The Great Seal Migrations

The great annual northward migration of the seals is one of the most remarkable phenomena of animal life. It seems to be without organization and without leadership, yet toward the end of March each year the hundreds of thousands of cow seals and pups scattered over thousands of square miles of water start at about the same time in three great groups bound for three specific places. It has been the same for centuries, perhaps millenia. Each animal moves at about the same rate so that all arrive within a few days of each other. They do not move in compact masses, like birds.

The American herd of about 1,500,000 is by far the largest of the three. It goes straight to the Pribiloff Islands where it goes ashore on two almost barren islands—St. Paul and St. George. The Japanese herd, numbering about 40,000, makes for Robben Island, off northern Japan. The Russian herd, now estimated at about 200,000, goes to a few rocky islands of the Commander archipelago, off Kamchatka.

The moving herds consist almost entirely of females and young. The bulls winter further north, tend to be solitary during the winter, and precede the cows to the summer homes. The breeding season lasts for about two months. During this time the bull never eats or touches a drop of water. He never leaves the land. He arrives sleek and fat from the ocean pasture and is able to survive entirely on stored energy. This keeps him alive, even when he fights scores of terrible battles with younger rivals. Towards the end of summer he naturally is a sorry-looking creature.

One day, actuated by some common impulse, cows and calves depart. Then the bulls, their arduous labors of race propagation over for ten months, draw back among the rocks and spend two or three days in sound sleep before returning to the sea to replenish themselves.

Cows have very little reserve energy and must return to the water every two or three days, leaving their nursing pups ashore. On her return from one of these feeding expeditions, a cow goes straight to her own pup among the thousands on the rocky beach. Presumably she locates it by the odor. Few animals grow more rapidly than the seal pup. Within a few weeks after birth it is almost as large as its mother. This is an essential provision of nature, for it must have sufficient size and strength to care for itself in the open sea, once the southward migration starts. It is fully the size of the mother when it comes back the next year. There is an old idea that seal pups must be taught to swim. This is denied by government observers at the Pribiloff breeding grounds. When thrown into the water for the first time they swim ashore without difficulty. They will not, however, venture into the sea voluntarily but must be pushed off the rocks by the mothers.

St. George and St. Paul islands are the only two spots under the American flag, except for certain atomic energy and military installations, which are absolutely barred to visitors without special government permits. These, as a rule, are given only to scientists studying the behavior of the seals. On each island there is an Aleut village whose inhabitants attend to the butchering of the animals each summer. This is confined entirely to three-year-old males who congregate by themselves. The only other killing permitted is by Aleuts along the coast for whom sealing is the traditional means of livelihood, but this now is so restricted that the annual toll is very small. The sealing must be done from an open boat, use of firearms is prohibited, and the Aleuts cannot be under contract to furnish skins.