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BC Conservation Data Centre: Species Summary


Botaurus lentiginosus
American Bittern

 
Scientific Name: Botaurus lentiginosus (Rackett, 1813)
English Name: American Bittern
 
Classification / Taxonomy
Scientific Name - Concept Reference: American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in The Auk]. Also available online: http://www.aou.org/.
Classification Level: Species
Species Group: Vertebrate Animal
Species Code: B-AMBI
Kingdom Phylum Class Order Family
Animalia Craniata Aves Pelecaniformes Ardeidae
   
Conservation Status / Legal Designation
Global Status: G5 (Apr 2016)
Provincial Status: S3B,SNRN (Mar 2015)
BC List: Blue
Provincial FRPA list:   
Provincial Wildlife Act:
COSEWIC Status:
SARA Schedule:
General Status Canada: 4 - Secure (2005)
Migratory Bird Convention Act: Y
   
Ecology & Life History
General Description: A stocky wading bird with a straight pointed bill, relatively short neck and legs, and somewhat pointed wings; darker flight feathers; bill dull yellow with a dusky tip on the upper mandible; legs and feet are greenish yellow; breeding feathering includes generally inconspicuous white ruffs on the shoulders and two small green patches on the back; wing span 107 cm (NGS 1983). Terrestrial locomotion is slow and stealthy; flight is rapid and usually low.

MORPHOLOGY AND PLUMAGES: A brown, medium-sized heron, 60-85 cm long, with a stout body and neck and relatively short legs (Palmer 1962, Cramp 1977, Hancock and Kushlan 1984). Adult plumage is all brown above (finely flecked with black) and heavily streaked with brown and white below. The crown is rusty- brown. An elongated, black patch extends from below the eye down the side of the neck, a characteristic unique among herons (Hancock and Kushlan 1984). The throat is white. Sexes are similar, except that the male is slightly larger (Palmer 1962). Juveniles differ only in lacking black neck patches, which are obtained in the first winter. Plumage does not change seasonally. In flight, seem hurried, ungraceful, and stiff. When disturbed, they often freeze in an upright, concealing posture, with head and bill upturned.

VOCALIZATIONS: During the breeding season, males repeat from two to 10 times a distinctive, far-carrying call, rendered as "pump-er-lunk" by Palmer (1962), and which is often preceded by a series of clicking and gulping sounds. A detailed, anatomical description of how they vocalize, through inflation of the esophagus, was provided by Chapin (1922). They rely on their resounding calls to communicate among the dense, visually restricting emergent vegetation that dominates nesting habitats. Low frequency sounds, such as their "booming," attenuate less rapidly and are audible at greater distances in dense marsh vegetation than high frequency sounds (Cosens and Falls 1984). When flushed from a marsh, they often emit a hoarse "kok-kok-kok" or nasal "haink" (Palmer 1962).

EGGS: Eggs measure 49 by 37 mm and are elliptical, buff-brown to deep olive-brown, smooth, and slightly glossy (Harrison 1978).
Global Reproduction Comments: Nesting occurs solitarily (non-colonially) on all-purpose territories that provide both feeding and nesting sites, but occasionally up to a few pairs nest in a small area (Harrison 1979). Polygyny is suspected to occur (Palmer 1962). Mating rituals are elaborate, and involve display of a tuft of white nuptial feathers located on the sides of the neck (see Baker 1980, Johnsgard 1980). BOTAURUS bitterns may undergo a change in iris color from yellow to orange during courtship (Wood 1986).

The nest consists of a platform of reeds, sedges, cattail, or other available emergent vegetation, and is lined with fine grasses. Nests are usually placed on the ground, in a tussock, a few inches above water, or are floating; are surrounded by water, and have dense, overhead cover (Bent 1926, Vesall 1940, Cogswell 1977, Harrison 1978, Terres 1980). Nests may also be built in grassy uplands (Vesall 1940, Duebbert and Lokemoen 1977). Nests are usually accessed by two, well-beaten pathways (Gabrielson 1914).

Egg-laying begins in late April or early May, about a month after the arrival at nesting areas, and continues until mid-June (Bent 1926). In the north-central U.S., nests may contain eggs from about early May to early July (Brewer et al. 1991). Clutch size ranges from two to seven eggs, usually three to five (Duebbert and Lokemoen 1977, Graber et al. 1978). Incubation, by the female only, begins with the first egg (Palmer 1962). Hatching occurs after 24-28 days (Burns 1915, Bent 1926, Vesall 1940), and chicks remain at or near the nest for two weeks (Gabrielson 1914, Vesall 1940, Harrison 1979, Terres 1980). Chicks are fed only by the female, and are given fish, frogs, snakes, crayfish, and mice (Gabrielson 1914, Byers 1951). Nests often become fouled with food debris (Vesall 1940). Post-fledging behavior of young is unreported.

