Tracking the Polar BearHow polar bears cope with theDr. Jon Aars, Norwegian Polar 

Tracking the Polar Bearp pcurrent climate changes

gInstitute

Jon Aars, Norwegian Polar Institute

Illustration: Rasmus Hansson

Polar bear

Black bear

Brown bear

Polar bears are carnivoresPolar bears are carnivores,

and specialists on hunting iceand specialists on hunting ice associated seals

Ringed sealPhoca hispida

Bearded sealErignath s barbat s Phoca hispidaErignathus barbatus

Bears do not only eat seals

climate

Sea ice

Ice associated seals Polar bears

Importance of sea ice:‐food‐mating‐travel between feeding, mating and denningareas

Most mating occurs on sea ice

72% in Svalbard72% in Svalbard,Derocher et al. 2010

Marking of polar bears in Svalbardg p

Platform for polar bearcapture‐recapture work

Gl i f t i t tGlacier fronts importanthabitat (hunting ringedseal pups in spring)

Getting data and samples

Blood cell countsAge determination

Studies of movement

Different space use strategies

Also large differencesin swimming behaviorin swimming behavior

% time in water

mon

th

Sea ice connects subpopulationsfrom different areasfrom different areas

GreenlandGreenland

L SLaptev Sea

N. Kara Sea

Barent Sea

Svalbard

Norway RussiaS. Kara Sea

Russia

Mauritzen et al. 2002

DDDD

All bears den on islands in theSvalbard areaSvalbard area

Late sea ice arrival at Hopen fewLate sea ice arrival at Hopen = few maternety dens

dens

30

40

1996

mat

erni

ty d

20

30

19951998

LATE SEA ICE = FEW DENS

umbe

r of m

101997 1999

2003

Oct 27

Nov 6Nov 1

6

Nov 26

Dec 6

Dec 16

Dec 26

Jan 5

Jan 15

Jan 25

Feb 4Feb 14

Nu

0

1997 1999

20002001

20082002

Date of arrival of 60% sea ice cover

N N D D

Derocher et al., in revision

Sea ice arrival at Hopen too late for adult females to get there and den in most recentyears

e

1 Feb

60%

sea

ice

1 Dec

1 Jan

Arr

ival

of6

1 Nov

1 Oct

1980 1985 1990 1995 2000 2005 2010

Year

60% sea ice days 1oct‐31dec

hopen

storfjorden

kongsøya

Nordaustlandet

k itøkvitøya

Western Hudson Bay: earlier sea ice break up, lower survival ofyoung and old bears

Regehr et alRegehr et al., J Wildl Managem, 2007

In Alaska, less and less bears den in multi yearpack ice, and rather den on land

1985‐1994

1998‐2004

Reduction from 62% to 37% of observed maternity dens in multi year ice

Fischbach et al., polar biology, 2007

Survival and reproduction affected by increasedperiod of ice free waters in Southern Beaufortperiod of ice free waters in Southern BeaufortSea

2001–2003, the ice‐free period = mean 101 days (90‐119), p y ( )female survival was high (0.96–0.99)

In 2004 and 2005, the ice‐free period = mean 135 days (134‐135) adult female survival was low (0.73–0.79). 

Breeding rates and cub littersurvival also declined with increasing duration of the ice‐free period

Regehr et al. Journal of Animal Ecology 2010, 79, 117–127