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Montana Animal Field Guide

Montana Field Guides

American Bittern - Botaurus lentiginosus

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Species of Concern

Global Rank: G4
State Rank: S3B

Agency Status
FWP Conservation Tier: 2
PIF: 3

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Copyright by Borror Laboratory of Bioacoustics, Department of Evolution, Ecology, and Organismal Biology, Ohio State University, Columbus, OH, all rights reserved.
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. The American Bittern is 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 and finely flecked with black; 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 (Gibbs et al. 1992). Juveniles differ only in lacking black neck patches, which are obtained in the first winter. Plumage does not change seasonally.

Diagnostic Characteristics
Differs from night-herons in the following ways: wings are pointed rather than rounded; flight feathers are much darker than back (vs. no contrast), upperparts lack white spotting; and bill is more slender. Much larger than the Least Bittern (average length 71 cm vs. 33 cm). Differs from similar juvenile Green Heron in being larger (length 71 cm vs. 46 cm) and in having flight feathers of wings obviously darker than the middle of the back.

General Distribution
Montana Range

Western Hemisphere Range


Distribution Comments
American Bitterns breed across a large portion of Canada and the U.S., occurring from n. British Columbia and s. Northwest Territories to Newfoundland in the north and from s. California to Virginia in the south. They winter inland across the southern tier of the U.S. south through Mexico to Guatemala and Belize, along both coasts from British Columbia and New Jersey to Nicaragua, and in parts of the West Indies.

Summary of Observations Submitted for Montana
Number of Observations: 301

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density


(direct evidence "B")

(indirect evidence "b")

No evidence of Breeding
(transient "t")

(regular observations "W")

(at least one obs. "w")


(Records associated with a range of dates are excluded from time charts)

Bitterns typically arrive from late April to early May, nest from late May through July, and are gone by late September. The earliest sighting was at Terry on 23 April 1893 (Cooke 1913) and the latest was on the Missoula CBC on 19 December 1981; the latter record is the only documented occurrence on a Montana CBC.

American Bitterns favor large freshwater wetlands with tall emergent vegetation such as cattails and bulrushes. Sparsely vegetated wetlands are occupied occasionally, tidal marshes rarely. The typical nest is a platform of dried rushes, sedges, and cattails placed in dense emergent vegetation over shallow water (Gibbs et al. 1992). Bitterns forage along shorelines, in dense marsh vegetation, and in wet meadows. Winter range include areas where temperatures stay above freezing and waters remain open. Managed wetlands, such as those at wildlife refuges, are often used.

Ecological Systems Associated with this Species
  • Details on Creation and Suggested Uses and Limitations
    How Associations Were Made
    We associated the use and habitat quality (high, medium, or low) of each of the 82 ecological systems mapped in Montana for vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
    1. Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2001, Adams 2003, and Werner et al. 2004);
    2. Evaluating structural characteristics and distribution of each ecological system relative to the species’ range and habitat requirements;
    3. Examining the observation records for each species in the state-wide point database associated with each ecological system;
    4. Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of “observations versus availability of habitat”.
    Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.  In general, species were associated as using an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.  However, species were not associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if point observations were associated with that system.  High, medium, and low habitat quality was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species in the literature.  The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignments of habitat quality.  If you have any questions or comments on species associations with ecological systems, please contact Bryce Maxell at or (406) 444-3655.

    Suggested Uses and Limitations
    Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.  These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.  Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.  Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.  Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).  Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species’ known geographic range.

    Literature Cited
    • Adams, R.A.  2003.  Bats of the Rocky Mountain West; natural history, ecology, and conservation.  Boulder, CO: University Press of Colorado.  289 p.
    • Dobkin, D. S.  1992.  Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34.  Missoula, MT.
    • Foresman, K.R.  2001.  The wild mammals of Montana.  Special Publication No. 12.  Lawrence, KS: The American Society of Mammalogists.  278 p.
    • Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998.  Montana atlas of terrestrial vertebrates.  Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT.  1302 p.
    • Hutto, R.L. and J.S. Young.  1999.  Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32.  72 p.
    • Maxell, B.A.  2000.  Management of Montana’s amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species.  Report to U.S. Forest Service Region 1.  Missoula, MT: Wildlife Biology Program, University of Montana.  161 p.
    • Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath.  2004.  Amphibians and reptiles of Montana.  Missoula, MT: Mountain Press Publishing Company. 262 p.

Food Habits
American Bitterns eat mainly insects, amphibians, crayfish, small fish and small mammals, occasionally garter snakes at pond margins. Contents of 133 stomachs with food items comprised 23% insects, 21% amphibians, 21% fish, 19% crayfish, 10% small mammals, 5% snakes, and smaller quantities of crabs, spiders and other invertebrates (Gibbs et al. 1992). One collected in the Flathead Lake region was filled with dragonflies (Silloway 1903)

During the breeding season, males repeat from two to ten times a distinctive, far-carrying call, rendered as "pump-er-lunk" (Gibbs et al. 1992), and which is often preceded by a series of clicking and gulping sounds. Relies on stealth more than pursuit to forage. Waits motionless for long periods to capture passing prey. In flight, bitterns seem hurried, ungraceful, and stiff. When disturbed, they often freeze in an upright, concealing posture, with head and bill upturned. The BBS is a poor means of surveying bitterns, and little is known about population trends and general biology throughout their range. Viewed as decreasing in numbers in the Fortine area (Weydemeyer 1975).

Reproductive Characteristics
Nests with eggs have been found in Montana as early as 1 June, and flightless young have been seen into late July and early August (Montana Bird Distribution Committee 2012). A nest with one fresh egg was found 19 June at Bowdoin NWR (Willett 1907). In the Fortine area, data from 10 nests in hayfields included a nest with 5 eggs on 4 June, newly hatched young 8 July, and records for third-grown young range from 22 July to 1 August (Weydemeyer 1975). Clutch size across the range is 2 to 7 eggs (Gibbs et al. 1992).

No management activities specific to American Bittern are currently occuring in Montana. A clear need exists to monitor numbers and assess nesting success and productivity in the state. Protection of large wetlands (> 10 ha) with emergenct vegetation is the most urgent management need.

Threats or Limiting Factors
Owing to 200 years of wetland losses in the U.S., numbers almost surely have declined since European colonization. Eutrophication, siltation, chemical contamination, and human disturbance also seriously degrade habitat quality. Isolation of wetlands and stabilized water regimes may also contribute to reduced habitat quality.

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Citation for data on this website:
American Bittern — Botaurus lentiginosus.  Montana Field Guide.  Montana Natural Heritage Program and Montana Fish, Wildlife and Parks.  Retrieved on April 17, 2014, from
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