CARNIVORES: Polar Bears
The polar bear (Fig. 1) is
the largest member of the family Ursidae. Males are
approximately twice the size of females. On average,
adult males weigh 500 to 900 pounds (250 to 400 kg),
depending on the time of year. An exceptionally large
individual might reach 1,320 to 1,760 pounds (600 to 800
kg). Adult females weigh 330 to 550 pounds (150 to 250
kg) on average, although a pregnant female just prior to
going into a maternity den could be double that weight.
Polar bears have a heavy
build overall, large feet, and a longer neck relative to
their body size than other species of bears. The fur is
white, but the shade may vary among white, yellow, grey,
or almost brown, depending on the time of year or light
conditions. The pelage consists of a thick underfur
about 2 inches (5 cm) in length and guard hairs about 6
inches (15 cm) long. Polar bears have a plantigrade gait
and five toes on each paw with short, sharp,
nonretractable claws. Females normally have four
functional mammae. The vitamin A content of the liver
ranges between 15,000 and 30,000 units per gram and is
toxic to humans if consumed in any quantity.
Polar bears are
distributed throughout the circumpolar Arctic. In North
America, their range extends from the Canadian Arctic
Islands and the permanent multiyear pack ice of the
Arctic Ocean to the Labrador coast and southern James
Bay. The southern limit of their distribution in open
ocean areas such as the Bering Sea or Davis Strait
varies depending on how far south seasonal pack ice
moves during the winter (Fig. 2).
From freezeup in the fall,
through the winter, and until breakup in the spring,
polar bears are dispersed over the annual ice along the
mainland coast of continental North America, the
inter-island channels, and the shore lead and polynia
systems associated with them. Polar bears are not
abundant in areas of extensive multiyear ice, probably
because of the low density of seals there.
Polar bears use a variety
of habitats when hunting seals, including stable
fast-ice with deep snowdrifts along pressure ridges that
are suitable for seal birth lairs and breathing holes,
the floe edge where leads are greater than 1 mile wide
(1.6 km), and areas of moving ice with seven-eighths or
more of ice cover. Bears may be near the coast or far
offshore, depending on the distribution of these
habitats. Ringed seals (Phoca hispida) and sometimes
bearded seals (Erignathus barbatus) maintain their
breathing holes from freezeup in the fall to breakup in
the spring. Bears can hunt more successfully in areas
where wind, water current, or tidal action cause the ice
to continually crack and subsequently refreeze.
During winter, bears are
less abundant in deep bays or fiords in which expanses
of flat annual ice have consolidated through the winter.
In places where the snow cover in the fiords is deep,
large numbers of ringed seals give birth to their pups
in subnivean lairs in the spring. Consequently, polar
bears in general, but especially females with newborn
cubs, move into such areas in April and May to hunt seal
During summer, the
response of the bears to the annual ice melts varies
depending on where they live. Bears in the Beaufort and
Chukchi seas may move hundreds of miles to stay with the
ice. Bears in the Canadian arctic archipelago make
seasonal movements of varying distances depending on ice
conditions. Polar bears travel seasonally to remain
where ice is present because they depend on the sea ice
for most of their hunting.
In Hudson Bay, James Bay,
parts of Foxe Basin, and the southeastern coast of
Baffin Island, the ice melts completely in the summer
and there are no alternate areas with ice close enough
to migrate to. In these areas the bears may be forced
ashore as early as the end of July to fast on land until
November. Some bears remain along the coast while others
move inland to rest in pits in snow banks or in earth
dens in areas of discontinuous permafrost. By late
September or early October, bears that spent the summer
on land tend to move toward the coast in anticipation of
freezeup. Many conflicts with people occur in the fall
when bears are waiting along coastal areas for the sea
ice to form.
Polar bears feed on ringed
seals and to a lesser degree on bearded seals. About
half of the ringed seals killed during the spring and
early summer are the young of the year. These young
seals are up to 50% fat by weight and are probably easy
to catch because they are vulnerable and inexperienced.