Apparently single-brooded (Palmer 1962). In upland habitats in North and South Dakota, 57% of 72 nests hatched at least one egg (Duebbert and Lokemoen 1977). Little is known about sources of egg, chick or post-juvenile mortality, age at fledging or first breeding, or territory size. Age at fledging for the closely-related Eurasian bittern is 50-55 days (Cramp 1977). One banded American bittern lived at least eight years (Clapp et al. 1982). Probably undergoes extensive post-breeding dispersal, which has resulted in numerous sightings, mostly between September and December, at locations as distant as Iceland, Norway, and Great Britain (Cramp 1977). Information on molt is incomplete. Adults undergo a complete post-breeding molt from August to November, and possibly a pre-breeding renewal of body plumage (Palmer 1962, but see Bent 1926).
Global Ecology Comments: Basically solitary. Low population density. Too little is known of rates of predation on nests and adults to infer the importance of predation as a factor limiting populations. Similarly, only minimal information is available on the effects of parasites and disease. Wading birds are known to be susceptible Type C botulism (occasionally), avian cholera (infrequently), chlamydial infections (frequently), sarcocystis (rarely), and aspergillosis (infrequently) (Friend 1987). Known to harbor lice and flies (Peters 1936) and a number of species of nematodes (Boyd 1966).
Migration Characteristics:
(Global / Provincial)		 
    Nonmigrant:
    Local Migrant:
    Distant Migrant:
    Within Borders Migrant: 		Y /
Y /
Y /
na /
Global Migration Comments: These birds arrive at nesting areas in the northeastern U.S. in mid to late March, about a month before the more southerly wintering least bittern (Bent 1926), but peak numbers of birds may not arrive until mid-April (Palmer 1962). Arrives in the Great Lakes region primarily in April. Wanders considerably after breeding. Southward migration extends from September to October and November (Palmer 1962).
Habitats:
(Type / Subtype / Dependence) 		Agriculture / Cultivated Field / Facultative - occasional use
Agriculture / Hedgerow / Facultative - occasional use
Agriculture / Pasture/Old Field / Facultative - occasional use
Grassland/Shrub / Grassland / Facultative - occasional use
Lakes / Lake / Facultative - frequent use
Lakes / Pond/Open Water / Facultative - frequent use
Other Unique Habitats / Estuary / Facultative - frequent use
Riparian / Riparian Herbaceous / Unknown
Wetland / Marsh / Obligate
Global Habitat Comments: BREEDING: Primarily large freshwater and (less often) brackish marshes, including lake and pond edges where cattails, sedges, or bulrushes are plentiful and marshes where there are patches of open water and aquatic-bed vegetation. Occurs also in other areas with dense herbaceous cover, such as shrubby marshes, bogs, wet meadows, and, rarely, hayfields (Brewer et al. 1991). Readily uses wetlands created by impoundments. Wetlands of 2.5 ha or more may support nesting; smaller wetlands may serve as alternate foraging sites (Gibbs and Melvin 1992). See Hanowski and Niemi (1990) for a quantitative study of habitat in Minnesota.

Nests primarily in inland freshwater wetlands, sometimes in tidal marshes or in sparsely vegetated wetlands or dry grassy uplands. Breeding occurs primarily in wetlands with tall emergent vegetation. Sparsely vegetated wetlands and dry grassy uplands are sometimes used, as are tidal marshes in some areas (Stewart and Robbins 1958, Swift 1987). In comparison to the sympatric least bittern (IXOBRYCHUS EXILIS), uses a wider variety of wetland cover types, less densely vegetated sites, shallower water depths, and primarily freshwater habitats.

Wetlands used in Maine were dominated by emergent and aquatic-bed (floating-leaved and submergent) vegetation, had a high diversity of vegetative life forms, and a high degree of cover/water interspersion (Gibbs et al. in press; Gibbs and Melvin 1990). Portions of wetlands used were dominated by sedges (CAREX spp.), broad-leaved cattail (TYPHA LATIFOLIA), and ericaceous shrubs. In a study of Quebec lakes, lakes with patches of floating-leaved plants, emergent growth along shorelines, and abundant amphibian populations were preferred (DesGranges and Houde 1989).

