(DRAFT) - Taxonomy
Species bear, polar
Species Id M050060
Date 26 AUG 96
TAXONOMY
NAME - bear, polar
OTHER COMMON NAMES -
ELEMENT CODE -
CATEGORY - Mammals
PHYLUM AND SUBPHYLUM - ,
CLASS AND SUBCLASS - ,
ORDER AND SUBORDER - ,
FAMILY AND SUBFAMILY - ,
GENUS AND SUBGENUS - Ursus,
SPECIES AND SSP - maritimus,
SCIENTIFIC NAME - Ursus maritimus
AUTHORITY - Phipps
TAXONOMY REFERENCES - 232
Taxonomy - 1 (DRAFT) - Status
Species bear, polar
Species Id M050060
Date 26 AUG 96
STATUS
Coded Status
Subsistence
See Comments
REFERENCES FOR STATUS - 232
COMMENTS ON STATUS -
Federal: Polar bears are federally protected under the Marine Mammal
Portection Act of 1972 (MMPA PL 92-552). The USFWS administers polar bears
for the federal government *232*.
State: The State of Alaska may petition the federal government for renewed
managerial authority over 10 species of marine mammals, including polar bear
*232*.
The MMPA effected a moratorium on the taking of marine mammals by anyone
other than Alaska Natives, who can take them for subsistence without
restriction, provided waste does not occur *232*.
Status - 1 (DRAFT) - Distribution
Species bear, polar
Species Id M050060
Date 26 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
HABITAT - TERRESTRIAL
MARINE
REFERENCES FOR HABITAT - 232
LAND USE -
Snow or Ice: All Classes
Water
REFERENCES FOR LAND USE - 232
COMMENTS ON HABITAT ASSOCIATIONS -
In Alaska, polar bears are associated with shore-fast and drifting pack ice.
Polar bears are associated wtih sea ice; their aquatic habitat requirements
are those that allow the formation of sea ice and abundant and accessible
populations of seals, their primary food. Alaskan polar bears spend little
time on land except for maternal denning and occasional feeding, especially
on beached carrion. During years of heavy ice and late breakup, they may
summer on land more by accidnet than by design *232*.
In general, polar bears spend most of their time on sea ice in which their
main food, seals, is both abundant and accessible. Depending on the time of
year, that may be the flaw zone, the shore-fast ice, or the edge of the
summer pack *232*.
Polar bears feed primarily in the flaw zone but also hunt and/or scavenge on
the shore-fast ice, in land, on the drifting pack ice, and, occasionally,
in open water *232*.
ANIMAL/PLANT SPECIES ASSOCIATIONS -
Walrus
Trichinella spiralis
REFERENCES FOR SPECIES ASSOCIATIONS - 232
COMMENTS ON SPECIES ASSOCIATIONS -
Although polar bears are known to kill walruses, usually only the young are
taken; polar bears killed by (pesumably large) walruses have been reported.
Both adult males and adult females have been observed eating cubs, but this
is not common and is unlikely to be a major source of mortality.
Intraspecific aggression is not likely to be a significant mortality factor
in itself, although it may keep some animals, particularly subadults, out
of prime feeding areas. The parasite most commonly found in Alaskan polar
bears is Trichinella spiralis, probably from ingestion of infected seals,
walruses, or other bears *232*.
Habitat Associations - 1 (DRAFT) - Food Habits
Species bear, polar
Species Id M050060
Date 26 AUG 96
FOOD HABITS
TROPHIC LEVEL -
CARNIVORE
REFERENCES FOR TROPHIC LEVEL - 232
LIFESTAGE FOOD FOOD PART
General Mammalia Not Specified
General Carrion Not Specified
General Phocidae Not Specified
General Monodontidae Not Specified
General Mammalia Not Specified
General Aves Not Specified
General Aves Egg/Fetus stage
General Plants Not Specified
Adult Ursidae Juvenile stage
General See Comments; Food See Comments
Adult See Comments; Food See Comments
Juvenile Mother's milk Not Applicable
Juvenile See Comments; Food See Comments
REFERENCES FOR GENERAL FOOD - 232
REFERENCES FOR ADULT FOOD - 232
REFERENCES FOR JUVENILE FOOD - 232
COMMENTS ON FOOD -
Polar bears in Alaska feed primarily on ringed seals (Phoca hispida) and, to
a lesser extent, on bearded seals (Erignathus barbatus). Belukha whales
(Delphinapterus leucas) and walruses (Odobenus rosmarus) are occasionally
taken. Carrion, including whale, seal, and walrus carcasses, is scavenged
frequently, especially along the coasts of St. Lawrence Island and the
northern Bering Sea. In other areas, polar bears are known to occasionally
eat small mammals, birds, eggs, and vegetation when on land, especially in
postdenning and summer periods; however, the small amount of time that
Alaska polar bears spend on land makes these sources of food relatively
unimportant *232*.
