Why do some birds migrate in this way? The answer lies with food. Birds that live in warmer zones nearer the equator can find food all year round but the days in these regions are much shorter – as little as 12 hours on the equator itself. Because most bird species feed by sight, this limits the time they can spend feeding, a particular problem for birds trying to gather enough food to feed hungry chicks. By moving north or south to warmer climates, migratory birds ensure that they can find food all year round, while taking advantage of the longer days nearer the poles.
All sorts of different birds migrate, sometimes traveling thousands of miles in the process. The most impressive migrant is the Arctic tern, which breeds north of the Arctic Circle but which migrates 11,000 miles south to the Antarctic as the northern summer turns to winter. Many species of ducks, geese and swans migrate south from the Arctic region to Europe, Asia and North America during the winter, returning north again in the spring to breed. Even tiny birds such as hummingbirds migrate; the ruby-throated hummingbird flies 500 miles from the south coasts of North America to Mexico’s Yucatan Peninsula, where it feeds on flowers during the colder winter months.
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