Potential Effects of Climate-change on Polar Bear Populations in the Circumpolar Arctic

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Potential Effects of Climate-change on Polar Bear
Populations in the Circumpolar Arctic
Ursus maritimus
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Description

• 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

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Description

• 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

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Distribution

• 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

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Distribution
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Diet

• 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

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Diet

• 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

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Diet

• 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

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Diet

• 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

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Hunting

• Bears capture seals by still hunting, stalking on
  land, aquatic stalking, and by stalking birth
  lairs.
• The type of hunting depends on the season.

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Hunting

• 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

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Hunting

• 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

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Hunting

• 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

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Hunting

• 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

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Eating 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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Reproduction

• 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

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Reproduction

• 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

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Reproduction

• 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

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Denning

• 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

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Social 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

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Population 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

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Population 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

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Population 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

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Population 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

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Population Dynamics

• Greenland
• Natives may hunt polar bears but arent allowed
  to sell any parts
• About 100 bears are harvested annually

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Population 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

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Population 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

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Mortality

• 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

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Economic 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

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Habitat

• Pack ice
• Hunting platform and protective cover
• Open water
• Presence of seals
• Land
• For denning, cover, and supplemental food

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• How is the climate change effecting
  Polar Bears?

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Changes in Climate

• The earths climate is predicted to change
• Human activities are altering the chemical
  composition of the atmosphere
• Buildup of greenhouse gasses

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Changes 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

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Changes 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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Warming 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

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Whats 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

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Effects 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

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Effects 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

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Polar 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

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Climatic 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

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How 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

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Western 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

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Decline 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

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Decline 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

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Hudson Bay

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Climatic 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

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Climatic 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

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Climatic 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

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Increased 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

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Increased 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.

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Human-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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Human 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)

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Human 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

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Nuisance 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

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Conservation 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

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Conservation

• 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

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Management Strategies

• Research is needed
• Current distribution
• Habitat requirements
• Food habits
• Patterns of land use
• Reproductive behavior
• Ability to sustain a certain rate of mortality

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Some 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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