Types of Feeding Areas Used: Polar bears feed primarily in the flaw zone
but also hunt and/or scavenge on the shore-fast ice, on land, on the driftin
pack ice, and, occasionally, in open water. A study noted:
shore lead polynya systems also appear to support higher densities of
seals and polar bears during the winter than do the adjacent fast ice
areas. Whenever the leads freeze over, the seals simply maintain
breathing holes in the young ice until the lead opens up again.
Consquently, it is easier for seals to breathe there while feeding than
to maintain their own breathing holes in areas which are continuously
frozen, or to compete for access at breathing holes being maintained by
other seals. The moving ice appears to be the habitat of bearded seals
and an area where subadult and possibly non-breeding ringed seals
Food Habits - 1 (DRAFT) - Food Habits
Species bear, polar
Species Id M050060
Date 26 AUG 96
concentrate as well. Polar bears appear to be more abundant in these
areas in which the ice continuously opens and re-freezes, partly because
the seals are more abundant there and possibly also because the breathing
holes are not covered deeply with drifted snow so that the seals are more
vulnerable to predation.
A study analyzed 627 sightings of polar bears or their tracks in the spring
of 1970-1979 in the western Canadian Arctic; 82% of all sightings were from
floe edges and areas with 88% or greater coverage of moving ice. Adult males
preferred moving ice; subadult males'preference was less pronounced but
still significant; slightly more sightings occurred at floe edges. Adult
females with cubs of the year preferred fast ice, as did subadult females,
but to a slightly lessr extent. Observations of lone adult females and
females with older cubs showed no significant difference in choice of ice
habitat, but females with yearlings were found more often in areas with 88%
or greater coverage of moving ice. and females with two-year-olds were found
more often at floe edges. Most bears hunt in the drifting pack ice and the
flaw zone rather than on fast ice; however, in order to avoid adult male
bears (which occasionally kill cubs) females with very young cubs hunt on
fast ice, primarily by opening ringed seal birth lairs. On shore-fast ice,
polar bears hunted and slept almost exclusively in rough ice and used flat
ice significantly less often than its availability in the area would
indicate. Although polar bears are slower and less agile in open water than
are seals, bears have been documented catching ringed seals in ice-free
water. Land is a relatively unimportant feeding area for Alaskan bears,
except for scavenging carrion *232*.
Factors Limiting Availability of Food: The main factor limiting
availability of food to polar bears are the distribtuion of seals and ice
conditions favorable to seal hunting. Intraspecific agonistic interactions
over food, especially large adult males chasing off other bears, may also
limit the availability of food for some individuals, especially for
subadults. In young bears, age (experience) affects hunting success. One-
and two-year-old bears were found to not hunt in spring. In summer, the
percentage of time spent hunting and the duration of still hunts were equal
for both one- and two-year-olds but were shorter than for adult summer
hunts. Although total time spent hunting was equal for one- and
two-year-olds, two-year-olds spent twice as much of that time still-hunting,
and their kill rates approached those of adults. Although polar bears are
known to kill walruses, usually only the young are taken; polar bears killed
by (presumably large) walruses have been reported *232*.
