Our Last Great Wilderness

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To walk the tundra in summer is a chore, but well worth the effort. The dry winds blowing in from the ice-covered ocean bring little precipitation, but what there is stays on the surface, because the ground below is frozen; and since the region is flat, little flows away. The result is an endless series of puddles large and small.

 

These ponds are the summer home of all kinds of waterfowl, including phalaropes, whose heads jerk back and forth as they swim like little toy ducks. A remarkable feature of the tens of thousands of lakes south of Point Barrow, northernmost tip of United States territory, is that virtually all of them are elongated in precisely the same direction—slightly west of north. The orientation of the lakes has nothing to do with local geology, and they were not gouged by a flowing ice sheet. Scientists working on the North Slope are still seeking an explanation.

Walk across the tundra with your eyes alert and you will see the signs of an extraordinary ecology. Snaking through the covering of grass, sedge, lichens, and moss that is often knee-deep are countless little channels that hug the ground. Every now and then mouselike creatures scurry along one of these passages.

They are lemmings. Their channels are formed as tunnels under the snow during the winter, for lemmings do not hibernate and must push under the snow in search of cotton grass and other food. At the peak of the lemming population cycle that comes every three or four years, the tundra is swarming with the animals. Overhead a jaeger, a predatory gull with a spearlike tail, may be circling, waiting his chance to swoop on one of them. Here and there on the ground lie objects that look like black golf balls. These are owl pellets—the regurgitated remains of lemmings eaten by snowy owls, which digest the nourishing parts of the animal, then regurgitate a snug ball of fur and bones.

What fascinates the ecologists is the relative simplicity of relationships between the various life forms that make the North Slope beautiful and exciting. To a certain extent the larger animals all wax and wane in step with the lemming cycle. When the lemmings are plentiful, with as many as two hundred per acre, those who prey on them thrive: the jaegers, owls, and foxes in particular, but also, to some extent, the wolves, weasels, and wolverines.

The great puzzle is what causes the lemming cycles. What, too, accounts for tales of their mass suicides, when thousands plunge into the sea? Early explanations included such farfetched ideas as their desire to reach an ancestral home, a lost continent west of Norway, where mass lemming plunges are famous.

 

A more recent thesis has been that because of their extraordinary rate of multiplication they overwhelm their food supply. (The female gestates her young in twenty days and bears as many as thirteen in a litter. The newly born are ready to breed within three weeks.) According to this theory the forage, depleted by overgrazing, takes two or three years to recover in the harsh climate, and so lemming hordes set out in search of new pastures, plunging into every body of water that stands in their way, be it a narrow pond or the ocean.

It has recently been reported, however, that the population “crashes” occur before the food is exhausted, and the dying animals are not skinny. Some believe a change in blood chemistry, caused either by the stress of overcrowding or by a long spell of warm weather, affects the lemming brain, leading to erratic behavior and finally death.

Despite such puzzles, the ecology of the North Slope is far simpler than that of warmer environments, where many more life forms and other factors interact. Hence the North Slope is uniquely suited for the study of ecology.

Not that it lacks diversity. At Barrow there are about one hundred species of hollow-stemmed, or vascular, plants. During the two-month growing season the tundra abounds in color—purple and white anemones, poppies, saxifrage, and roses. Because the time for seeds to germinate and establish themselves is short, the tundra plants tend to belong to species that propagate themselves by spreading, like strawberry shoots or ivy, rather than by seed.

However, the continuous daylight of early summer helps make up for the shortness of the season. At Prudhoe Bay the sun does not set from May 14 to July 30 (and it does not rise from November 24 to January 17).

In winter the sharp demarkation between North Slope and Arctic Ocean tends to disappear. Both are frozen and snow-covered. Walking out to sea from the Prudhoe Bay shore this spring I found it impossible to tell when you left land and were walking on the sea. Farther out, though, the pack ice is forever in motion. Borne by wind and current, the floes grind and shriek against one another, sometimes overriding when an onshore wind presses them against the coast, sometimes buckling to form giant pressure ridges.