Chasing Monarchs
on Both Sides of the Continental Divide

"The 'Berlin Wall' model of monarch migration was based on assumption and repetition rather than fact," says Pyle.

Author and naturalist Dr. Robert Pyle traveled extensively on both sides of the Continental Divide one year during fall migration, watching for migratory monarchs. Whenever he found a monarch, he noted the direction it flew and then chased its invisible path until he found another monarch. All along the way, he interviewed the people he met and asked them when and where monarchs had been seen. His book, "Chasing Monarchs" chronicles his journey.

“By physically traveling with the monarchs, day by day, north to south, I hoped to shed a few lumens of light on several mysteries of the monarchs,” he said.

Do the Rocky Mountains truly form a barrier between the eastern and western monarch populations? A basic assumption of North American natural history was based on thin evidence, concluded Pyle. The eastern and western monarch populations are not the distinct entities scientists have long assumed.