Feeding Behavior: Hunting behavior falls into two categories, still-hunting
and stalking, with several variations on each. When still-hunting, a bear
lies, sits, or stands by a pool or breathing hole waiting for a seal to come
to the surface. Stalking hunts of basking seals were made either by
creeping up behind irregularities on the ice surface or by slipping into the
water and swimming cautiously to the seal. Still-hunts were far more common
than were stalking hunts and were far more successful. Winter and spring
hunting on the fast ice appears to require a higher level of proficiency
than hunting in the summer. In fast ice. the subnivian birth lairs and
breathing holes of seal must be located accurately by smell from a distance
and the arrival of a seal at its hole beneath the snow must be detected.
Then, with a rush, the top of the lair must be broken over the breathing
Food Habits - 2 (DRAFT) - Food Habits
Species bear, polar
Species Id M050060
Date 26 AUG 96
hole and the seal caught. Most bears begin feeding on the seal immediately
after capture, usually eating just the skin and blubber. The remains were
scavenged by arctic foxes, other bears, or, occasionally, birds. During and
after a feeding period, bears usually washed and licked themselves, spending
up to 15 minutes on a final washing. In spring and summer, the maximum
numbers of seals are hauled out on the surface of the ice in the afternoon
and the minimum in the early morning. Hunting success is far higher for
still-hunting at breathing holes than for stalking basking seals, so most
bears hunt in the early morning (0100-0800) and sleep in the afternoon
*232*.
Caloric Requirements: From tracking and observing marked bears, a study
estimated that, on the average, each adult bear would need to kill one
average-sized ringed seal every 6.5 days. Based on a model using average
sizes of ringed seals and polar bears, observed caloric requirements of
captive polar bears, and caloric values of whole ringed seals, another study
calculated that a 27.8 kg ringed seal would supply the energy requirements
of a 229 kg polar bear for 6.4 days *232*.
COMMENTS ON ADULT FOOD -
In order to avoid adult male bears (which occasionally kill cubs) females
with very young cubs hunt on fast ice, primarily by opening ringed seal
birth lairs *232*.
COMMENTS ON JUVENILE FOOD -
Intraspecific agonistic interactions over food, especially large adult males
chasing off other bears, may also limit the availability of food for some
individuals, especially for subadults. In young bears, age (experience)
affects hunting success. One- and two-year-old bears were found to not hunt
in spring. In summer, the percentage of time spent hunting and the duration
of still hunts were equal for both one- and two-year-olds but were shorter
than for adult summer hunts. Although total time spent hunting was equal for
one- and two-year-olds, two-year-olds spent twice as much of that time
still-hunting, and their kill rates approached those of adults *232*.
Lactation Period: Polar bear cubs nurse for at least one year and usually 2
to 2-1/2 years *232*.
Food Habits - 3 (DRAFT) - Environment Associations
Species bear, polar
Species Id M050060
Date 26 AUG 96
ENVIRONMENTAL ASSOCIATIONS
G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
BA Slope: Specified in Comments
RA Slope: Specified in Comments
BA Coastal Features: Specified in Comments
RA Coastal Features: Specified in Comments
FA Aquatic Habitat Zonation: Open water [pelagic zone]
FA Aquatic Habitat Zonation: Specified in Comments
G Slope: Specified in Comments
G Coastal Features: Specified in Comments
G Aquatic Habitat Zonation: Specified in Comments
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 232
REFERENCES FOR FEEDING ADULT ENVIRONMENTAL ASSOC_ - 232
REFERENCES FOR RESTING ADULT ENVIRONMENTAL ASSOC_ - 232
REFERENCES FOR BREEDING ADULT ENVIRONMENTAL ASSOC_ - 232
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
Aquatic: Polar bears are associated with sea ice; their aquatic habitat
requirements are those that allow the formation of sea ice and abundant and
accessible populations of seals, their primary food *232*.
Terrestrial: Although in other areas (Hudson Bay, e.g.) polar bears
regularly summer on land, Alaska polar bears spend little time on land
except for maternal denning and occasional feeding, especially on beached
carrion. During years of heavy ice and late breakup, they may summer on
land more by accident than by design *232*.
Summer use and dens: During periods in summer when the drifting pack ice
is within a few miles of the coast, bears easily swim ashore to scavenge
carrion along the shore. They probably do not make the summer dens found in
other areas, such as Hudson Bay, although they may make temporary earth or
snow shelters for thermoregulation or protection from insects *232*.
