A hundred million monarchs migrate each year. Gliding, flapping, hitching rides on thermals like any hawk or eagle, they fly as far as four thousand miles and as high as two thousand feet, rivaling the great animal migrations of Africa, the flocking of birds across North America.

The Rarest of the Rare: Vanishing Animals, Timeless Worlds - The Winter Palace of Monarchs (p. 132), Vintage Books. 1997