What tells the cows that it's time to start grazing? Perhaps its the sun, or the returning red winged blackbirds or even the gulls. One day they are staying close to their feeder, and then, just like that, they hit the pasture. Sure, there's nothing but the promise of green grass. now So maybe they are just listening to the rumble of the earth springing to life. But its there, they hear it. Link to commercial site removed as spam. Signature edited as spam. This is your second warning.