Winter dens: In Canada, the USSR, Norway, and Greenland, males and females
of all ages have been found in winter dens. In the Beaufort Sea, only
pregnant females have been found to stay in winter dens (maternity dens)
for extended periods, although probably any bear may excavate a temporary
Environment Associations - 1 (DRAFT) - Environment Associations
Species bear, polar
Species Id M050060
Date 26 AUG 96
shelter during particularly bad storms *232*.
Maternity dens: In Alaska, maternity dens have been found on the mainland
(up to 48 km from the coast), offshore islands, shore-fast ice, and
drifting pack ice. Often, dens are on slopes of 20 to 40 degrees or on
coastal bluffs or river banks. Ice movement and time of freeze-up are
affected by weather and wind patterns and probably determine the
distribution of females that come to the coast in search of den sites. The
coast of Alaska is not one of the "core," or particularly high-density,
denning areas such as Wrangel Island or Svalbard. Prior to 1983, despite
major search efforts from 1967 through 1976, substantial human activity in
potential denning areas in recent years, and an estimate of at least 150
female Alaskan bears that should be denning each year, fewer than 50 dens
had ever been reported on land in Alaska. Conditions leading to maternity
denning on pack ice are unknown, but in 1984 12 of 14 dens found by
following radio-tagged females were on drifting pack ice. The relative
frequency of denning on pack ice and on land is currently being
investigated. The main habitat requirement for a maternal den site,
whether on land or sea ice, is snow deep enough for den excavation and
protected enough not to thaw during the denning period. Another factor
that may be important, especially in Alaska, is the occurence of seals
nearby and ice conditons that enable bears to catch seals during pre- and
postdenning periods. On land in Alask, such denning habitat requirements
are met by any area within 30 to 40 mi of the coast with enough relief for
snow to drift and stay in sufficient depth for den excavation from October
or November until April *232*.
Ice: In general, polar bears spend most of their time on sea ice in which
their main food, seals, is both abundant and accessible. Depending on the
time of year, that may be the flaw zone, the shore-fast ice, or the edge of
the summer pace *232*.
COMMENTS ON RESTING ADULT ENVIRONMENTAL ASSOC_ -
Summer use and dens: During periods in summer when the drifting pack ice
is within a few miles of the coast, bears easily swim ashore to scavenge
carrion along the shore. They probably do not make the summer dens found in
other areas, such as Hudson Bay, although they may make temporary earth or
snow shelters for thermoregulation or protection from insects *232*.
Winter dens: In Canada, the USSR, Norway, and Greenland, males and females
of all ages have been found in winter dens. In the Beaufort Sea, only
pregnant females have been found to stay in winter dens (maternity dens)
for extended periods, although probably any bear may excavate a temporary
shelter during particularly bad storms *232*.
Maternity dens: In Alaska, maternity dens have been found on the mainland
(up to 48 km from the coast), offshore islands, shore-fast ice, and
drifting pack ice. Often, dens are on slopes of 20 to 40 degrees or on
coastal bluffs or river banks. Ice movement and time of freeze-up are
affected by weather and wind patterns and probably determine the
distribution of females that come to the coast in search of den sites. The
coast of Alaska is not one of the "core," or particularly high-density,
denning areas such as Wrangel Island or Svalbard. Prior to 1983, despite
Environment Associations - 2 (DRAFT) - Environment Associations
Species bear, polar
Species Id M050060
Date 26 AUG 96
major search efforts from 1967 through 1976, substantial human activity in
potential denning areas in recent years, and an estimate of at least 150
female Alaskan bears that should be denning each year, fewer than 50 dens
had ever been reported on land in Alaska. Conditions leading to maternity
denning on pack ice are unknown, but in 1984 12 of 14 dens found by
following radio-tagged females were on drifting pack ice. The relative
frequency of denning on pack ice and on land is currently being
investigated. The main habitat requirement for a maternal den site,
whether on land or sea ice, is snow deep enough for den excavation and
protected enough not to thaw during the denning period. Another factor
that may be important, especially in Alaska, is the occurence of seals
nearby and ice conditons that enable bears to catch seals during pre- and
postdenning periods. On land in Alask, such denning habitat requirements
are met by any area within 30 to 40 mi of the coast with enough relief for
snow to drift and stay in sufficient depth for den excavation from October
or November until April *232*.
