Sunday morning Holly and I were laying in bed counting raindrops when we heard a lone songbird calling through the wet branches. Holly thought it sad that she'd been left behind while all the others flew south as the old adage goes. Turns out not all birds "fly south" for the winter. Some other animals also migrate, including butterflies and even some fish. Somehow they know its time to start their annual journey because the duration of sunlight each day begins to erode. Like us, some animals have built in clocks which tell them its time to leave in search of warmer weather. Scientists aren't precisely sure how birds know they're going the right way. The romantic say they navigate their way following the stars or the sun, that they learn the way from their parents, or that they can use the earth's magnetic field to line themselves up. And well, that works for me.