In 1962, 5 Swans escaped a Maryland estate; 40 years later, about 4,000 threatened the Bay

Five mute swans escaped from an estate in Maryland in 1962 and their descendants multiplied to nearly 4,000 in the Chesapeake Bay region within four decades.

The invasive birds eat large amounts of underwater grasses and have also been linked to the displacement of native birds, raising concerns among wildlife managers about their growing impact on the Bay's ecosystem.