At Horicon Marsh in Wisconsin, responded to tape-recorded calls only from shallow water cattail and dry cattail habitats and seemed to avoid deepwater cattails (Manci and Rusch 1988). At moist soil impoundments in Missouri, associated with water depths of less than 10 cm and vegetative cover characterized as "rank, dense, or sparse." Habitat use was not associated with "open" or "short" vegetative cover or water of depths of greater than 10 cm (Fredrickson and Reid 1986). In Minnesota, seven breeding territories had a mean water depth of 10 cm, vegetation height of 1.3 m, and density of sedge and grass stems of 117 stems/m squared (Hanowski and Niemi 1986).

NON-BREEDING: Migrant bitterns were flushed at 25 sites during spring in Missouri with mean water depth of 26 cm, vegetation height of 63 cm, and stem density of 157 stems/m squared. Characteristics of 35 flush sites in fall were similar, except that vegetation was taller (118 cm) (Reid 1989). In areas where temperatures stay above freezing and waters remain open, especially in coastal regions where the ocean moderates climate (Root 1988). Wintering habitat is much like breeding habitat, and overwintering populations are heavily dependent on managed wetland areas, such as those occurring at wildlife refuges (Root 1988). Occasionally occurs in habitats that are more open than the usual ones. Overwintering occasionally takes place in brackish coastal marshes (Hancock and Kushlan 1984).
Food Habits: Carnivore: Adult, Immature
Invertivore: Adult, Immature
Piscivore: Adult, Immature
Global Food Habits Comments: Eats mainly fishes, crayfishes, amphibians, mice and shrews, insects, and other animals (Palmer 1962). Feeds young by regurgitation. Stealthy forager. The trunk is highly compressed to facilitate movement through dense vegetation. The repertoire of feeding behaviors is relatively small. Of 28 recognized heron foraging behaviors (Kushlan 1978), only four are used: standing in place, neck swaying (which may enable bitterns to overcome glare or permit a quicker strike by having muscles in movement when strike begins), walking slowly, and walking quickly. This is a solitary feeder that relies more on stealth than pursuit to capture prey. Its coloration, particularly its ventral stripes, provides camouflage in dense, vertical marsh vegetation, complements its inactive feeding repertoire, and permits solitary foraging (Kushlan 1978). Crypsis is thought to function mostly to reduce visibility to prey and competitors rather than to predators (Kushlan 1978).

The long, thick bill enables the taking of a variety of large and small prey (Kushlan 1978), a conclusion supported by analyses of stomach contents. Based on 160 specimens (133 with food remains) collected throughout North America, stomach contents included insects (23%, including many Odonates), frogs and salamanders (21%), fish (21%, including catfish, sunfish, yellow perch, suckers, killifishes, and sticklebacks), crayfish (19%), mice and shrews (10%), snakes (5%), and small quantities of crabs, spiders, and unidentified invertebrates (Cottam and Uhler 1945). Nine stomachs from Pennsylvania contained fish, frogs, crayfish, watersnakes, snails, beetles, and grasshoppers (Warren 1890). Have been observed intercepting dragonflies in midair (Dudones 1983). Garter snakes (THAMNOPHIS SIRTALIS) feeding on frogs at pond margins are occasionally eaten (Ingram 1941). A captive individual ate 23.9 g (dry weight) of food (mice) per day, and required 22 hours to digest a meal and eject a pellet (Rhoades and Duke 1975).
Global Phenology: Crepuscular: Adult, Immature
Nocturnal: Adult, Immature
Global Phenology Comments: More active when light intensity is low (Palmer 1962).
Provincial Phenology:
(1st half of month/
2nd half of month)
Colonial Breeder: N
Length(cm)/width(cm)/Weight(g): 71/ / 706
Elevation (m) (min / max): Global: 
Provincial: 
   
 
Distribution
Endemic: N
Global Range Comment: BREEDING: southeastern Alaska and southern Mackenzie to Newfoundland, south to southern California, central Arizona (formerly), southern New Mexico, central Kansas, central Missouri, central and western Tennessee, western Kentucky, central Ohio, southern Pennsylvania, northeastern West Virginia, eastern Maryland, and eastern Virginia (rarely North Carolina); locally in Texas, Louisiana, Florida, and Mexico south to Puebla and the state of Mexico (AOU 1983). In the northeastern U.S., abundance declines sharply south of northern New England and New York (Gibbs and Melvin 1992). Range is large but highly discontinuous due to restricted habitat. NON-BREEDING: southwestern British Columbia, northern Nevada, northern Texas, Ohio Valley (rarely), and New York south to southern Mexico (rarely or formerly to Panama) and the West Indies (AOU 1983). Occurs in winter primarily near the coast; areas of relatively high density include southern Florida, San Joaquin Valley (California), eastern North Carolina (no longer common, H. LeGrand, pers. comm.), Okefenokee Swamp, southern Louisiana, and various national wildlife refuges elsewhere (Root 1988).
 