Less frequently taken prey include walrus (Odobenus
rosmarus), white whales (Delphinapterus leucas),
narwhals (Monodon monoceros), and harp seals (Pagophilus
groenlandicus). Polar bears also eat small mammals, bird
eggs, sea weed, grass, and other vegetation, although
these food sources are much less common and probably not
Polar bears are curious
animals and will investigate human settlements and
garbage. They have been observed to ingest a wide range
of indigestible and hazardous materials, such as plastic
bags, styrofoam, car batteries, ethylene glycol, and
General Biology, Reproduction, and Behavior
Polar bears mate on the
sea ice in April and May. Implantation of the embryo is
delayed until the following September. The adult sex
ratio is even, but because females normally keep their
young for about 2 1/2 years, they usually mate only once
every 3 years. This creates a functional sex ratio of
three or more males per female that results in intensive
competition among males for access to estrus females.
Maternity dens are usually
dug in deep snow banks on steep slopes or stream banks
near the sea by late October or early November,
depending on the availability of snow. In the Beaufort
Sea, a large proportion of the females den on the
multiyear pack ice several hundred miles (km) offshore.
On the Ontario and Manitoba coasts of Hudson Bay, female
polar bears may have their maternity dens 30 to 60 miles
(50 to 100 km) or more inland, though this is quite
unusual elsewhere in polar bear range.
Pregnant females normally
have 2 young between about late November and early
January. At birth, cubs weigh about 1.3 pounds (0.6 kg),
have a covering of fine hair, and are blind. They are
nursed inside the den until sometime between the end of
February and the middle of April, depending on latitude.
When the female opens her den, the cubs weigh 22 to 26
pounds (10 to 12 kg). The family remains near the den,
sleeping in it at night or during inclement weather for
up to another 2 weeks while the cubs exercise and
acclimatize to the cold, after which they move to the
sea ice to hunt seals.
The mean age of adults in
a population is 9 to 10 years and average life
expectancy is about 15 to 18 years. Maximum recorded age
of a male in the wild is 29 years. Few male polar bears
live past 20 years because of the intense competition
and aggression among them. The oldest age recorded for a
wild female polar bear is 32 years.
Depending on the age and
sex class, polar bears spend 19% to 25% of their total
time hunting in the spring and 30% to 50% of their time
hunting in the summer. Polar bears capture seals mainly
by stalking them, by waiting for them to surface at a
breathing hole or, in the spring, by digging out seal
pups and sometimes adults from birth lairs beneath the
snow. When a polar bear kills a seal it immediately eats
as much as it can and then leaves. Polar bears do not
cache food and normally only remain with a kill for a
short time. In the case of a large food supply such as a
dead whale or a garbage dump, individual bears may
remain in an area for several days or even weeks.
Polar bears sleep about 7
to 8 hours a day. They tend to be more active at “night”
during the 24-hour daylight that prevails in the summer
months, and to sleep during the day. Within 1 or 2 hours
after feeding, they will usually sleep, regardless of
the time of day. Before sleeping, females with cubs
often move away from areas where other bears are active,
probably to reduce the risk of predation on the cubs by
and Damage Identification
Threat or damage from a
polar bear differs from that of other bears because it
can occur at any time of the year. Conflicts are
commonly referred to as “threat to life or property” (TLP)
or “defense of life or property” (DLP). Although polar
bears are the most predatory of the three North American
bears, their threat to human life has been low.
Historically, northern people (Inu, Inuit, Inuvialuit,
and Inupiat) were aware of the threat posed by polar
bears. Legends and artwork portray conflicts between
northern people and polar bears. In recent times, polar
bears have injured or killed people living and working
in the Arctic. Fleck and Herrero (1988) provide a
detailed discussion of polar bear-people conflicts in
the Northwest Territories and other areas. The
Bear-People Conflict Proceedings (Bromley 1989) includes
several papers on handling and preventing encounters
Damage to property can be
serious in the remote and sometimes harsh arctic
environment, where food and shelter may be essential to
survival. Most property damage occurs at small
semipermanent hunting camps, industrial camps, and in
communities. Damage includes destruction of buildings
and their contents, predation of tied dogs, destruction
of snowmobile seats and other plastic or rubber products
or equipment, and raiding of food caches.
Polar bears are protected
in Canada and the United States. In Canada, polar bears
are legally hunted. Seasons, protected categories, and
quotas apply. In Alaska, polar bear hunting is not
legal, but native people may kill animals for
subsistence. In Russia and Svalbard, polar bears are
completely protected. In Greenland, polar bears are
legally harvested by Inuk hunters. Females with cubs in
dens are protected.
