Even people who love squirrels might have been unnerved at what Philo Romayne Hoy, a doctor and amateur naturalist in Racine, Wis., witnessed in the autumn of 1842: thousands of squirrels scurrying across the landscape in an unbroken wave.
On they came, day after day, a great, unrelenting tide of Sciurus carolinensis: the Eastern gray squirrel. Hoy saw a similar spectacle in 1847, 1852 and again in 1857.
He wasn’t alone. The mass movement of squirrels across different portions of North America is noted in the journals of hunters, explorers, farmers and others. Every few years, thousands upon thousands of Eastern gray squirrels moved in a roughly southeasterly direction, usually in the fall. They surged through forests, their natural habitat, and into prairies, an unnatural one. They tore through cornfields like earthbound locusts, making the stalks pulsate as if buffeted by a strong wind.
