CBC In Depth
INDEPTH: POLAR BEARS
The Shrinking Polar Bears
CBC News Online | July 06, 2004

From The National | October 1999

Polar Bear Our story concerns an animal that is closely associated with this country, pride of the north; the polar bear. Now they certainly capture the imagination of many people around the world. We look at what science has to say about one set of polar bears, those living near Churchill, Manitoba, on and off the shores of Hudson Bay. Scientist Ian Stirling believes they are sending a signal from the eco-system. And as he studies their declining weight and falling birth rate, he worries something may be very wrong. The National's Eve Savory takes us to "The Shrinking Bears" of Hudson Bay.

They call helicopter pilot Steve Miller the "Eagle" for his acute vision.

His passenger, Ian Stirling, calls Miller's ability to anticipate bear behavior, "Eagle magic". Stirling is one of the world's top authorities on polar bears.


Steve Miller
For 18 years "the Eagle" has maneuvered Ian Stirling and his tranquillizing dart rifle to a perfect shooting position four to five metres above the ground.

"I think we're going to have to jabpole the first two with a little bit in the neck," Stirling says. "Oh yeah, the third one is down as well, that's good"

The team, which includes colleagues like research scientist Nick Lunn, is the reason humans know more about the 1,200 polar bears of Western Hudson Bay than any other polar bear population in the world.

The three young males are getting a just-for-safety Telozol chaser. The drug has already left them conscious, but immobolized and tranquillized.

They'll stay this way for the next two to three hours.


Ian Stirling
"Once he's lying like this then he can breathe out of both lungs comfortably. And you don't want him to be lying head down because you don't want his viscera against his diaphragm, so he's nice and comfortable, breathing perfectly, I can take out the dart and I can not worry about him now," Stirling says.

Eighty per cent of the adult bears in the Churchill area have been tranquillized, handled, tagged, tattooed, weighed and measured, had blood drawn, teeth checked, their behaviour and life history recorded, many more than once.

Of everything they check, it's the fat that tells the story.

Mother and cub "We take a subjective sort of fat condition, with three being average size, and what we basically do is we're feeling along the spine for how much fat is in here. A really big pregnant female with a lot of fat would be a five out of five. They are just big tubs of jelly with little, stubby legs sticking out," Stirling says.

The Canadian Wildlife service has been gathering data on the Churchill bears for more than 30 years. Other polar bear countries can only envy the depth of knowledge Canada has.

"It's quite unique, extraordinarily valuable especially now when we're trying to look at the effects of long term changes in climatic or ecological conditions, because we have detailed information on the situation before. And that's very unusual," Stirling says.

That is why they know something is wrong.

"He's not as fat as he would have been 15 years ago. He's probably 80-90 kilograms lighter than he would have been 15 years ago."

The reason is the polar bears are ice bears and the ice is disappearing

Bear paw "You can see the size of the paws that these guys have, for swatting seals, big claws for gripping on the ice or tearing a seal apart," Stirling says.

Polar bear on ice The first bear to step on the ice was probably a grizzly - and it has had a couple of hundred thousand years to become the perfectly adapted ice animal it is.

White hair for camouflage; black skin to absorb heat, and for insulation - fat - lots of fat.

Polar bears don't hunt prey, they stalk it. Marine mammals are their prey and ice their essential platform.

But the bears of Hudson Bay have got used to living on ice that melts completely every summer.

So in late July, these bears have always been forced to come ashore, and with no ice to hunt from they just don't eat until freeze up in late November.

Three bears To get through that summer of fasting the bears have to really layer on the fat before the ice breaks up.

"So if that [breakup] gets shortened by two or three weeks, that's a lot of energy they don't get to store in their fat and that's pretty important to them.

And that's the trend. These days breakup is, on average, 10 to 14 days earlier than a couple of decades ago.

This year was much worse. The bears were forced off the ice and into their summer fast almost four weeks earlier than normal. The whole region is being affected.

Checking bear "This is an amazingly dry year. Sometimes when you see the bears running, dust comes up from under their feet. The tundra out here crackles when you walk on it. And things like this, this used to be a lake."

A few years ago he and other scientists used to swim in this lake near a geese field station.

Temperatures in western Hudson Bay have been steadily rising 0.3 to 0.4 degrees every decade since 1950.

The result this year, vegetation bloomed a month early and then died in the drought.

Satellite photo


As for the ice, a satellite photo supplied by the Canadian Ice Service shows what Hudson Bay traditionally looked like on July 1. The ice is just beginning to melt.



A second photo shows what Hudson Bay looked like on July 1, 1999. It's open water. If things keep getting warmer, this is probably the direction of the future.

The extra weeks of fasting are hurting all the bears but it's the females and their nursing young that are showing the greatest distress.

Checking bear The mother has been darted and cannot move; the two cubs will be given a tiny dose by hand. Nick and Ian move in from either side so the cubs feel surrounded. The safest place is with their mother.

They are eight or nine months old, completely dependent on her.

At this age they won't be weaned for at least one more year, probably two.

Once all three are quiet. Ian Stirling gives them a shot of penicillin to prevent infection from the dart and the handling.

Both cubs are female. And they had a brother, who is missing.

"She had triplets this spring´┐Ż so she's lost one," Lunn says.

"It probably starved, just not enough food to go around. The cubs compete with each other for nipples too, so the weaker you get, you get less, and eventually you get left behind or die," Stirling says.

Of the families they caught this spring and found again this fall fewer than two thirds of the cubs have survived. And it's early yet.

The odds are the number they tattoo on the smaller cub's lip won't be seen again.

"This cub is pretty lean, give it a two for condition, you can feel the whole pelvic girdle. I wouldn't give her a really high chance for survival," Stirling says. "The timing of breakup is really important to these family groups because a mother like that has to not only be able to store enough fat for herself to survive but she has to store enough for her cubs."

Bears

Checking teeth
Measuring head
Checking fat
The Quetelet Index
C = (W/L2 x 100)
The Quetlet index measures the health of polar bears.
where: C = index of condition, w = weight in kilograms, and L = body length in metres.
  1. bag of bones, basically skeleton hanging over a frame, may be sick or starving.
  2. thin, spine visible under fur, feel pelvic girdle under skin because no fat
  3. average level of fatness
  4. very fat, when lying on stomach, whole body ripples like the proverbial bowl full of jelly when jiggled a bit by hand
  5. obese, body practically round, belly and sides hanging down with fat when walking; usually only pregnant females reach this state


A pregnant bear in Churchill tucks herself away in a cool earth den dug into the permafrost. She stays there all winter, gives birth in mid-November or later, and she and her cubs live off her fat until they come out in March.

Her fast has lasted twice as long as the bears that hit the ice in November. She'll have lost well over half her body weight and be desperate to put on fat so she can nurse her cubs.

With perfect timing the ice delivers plump, newly weaned and helpless seal pups.

But with warming, every day of earlier breakup is one day less for the bear to hunt and rebuild her stores of energy for the coming summer of hunger.

The scientists have found that for every week the ice breaks up earlier the bears come ashore 10 kilos lighter.

Ian Stirling "It means she's not able to lay down as much fat or produce enough milk and so something goes and it starts with the weaker smaller cub. These two cubs, this one is smaller and thinner, and if push comes to shove, it's going to be the one that goes next," Stirling says.

Not only are more cubs dying but the birth rate has dropped 15 per cent.

In 1991, Mount Pinatubo in the Philippines blew its top and the sulphuric acid particles it sent into the atmosphere cooled the planet. The following summer the ice on Hudson Bay melted almost a month later.

"That had a dramatic effect on the bears," Stirling says. "They were bigger, they were heavier, they had more cubs, the cubs survived better. And the cubs that were born in that year, we call them the Pinatubo bears, because so many of them survived from that particular year class."

In the air again, Eagle Miller starts herding his 4,864th bear.

Miller "It's just like people, everyone is different, and as we're approaching them we have to sort of read them and see whether they're going to defy us, or they're going to be afraid of us," Miller says. "Once the first one's down, you go in, take out the second one, move him back to the first one, go back for the third one, bring him back in too, lay them out one, two, three, its relatively simple once you've done it a few times."

On the ground, they find an adult female and a yearling cub. The mother is small and very thin.

"You put your hand on the top of her back, and you can feel her ribs," Stirling says. She's straight down, on the sides here when she should be round on her sides like she is."

Her condition is a mere two. She's just got clear fluid, she doesn't seem to have much milk.

So she's not going to have any more milk to give the cub; the cub's going to pretty much make it on what he's got. In fact being this close to Churchill, it's quite likely she's going to end up in the polar bear jail in a month or two.

Polar bear jailPolar bear jail


The Polar bear jail has 23 cells and no rations. It's usually the females with cubs and the young bears - the inexperienced hunters - who get hungry enough to risk the trip to town and end up here waiting for their airlift north.

As the bears get thinner and more desperate they'll cross paths with humans more often.

Early this July, a skinny one-and-a half year old male killed a woman and mauled a child and a man at Corbett inlet north of Churchill.

Wayde Roberts is Manitoba's natural resource officer in Churchill, the man you call when a bear comes visiting.

Wayde Roberts "With this early breakup and the winds etc., we had a lot more bears offload north, and they're not used to dealing with the bear at that time of year," Roberts says. "In a normal year there wouldn't be a bear in that area for another month, if at all."

By September 17th this year, he had 85 bear calls-- several times the normal number.

"This year we're noticing already the bears are skinnier," Roberts says. "Our wildlife people are saying in actuality the bears are smaller as well. The large 1,400 to 2,000 pound bears aren't around anymore."

The town of Churchill needs those bears. Tourism accounts for 60 per cent of the town's economy.

In bear season Tundra Buggy Tours books a year in advance; and fills 426 seats every day, seven days a week. Fifteen thousand tourists come to Churchill; and almost all of them come for the bears.

"It's like a dream come true," one tourist says "Now you know they're really real. They're not those little fluffy things you sit on your dresser....wow."

The warming trend over Hudson Bay is what scientists have predicted will happen with global warming. At the very least it's a dry run.

The models predict the area will be three to five degrees warmer within 50 years. With every degree, breakup will happen one week earlier.

Ian Stirling "Some people have asked me why wouldn't they walk, further north," Stirling says. "The reason is there's already bears there. The other reason is that these bears grew up here, they know this area. They are committed to being here and if the ice just gets less and less and less, I mean I don't want to sound like a sensationalist, if the climate keeps on warming, ultimately there won't be polar bears in this part of the world."

The polar bears of the western and southern Hudson Bay are at the southern most extreme of polar bear range, and that makes them a sentinel, a warning signal for what could happen to all polar bears and many other species if the climate continues to warm.

"It's not just the bears, it's everything," Roberts says. "We have 200 nesting birds in this area. Everything is going to be affected by this. Also what is the seal population going to do? It will probably drop as well because they need the ice to raise their pups. So if we lose our seal population we're going to lose our bear population. So it's a sad thing.

Bear head On our last run, Eagle spots three huge males. Or so it seemed from the air.

And two of them- one a Pinatubo cub - were fat and healthy. But a male born one year later, when the warming trend had returned, is starving.

"He's going to be a bag of bones by the time freeze-up comes," Stirling says.

In the 12 hours we spent with Ian and Nick and the Eagle, they caught 18 polar bears. It is unlikely all 18 will survive for the scientists to find again next year.

These magnificent and intelligent animals of the ice fear almost nothing.

Yet the research gathered here demonstrates if the climate continues to warm, polar bears everywhere will be among the world's most vulnerable creatures.






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