Deterring polar bears in
Alaska is restricted to wildlife officers because polar
bears are protected by the Marine Mammal Protection Act.
This policy is being questioned because it does not
allow companies or private individuals to deter a bear
in a problem situation. It is, however, legal for anyone
to shoot a bear in defense of life. In Canada it is
legal for anyone to attempt to deter, and if necessary
destroy, a bear in defense of life or property. Any bear
killed in either jurisdiction must be reported to the
nearest wildlife office.
Damage Prevention and Control Methods
conflicts has been given considerable attention in the
Canadian and Alaskan Arctic since the mid-1970s.
Reducing the number of polar bear-people conflicts has
increased the safety of people living and working in the
Arctic and reduced the number of polar bears killed in
problem situations. An active public information and
education program will help inform people how to prevent
bear problems. Most wildlife agencies in bear country
have a variety of public education materials available
that are specifically designed to help people prevent
bear problems and better handle any that may occur.
Special information and training workshops have been
developed by the Department of Renewable Resources,
Northwest Territories, and adopted by wildlife agencies
and industry in other jurisdictions. The workshops
instruct people on how to prevent bear conflicts. Two
publications to assist workshop instructors are
available (Clarkson and Sutterlin 1983, and Clarkson
1986a). The Safety in Bear Country Manual (Bromley 1985,
Graf et al. 1992) has been used as a reference text for
Many bear problems occur
at industry camps and work sites. When designing and
setting up camps, the number of conflicts can be reduced
by considering the potential bear problems. Keeping a
clean camp and reducing the number of attractants will
reduce bear problems. Once a bear has received a food or
garbage reward from a camp, it will quickly associate
the camp with available food. Most bears that are
habituated to human food or garbage are destroyed in a
problem bear situation. To reduce the number of problems
and problem bear deaths, careful planning and
precautions should be taken.
A “Problem Bear Site
Operations Plan” was developed to help industrial
operations better plan and prevent bear problems
(Clarkson et al. 1986b). The plan helps camp safety
officers, team leaders, and managers locate and design
facilities and programs that are site specific. It
contains information and emergency contact telephone
numbers, site design, personnel responsibilities, and
techniques to detect and deter bears. The plan can be
included in the Safety in Bear Country Manual as an
additional chapter. Problem Bear Site Operation Plans
have been developed for polar bear concerns at the
arctic weather stations and for oil exploration
activities in the Beaufort Sea. Each plan deals with
being prepared for and preventing polar bear problems at
Avoiding and responding to
close encounters with polar bears is addressed by
Bromley (1985), Fleck and Herrero (1988), Stirling
(1988a), and Graf et al. (1992). While each polar bear
encounter is different, the chance of a serious or fatal
bear problem can be reduced by keeping alert and being
informed and prepared to deal with any bear problems
that may arise.
Heavy woven-wire fences
are effective in keeping bears out of an area. Fences
must be constructed of sturdy materials and properly
maintained to prevent bears from entering the exclosure.
The fence should be a minimum of 6 feet (2 m) high, and
the bottom should be secured to the ground or a cement
foundation to prevent bears from lifting the fence and
crawling under the wire. Keep fence gates closed when
not in use to prevent bears from entering the area.
Electric fences have been
tested on polar bears with limited success; grounding
problems during winter months have been the primary
obstacle. Davis and Rockwell (1986) describe an electric
fence they used to protect a camp during the summer
months along the Hudson Bay coast.
The use of high metal
platforms, such as oil rig caissons, or offshore
drilling ships, prevents bears from getting access to
work and living areas. Sturdy metal buildings and iron
bar cages have been successfully used to store food and
equipment, and prevent polar bear access.
Regular snow removal from
work and living areas in polar bear habitat will help
make these sites safer by reducing potential hiding
spots and increasing visibility for personnel. Install
lighting around the work site to increase visibility and
staff safety. Proper design and set-up of work and
living sites will help reduce potential problems.
Regular camp maintenance and proper handling and storage
of food, wastes, and oil products will help reduce bear
Deterrents and Frightening
Nonlethal deterrents are
used on polar bears in an attempt to scare them away
rather than destroy them. Deterrents range from
snowmobiles and vehicles to 12-gauge plastic slugs and
cracker shells. Choosing an appropriate deterrent will
depend on the type of problem and specific location
(Table 1). Regardless of the type of deterrent used, all
encounters with bears should be supported by an
additional person equipped with a loaded firearm.