COMMENTS ON FEEDING ADULT ENVIRONTAL ASSOC_ -
Types of Feeding Areas Used: Polar bears feed primarily in the flaw zone
but also hunt and/or scavenge on the shore-fast ice, on land, on the driftin
pack ice, and, occasionally, in open water. A study noted:
shore lead polynya systems also appear to support higher densities of
seals and polar bears during the winter than do the adjacent fast ice
areas. Whenever the leads freeze over, the seals simply maintain
breathing holes in the young ice until the lead opens up again.
Consquently, it is easier for seals to breathe there while feeding than
to maintain their own breathing holes in areas which are continuously
frozen, or to compete for access at breathing holes being maintained by
other seals. The moving ice appears to be the habitat of bearded seals
and an area where subadult and possibly non-breeding ringed seals
concentrate as well. Polar bears appear to be more abundant in these
areas in which the ice continuously opens and re-freezes, partly because
the seals are more abundant there and possibly also because the breathing
holes are not covered deeply with drifted snow so that the seals are more
vulnerable to predation.
A study analyzed 627 sightings of polar bears or their tracks in the spring
of 1970-1979 in the western Canadian Arctic; 82% of all sightings were from
floe edges and areas with 88% or greater coverage of moving ice. Adult males
preferred moving ice; subadult males'preference was less pronounced but
still significant; slightly more sightings occurred at floe edges. Adult
females with cubs of the year preferred fast ice, as did subadult females,
but to a slightly lessr extent. Observations of lone adult females and
females with older cubs showed no significant difference in choice of ice
habitat, but females with yearlings were found more often in areas with 88%
or greater coverage of moving ice. and females with two-year-olds were found
more often at floe edges. Most bears hunt in the drifting pack ice and the
flaw zone rather than on fast ice; however, in order to avoid adult male
bears (which occasionally kill cubs) females with very young cubs hunt on
fast ice, primarily by opening ringed seal birth lairs. On shore-fast ice,
polar bears hunted and slept almost exclusively in rough ice and used flat
ice significantly less often than its availability in the area would
indicate. Although polar bears are slower and less agile in open water than
are seals, bears have been documented catching ringed seals in ice-free
Environment Associations - 3 (DRAFT) - Environment Associations
Species bear, polar
Species Id M050060
Date 26 AUG 96
water. Land is a relatively unimportant feeding area for Alaskan bears,
except for scavenging carrion *232*.
COMMENTS ON BREEDING ADULT ENVIRONMENTAL ASSOC_ -
Maternity dens: In Alaska, maternity dens have been found on the mainland
(up to 48 km from the coast), offshore islands, shore-fast ice, and
drifting pack ice. Often, dens are on slopes of 20 to 40 degrees or on
coastal bluffs or river banks. Ice movement and time of freeze-up are
affected by weather and wind patterns and probably determine the
distribution of females that come to the coast in search of den sites. The
coast of Alaska is not one of the "core," or particularly high-density,
denning areas such as Wrangel Island or Svalbard. Prior to 1983, despite
major search efforts from 1967 through 1976, substantial human activity in
potential denning areas in recent years, and an estimate of at least 150
female Alaskan bears that should be denning each year, fewer than 50 dens
had ever been reported on land in Alaska. Conditions leading to maternity
denning on pack ice are unknown, but in 1984 12 of 14 dens found by
following radio-tagged females were on drifting pack ice. The relative
frequency of denning on pack ice and on land is currently being
investigated. The main habitat requirement for a maternal den site,
whether on land or sea ice, is snow deep enough for den excavation and
protected enough not to thaw during the denning period. Another factor
that may be important, especially in Alaska, is the occurence of seals
nearby and ice conditons that enable bears to catch seals during pre- and
postdenning periods. On land in Alaska, such denning habitat requirements
are met by any area within 30 to 40 mi of the coast with enough relief for
snow to drift and stay in sufficient depth for den excavation from October
or November until April *232*.
