Anthropogenic global warming is occurring more rapidly in the Arctic than elsewhere, and has already caused significant negative effects on sea ice-dependent species such as polar bears. In the cover story of the Sept/Oct issue of Conservation Letters, Derocher et al examine rapid ecosystem change and polar bear conservation. The authors discuss issues that need consideration if large numbers of polar bears are forced to remain on land, or on offshore ice, with inadequate energy reserves to survive prolonged open water periods. Lead author Andrew Derocher contributed to the photo essay (including all photos) to highlight key observations from the paper. SCB members can log in to their member home page to read the paper.
A Photo Essay: Rapid ecosystem change and polar bear conservation (Conservation Letters)
1. The cover story of the September / October issue of Conservation
Letters examines rapid ecosystem change and polar bear conservation.
SCB Members log in to your member home page Conservation Letters
www.conbio.org
2. Rapid Ecosystem Change and Polar Bear Conservation
A photo essay…
Photos by lead author Andrew Derocher
Conservation Letters
September/October 2013
Impact Factor: 4.356
Edited by Andrew Knight, Editor-in-Chief, Conservation Letters
Published by Wiley
3. Derocher et al address issues that need
consideration if large numbers of polar bears are
forced to remain on land, or on offshore ice,
with inadequate energy reserves to survive
prolonged open water periods
4. The sea ice habitat upon which polar bears depend for successful foraging is
rapidly declining in response to greenhouse gas driven global warming
(Derocher et al 2013)
PHOTO: A breeding pair (male on left) on sea ice - Beaufort Sea (April 2013). The bears rely on
sea ice as their primary habitat to hunt, mate & travel. The female will either den on thick
multiyear ice or move onto land to over winter and give birth to cubs in a snow den.
5. Rapid Ecosystem Change and Polar Bear Conservation
Conservation Letters
A sub-adult female polar bear on a frozen lake along the shore of Hudson Bay. Small bears
like this are usually wary of adult males which can be predatory.
6. When superimposed over the long-term declining trend, annual variability in sea ice
makes it is increasingly likely that we will soon see a year where sea ice availability for
some polar bear populations is below thresholds for vital rates
(Derocher, et al 2013).
PHOTO: Typical near shore polar bear habitat in the Beaufort Sea in late spring. As the ice
starts to melt, the increase in open water reduces hunting success for polar bears because their
prey (ringed & bearded seals) have more places to safely surface.
7. Rapid Ecosystem Change and Polar Bear Conservation
Conservation Letters
A four month old cub caught in the Beaufort Sea with its mother. Studies showing reduced
body condition, declining reproduction, and lower survival have been correlated with
reduced availability of sea ice.
8. Polar bear conservation is predicated on the existence of suitable habitat and the
protection of such habitat cannot be accomplished unless GHG emissions are
sufficiently reduced to stop the rise in global temperatures (Derocher, et al 2013).
PHOTO: The prolonged mother-offspring bond in polar bears usually lasts for 2.5 years and
results in low potential population growth rates. This 11 month old cub on the shores of
Hudson Bay, Canada, will come close to the size of its mother by weaning.
9. When forced ashore in summer or far offshore on multiyear ice, polar bears
experience greatly reduced energy intake, rely on stored fat, and decline in mass
(Derocher, et al 2013).
PHOTO: While polar bears are justly considered marine mammals, they usually avoid
swimming unless they are hunting. This bear is responding to the presence of a helicopter
and is using water as an escape habitat.
10. None of the five nations with jurisdiction over polar bears (Norway, Russia,
United States, Canada, and Greenland) has a plan for responding to sudden
changes in polar bear populations caused by nutritional stress
(Derocher, et al 2013).
PHOTO: Lead author Andrew Derocher of the University of Alberta takes skull
measurements on a live-captured polar bear in the Beaufort Sea as part of a monitoring
program to assess population size and condition.
11. Rapid Ecosystem Change and Polar Bear Conservation
Conservation Letters
A typical ringed seal pup kill site in the Beaufort Sea in spring. Ringed seal females give
birth to pups under snow along the ridged ice and polar bears hunt these areas for
vulnerable pups and their mothers.
12. Rapid Ecosystem Change and Polar Bear Conservation
Conservation Letters
A partially consumed adult ringed seal in the Beaufort Sea. Polar bears
preferentially feed on the blubber of seals with about 92% of the energy consumed
deposited directly into the bear's own fat cells.
13. Consultation between managers, policy makers, scientists, local residents, subsistence
hunters, & other stakeholders...is essential for effective conservation planning
(Derocher, et al 2013).
PHOTO: Adult males play fighting along the coast of Hudson Bay, Canada. Without access to
food while on land, adult males can be social and play fighting is thought to allow skill development
for future competition for mates or food.
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Rapid ecosystem change and polar bear conservation
www.conbio.org
PHOTO: A sub-adult polar bear wandering the shores of Hudson Bay waiting for the
return of winter. Delayed freeze-up is causing increased risk of starvation in the
population.