Graf et al. (1992)
reviewed several deterrents that are useful for polar
bears. Clarkson (1989) recommends the use of a 12-gauge
shotgun and a “three-slug system” (cracker shell,
plastic slug, and lead slug). Deter bears from a site as
soon as they are seen in the area, to prevent them from
approaching closer and receiving some type of food or
garbage reward. Figure 3 identifies the appropriate
distances for deterring versus destroying a bear. Each
bear deterrent situation is different, and depends on
the bear’s behavior and safety options available at the
site. When deterring a bear with a plastic slug, aim for
the large muscle mass area in the hind quarters (Fig.
4). The neck and front shoulders should be avoided to
minimize the risk of hitting and damaging an eye.
Detecting a polar bear
that is approaching a work or living area is an
important part of handling bear problems. Bear detection
systems range from a simple tripwire to more technical
electronic monitoring devices (Table 2). If a bear is
approaching a work or living area, the personnel on site
should have time first to ensure their safety and second
to prepare to deter the bear. Detection systems must be
properly installed and maintained to be effective. If
bear problems are rare, a system that is too technical
or difficult to maintain will soon be neglected. Bear
monitors and dogs should have previous experience with
bears. An experienced bear dog can act both as a
detection and deterrent system.
Capsaicin (oleoresin of
capsicum or concentrated red pepper) spray has been
tested and used on black and grizzly bears (Hunt 1984),
but has not yet been tested on polar bears. It may
become more popular where restrictions on firearms are
in place. Capsaicin needs to be scientifically tested
before it can be formally recommended for polar bear
No toxicants are
registered for use on polar bears.
No fumigants are
registered for use on polar bears.
Live traps used to capture
polar bears include culvert or barrel traps and foot
snares. Both have been used to capture all three bear
species in North America. The culvert trap has been used
to capture polar bears at Churchill, Manitoba, and in
the eastern Northwest Territories. It can also be used
for short-term holding and transporting of captured
polar bears. Foot snares were used in polar bear
research in the early 1970s and are useful in some
situations today. A detailed description of using the
culvert trap and foot snare is found in the Black Bears
chapter in this handbook. In the early to mid-1900s,
large leghold traps were used along the Arctic coast.
These are no longer used today.
bear-people conflicts require that problem bears be
shot. Polar bears can be aggressive in attempting to
obtain food, especially if they are in poor condition
and near starving. If it is necessary to destroy a polar
bear, it should be done as efficiently and humanely as
possible. The 12-gauge pump action shotgun with lead
slugs is an effective weapon for destroying a bear at
close range (less than 100 feet [30 m]). It can also be
used to deter a polar bear. High-powered rifles of
.30-06 or larger caliber are also effective in
destroying bears. A rifle used for bear protection
should be equipped with open sights for close-range use.
Generally, if a bear is
beyond 150 feet (45 m), destroying it is not necessary
because the bear can be deterred before it comes closer.
If it is necessary to destroy a bear beyond 100 feet (30
m), a high-powered rifle will be more accurate and have
more penetration energy. Whether a shotgun or rifle is
used, bears should be shot in the chest/vital organ area
(Fig. 4). Handguns are not recommended for bear
protection or for destroying problem bears. Proper
training and practice is necessary to effectively use a
firearm for bear protection or for destroying a bear.
Polar bears are often immobilized in problem situations.
Bears can be drugged while free ranging by darting them
from the ground or from a helicopter, or darting after
capture in a culvert trap or foot snare. Darts can be
fired from a rifle or pistol. A jab stick can be used to
immobilize bears captured in a culvert trap, but is not
recommended for bears in a foot snare.
Darting from a helicopter
(Bell 206 Jet Ranger or similar size), has been used for
research and problem bear management. The helicopter
should be equipped with a shooting window and have sling
capabilities for moving bears. The helicopter should
slowly approach the bear from behind at an altitude of
20 to 30 feet (6 to 10 m). Shooting distance from a
helicopter is usually less than 30 feet (10 m). Bears
should be darted in the large muscle areas of the neck,
shoulder, or upper midback. Several immobilizing drugs
have been used on polar bears in the past, however,
Telazol is presently considered the most effective.