Environment Associations - 4 (DRAFT) - Life History
Species bear, polar
Species Id M050060
Date 26 AUG 96
LIFE HISTORY
Reproductive Habitat: Most mating occurs on the sea ice near open leads
where most bears (except females with cubs of the year) concentrate in
spring *232*.
Reproductive Seasonality: Male Alaskan polar bears show evidence of
spermatogenesis from February through April; pairs of an adult male and a
female in estrous have been seen in Alaska through May and, in Spitsbergen,
observed mating or attempted mating through late June. The earliest and
latest dates at which evidence of estrous has been observed in female polar
bears in Alaska are 21 March and 15 May; although estrous may have occurred
before or after these dates, opportunities to make observations were
limited. Mating in Alaskan polar bears therefore occurs mostly in March,
April, and May. Ovulation is probably induced, and implantion is delayed
until about September. In late October or November, pregnant females seek
out denning areas on land or on drifting sea ice, depending on ice movements
and the speed of the freeze-up. Cubs are born in December or January, and
the female and cubs break out of the dens in late March or early April. The
average time spent in the maternity den area after initial breakout was 14
days. The females ate little, the cubs nursed, acclimated to outside
temperatures, played, and developed their motor skills before moving out of
the den area and onto sea ice *232*.
Reproductive Behavior: Males locate females in estrous by following their
tracks. Males are promiscuous and may fight over females; no territories
are maintained. No information was found on how long pairs remain together
*232*.
Age at Sexual Maturity: The average age of first successful breeding for
female polar bears in the Alaska Beaufort Sea averages 5.4 years and ranges
from 3 to 7 years. Although mature sperm have been found in the reproductive
tracts of male bears from 3 to 19 years, ages of males captured with females
during the breeding season ranged from 3 to 11 years. Maximum breeding age
has not been determined, but maximum ages of reproductively active males and
females observed were 19 and 21 years, respectively *232*.
Frequency of Breeding: Females usually breed at about the time of
separation from young (about 28 months postpartum); therefore, litters are
generally produced about every three or four years *232*.
Fecundity: In the Alaskan Beaufort Sea, female polar bears usually give
birth to two cubs, less often one, and rarely three. Mean litter sizes of
cubs (observed sometime after leaving the den), yearlings, and two-year-olds
were 1.58, 1.65, and 1.47, respectively. Another study estimated average
number of cubs born per litter was between 1.70 and 1.98 *232*.
Gestation: In polar bears, implantation is delayed, so the time from
conception to parturition is relatively long, 195-265 days *232*.
Lactation Period: Polar bear cubs nurse for at least one year and usually 2
to 2-1/2 years *232*.
Life History - 1 (DRAFT) - Life History
Species bear, polar
Species Id M050060
Date 26 AUG 96
Natural Factors Influencing Populations: Natural mortality factors,
diseases, and parasites of polar bears are poorly known. Survival rates of
bears in Alaska cannot be accurately calculated from existing data, but the
overall compostiton of the population has been estimated at 32% young (0-2
years old), 43% older females, and 25% older males. In Ontario, a study
found the mortality rate of cubs from the time of den abandonment to their
first autumn to be 15%. Changes in the abundance of seals may affect the
distribution of polar bears as well as their reproductive and cub survival
rates. In the Canadian Beaufort Sea during the winters of 1973-1974 and
1974-1975, numbers of ringed and bearded seals dropped by about 50% and
their productivity by 90%. Numbers of adult polar bears declined markedly in
the area, and the large reduction of yearlings observed in 1974 and 1975
indicated a high level of cub mortality prior to one year of age. Both adult
males and adult females have been observed eating cubs, but this is not
common and is unlikely to be a major source of mortality. Adult males fight,
especially during the breeding season, as evidenced by tracks, wounds, and
scars. Adult females may also be scarred, but this is found less often. A
study noted that an adult male and female with a 2.5 year old cub fought and
wounded each other over a seal the female had killed. After several charges
and some fighting, all three bears fed on the carcass at once. Intraspecific
aggression is not likely to be a significant mortality factor in itself,
although it may keep some animals, particularly subadults, out of prime
feeding areas. The parasite most commonly found in Alaska polar bears is
Trichinella spiralis; 64% of 292 Alaskan bears examined had Trichinella
larvae, probably from ingestion of infected seals, walruses, or other bears
*232*.
Human-related Factors Influencing Populations: A summary of possible
impacts from human-related activities includes: attraction to artificial
food source; harassment, active; harassment, passive; interference with
reproductive behavior (disturbance of denning bears); mortality due to
ingestion of chemicals; mortality due to ingestion of petroleum or petroleum
products; and reduction of food supply *232*.
LIFE HISTORY CODES -
Breeding/Spawning Season: January
Breeding/Spawning Season: February
Breeding/Spawning Season: March
Breeding Spawning Season: April
Breeding/Spawning Season: May
Breeding/Spawning Season: June
Breeding/Spawning Season: December
Mating System (Single breeding season): Promiscuity (
Parental Care of Young: Female
Average Number of Offspring/Reproductive Effort: 1
Average Number of Offspring/Reproductive Effort: 2
Average Number of Offspring/Reproductive Effort: 3-4
Gestation/Incubation Period: 5-6 months
Gestation/Incubation Period: 7-8 months
Gestation/Incubation Period: Greater than 8 months
Foraging Strategy: Stalking
Life History - 2 (DRAFT) - Life History
Species bear, polar
Species Id M050060
Date 26 AUG 96
REFERENCES FOR LIFE HISTORY- 232
Life History - 3 (DRAFT) - Management Practices
Species bear, polar
Species Id M050060
Date 26 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Restricting/regulating human use of habitats
Beneficial Restricting/regulating human disturbance of populations
Beneficial Controlling pollution [thermal, chemical, physical]
Beneficial Regulating harvest of species being described
Beneficial Other management practices [specified in comments]
REFERENCES FOR BENEFICIAL MANAGEMENT PRACTICES - 232
COMMENTS ON MANAGEMENT PRACTICES -
POPULATION MANAGEMENT HISTORY
Summary of Harvest: Within the Arctic and Western regions, the harvest of
polar bears has ranged from 29 bears reported taken in 1979 to 405 bears
reported taken in 1966. These figures are minimum estimates of harvest,
especially after 1973, when implementation of the MMPA made reporting
harvest voluntary. Prior to the late 1940's, most polar bear hunting in
Alaska was by Eskimos for food and hides for sale. Based on fur export
records for 1925-1953, estimated annual harvest averaged 117 bears. Trophy
hunting with the aid of aircraft began in the late 1940's, and the annual
harvest increased to a high of 405 in 1966. State regulations became more
and more restrictive as the efficiency of guides and the number of hunters
increased; between 1960 and 1972, an average of 260 polar bears was taken
annually. Alaska banned polar bear hunting with aircraft in 1972. Proposed
regulations for hunting from the ground were never implemented because the
MMPA was passed *232*.
Period of State Authority: During the period of state management of polar
bears, 1960 through 1972, no accurate estimates of population size, rates of
reproduction, or natural mortality yet existed. Management was based on
harvests at what were judged to be moderate levels, protection of females
with young, collection of specimens and other data from hunters, who were
required to present hides and skulls to ADF&G representatives for sealing,
sightings from trophy-hunter guides, and data from mark-and-recapture
projects and other research carried out by the ADF&G beginning in 1966.
Shortly after passage of the MMPA, the state requested return of managerial
authority for certain species, including polar bears, as provided for in the
act. After a review period of six years, Alaska's request for return of
management was approved but with stipulations that were unacceptable to the
state *232*.
Period of federal authority: The federal government had manageial authority
of polar bears prior to 1960 and from 1972 to the present. The MMPA
effected a moratorium on the taking of marine mammals by anyone other than
Alaskan Natives, who can take them for subsistence without restriction,
provided waste does not occur. The act does not protect females with
young. Polar bears are currently administered by the USFWS for the federal
government, with no restrictions on take *232*.
