Title: Potential Effects of Climate-change on Polar Bear Populations in the Circumpolar Arctic
1Potential Effects of Climate-change on Polar Bear
Populations in the Circumpolar Arctic
Ursus maritimus
2Description
- Heavy, stout bodies with muscular legs and necks
- Males
- 2.5 3 meters in length
- 775-1,500 pounds
- Females
- 2-2.5 meters in length
- 330-550 pounds
- Live to about 20 yrs.
- In London, one lived to 41
- Look white but fur is actually pigment-free
-
3Description
- Only the nose and footpads are without fur
- Feet are partially webbed
- Aids in swimming
- Can swim for over 60 miles and 6 miles/hour
without resting - Can run up to 25 miles/hour for short distances
- Have sharp claws for traction on slippery ice
- Blubber can measure 4.5 inches thick
4Distribution
- Circumpolar in distribution
- Always associated with sea ice
- In NA, polar bears range from Alaska on west
coast to Baffin Island, and Newfoundland and
Labrador on the East coast - Distributed throughout coastal habitat and on the
Arctic Sea
5Distribution
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7Diet
- Opportunistic feeders
- Almost exclusively carnivorous
- Ring seals are primary food source, prefer fat
- Spring- ½ of ring seals killed are newborn pups,
but weaned pups and post-parturient females are
also killed
8Diet
- Polar bears also kill beluga whales and walruses
- Polar bears will scavenge on seal, whale, and
walrus carcasses, but rarely on carcasses of
terrestrial animals - Occasionally birds, eggs, vegetation and small
mammals are eaten
9Diet
- Food Chain is simple
- Zooplankton feed on algae on bottom of ice
- Arctic cod feed on zooplankton
- Ringed seals feed on arctic cod
- Polar bears feed on ringed seals
- Small changes in food chain can have drastic
affects - Changes in environment
10Diet
- Can go long periods without feeding
- Males usually go about 3-4 months without eating
because of melting ice - Pregnant females go without food for 8 months
- Longest among mammals
11Hunting
- Bears capture seals by still hunting, stalking on
land, aquatic stalking, and by stalking birth
lairs. - The type of hunting depends on the season.
12Hunting
- Still Hunting
- Used year round
- Waits for the seals to surface through breathing
holes - It then bites onto the head or upper body and
flips it out of the water - This usually takes less than an hour
13Hunting
- Stalking on land
- Used in summer when seals are landed on ice
- Once a seal is spotted, a polar bear will slowly
sneak towards it - When it is within about 50 feet it charges the
seal and grabs it with its claws or teeth
14Hunting
- Aquatic stalking
- Used in summer when seals haul out on ice
- Polar bear swims toward a landed seal and it
grabs the seal when it reaches the ice edge
15Hunting
- Stalking birth lairs
- Used in spring when ringed seals give birth
- Birth lairs are caves built under snow drifts
next to a hole - Mother breaks through the roof and and grabs the
seal
16Eating habits
- Once a seal is captured, polar bears bite it
several times on the head and neck - The skin and fat are eaten first, followed by the
meat - Usually dont eat the entire kill
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18Reproduction
- Polygamous
- Breed from March May on sea ice
- Several males follow 1 female (farther than 62
mi) and may result in intense fights - Exhibit delayed implantation until September or
October when female enters den - Gestation 8 months
- 1-4 cubs, usually 2
19Reproduction
- 6 out of 10 cubs die in 1st year
- Starve, predation, accidents
- Drink mothers milk (richest of all carnivores)
- 20 months
- Weaned at about 2-3
- Depends on location
20Reproduction
- Sexual Maturity
- Females 4 years
- Males 6 years
- Cubs
- Cubs usually weigh between 0.5-1 kg
- Lactation lasts1.5-2.5 yrs
- Cubs remain with mothers for 2-3 yrs
21Denning
- Females seek out maternity dens in late August
but dont usually enter them until October - Usually are on south facing slopes
- Most are on land
- Dens are usually 2m (L) x 1.5m (W) x 1 m (H)
- Temp is usually 20 degrees F warmer inside the den
22Social Structure
- Adult bears remain solitary except in breeding
season - Parental care provided by female only
- Males will often prey upon cubs and females
- Females may move into habitats with less
resources to avoid cannibalism by males
23Population Dynamics
- Overall species is stable, but are vulnerable to
oil and gas exploration as well as human - encroachment
- As development continues in Arctic, the potential
for contamination of the bears food and chances
of oil spills increase greatly - At highest trophic level, more vulnerable to
