The most amazing thing about monarch butterflies is the enormous migration that North American monarchs undertake each year.
Every fall, millions of these delicate insects leave their home range in Canada and the United States and begin flying south towards southern California or central Mexico, more than 3,200 km away! They return to the same forests each year, and some even find the same tree that their ancestors landed on.
Some estimates say up to a billion butterflies arrive in the mountains of Mexico each year.
Scientists aren’t sure how migrating monarchs know which way to go, since they only live a few months and none makes the journey more than once.
Toward the end of winter, the monarchs in Mexico and California mate. The males then die, while the females head north, depositing eggs on milkweed plants along the way and eventually dying themselves.
Scientists think North American monarchs have been making their amazing annual journey for thousands of years.
But logging in Mexico has greatly reduced forests where these butterflies roost.
Since 1983, the International Union for Conservation of Nature has listed the monarch migration as a threatened phenomena.