Management Practices - 1 (DRAFT) - Management Practices
Species bear, polar
Species Id M050060
Date 26 AUG 96
1973 International Agreement on Conservation of Polar Bears: All nations
with polar bears under their jurisdiction (Canada, Greenland, Norway, the
United States, and the USSR) provided for international management of polar
bears in the 1973 International Agrement. It creates a de facto "high seas"
sanctuary for bears by not allowing them to be taken by aircraft, large
motorized boats, or in areas where they have not been taken by traditional
means in the past. It states that nations shall protect the ecosystems of
which polar bears are a part and that nations shall conduct national
research and exchange research results and harvest data. Annexes to the
agreement request an international hide-marking scheme to control illegal
traffic in hides, the protection of cubs and females with cubs, and the
prohibition of hunting in denning areas when bears are moving into the areas
or are in dens. The United States, by allowing Native Alaskans to take
females with young, is not in full compliance with the agreement *232*.
Convention on International Trade in Endangered Species of Wild Fauna and
Flora (CITES): More than 50 countries have signed CITES, which took effect
in July 1975. In each member nation, a permit is required to export certain
animals or parts thereof, including polar bears. Polar bears are listed in
Appendix II (potentially threatened with extinction) of CITES *232*.
CURRENT POPULATION MANAGEMENT
Mangement Objectives: One general goal of the MMPA is to maintain the
stocks of marine mammals at optimum sustainable population (OSP) levels.
Under existing regulations, OSP is defined as "... any population level
smaller than or equal to the largest average supportable level within the
ecosystem (carrying capacity) and larger than or equal to the population
level for a given species or stock that results in maximum net
productivity". A second general goal of the MMPA, as ammended in 1981, is
to provide for continued subsistence use. USFWS policies with respect to
polar bears are as follows: recognition of polar bears as a renewable
resource of considerable historic and current value to humans; maintainance
of an optimum sustainable polar bear population and the health and stability
of the marine ecosystem of which they are a part; management of polar bears
based on sound, objective biological data; encouragement of cooperative
management and survey and research programs at local, state, national, and
international levels; public participation in planning; subsistence use as
the priority consumptive use of polar bears; recognition of the rights and
interests of citizens to use and enjoy the resource; and support return of
management authority of polar bears to the State of Alaska. Specific goals
of the USFWS to implement the above policies are as follows: maintain the
Alaskan polar bear population within the OSP range and at a minimum of 5,700
animals; monitor the population health and status; regulate and monitor the
harvest; determine seasonal and annual distribution and movement patterns;
monitor coastal and offshore energy and mineral development that may affect
polar bears and provide recommendations to minimize impacts; delineate and
protect essential habitats such as significant denning and other
concentration areas; minimize impacts of oil pollution on polar bears and
their habitat; provide for regulated subsistence use of polar bears as the
first priority; provide for regulated incidental take; provide for taking of
polar bears for scientific and public display purposes; provide for a
regulated sports hunt if MMPA is changed; provide for nonconsumptive uses
Management Practices - 2 (DRAFT) - Management Practices
Species bear, polar
Species Id M050060
Date 26 AUG 96
where feasible; fully implement the International Agreement on the
Conservation of Polar Bears; and facilitate the return of marine mammal
managerial authority to the State of Alaska *232*.
Management Considerations: The MMPA was ammended in 1981 to provide for
continued subsistence use. As defined in the amendment, subsistence use is
"the customary and traditional use by rural Alaska residents of marine
mammals for direct personal or family consumption of food, shelter, fuel,
clothing, tools or transportation and for making and selling of handicraft
articles from non-edible by-products of marine mammals taken for personal or
family consumption". Although the harvest must be accomplished in a
nonwasteful manner, no restrictions are placed on the age or sex of animals
that may taken; percentages of females and animals of "unknown" sex in total
harvest numbers have increased since implementation of the MMPA in 1973.
The federal government cannot regulate subsistence take under the MMPA
unless a species is declared depleted; the state, however, if managerial
authority is transferred, may be able to regulate the harvest for
subsistence as well as for other purposes if the subsistence harvest is
considered a threat to the population *232*.
Management Practices - 3 (DRAFT) - References
Species bear, polar
Species Id M050060
Date 26 AUG 96
References
232 * State of Alaska Department of Fish, and Game. 1986. Alaska
Habitat Management Guide: Life Histories and Habitat
Requirements of Fish and Wildlife. (ed.). Alaska Department of
Fish and Game Juneau, Alaska:763.
References - 1