Bird of the Month - April 2004
American
Bittern
Botaurus lentiginosus
Bitterns are streaked herons of marshes and similar wetlands. As a group, they are best represented in the Old World tropics. Of the world’s fourteen species, only the American and Least bitterns are found in North America. The Least Bittern is a very rarely detected visitor to our area, while the American Bittern occurs widely and is often seen.
One’s first acquaintance with the American Bittern may surprise both the birder and the bird, as a rangy brown form springs into the air from close at hand in a sapling-dotted old pasture and flies off with smooth, powerful wingbeats---leaving a lucky vole to live another hour. Or a hunter of frogs may catch the eye with its last fluid movement into a persistent stillness against cattails, its gaze never wavering from the face of the observer---also motionless, binoculars trained. Many will recall their first bittern as a remarkable sound coming from within a marsh, a peculiar and penetrating voice accompanying the songs of Common Yellowthroats and Red-winged Blackbirds. Although few persons see these birds commonly, over time even a casual birder or naturalist comes to recognize them and gain a fondness for them. Bitterns are typically found in untrammeled places in which other wildlife dependent on wetlands make a stand. Unfamiliar wonders and routines alike may be witnessed wherever bitterns are to be encountered; they stamp a landscape as worthy of paying the honor of attention.
Marshes and other freshwater wetlands with standing water and luxuriant overhead cover---cattails, reeds, rushes, or shrubbery---support American Bitterns during the breeding season. Patches of such habitat of size and quality sufficient to attract nesting bitterns is scarce and localized in the Redwood Region. During the five years of the Humboldt County Breeding Bird Atlas surveys, American Bitterns were detected in only 9 of the 425 blocks, with one Confirmed Breeding record: a family group watched and photographed by George Green and others at the Arcata Marsh in late July and early August 1995.
Bitterns are seen more often from October through April, when migrants and winter visitors move into the region. Favored sites on the north coast include Lake Earl, Goodwin’s Pond, Dry Lagoon, Essex Pond, and marshes around Humboldt Bay and in the Eel River delta. Migrants are occasionally seen in the open in grazed pastures or along exposed sloughs. Few have been found well away from the coastal lowlands in northwestern California.
Where they breed, American Bitterns may be heard at intervals throughout the day and night, as males deliver a ‘pumping’ song that sounds like a pile being driven into wet ground. A flat or saucer-shaped platform of dead marsh vegetation is built by the female, who incubates 4-5 eggs for 28-29 days. Nestlings remain in or at the nest until they fledge 42-49 days later (Ehrlich 1988, The Birders Handbook). In the manner of other herons, both adults feed the young by regurgitation.
These birds may be recognized by their fairly large size, larger than a Green Heron; brownish plumage with darker flight feathers; noticeably streaked appearance, and black marks at the side of the throat. In flight they look heavy-billed, and their large feet can easily be seen projecting beyond a short tail. Upon flushing, a bittern may utter a sharp call-note, but generally they are silent.