The American Bittern , Botaurus lentiginosus,foraging in wetlands. This bird is migratory in Maine. They need open water to forage for food. Unlike other herons, they walk slowly around in dense marsh grass. Other herons favor more open growth. When a bittern is alerted, it raises its head and neck straight into the air and freezes then slightly weaves its neck back and forth. It is believed this is to mimic the waving of tall marsh grass making them less visible to predators. The American Bittern gets its nicknames from its call: stake-driver, thunder-pumper, and mire-drum. American Bitterns are summer birds in Maine.