Feeds

Melting ice kills polar bears, say boffins

Starving, not drowning

Top 5 reasons to deploy VMware with Tegile

Al Gore might have been partly right after all. Melting sea ice could indeed be contributing to the death of polar bears, but the cause is more likely starvation than drowning*.

Researchers analysing 20 years of population data of polar bears in Canada's Hudson Bay report a correlation between yearly survival rates of the very young and old polar bears, and the date the pack ice began breaking up.

The problem lies in the dependence of the bears on the ice for hunting. The bears have to gorge themselves on seal pups as soon as they emerge from hibernation to store enough energy to make it through the summer, when the sea ice breaks up. The earlier the ice breaks, the tougher the summer will be on the less able hunters - the cubs and the very old.

This means the more vulnerable bears are not fattening up properly before winter, so more perish during the cold months of hibernation.

"Survivorship has dropped in the cubs, sub-adults and very old animals and is directly related to the date of break-up," Ian Stirling, a biologist with the Canadian Wildlife Service in Edmonton, Alberta, and an author on the report, told Nature's news site.

The team captures and tags bears during the hunting season, tracking and, where possible, recapturing them the following year to see how well they have survived the winter. In the time the census has been running (since 1984) the polar bear population has fallen 20 per cent.

The results are not entirely surprising. Other studies have found bears are getting thinner. A survey by Martyn Obbard, who works for the Ontario Ministry of Natural Resources, found that bears captured in the last five years weighed 15 per cent less, on average, than they did 20 years ago.

Hudson Bay is at the very southern tip of normal polar bear hunting grounds (the polar cap) and as such is seen as an indicator of what could happen to the rest of the ice cap, if the planet gets warmer, as many scientists expect it will.

The timing of the break-up of the sea ice does vary, the researchers say, but the overall trend is towards longer periods of open seas. The ice now clears in the bay roughly three weeks earlier than it did 30 years ago, the scientists say.

The findings are reported in the November issue of the Journal of Wildlife Management. ®

Bootnote

Polar bears that are not drowning or starving thanks to melting ice are instead being driven south, interbreeding with local grizzlies, and being shot dead. It is a tough life, it seems, being a bear.

*In his film, An Inconvenient Truth, Gore asserted polar bears are drowning on long swims between icebergs, thanks to global warming. Although there is some anecdotal evidence to support the claim of drowning bears, the idea that climate change is causing this is not backed by mainstream science. A UK judge ruled that teachers showing the film to children must make this clear.

Remote control for virtualized desktops

More from The Register

next story
Renewable energy 'simply WON'T WORK': Top Google engineers
Windmills, solar, tidal - all a 'false hope', say Stanford PhDs
FORGET the CLIMATE: FATTIES are a MUCH BIGGER problem - study
Fat guy? Drink or smoke? You're worse than a TERRORIST
SEX BEAST SEALS may be egging each other on to ATTACK PENGUINS
Boffin: 'I think the behaviour is increasing in frequency'
HUMAN DNA 'will be FOUND ON MOON' – rockin' boffin Brian Cox
Crowdfund plan to stimulate Blighty's space programme
Post-pub nosh neckfiller: The MIGHTY Scotch egg
Off to the boozer? This delicacy might help mitigate the effects
I'M SO SORRY, sobs Rosetta Brit boffin in 'sexist' sexy shirt storm
'He is just being himself' says proud mum of larger-than-life physicist
NASA launches new climate model at SC14
75 days of supercomputing later ...
Britain's HUMAN DNA-strewing Moon mission rakes in £200k
3 days, and Kickstarter moves lander 37% nearer takeoff
prev story

Whitepapers

Why and how to choose the right cloud vendor
The benefits of cloud-based storage in your processes. Eliminate onsite, disk-based backup and archiving in favor of cloud-based data protection.
Getting started with customer-focused identity management
Learn why identity is a fundamental requirement to digital growth, and how without it there is no way to identify and engage customers in a meaningful way.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Beginner's guide to SSL certificates
De-mystify the technology involved and give you the information you need to make the best decision when considering your online security options.
New hybrid storage solutions
Tackling data challenges through emerging hybrid storage solutions that enable optimum database performance whilst managing costs and increasingly large data stores.