At a Glance

Extensive freshwater marshes are the favored haunts of this large, stout, solitary heron. It is seldom seen as it slips through the reeds, but the odd pumping or booming song of the American Bittern is often heard at dusk or at night, carries for long distances across the marsh.
Category
Herons, Egrets, Bitterns, Long-legged Waders
IUCN Status
Least Concern
Habitat
Coasts and Shorelines, Freshwater Wetlands, Lakes, Ponds, and Rivers, Saltwater Wetlands
Region
Alaska and The North, California, Eastern Canada, Florida, Great Lakes, Mid Atlantic, New England, Northwest, Plains, Rocky Mountains, Southeast, Southwest, Texas, Western Canada
Behavior
Direct Flight
Population
2.500.000

Range & Identification

Migration & Range Maps

May be permanent resident in a few areas at southern edge of its breeding range but most are migrants. Some winter south to West Indies and Central America. May migrate mostly at night.

Description

Sexes similar; female slightly smaller — Length: 23 - 34 in (58 - 86 cm); wingspan: 41 - 46 in (104 - 117 cm); weight: 13 - 34 oz (370 - 960 g). Warm brown overall, with strong stripes below. Black neck mark is obvious on the adult American Bittern, replaced by brown on juvenile. Compare to young night-herons. Least Bittern shares marsh habitat but looks very different.
Size
About the size of a Heron, About the size of a Mallard or Herring Gull
Color
Black, Brown, Tan, White, Yellow
Wing Shape
Broad, Pointed
Tail Shape
Short

Songs and Calls

On breeding grounds, a loud pumping sound, oong-KA-chunk! repeated a few times and often audible for half a mile. Flight call a low kok-kok-kok.
Call Pattern
Flat, Undulating
Call Type
Odd

Habitat

Marshes and reedy lakes. Breeds in freshwater marshes, mainly large, shallow wetlands with much tall marsh vegetation (cattails, grasses, sedges) and areas of open shallow water. American Bittern winters in similar areas, also in brackish coastal marshes. Sometimes feeds in dry grassy fields.

Behavior

Eggs

The American Bittern typically lays 3-5 eggs, sometimes 2-7. Eggs are a pale brown to olive-buff. Incubation is by female only, 24-28 days.

Young

Evidently only the female American Bittern cares for the young, feeding them by regurgitation of partly-digested items. Young may leave nest after 1-2 weeks, but remain nearby and are fed up to age of 4 weeks. Age at first flight unknown, possibly 7-8 weeks.

Feeding Behavior

Forages mostly by standing still at edge of water, sometimes by walking slowly, capturing prey with sudden thrust of bill. May forage at any time of day or night, perhaps most actively at dawn and dusk.

Diet

Mostly fish and other aquatic life. Eats fish (including catfish, eels, killifish, perch), frogs, tadpoles, aquatic insects, crayfish, crabs, salamanders, garter snakes. American Bittern has been seen catching flying dragonflies. In drier habitats may eat rodents, especially voles.

Nesting

Male American Bittern defends its nesting territory by advertising presence with "booming" calls. Courtship displays not well known; male may hold head low and fluff out white feathers on sides. One male may mate with two or three females. Nest: Site is usually in dense marsh growth above shallow water, sometimes on dry ground among dense grasses. Nest (apparently built by female alone) is a platform of grasses, reeds, cattails, lined with fine grasses.

Conservation

Conservation Status

American Bittern has declined seriously in southern part of breeding range, mostly owing to loss of habitat. Still numerous as a breeder in parts of Canada. Vulnerable because of its reliance on large marshes. Acid rain may reduce food supplies in some areas.

Climate Map

Audubon’s scientists have used 140 million bird observations and sophisticated climate models to project how climate change will affect the range of the American Bittern. Learn even more in Audubon’s Survival By Degrees project.

Climate Threats Facing the American Bittern

Choose a temperature scenario below to see which threats will affect this species as warming increases. The same climate change-driven threats that put birds at risk will affect other wildlife and people, too.

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