), streamlining (s) and most importantly thermo-regulation (t). Although polar bears have hollow hairs to increase the insulative properties of their fur, it is really the 4-5 inches of blubber that protects polar bears from the extremely cold conditions that they face. Adequate denning sites (4)are also a necessity so female polar bears (polar bears do not technically hibernate and males are active all year) can give birth. These can be on the icepack or on land. The last I would say is space (5). Humans and large predators typically do not get along well so if the human populations in the arctic were to grow, conflicts between polar bears and humans may increase. Churchill Manitoba residents have learned to deal with the bears in such a way to limit these conflicts and frankly it takes a certain type of person to deal with the extreme climate and isolation of the Arctic region, which works in the bear’s favor. However, money talks and opening up north slope oilfields could draw more people into the northern regions of North America and increase bear/human conflicts.

What impact does global warming/climate change have on polar bears specifically?

The main impact would be on the polar bear food supply. Less ice surface equals less hunting habitat and possibly less breeding areas for the seals that they hunt. As it is, in some areas, many young bears come off the ice in summer and basically don’t eat until the ice reforms in late October/ November. They exist in a state of walking hibernation where their metabolism is lowered to save energy. They survive on the fat reserves that they accumulate from feeding on seals in the winter. One of the main concerns is that if the ice forms later in the fall than it does now, many of these landed bears might starve before they make it back out onto the ice to hunt.

Is the predicament of polar bears and climate change one that can be fixed? (If so, please elaborate.)

There are two ways to look at it. We can keep on keeping on and just assume that the folks that say this situation is just a natural climactic swing in temperatures and things will fix themselves over time are correct (which they may be). Or we can conserve energy as much as we can to lessen the amount of petroleum-based products that are burned — releasing carbon-dioxide, methane and other greenhouse gases into the atmosphere. Simple things like turning lights off, walking or riding bikes to nearby places rather than always getting a ride, taking public transportation, purchasing energy efficient appliances and automobiles, recycling and reusing materials all help to lower the amount of greenhouse gases that we release. Also, reducing the rate that forests, which are natural buffers against a buildup of carbon dioxide, are cut down would go a long way towards reducing the effects of our emissions. Which is the most responsible choice? I would definitely say the energy conservation route is the way to go regardless of what the cause of climate change is. Whether these actions can ultimately ward off the effects of climate change, I can’t say for sure, but they are a step in the right direction any way you look at it.

Would it be plausible to relocate polar bears if their habitat deteriorated to a point where they could no longer survive?

No — no habitat equals no survival for the species in the wild. They can’t just be plopped down anywhere and be expected to survive. They are adapted to certain conditions and would be outcompeted by other animals that are adapted to the existing conditions. In captivity, some could live on but the capacity of Zoos to care for large numbers of the bears is very limited.

What is the best way for the public to become aware of the polar bear’s plight?

Fortunately, I think that the plight of the polar bear gets a lot of press. Polar bears are beautiful animals that people relate to easily. What we in the business call charismatic megafauna. They are much easier to sell than many other species, like say an endangered species of tiger beetle, which may come across as less endearing but might be even more in danger of extinction. The American public is easily impacted by what they see in the media. There was a polar bear segment on the Olympic broadcast the other night! Millions of people likely tuned into that. However, the focus of the American media frequently shifts and while polar bears are a hot topic now, they may be yesterday’s news in a year or so. That is why it is important for facilities like the Maryland Zoo in Baltimore and Polar Bears International to continue to inform the public about what they can do to help insure that there will be polar bears for future generations to appreciate. Zoos are especially important because people form stronger emotional bonds with an animal they see in person as opposed to those they see in pictures. It makes it real to them. Once they make this personal connection, it is much easier to get people to care about the survival of their wild counterparts.

Who/what would be impacted if polar bears began to be significantly impacted by climate change?

Polar bears perform special services within their environment. Certainly seal populations would be impacted by the loss of an important predator. Predators can be very important because they keep prey populations in check- preventing them from overpopulating and possibly over harvesting their prey species. Predators also play a role in preventing the spread of disease by culling out sick and weak individuals. The scraps from polar bear kills are an important winter food source for arctic foxes and several species of bird scavengers. Since the disappearance of the polar bears impacts these species, the changes in their populations will also affect other species that the seals, fish, foxes and scavenging birds interact with. The loss of one species sends ripples throughout an ecosystem’s energy cycle. Losing the polar bear would also serve as a warning just like a canary in a mine (canary’s were used to tell miners if the oxygen levels in the cave were to suddenly drop because such drops would kill the canary first). If we can negatively impact a species all the way in the Arctic by chemicals that we release in more heavily inhabited areas of the world, how long will it be before we begin to negatively impact our ability to survive the conditions we are creating.

