Sunday, November 11, 2001		Nature

GRIZZLIES or North American brown bears arrive each year at cataracts on Canada’s major rivers like Mackenzie, where they wait for the salmon to pass through on their way to the redds in the headwaters. The salmon are plump and full of eggs and milt. Their struggles up the foaming waters, makes catching them easy for the bears. Some bears just open their mouths and the salmon, quite literally, jump right in.

Grizzly and the bald eagle are two of America’s well-known animals that realise the importance of being at the right place at the right time and they plan their arrival to the movements of Pacific salmon, which like their relatives in other parts of the world, return to their home rivers to spawn. A clock could almost be set to their arrival, with different species of fish entering the rivers at different times of the year.

In July, the sockeye salmon enter the rivers of Alaska and British Columbia. They congregate in huge numbers in the estuaries, where they fall prey to killer whales and seals, before making the perilous journey up-river to the salmon redds at the head of the river, where they deposit their eggs and milt. Waiting for them, along the river-bank, are not only the nets and lines of fishermen and anglers, but also the massed claws of countless grizzlies.

Grizzly bears would not normally accept other bears to be in such close proximity, but with the expected food boom they are slightly more tolerant of each other. Fights do break out as the grizzlies line up at convenient cataracts. They jostle one another for the best positions on rocks in mid-stream, the more mature bears gaining the prime sites, and they wait for the salmon to run. At rapids and low waterfalls, the salmon must fight hard to swim up and over the white water, and it is here that they are most vulnerable.

With a lightning swipe of the forepaw, a grizzly can hook a salmon as it leaps clear of the water or scoop one out of the shallows.. Some bears simply stand in the water at the top of the rapids and wait for the fish to, quite literally, jump into their mouth.

With the run complete and with full bellies, the bears head for the hills and for winter hibernation. The surviving salmon reach their spawning grounds, where many die, exhausted by the supreme effort of procreation some live on, returning to the sea, to spawn another day, but on the return’s journey their is another gauntlet to run.

In the pine trees bordering the Chilkat River, large numbers of bald eagles begin to gather. They are on their migration south to warmer climes, but they stop off for one last feast. In the river, dead, dying and exhausted salmon are washed down-river, easy pickings for the assembled predators. The eagles swoop in and snatch slamon from the shallows, the wriggling fish impaled on the eagle’s powerful talons. Bears, raccoons and foxes join the easy hunt. It is the last of the summer food and a final opportunity to stock up before winter.