American Bittern

Species Profile

Scientific name: Botaurus lentiginosus

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Current Status: In Pennsylvania, the American bittern is listed as state endangered and protected under the Game and Wildlife Code. Although not list as endangered or threatened at the federal level, the American bittern is a species of high concern in the Upper Mississippi Valley/Great Lakes Region of the North American Waterbird Conservation Plan and is a U. S. Fish and Wildlife Service migratory bird of conservation concern in the Northeast. All migratory birds are protected under the Migratory Bird Treaty Act of 1918.

Population Trend: American bitterns (Botaurus lentiginosus) are uncommon to rare regular migrants in most of Pennsylvania. In Crawford County, however, they are regular breeding residents in scattered large wetlands, especially Geneva Marsh on State Game Lands 213. Nesting activity was confirmed or suspected in 17 counties in the twentieth century. The 2nd Pennsylvania Breeding Bird Atlas (2004-2008) includes two confirmed breeding records (Centre County and Tioga County), which is three less than reported during the first Breeding Bird Atlas (1983-1989). The Marsh Creek wetland (State Game Lands 313), locally known as "The Muck," supports a good population of this species and other wetland birds, giving it the well-deserved designation as a Pennsylvania Important Bird Area (IBA). The American bittern has suffered greatly from the loss of wetland habitat, especially in southeastern Pennsylvania, where many marshes once used by breeding bitterns have been filled or reduced in size for development or choked by sedimentation. This species has been heard in Quakertown Swamp, Bucks County, however, another Pennsylvania IBA. The American bittern was listed as a threatened species from 1979 until 1997, when it was reclassified as endangered.

Identifying Characteristics: This large, cryptically-colored heron is usually seen when flushed from marshes. It is easily identified by its large size – up to 34 inches tall and with a 50-inch wingspan – and its streaked, brown plumage. At rest, its black moustache-like cheek markings are diagnostic. In flight, conspicuous black outer wings are characteristic. The secretive American bittern may be best known for its habit, when it feels threatened, of standing upright with its bill pointing upward. At times, it even sways from side to side, moving like the tall reeds and grasses surrounding it. In this pose the bird blends in with its surroundings and easily goes unnoticed. One of the best ways to find this species is by hearing its far-carrying, deep and resonant vocalization: Pump-a-lunk! Pump-a-lunk! or Oong-ka'-choonk, Oong-ka'-choonk.

Biology-Natural History: American bitterns nest in marshes across the northern United States and southern Canada. They winter across the southern United States, through Mexico and into Central America. Bitterns are stealthy birds that are most active in the early and late hours of the day. Pairs nest singly, not in colonies like many other herons. This bird may be found year-round in Pennsylvania, but bitterns are most often seen here during spring and fall migrations. A few nest in scattered marshes across Pennsylvania, particularly in the northwest's Pymatuning region. American bitterns build platform nests of reeds and grasses near the water, and normally lay a clutch of three to seven buff or olive-brown eggs. Young hatch in 24 to 28 days and leave the nest after another two weeks. They are often seen stalking along shorelines and marshes where they prey on frogs, fish, snakes, crayfish, insects and other aquatic organisms.

Preferred Habitat: American bitterns require large wetland habitats. They are most likely found in marshes and wetland borders along lakes, ponds, rivers and streams. American bitterns seem to prefer to breed in extensive freshwater marshes, especially those with dense stands of cattails and thick patches of bulrushes, grasses and sedges and pockets of open water. During migration, bitterns can visit a variety of wet habitats including small marshes, ditches and wet meadows.

Reason for Being Endangered: The American bittern is endangered because of its dependency on specialized marshes; wetlands have declined by more than 50 percent in Pennsylvania over the past two centuries. Marshes remain at risk from sedimentation, eutrophication, chemical pollution and, to a lesser degree, encroachment. Habitat protection is essential for the recovery of this species.

Management Programs: Areas in Pennsylvania where American bitterns regularly nest have been identified and are being protected, when possible, from development. Protection efforts include easements, land acquisition and public education. Game Commission biologists and others who routinely perform bird survey work will continue to monitor the species for changes in distribution and nesting occurrences. The Game Commission also has been working with partners on the timing and duration of water manipulation in managed wetlands to promote seed germination as well as waterfowl, shore-bird, and marshbird habitat. For American bitterns and other species preferring dense vegetation and low to moderate water depth (two to four inches), water should be drawn slowly in late spring to allow for seed germination and create a mixture of mud flat, shallow emergent vegetation, and decaying plant matter (which is rich in aquatic invertebrates) in deeper areas. Maintaining stable water levels during the nesting season will enhance the species' breeding success. Also, removing invasive plant species (purple loosestrife, for example) and protecting wetlands from sediment and chemical pollution will benefit American bitterns and other wildlife.

Sources:
Carnegie Museum of Natural History. 2nd Pennsylvania Breeding Bird Atlas. Web. 24 July 2009.

Leberman, Robert C. American bittern. In Atlas of Breeding Birds in Pennsylvania (D. Brauning, Editor). University of Pittsburgh Press, Pittsburgh, Pennsylvania. Lowther, Peter, Alan F. Poole, J. P. Gibbs, S. Melvin and F. A. Reid. 2009. American Bittern (Botaurus lentiginosus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology.

McWilliams, G. M. and D. W. Brauning. 2000. The Birds of Pennsylvania. Cornell University Press. Ithaca, New York.

U.S. Geological Survey.Northern Prairie Wildlife Research Center website.

Suggested further reading:
Bent, A. C. 1963. Life histories of North American marsh birds. Dover Publications. New York, New York.

Gross, D. A. and C. D. Haffner. 2009. Wetland bird communities: boreal bogs to open water. In Avian Ecology and Conservation: A Pennsylvania Focus with National Implications (S. Majumdar, T. Master, M. Brittingham, R. Ross, R. Mulvihill, and J. Huffman, Eds.). Pennsylvania Academy of Science, Easton, Pennsylvania. 350 pp.

Kushlan, James A. and others. 2002. Waterbird Conservation for the Americas: The North American Waterbird Conservation Plan, Version 1. Waterbird Conservation for the Americas. Washington, DC, U.S.A.

NatureServe. 2009. NatureServe Explorer: An online encyclopedia of life. Version 7.1. NatureServe, Arlington, Virginia. Search for "American Bittern."

Pennsylvania Game Commission and Pennsylvania Fish and Boat Commission. 2005. Pennsylvania Wildlife Action Plan. Harrisburg, Pennsylvania.