accumulation of environmental toxins
24Population Dynamics
- Total population is about 22,000-27,000
- 5 nations with polar bear populations
- Canada has the most (15,000)
- Greenland
- Norway
- U.S
- Russia
- All are involved with the International Agreement
for the Conservation of Polar Bears
25Population Dynamics
- Canada Polar Bears
- 15,000
- Smaller in size, weigh less, and have fewer cubs
- Native hunting is allowed under the provision of
the International Agreement - Each community is given a quota
- About 500 bears are harvested each year
- Natives are allowed to sell hunting rights to
non-natives
26Population Dynamics
- Norway
- Completely protected since 1973
- Svalbard islands
- Population has rebounded from about 1000 up to
2000 - PCB levels are the main concern here
- Levels are about 2 ½ to 17 times higher than in
NA
27Population Dynamics
- Greenland
- Natives may hunt polar bears but arent allowed
to sell any parts - About 100 bears are harvested annually
28Population Dynamics
- Russia
- Russian natives recently allowed to hunt them
- Russian economy has collapsed due to loss of law
and order - Poaching has become a major problem
- High levels of pollutants
29Population Dynamics
- U.S.(Alaska)
- Hunting by natives is allowed for subsistence
- 100 harvested annually
- Restrictions
- Carcasses must be used
- Not allowed to sell the skins
- Although may make and sell products from them
30Mortality
- Man is only natural enemy
- Human presence in bear habitat leads to
human-bear conflicts and usually result in
killing of bear - Bears may also be killed for wandering into areas
of human development - Usually adult females trying to find food
for dependent young
31Economic Value
- Untanned pelts sell for 500-3000
- Depending on size and quality
- Annual economic value of the hunts and hides are
about 1 million in Canada - Bear meat
- Consumed by humans and used as dog food
- Bear liver Vitamin A
32Habitat
- Pack ice
- Hunting platform and protective cover
- Open water
- Presence of seals
- Land
- For denning, cover, and supplemental food
33- How is the climate change effecting
Polar Bears?
34Changes in Climate
- The earths climate is predicted to change
- Human activities are altering the chemical
composition of the atmosphere - Buildup of greenhouse gasses
35Changes in Climate
- Since beginning of
- industrial revolution
-
- Conc. of carbon dioxide has increased by 30
-
- Conc. of methane have more than doubled
-
- Conc. of nitrous oxide have increased by 15
-
36Changes in Climate
- Global temps are rising (land surface temp has
risen .45-.6 degrees Celsius) - Precipitation has increased by about 1 over
worlds continent in the last century - Sea level has risen 15-20 cm in the last century
-
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39Warming of Arctic climate
- The warming of the climate is due to increasing
conc. of greenhouse gasses in the atmosphere - A major concern is how this may effect ice on the
Arctic Ocean - More warming means less ice in the Arctic
40Whats causing it?
- Humans are causing concern for the polar bears
future - Altering the global climate
- Burning fossil fuels gasoline and coal
- Clearing large swaths of forest
- Releasing vast amounts of carbon dioxide
41Effects of Arctic Climate Change
- Scientists believe the extra carbon dioxide may
cause warmer temperatures - At North and South poles it could lengthen the
winters - Longer polar winters could help create a hole in
the Arctics ozone layer - Melting sea ice
- Keeps polar bears from main food source, ringed
seals - Ringed seals are becoming less accessible due to
shorter ice season
42Effects of Arctic Climate Change
- NASA study found that a 2.9 decline per decade
in total Arctic sea ice over last 20 yrs - New Canadian study further concludes the sea ice
season in western Hudson Bay has been reduced by
about 3 weeks in same time period - As a result of declining sea ice the polar bears
have less time to hunt and are returning to land
in poor conditions - Male and female weight is declining and females
are having fewer cubs - Hasnt been a population decline yet, but could
in the future
43Polar bears and Sea Ice
- Sea ice is essential to polar bears
- In order to hunt seals, the polar bears have to
walk across the ice - Also used for travel route to seek mates during
breeding season - Maternity denning
- Dispersal routes
44Climatic effects on Polar bears as well as seals
- Less sea ice means less food for polar bears
- Less food means lower reproductive rates
- Seals are also being effected
- Seals depend on ice to give birth and nurse their
pups -
-
45How are seals and bears effected?
