"Because of the numerous squirrel migrations, John Audubon and John Bachman were convinced that the squirrels on the move were a separate species from the gray squirrels and used the scientific name Sciurus migratorius.

One of the earliest referenced migrations occurred in 1749 in Pennsylvania. Records show the state spending 3 cents for each squirrel killed. Over 640,000 were turned in for bounty.

Sometimes, hunts were organized to control the migration. One hunt in 1822 killed almost 20,000 squirrels. These hunts continued through the 1850s. In 1857, it was reported a hunter killed 160 in one day."