New York Status: Special Concern
Federal Status: Not Listed
The American bittern is a medium-sized member of the Ardeidae (heron) family, weighing 0.8 to 1.1 lbs with a body length of 23.6 to 33.5 inches. This secretive marsh bird is quite distinguished with yellow, downward focused eyes and a long black streak running down the both sides of the neck. Brown upper parts and brown-and-white streaking on the neck and chest help bitterns to blend in with wetland vegetation, like cattails (Typha sp.). When they "freeze" in an alarm posture with neck and bill extended skyward, they're difficult to see while hiding in the vegetation.
While they may be difficult to locate visually, their presence is detected by a very distinct call. Early in the breeding season, they are revealed by low, gulping "pump-er-lunk" calls that resonate throughout wetlands as males defend their territories and attempt to attract a mate.
From mid-May to early July, the female produces a clutch of two to seven eggs which she will incubate for 24 to 28 days. After hatching, the altricial (helpless) young remain in the nest for two weeks. They remain near the nest site as they continue to be fed by adults for another two to four weeks. The majority of their diet is sourced from nutritionally-rich, diverse wetland habitat. The young are fed regurgitated food from the parents until fledging, though the precise age of fledging remains unknown.
Distribution and Habitat
American bitterns return to New York in early spring to establish breeding territories in interior freshwater wetlands and occasionally coastal salt marshes. Beginning in late April, they gather dead plant material to construct platform nests. Located over standing water, the nest site is well concealed by emergent vegetation such as cattails, bur-reed (Sparganium sp.), or bulrushes (Scirpus sp.). Occasionally, nests are placed in grasslands or fields next to wetlands.
This elusive species overwinters in wetlands along the southern Atlantic coast, throughout the Gulf coast states, west to California, and south throughout Central America. A few individuals venture as far as the Bahamas and Greater Antilles. The breeding range encompasses much of Canada and the U.S., extending from Newfoundland west to British Columbia, south to Virginia and westwards to the Pacific coast.
Historical accounts indicate that American bitterns were once common throughout New York State. Widespread wetland loss and degradation have contributed to population decline of this wetland obligate species.
Currently, the American bittern is considered a Species of Special Concern in New York State. It is listed as Endangered in several neighboring states, including Connecticut, Massachusetts and Pennsylvania.
Data from the North American Breeding Bird Survey (BBS) show a declining trend throughout its range. Similarly, the 2000-2005 New York Breeding Bird Atlas revealed a ten percent decrease in distribution throughout the state since the 1980s. The American bittern population decrease in New York State is directly dependent on the population decline as they're heavily reliant on wetland habitat.
Management and Research Needs
A concrete understanding of American bittern distribution, population status, and habitat associations has been hindered by the difficulty of monitoring secretive, marsh-dwelling species. A National Marsh Bird Monitoring Program is underway to address this issue by using a targeted survey protocol to elicit responses from secretive marsh bird species.