A solitary species, the American Bittern is more often heard than seen. It is a stout heron, with mottled buff-brown plumage. Its neck can be held in to appear short and sturdy, or extended to look long and slender. Its upperparts are solid brown, with darker outer wings. The adult has a dark streak on either side of its neck; the streak is absent on the juvenile.
American Bitterns are found in dense freshwater marshes and extensive wet meadows. They prefer wetlands with thick cattail and bulrush, mixed with areas of open water. In the winter, they can be found in a wider range of habitats, including flooded willow and salt marshes.
American Bitterns stand still at the edge of the water, sometimes walking slowly. Like most herons, they capture prey with sudden thrusts of their bills. They are most active at dawn and dusk. When alarmed, the bittern extends its neck and head vertically and freezes or sways with the breeze, blending in with the surrounding vegetation.
Its eyes are set low on its head, enabling the bittern to see forward when it stands in this pose. The bizarre call of the American Bittern is the easiest way to locate this hard-to-find bird. The call is often described as sounding like a water pump. This dramatic and unusual vocalization is often heard at dusk or dawn and can carry long distances. The American Bittern produces this sound by spectacular contortions performed with its air-filled esophagus.
Northern populations, where water freezes, are strongly migratory. In milder areas, where water doesn't freeze, they will likely stay in the same area year round. In areas where they migrate, they leave in late September or early October and return from late April to early May.