Lecture 13 Polar Bears (last unit)

Question 1

Polar Bear Overview (3)

Answer 1

Marine mammals

Live, travel, mate, and feed on sea ice

Sea ice phenology influences access to prey, timing of migration, access to mates

Question 2

Polar Bear adaptation to ice (4)

Answer 2

Fur

Paws

Head Shape

Dietary Efficacy

Question 3

Polar Bear Diet (2)

Answer 3

Varies by region
Includes:
* ringed seal
* bearded seal
* harp seal
* harbour seal
* hooded seal
* Walrus
* Beluga
* Bowhead whale
* narwhal

TLDR: mostly seals and other marine mammals

Question 4

Reproduction (6)

Answer 4

1. Mating season during the hyperphagic period (spring) - male compete
2. implantation of egg inter uterus wall may be delayed until conditions improve (reliant on body condition)
3. head into the dens (fall)
4. cubs are born in den ~1.7lbs (winter)
5. Nursing cubs (rest of winter - spring)
6. leave the den (early spring)

Question 5

movement (3)

Answer 5

• Bears are constantly on the move
• Search for high concentrations of sea ice
  *swimming costs lots of energy = better to walk

Question 6

Migration (4)

Answer 6

Associated with season change
* Polar bears migrate as sea ice melts in spring
* Timing changes as length of sea ice season changes
*Tortuosity = path curviness
* Date on Land = end of migration

Question 7

Ice and Migration (4)

Answer 7

*High variability increases tortuosity → decreases efficiency of directional movement
* High variability represents ice that persists longest
* Bears come to land later to utilize ice for hunting
* Cost of swimming as ice retreats

Question 8

Ice free season (4)

Answer 8

Bears are forced onto land
No access to primary food sources = Fasting period
1980’s = mid July - early November
now = Mid JUNE to late November

Question 9

Bears on land (4)

Answer 9

*Fasting
* Males and females separate
* Energy saving metabolism
* Lose ~1 kg per day

Question 10

alternative food (3)

Answer 10

• Lipivores – made to eat fat
• Beached whales provide valuable food, but typically rare
  *berries, eggs, birds, small mammals, etc.

Question 11

human bear conflict (2)

Answer 11

As arctic warms -> more human activity -> more human-bear conflict
* Less time on ice drives more conflict -> More scavenging
in/near human communities