Navigation Links
For polar bears, it's survival of the fattest
Date:3/19/2013

One of the most southerly populations of polar bears in the world and the best studied is struggling to cope with climate-induced changes to sea ice, new research reveals. Based on over 10 years' data the study, published in the British Ecological Society's Journal of Animal Ecology, sheds new light on how sea ice conditions drive polar bears' annual migration on and off the ice.

Lead by Dr Seth Cherry of the University of Alberta, the team studied polar bears in western Hudson Bay, where sea ice melts completely each summer and typically re-freezes from late November to early December. "This poses an interesting challenge for a species that has evolved as a highly efficient predator of ice-associated seals," he explains. "Because although polar bears are excellent swimmers compared with other bear species, they use the sea ice to travel, hunt, mate and rest."

Polar bears have adapted to the annual loss of sea ice by migrating onto land each summer. While there, they cannot hunt seals and must rely on fat reserves to see them through until the ice returns.

Dr Cherry and colleagues wanted to discover how earlier thawing and later freezing of sea ice affects the bears' migration. "At first glance, sea ice may look like a barren, uniform environment, but in reality, it's remarkably complex and polar bears manage to cope, and even thrive, in a habitat that moves beneath their feet and even disappears for part of the year. This is an extraordinary biological feat and biologist still don't fully understand it," he says.

From 1991-97 and 2004-09, they monitored movements of 109 female polar bears fitted with satellite tracking collars. They tagged only females because males' necks are wider than their heads, so they cannot wear a collar. During the same period, the team also monitored the position and concentration of sea ice using satellite images.

"Defining precisely what aspects of sea ice break-up and freeze-up affect polar bear migration, and when these conditions occur, is a vital part of monitoring how potential climate-induced changes to sea ice freeze-thaw cycles may affect the bears," he says.

The results reveal the timing of polar bears' migration can be predicted by how fast the sea ice melts and freezes, and by when specific sea ice concentrations occur within a given area of Hudson Bay.

According to Dr Cherry: "The data suggest that in recent years, polar bears are arriving on shore earlier in the summer and leaving later in the autumn. These are precisely the kind of changes one would expect to see as a result of a warming climate and may help explain some other studies that are showing declines in body condition and cub production."

Recent estimates put the western Hudson Bay polar bear population at around 900 individuals. The population has declined since the 1990s, as has the bears' body condition and the number of cubs surviving to adulthood.

Because polar bears' main food source is seals, and these are hunted almost exclusively on sea ice, the longer bears spend on land, the longer they must go without energy-rich seals. "Climate-induced changes that cause sea ice to melt earlier, form later, or both, likely affect the overall health of polar bears in the area. Ultimately, for polar bears, it's survival of the fattest," says Dr Cherry.

He hopes the results will enable other scientists and wildlife managers to predict how potential climate-induced changes to sea ice freeze-thaw cycles will affect the ecology, particularly the migration patterns, of this iconic species.


'/>"/>

Contact: Becky Allen
44-012-235-70016
Wiley
Source:Eurekalert  

Related biology news :

1. New gene variant may explain psychotic features in bipolar disorder
2. Polar bear researchers urge governments to act now and save the species
3. Dartmouth research offers new control strategies for bipolar bark beetles
4. MBL scientists find bipolar marine bacteria, refuting everything is everywhere idea
5. Missing polar weather systems could impact climate predictions
6. Finding life in the volcanic systems of the Antarctic Polar Front
7. Making sense out of the biological matrix of bipolar disorder
8. University of Texas Medical Branch selected to manage Center for Polar Medical Operations
9. Polar And LOOK Launch The Worlds First Pedal-Based Power Cycling System
10. Duck-billed dinosaurs endured long, dark polar winters
11. NRC authors brief federal agencies on the state of polar regions
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
For polar bears, it's survival of the fattest
(Date:3/15/2016)... 15, 2016 Yissum Research Development Company ... company of the Hebrew University, announced today the formation ... technology of various human biological indicators. Neteera Technologies has ... from private investors. ... detection of electromagnetic emissions from sweat ducts, enables reliable ...
(Date:3/10/2016)... India , March 10, 2016 ... a new market research report "Identity and Access Management ... & Audit, Compliance, and Governance), by Organization Size, by ... to 2020", published by MarketsandMarkets, The market is estimated ... USD 12.78 Billion by 2020, at a Compound Annual ...
(Date:3/8/2016)... March 8, 2016   Valencell , the ... announced it has secured $11M in Series D ... a new venture fund being launched by UAE-based ... from existing investors TDF Ventures and WSJ Joshua ... continue its triple-digit growth and accelerate its pioneering ...
Breaking Biology News(10 mins):
(Date:5/23/2016)... Oxitec CEO Hadyn Parry will testify ... before the United States House Committee on Science, Space and ... controlling the spread of the Aedes aegypti mosquito, ... (Logo: http://photos.prnewswire.com/prnh/20150630/227348 ) Oxitec has pioneered ... in Brazil , Panama ...
(Date:5/23/2016)... ... May 23, 2016 , ... ... molecular nanotechnology, announced the winners for the 2015 Foresight Institute Feynman Prizes. ... given in two categories, one for experiment and the other for theory in ...
(Date:5/20/2016)... ... 20, 2016 , ... Kablooe Design, a leading provider of product design and ... anniversary of the business. “We have worked hard to build long-term relationships,” says President ... privilege and honor of serving their product design and development needs through the years.” ...
(Date:5/19/2016)... ... May 19, 2016 , ... Anton Paar USA, located in ... office building is complete. The new structure adds a third office building to the ... USA purchased 2.4 acres of land, along with office space adjacent to the ...
Breaking Biology Technology: