INDEPTH: POLAR BEARS
The Shrinking Polar Bears
CBC News Online | July 06, 2004
From The National | October 1999
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
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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
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"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.
"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
"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.
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.
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.
"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.
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.
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…
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."
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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.
- bag of bones, basically skeleton hanging over a frame, may be sick or starving.
- thin, spine visible under fur, feel pelvic girdle under skin because no fat
- average level of fatness
- very fat, when lying on stomach, whole body ripples like the proverbial bowl full of jelly when jiggled a bit by hand
- obese, body practically round, belly and sides hanging down with fat when walking; usually only pregnant females reach this state
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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.
"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.
"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.
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.
"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.
"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.
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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