Manitoba, Ontario polar bears doomed, says expert.

[abc]

Manitoba, Ontario polar bears doomed, says expert.

By Bartley Kives, November 17, 2011

Polar bears may survive high up in the Arctic but Manitoba and Ontario's
bears are all but doomed, says the world's best-known expert on the
species.


WINNIPEG — Polar bears may survive high up in the Arctic but Manitoba and
Ontario's bears are all but doomed, says the world's best-known expert on
the species.

Wildlife biologist Ian Stirling, who's been studying polar bears for 41
years, believes it is now too late to prevent the iconic Arctic species
from being extirpated from the shores of Hudson Bay.

Increasingly long ice-free periods on the bay have led to less feeding on
seals, lighter females, fewer births and more mortality among the
southernmost subpopulations of polar bears, according to research
conducted by Stirling, other biologists and climatologists over the past
three decades.

Stirling believes this will lead to the disappearance of polar bears from
northeastern Manitoba, northern Ontario and parts Nunavut and Quebec
within decades, barring the unlikely event the planet quickly begins to
cool.

"Things definitely don't look good for the Western Hudson Bay and
Southern Hudson Bay populations," Stirling said in an interview on
Wednesday, referring to the world's southernmost polar-bear
subpopulations.

"Long term, if we don't stop climate warming and the continued melt of
sea ice, that population will disappear, maybe in 30 or 40 years,"
Stirling said. "We could keep parts of the northern ice area. We're not
going to save Hudson Bay. It's too late for that, unless we could cool it
down."

Stirling, an adjunct professor of biology at the University of Alberta,
has devoted his life to the study of marine mammals, beginning with seals
and then moving on to polar bears. He's condensed some of his work into
Polar Bears: The Natural History of a Threatened Species, which pays
special attention to the well-known Western Hudson Bay subpopulation,
which includes all the bears along northeastern Manitoba.

As Stirling and other biologists have documented, Hudson Bay sea ice now
breaks up an average of three weeks earlier at Churchill, Man., than it
did three decades before. Since polar bears consume almost all their
calories on the ice, where they hunt for seals, this has led to fewer
meals, declining weights, fewer births and more cannibalism among bears
in the area, said Stirling, citing well-known research.

What's less well-understood is the fact these missing weeks deprived
polar bears of meals at the most crucial feeding time for the carnivores.
That's because seal pups are just the right size when sea ice breaks up.

"All seals aren't equal, as far as polar bears are concerned," he said,
noting the ideal polar bear meal is about six weeks old.

"At that stage, they're little balls of fat. They aren't very smart about
predators," Stirling said. "What's happening at breakup is the bears are
losing access to the seals at the most important time."

The average polar bear eats about 43 seals a year. Missing out on two or
three of those meals is enough to cause a female polar bear to lose
enough mass to give birth to underweight cubs or no cubs at all, said
Stirling, noting the relationship between sea ice, feeding and fertility
has profound implications for the survival of the species.

In 2010, Andrew Derocher, Stirling's former graduate student, teamed up
with a pair of mathematicians to crunch these variables in an attempt to
predict the future the Western Hudson Bay subpopulation. They concluded
the species will soon reach a tipping point where the population will
plummet quickly.

Some conservationists fear this tipping has arrived, as the Western
Hudson Bay population is declining. In 1987, biologists estimated there
were 1,194 bears in the region by marking and recapturing individual
bears. In 2004, the same sort count adjusted that population down to 935.

Aerial surveys, which are considered less reliable, came up with
startlingly low numbers early this year. A new reliable count is expected
early in 2012, said Daryll Hedman, a Manitoba Conservation wildlife
manager.

Provincial officials have been hesitant to endorse gloomy predictions by
biologists. But Manitoba Conservation data bolsters the idea bears are
growing hungrier.

The number of problem bears officials are forced to handle around
Churchill every year is, on average, higher during years when ice breaks
up earlier than usual, said Stirling. However, more sightings of bears on
land can lead to the erroneous belief polar-bear populations are
increasing when in fact bears are simply hungrier.

"They're looking for an alternate food source because a large carnivore
doesn't lie down under a tree and quietly starve to death like an Arctic
hare. They're going to look for something else," said Stirling,
cautioning they won't travel far enough to survive in the long term.

"There's no place to move," he said. "Up the coast is already inhabited."