Ancient polar bears survived low ice periods on dead whales: study

Same study suggests bears aren’t likely to be able to rely on the same solution again

New research suggests an answer to the mystery of how polar bears survived previous eras of low sea ice.

But the same paper, published Tuesday in Frontiers of Ecology and the Environment, says the bears aren’t likely to be able to rely on the same solution again.

“I don’t think we can assume what worked in the past is going to work in the future,” said Kristin Laidre of the University of Washington.

Genetic research says polar bears diverged from other bears at least 150,000 years ago and probably as long as 500,000 years ago. That means the species lived through several low-ice periods, including a major warm period about 130,000 years ago.

At that time, while some year-round sea ice is thought to have remained, total coverage was greatly reduced and mostly found in the very highest reaches of the Arctic. Despite the bears needing sea ice to hunt fat-rich seals, somehow they survived.

RELATED: No change to Canada’s climate plans as UN report warns of losing battle

Laidre and her co-author Ian Stirling from the University of Alberta theorize those long-ago bears made it through an extended period of low ice by scavenging whale carcasses washed up on Arctic beaches.

“Polar bears likely survived those periods by accessing stranded marine mammal carcasses, and most likely large whale carcasses,” Laidre said. “They’re such large carcasses that they can be packages of food for, in some cases, years.”

The researchers calculated that a population of about 1,000 bears would need about 20 bowhead whale carcasses to remain healthy through the spring foraging season and about eight carcasses during the summer, when the bears eat less.

They then looked at mortality rates of large whales and what percentage of them might float long enough to wash up on a beach. Those numbers matched well with observed numbers of whale carcasses found in various parts of the Arctic.

A stretch of Russian coastline along the Chukchi Sea, for example, averages about 10 carcasses a year between July and November. A small number of polar bears have learned to rely on that resource.

The numbers suggest that washed-up whales could have been at least a major supplement during poor seal hunting conditions — especially since polar bears are very good at feasting on and storing fat.

“I think they were very likely the main source of nutrition,” said Stirling.

The future of modern polar bears in the face of rapidly shrinking sea ice is much debated, with some arguing their survival through previous low-ice periods bodes well today.

Laidre and Stirling aren’t so sure.

RELATED: Sick orca J50 declared dead by 1 group while scientists remain hopeful

The pace of change is much faster today than in the past. Bears don’t have much time to learn new behaviours on a wide scale.

As well, there aren’t as many whales as there used to be.

“Most of the whale populations have been overharvested,” Stirling said.

At best, he said whale carcasses could buy bears a little more time.

“We may have a little bit longer timeline. Hopefully, we’ll get climate warming under control.

“For the various different species that depend on a polar ice ecosystem, we may be able to keep some of that in its natural condition.”

Bob Weber, The Canadian Press

Like us on Facebook and follow us on Twitter.

Just Posted

Lacombe Composite High School Cosmetology students hosts Hair Massacure

Fundraiser supports kids battling pediatric cancers

Lacombe Council asks for answers regarding Police Service deficit

Lacombe Police Service ran a $238,627 deficit in 2018

City of Lacombe releases 2018 Audited Financial Statements

City had an operating surplus of about $318,000

Wolf Creek Public Schools board meeting – April 18th, 2019

Board approves international field trip; deliberates budget; discusses dangers of vaping

Lacombe Generals honoured by City for winning Allan Cup

2019 Allan Cup champs celebrated after successfully hosting tournament

VIDEO: Police dog in Oregon struck by 200 porcupine quills during pursuit

The German shepherd had to be sedated and was in treatment for more than two hours

Calgary woman killed in B.C. highway crash

Crash closed highway for hours

Assessment says Alberta woman facing animal abuse charges fit to stand trial

April Dawn Irving, 59, is charged with 13 counts of cruelty to animals

Canadian privacy watchdogs find major shortcomings in Facebook probe

The probe followed reports that Facebook had let an outside organization use an app to access users’ personal info

Provinces, Ottawa talk 50/50 split on abandoned bus-route service

B.C. has paid $2 million on a bus service for the northern part of the province

Wilson-Raybould: Feds want to just ‘manage the problem’ of Indigenous Peoples

Former federal justice minister speaks at First Nations Justice Council meeting in B.C.

Oil and gas company confirms death of one of its employees in Yoho avalanche

Dana Coffield died when he was skiing in the Rocky Mountains

Cenovus CEO estimates production curtailments will deliver billions to taxpayers

The curtailment program started Jan. 1 was designed to keep 325,000 barrels per day off the market

Robbery in Leduc County estimated at $40,000

Leduc RCMP investigate break and enter and theft of firearms

Most Read