Authors / Contributors
Global Information Author: HAMMERSON, G., AND D.W. MEHLMAN
Last Updated: Dec 20, 1994
Provincial Information Author:
Last Updated:
   
References and Related Literature
American Ornithologists' Union (AOU). 1983. Check-list of North American Birds, 6th edition. Allen Press, Inc., Lawrence, Kansas. 877 pp.
Azure, D. A. 1998. Aspects of American Bittern ecology in northwest Minnesota. M.S. thesis. University of North Dakota, Grand Forks, North Dakota. 139 pp.
Brewer, R., G.A. McPeek, and R.J. Adams, Jr. 1991. The Atlas of Breeding Birds of Michigan. Michigan State University Press, East Lansing, Michigan. xvii + 594 pp.
Brininger, W. L., Jr. 1996. The ecology of the American Bittern in northwest Minnesota. M.S. thesis. St. Cloud State University, St. Cloud, Minnesota. 70 pp.
Brown, M., and J. J. Dinsmore. 1986. Implications of marsh size and isolation for marsh bird management. J. Wildl. Manage. 50:392-397.
Campbell, R.W., N.K. Dawe, I.McT. Cowan, J.M. Cooper, G. Kaiser, and M.C.E. McNall. 1990. The Birds of British Columbia, Vol. 1. Nonpasserines: Introduction, Loons through Waterfowl. Royal B.C. Mus. in association with Environ. Can., Can. Wildl. Serv. 514pp.
Carter, M., G. Fenwick, C. Hunter, D. Pashley, D. Petit, J. Price, and J. Trapp. 1996. Watchlist 1996: For the future. Field Notes 50(3):238-240.
Cogswell, H. L. 1977. Water birds of California. Univ. California Press, Berkeley. 399 pp.
Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1992. Birds in Jeopardy: the Imperiled and Extinct Birds of the United States and Canada, Including Hawaii and Puerto Rico. Stanford University Press, Stanford, California. 259 pp.
Forest Practices Code. 1997. American Bittern in Species and Plant Community Accounts for Identified Wildlife: Vol. 1. B.C. Minist. For. and B.C. Environ. 184pp.
Gibbs, J. P., and S. M. Melvin. 1992. American bittern, BOTAURUS LENTIGINOSUS. Pages 51-69 in K. J. Schneider and D. M. Pence, editors. Migratory nongame birds of management concern in the Northeast. U.S. Fish and Wildlife Service, Newton Corner, Massachusetts. 400 pp.
Hancock, J., and H. Elliot. 1978. The herons of the world. Harper and Row, New York.
Hands, H. M., R. D. Drobney, and M. R. Ryan. 1989. Status of the American bittern in the northcentral United States. Missouri Coop. Fish Wildl. Res. Unit Rep. 13 pp.
Hanowski, J. M., and G. J. Niemi. 1990. An approach for quantifying habitat characteristics for rare wetland birds. Pages 51-56 in Mitchell et al., editors. Ecosystem management: rare species and significant habitats. New York State Museum Bulletin 471.
Harrison, H. H. 1979. A field guide to western birds' nests. Houghton Mifflin Company, Boston. 279 pp.
Herkert, J. R., editor. 1992. Endangered and threatened species of Illinois: status and distribution. Vol. 2: Animals. Illinois Endangered Species Protection Board. iv + 142 pp.
National Geographic Society (NGS). 1983. Field guide to the birds of North America. National Geographic Society, Washington, DC.
Palmer, R. S. (editor). 1962. Handbook of North American birds. Vol. 1. Loons through flamingos. Yale University Press, New Haven. 567 pp.
Payne, R. B., and C. J. Risley. 1976. Systematics and evolutionary relationships among the herons (Ardeidae). Univ. Michigan Mus. Zool., Misc. Publ. No. 150. 115 pp.
Root, T. 1988. Atlas of wintering North American birds: An analysis of Christmas Bird Count data. University of Chicago Press. 336 pp.
Terres, J. K. 1980. The Audubon Society encyclopedia of North American birds. Alfred A. Knopf, New York.
U.S. Fish and Wildlife Service (USFWS). 1987. Migratory nongame birds of management concern in the United States: the 1987 list. U.S. Fish and Wildlife Service, Office of Migratory Bird Management, Washington, D.C. 63 pp.
 

Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.

Suggested Citation:

B.C. Conservation Data Centre. 1994. Species Summary: Botaurus lentiginosus. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Dec 26, 2025).