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Why do birds migrate south?
Question Date: 2006-03-08
Answer 1:

It does seem like a lot of trouble, doesn't it? If you lived in Milwaukee, where I live, the answer would be more obvious. Winters here are very cold, and it is hard for many kinds of birds to find food here in the winter because the ground is covered, there are few insects moving around, and there is little plant food around. A lot of birds that live in the northern half of the planet (the northern hemisphere) spend months in the southern hemisphere.

When we are having our winter, it is summer in the southern part of the world. Nearest the equator, there really is no summer or winter. Closer to the poles, the seasons get more and more extreme. This is because of the angle of the sun as it hits the Earth, but that's a whole new topic.

Many birds migrate from where conditions are bad to where they are good. When things get good back here in the northern hemisphere, these birds fly back to take advantage of all of the food that's around in the spring. There is even a species of bird that spends half the year in the North Pole and half the year in the South Pole. Now that's a long trip.

If you live in a place like Santa Barbara, CA, the "winter months" don't seem that bad. Some birds will just stay year-round. Even here in Wisconsin, we have year-round resident birds. But many birds can do better by flying south where there's more food.

Here's some "food for thought." How do you think birds find their way on these long journeys? Do you think they are born knowing the way, or do they have to learn it? Why don't more mammals migrate?

Answer 2:

During the summer, the climate warms up, and the parts of the Earth that are comfortable for a given species move poleward. During the winter, climate gets cold again, and climes that are comfortable move toward the equator. Of course, while winter is happening in the Northern Hemisphere, summer is happening in the Southern Hemisphere, and vice-versa. Birds simply move to parts of the world that they can live in in response to the seasons.

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