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The largest of the
land living carnivores, the polar bear, is one of the
most powerful predators in the Arctic, observes Nutan Shukla
The nomadic
polar bear
THE largest of the land-living
carnivores, the polar bear, is one of the most powerful
predators in the Arctic. Unlike its other relatives who
are found in different parts of the world and are
omnivorous, this massive predator is exclusively
carnivorous and feeds predominantly on seals. Its
semiaquatic lifestyle is a new adaptation for the bear
family which helps him in finding food in the snowy
deserts of the northern polar region. A layer of fat
beneath the skin and thick fur keep it warm in its frozen
world.
These beautiful, white
creatures lead nomadic life, preferring to travel from
one site to another where food is seasonally plentiful.
They are expert seal killers and catch them while they
are still in water. Bears seek out a breathing hole,
which can be identified by the oily secretions on the
surrounding ice, and sit there patiently. These holes are
used by seals to come out of water to breath. As the head
of the seal appears, quick as lightning, the bears
enormous forepaw strikes out and hooks the seal up on to
the ice, its skull crushed with one bludgeon-like blow to
the head or its neck broken with one bite of the polar
bears formidable jaws.
Seals and their pups
hauled out on ice flows are stalked from across the ice
and in the water. The bear uses ridges and dips to
conceal its approach, slipping into the water for the
final few yards. It paddles gently forward, resembling a
chunk of floating ice.
One polar bear was once seen to stalk a seal
and each time the victim turned, the bear would freeze
and place its paw over its black nose to prevent the seal
from spotting it. Ringed seals are the most common seals
in the Arctic and so constitute the bulk of the polar
bear diet, although bearded, hooded and harp seals are
also sometimes taken.
The polar bear is unusual
among European and American mammals in having virtually
no ice age fossil record. Only a few scraps of bone,
perhaps no more than 20,000 years old, are tentatively
assigned to this species. The grizzly bear, whose fossil
remains extend far back into ice age deposits, is the
only likely direct ancestor of the polar bear.
At Wrangel Island in the
east Siberia Sea, polar bears attack walruses and their
pups. Over-enthusiastic bears jump on the backs of
adults, but are dislodged by one shake of the
walrus enormous bulk. The thick layer of blubber
protects them from the polar bears teeth and claws.
The bears are only successful if they can ambush a young
walrus before it escapes to the sea.
In early spring bears seek
out the breeding dens of ringed seals, which are found
buried below the snow over sea ice. Using brute force the
bear crashes through the roof of the den, surprising the
seal family and grabbing the youngsters.
In the same kind of
environment as that of polar bear, but at the other end
of the world, prowls another master of ambush, the
leopard seal. About ten feet long, with large,
reptile-like heads and huge jaws studded with vicious
teeth, leopard seals are solitary hunters. They attack
just about anything that moves in the southern ocean, as
long as it is smaller and more vulnerable, but their
favourite food is penguin. The ambush often takes place
at the edge of an ice shelf near a penguin colony, at
places where penguins dive into the water to go fishing.
If a leopard seal is about, penguins are agitated and are
reluctant to leave the safety of the ice. Eventually, the
weight of numbers forces the first birds to take the
plunge, just what the seal has been waiting for.
The penguin is grabbed in
the jaws, violently shaken and swallowed whole, minus the
head and feet. Large birds, like emperor and king
penguins, are dealt with in a different fashion; they are
shaken until the skin splits and then
unwrapped. A powerful flick of the
seals head literally peels off the birds skin
and feathers as far as the chin and legs, and the large
breast muscles are consumed, leaving the rest.
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