Richard Gullison, age l0, of Cross Creek, N.B., Canada, for his question:

How do birds hatch their eggs in the winter?

Every year flocks of birds fly back and forth between their winter and summer homes. When they return to us each summer they build nests and hatch their eggs. For this reason we may expect them to lay eggs when they go back to their winter homes in the fall, but they do not.

Some of our birds fly to the Gulf states to spend the winter, others fly farther south to Central and even to south America. The Arctic terns spend the summer in the north polar regions and fly down to visit the south polar regions during our winter months. Many birds of the Arctic fly south to spend the winter in British Columbia and other parts of Canada. They are used to chilly polar weather so the winters of Canada seem warm to them.

These terns., plovers and other northern birds arrive in Canada in the fall when robins are leaving to fly farther south. In the spring, the game of musical chairs changes around. The Plovers and their friends fly back north and robins come back to take their places. We expect northern birds to build nests when they arrive in the fall, dust as robins build nests when they return in the spring.

But this d0e8 not happen. Birds are good parents and want the best for their children. They plan to raise their chicks when the summer days are long and sunny.

Winter is no time to bring up baby birds because the days are short and cold. What's more. seeds and bugs are hard to find and the growing family would be short of food.

The parent birds have a simple way to solve family problems. They do not raise families in their winter homes. When the robins fly south to winter in the Gulf states, they build no nests and lay no eggs. You might say that they loaf through the winter months. The northern birds that fly down to Canada in the fall also loaf through the winter. When the blizzards blow, they shelter themselves in the furry evergreens. But they do not have to worry about hatching eggs and keeping them warm in zero weather. This is not the proper season to lay eggs and raise a family.

Family life must wait for the first breath of spring. Then the robins and their friends fly north to our woods and fields. They build their nests and hatch their eggs and still have time to sing. The terns and their friends have gone to enjoy the long, warm days of the far northern summer. And for them, too, summer is the season for hatching and raising baby birds. Their winter homes are in southern Canada and their family raising summer homes are in northern Canada.