Up and down, in and out, back and forth, here and gone; regular as the sun and moon and the seasons, quirky as the wind; sudden as a flood and slow as the ebb and flow of ice ages. Such are the essential rhythms of Chesapeake waters that underwrite the processions of life through the Bay region. Overlaying all, triggering the comings and goings of fish and fowl that comprise the migration shed. Come autumn, come swans flown 4500 miles from the Bering Sea and the Yukon; also geese from Hudson Bay and ducks from Saskatchewan prairie potholes. Monarch butterflies from Maine flicker through in rivers of color, bound for wintering spots in Mexico; and eels from every Chesapeake stream head for Sargasso spawning grounds. Spring brings a massive infusion of a vast variety of shorebirds that use the Chesapeake region as a waystation between the far reaches of South America to the Arctic tundra. These ancient movements, annual rituals repeated for millennia, weave a tapestry that enriches our lives, and oblige Chesapeake dwellers to maintain our hugely important waystation in this vaster scheme of comings and goings, the migration shed.