Telazol is a safe and predictable drug to work with
because there is a wide range of tolerance to high
dosages, the reactions of darted bears can be easily
interpreted, and the bears are able to thermoregulate
while immobilized. Dosages of 8 to 9 mg/kg or greater
are usually necessary to fully immobilize a polar bear
for measuring and tagging. Immobilization time for adult
bears depends on the injection site and weight of the
bear. On the average, a bear will be immobilized in 4 to
5 minutes after the first injection of Telazol. Cubs of
the year can be immobilized by hand or with a jabstick
after being captured on or near their immobilized
Transporting, and Relocating. Problem polar
bears that are captured or immobilized and not destroyed
are usually held in a culvert trap or other suitable
facility. Bears can be transported from a problem site
with a culvert trap and released at another location if
a road system exists. Road systems are limited in the
arctic and relocating problem bears with culvert traps
is usually not an effective option. In most cases,
captured and immobilized bears need to be relocated by
helicopter. Take precautions to ensure that bears are
not injured or suffering from hyperthermia when
transporting them in a cargo net below a helicopter.
In Churchill, Manitoba,
polar bears are captured in or near the town limits,
held in a polar bear holding facility and then flown out
to an area north of Churchill and released. Capturing
and holding the bears in the “polar bear jail” prevents
these bears from causing problems while they are waiting
for the ice to form on Hudson Bay. Bears kept in a
holding facility can be given water, but food is not
recommended because the bears may begin to associate
people and the holding facility with food. Although an
expensive program, the polar bear jail at Churchill has
reduced the number of polar bear problems and polar bear
Relocating problem bears
usually does not solve the problem since they often
return, sometimes from considerable distances. Polar
bears that are waiting along a coastline for ice to form
should be moved in the general direction they would
normally travel. Most of the polar bears released north
of Churchill travel out on the sea ice and do not return
to the townsite.
Economics of Damage and Control
No specific studies or
reports have documented the economic costs of polar bear
damage in the Arctic. Past polar bear problems have
ranged in cost from nothing to several thousands of
dollars. With the remote locations of camps and
communities and the expense of transporting food and
products in the Arctic, replacement costs are high. Lost
work time of personnel and programs can also be
substantial because of polar bear problems. In September
1983, Esso Resources Canada had to suspend drilling
until a wildlife officer could drug and remove a bear
that had happened onto the artificial island, costing
Esso about $125,000. A similar incident occurred in
1985, and cost Esso approximately $250,000 in lost work
Hiring bear monitors can
cost up to $250 per day to protect personnel, a camp, or
an industrial site from polar bears. The cost of
government staff and programs that are responsible for
handling polar bear problems will depend on the number
of problems. Churchill, Manitoba, has the most intensive
government program to handle polar bear problems. This
program costs the Manitoba government approximately
$120,000 per year (M. Shoesmith, pers. commun.).
Purchasing detection and
deterrent equipment and educating people on the proper
procedures to prevent and handle bear problems will cost
companies and agencies. These costs, however, are
minimal when compared to personnel safety, replacement
costs of property in the Arctic, and long-term polar
bear conservation concerns.
We gratefully acknowledge
the following for their continued support of our
research on bears in general, and polar bears in
particular: the Northwest Territories Department of
Renewable Resources, the Canadian Wildlife Service,
Polar Continental Shelf Project, Manitoba Department of
Natural Resources, World Wildlife Fund (Canada),
Northern Oil and Gas Assessment Program, and the Natural
Sciences and Engineering Research Council of Canada. All
people, organizations, government departments, and
industry previously involved in the Northwest
Territories’ “Safety in Bear Country Program” are
thanked for their past concern and support.
L. Graf and K. Embelton
assisted in word-processing and editing.
Tables 1 and 2 were
adapted from Graf et al. (1992).
Figure 1 drawn by Clint
Chapman, University of Nebraska.
Figure 2 was adapted from
Sterling (1988) by Dave Thornhill, University of
Figures 3 and 4 are from
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PREVENTION AND CONTROL OF
WILDLIFE DAMAGE — 1994
Division Institute of Agriculture and Natural Resources
University of Nebraska -Lincoln
United States Department
of Agriculture Animal and Plant Health Inspection
Service Animal Damage Control
Great Plains Agricultural
Council Wildlife Committee