Is it a predator, a change in the wind, a sudden noise, or just a shared internal signal? Whatever the cause, the spectacle of thousands of snow geese taking to the sky all at once is well worth seeing. The squawking, flapping and lift off of thousands of birds creates a churning rolling sky. Yet underneath it all is millennia of instinct, allowing the population to act as one, preventing true turmoil in the face of apparent chaos.