ames Bailey stands on the banks of Romney Creek, a broad but short tidal stream that flows through the US Army's Aberdeen Proving Ground and into the Chesapeake Bay north of Baltimore. Here, on a sunny fall day, an eastern deciduous forest sheds its autumn leaves quietly not far from a site where Army engineers test weapons, munitions, and other military equipment. A short distance upstream, some 30-40 roosting bald eagles eye the water for signs of fish. Downstream, great mounds of dried guano on Pooles Island in the Chesapeake Bay attest to the 600 pairs of great blue herons that nested there over the summer. At a nearby pond, some 2000 ducks and other migrating waterfowl rest on cool fall nights. If we weren't here, this land would be all marinas and condominiums, says Bailey, an Army wildlife biologist at Aberdeen. Instead, Aberdeen's 79,000 acres hold a healthy deer herd, beaver ponds, turkey vultures and black vultures, red-tailed and marsh hawks, and the largest bald eagle population on the northern Chesapeake. We are a de facto wildlife sanctuary, Bailey