Sandhill cranes are as old as the story of migration itself. Tall, gray-bodied, crimson-capped, they move with a purpose that has outlasted ice, drought, and the rise of cities. Fossil evidence places cranes much like today’s sandhills at roughly 2.5 million years old — ancient birds still threading North America along sky-roads older than our highways. The Two Big Routes — and Where Colorado Truly Fits Most people picture Nebraska’s Platte River when they think “crane migration,” and fair enough — more than half a million birds pour into the Central Flyway each March, creating one of the continent’s greatest wildlife spectacles. But Colorado tells a different story. The state lies on the Rocky Mountain Flyway, used primarily by the Rocky Mountain Population (RMP) of