Have you had the opportunity of firsthand experience with polar bears? If so, what has it been and how was the experience?

Not in the wild. I am an educator who has taught students many lessons based on our polar bears here at the Zoo. A few years back, we had a distance learning program where students could sit in out tundra buggy (a vehicle used in the arctic for people to watch and study polar bears), which is set in between our two polar bear yards, and talk to experts sitting in a working Tundra buggy outside Churchill Manitoba. They could see wild bears on the actual tundra while watching our bears in the exhibits below. That was pretty cool. The other day we were shoveling out the polar bear exhibit and one of our bear Anoki came over to watch through the glass. It is pretty wild when you know a polar bear is actually watching and is interested in what you are doing!

Would you say that the polar bear is more endangered than other arctic animals and why?

Technically, the polar bear is classified by the International Union for Conservation of Nature and Natural Resources (IUCN) as vulnerable which means that there is concern, because of possible changes to its environment, that it may soon reach the endangered level and possibly could eventually become extinct within the short-term. The polar bear’s livelihood depends on the ice pack more than the more terrestrial arctic animals so they stand to be more immediately affected by the climate change itself. Prior to this crisis and although there was some concern of noxious chemicals from pollution in the industrialized regions of the world building up in the fat tissue of some arctic species, the Arctic, because it is so lightly populated by humans has largely avoided the environmental problems found in more populated parts of the world. Therefore, most species have fairly stable populations. However, if the average temperatures of the Arctic rise ,there will likely be changes in the length of growing seasons and other climactic factors that may allow more southern species to move into and compete directly with arctic animals and plants. These changes would likely lead to changes in the population numbers of Arctic species in general and possibly to some extinctions as well.

Do you have any inspirational words of wisdom to say to teens who want to help with saving the polar bears?

Education is the key to any problem. I think if most people understand the problem and know what they can do to fix it (especially when it saves them money in the long run!), they will do it. Let them know that it helps their pocket book to do the right thing! The more voices out there letting people know what is happening, the more people will begin to understand and start to do something. However, there is a fine line between educating and brow-beating. People need to want to learn. Make it fun for people to learn about the subject. Don’t force it on them or they will not want to listen.

From Student A:

What polar bear conservation research or field work is the zoo doing?

Our three bears participated in a study on the role of pedal scent secretions in bear communication. Analysis of the behaviors observed during this study may help determine if secretions left in bear footprints help males to locate females in the Arctic. Our females also participated in a study on fecal hormonal levels and its relationship to determining pregnancy in Polar Bears. This study has many positive implications for reproduction and management of polar bears in zoos and is significant to polar bear conservation in the Arctic.

Is the zoo funding polar bear conservation research or field work? And if so, roughly how much is being spent on polar bear research or field conservation?

While not directly writing checks to Polar Bear conservation organizations, our contribution of staff time and expertise in the studies described above and the program mentioned below is just as valuable. It is difficult to place a monetary value on these contributions.

What partnerships does the zoo have, if any, with other organizations (such as Polar Bear International)?

We have close ties with Polar Bears International. Our partnership is summarized on our website in the Education section. Kathy Foat, the Vice President of Education here at the Zoo is on the advisory board of PBI and annually attends meetings with this group. She has been very active in the educational aspects of the organization and was instrumental in the creation of a PBI polar bear curriculum which is available on PBI’s website. Through this position, she also regularly meets with the foremost experts on wild polar bears and bears in captivity.

How does this research and field work positively impact wild polar bear populations?

Because wild polar bears spend a great deal of their lives on the relatively inaccessible polar ice cap, there is still a lot to learn about polar bear behavior in the wild. Any information that our staff can obtain by observing our bears here at the zoo under controlled conditions may be valuable in helping scientists to better understand the natural habits of polar bears in the wild. Also, the information brought back from the Polar Bear Camps and meetings, attended by our volunteers and staff, provides us with valuable information that we can use to spread the word about polar bear natural history and conservation. By backing up the information that we give out about polar bears to the general public with solid content gleaned from the many experts in the field that we have contact with through our involvement with PBI, other bear researchers and zoo personnel, we have a greater impact on the public’s understanding of the concerns that scientists have concerning climate change’s effect on polar bear populations. Awareness of a situation is a very important aspect in finding the solution.

Obviously, PBI’s website is a great source of information. You may want to also look at the American Association of Zoos and Aquarium’s Bear Taxon Advisory Group website. There are some contacts that might be helpful listed on the site.