- Polar bears having lower reproductive rates, this
will cause a decrease in the population
eventually - Seals will also experience a decline in
population due to loss of the platform to nurse
their pups and give birth
46Western Hudson Bay Polar Bears
- Here polar bears already spend 4 months of the
year fasting and rely on fat reserves during the
ice free period - This is the population that scientists believe
will be effected first - Avg weights of females are lower than they were
in the 1980s
47Decline in body conditionof Hudson Bay Bears
- If ice break-up began to occur 2 or 3 wks
earlier - Adult females may not be able to store enough
fat to produce cubs - Females may not be able to nurse cubs through the
ice free period - Decline in body condition of females would cause
an eventual decline in population because
mortality would out weigh cub production -
48Decline in body condition of Hudson Bay Bears
- Example
- Avg weights of female Polar Bears were a lot
lower in the later 1980s than they were in the
early 1980s - Lower cub survival and reproduction rates were
noted
49Hudson Bay
50Climatic Effects on Denning
- Fall-
- Multiyear pack ice moves south
- Open water between polar pack and the coast
freezes - Allows pregnant bears to reach the coast for
maternity denning
51Climatic Effects on Denning
- If polar pack is reduced
- and freezing of open
- water is delayed
- Females cant reach coast to den
- Will den on the multiyear ice
- Ex southern Beaufort Sea popln
-
52Climatic Effects on Denning
- Increased probability
- Of precip. with warming
- arctic
- If Rain
- Dens may collapse before female and cubs have
emerged - (ex) Beufort sea coast, 2 cubs and mother were
crushed to death from den collapsing on them
53Increased Precipitation effecting ring seal
birth lairs
- Seals give birth in March-
- April
- If precipitation was snow, it would benefit seal
pup survival before being weaned - It precipitation was rain, it would collapse
birth lairs causing predation of pups by polar
bears and arctic fox -
54Increased Precipitation effecting ringed seal
birth lairs
- Increased predation of seal pups by polar bears
and arctic foxes caused by increased rainfall
could lower the seal popln enough to cause a
decline in polar bear poplns.
55Human-Bear Interactions due to climate change
- Bears are coming to
- shore thinner, and later
- freeze-up is causing them to
- stay around longer
- This causes them to be nutritionally stressed and
wander into Churchill in search of food - Bears are often found scavenging in Churchills
dump
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57Human Bear Interactions due to climate change
- If ice free time gets
- longer, bears will become
- more nutritionally stressed
- and will have to get food
- wherever they can
- (This could increase probability of humans being
preyed upon)
58Human Bear interactions
- Polar Bear Alert Program
- Instigated at Churchill
- Ensure safety to people and protection of
property from bears - Ensure safety of bears and avoid harassment and
killing of bears -
59Nuisance Bears
- Nuisance Bears or bears
- entering the dump in
- Churchill
- Captured and held in a holding facility
- When ice freezes, the bears are released
- Some problem bears are airlifted to wilderness
25 mi north of Churchill right away instead of
being held
60Conservation Steps
- 1.) First International Scientific Meeting on the
Polar Bear, 1965 - Meeting set stage for international agreement on
polar bear conservation - 2.)The International Agreement on Conservation of
Polar Bears and Their habitat, 1973 - 5 nations (Canada, Greenland, Norway, U.S., and
Russia) agreed to protect polar bear habitat,
such as dennning, feeding areas, and migratory
routes ban hunting of bears from aircrafts and
boats conduct research and management and
exchange these results
61Conservation
- 3.)United States Marine Mammal Protection Act,
1972 - Polar bears are protected in U.S.(Alaska)
- Hunted only by Alaskan natives
- 4.) Convention on Intl Trade in Endangered
Species of Wild Fauna and Flora - In 1975, the polar bear was placed on Appendix II
(CITES), identified as threatened, or likely to
become endangered if trade isnt regulated. Intl
trade is permitted with proper documentation
issued by the govt of the exporting country - 5.)Intl Union for the Conservation of Nature and
Natural Resources/World Conservation Union - A worldwide conservation group consisted of
govt, non-govt , and independents
62Management Strategies
- Research is needed
- Current distribution
- Habitat requirements
- Food habits
- Patterns of land use
- Reproductive behavior
- Ability to sustain a certain rate of mortality
63Some solutions to the effects of the changing
climate on the bears
- Slow the buildup of
- greenhouse gases
- Use solar energy
-
- Reduce burning of fossil fuels
-
- Use wind power
-
- Plant trees
-
-
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