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The Migration Phenomenon

The Migration Phenomenon

Where do they come from? The monarch butterfly (Danaus plexippus) is a widespread tropical insect that ranges as far north as Canada. It cannot withstand freezing winter temperatures. To survive, monarchs migrate to safe overwintering sites that are neither cold enough to kill it, nor so warm that it wastes precious energy flying too much.

Monarchs west of the Rocky Mountains migrate to locations on the central California coast. Monarchs east of the Rockies spend their winters in the high mountains of central Mexico. En route, they may travel as far as 2,000 miles, covering one hundred miles per day, and flying as high as 10,000 feet. A mighty achievement for such a seemingly fragile insect!

Why is this migration so unique? In many migrating species, such as birds and whales, the same individuals travel the migration route year after year. In contrast, migrating monarchs have never been to their destination before. In fact, several generations of monarchs have lived and died since last year's butterflies departed.