How polar bearsco Trackingpewiththethe Polar Bear ... · In Alaska, less and less bears den in...
Transcript of How polar bearsco Trackingpewiththethe Polar Bear ... · In Alaska, less and less bears den in...
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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
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Illustration: Rasmus Hansson
Polar bear
Black bear
Brown bear
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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
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Bears do not only eat seals
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climate
Sea ice
Ice associated seals Polar bears
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Importance of sea ice:‐food‐mating‐travel between feeding, mating and denningareas
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Most mating occurs on sea ice
72% in Svalbard72% in Svalbard,Derocher et al. 2010
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Marking of polar bears in Svalbardg p
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Platform for polar bearcapture‐recapture work
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Gl i f t i t tGlacier fronts importanthabitat (hunting ringedseal pups in spring)
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Getting data and samples
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Blood cell countsAge determination
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Studies of movement
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Different space use strategies
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Also large differencesin swimming behaviorin swimming behavior
% time in water
mon
th
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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
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DDDD
All bears den on islands in theSvalbard areaSvalbard area
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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
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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
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60% sea ice days 1oct‐31dec
hopen
storfjorden
kongsøya
Nordaustlandet
k itøkvitøya
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Western Hudson Bay: earlier sea ice break up, lower survival ofyoung and old bears
Regehr et alRegehr et al., J Wildl Managem, 2007
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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
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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
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