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

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

2. 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

3. 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

4. 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

5. Distribution

7. 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

8. 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

9. 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

10. 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

11. 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.

12. 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

13. 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

14. 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

15. 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

16. 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 don’t eat the entire kill

18. 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

19. Reproduction… • 6 out of 10 cubs die in 1st year • Starve, predation, accidents • Drink mother’s milk (richest of all carnivores) • 20 months • Weaned at about 2-3 • Depends on location

20. 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

21. Denning • Females seek out maternity dens in late August but don’t 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

22. 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

23. 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

24. 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

25. 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

26. 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

27. Population Dynamics… • Greenland • Natives may hunt polar bears but aren’t allowed to sell any parts • About 100 bears are harvested annually

28. 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

29. 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

30. 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

31. 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

32. Habitat • 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?

34. Changes in Climate • The earth’s climate is predicted to change • Human activities are altering the chemical composition of the atmosphere • Buildup of greenhouse gasses

35. 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%

36. Changes in Climate • Global temps are rising (land surface temp has risen .45-.6 degrees Celsius) • Precipitation has increased by about 1% over world’s continent in the last century • Sea level has risen 15-20 cm in the last century

39. 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

40. What’s causing it? • Humans are causing concern for the polar bear’s future • Altering the global climate • Burning fossil fuels; gasoline and coal • Clearing large swaths of forest • Releasing vast amounts of carbon dioxide

41. 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 Arctic’s 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

42. 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 • Hasn’t been a population decline yet, but could in the future

43. 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

44. 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

45. 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

46. 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 1980’s

47. 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

48. 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

49. Hudson Bay

50. 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