Montana Field Guide

American Bittern - Botaurus lentiginosus

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).

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.

Montana Range

Breeding range is chiefly freshwater wetlands with tall, emergent vegetation. Sparsely vegetated wetlands occasionally, tidal marshes rarely. Winter range include areas where temperatures stay above freezing and waters remain open. Managed wetlands, such as those at wildlife refuges. (Gibbs, Melvin and Reid 1992).

Relies on stealth more than pursuit to forage. Waits motionless for long periods to capture passing prey. Eats mainly insects, amphibians, crayfish and small fish and mammals. (Gibbs, Melvin and Reid 1992).

Viewed as decreasing in numbers in the Fortine area.

Breed in freshwater wetlands. Clutch size is 2 - 7 eggs. (Gibbs, Melvin and Reid 1992). Nest record exists for June 19 at Bowdoin NWR. In the Fortine area, eggs seen Jun 4, newly hatched young Jul 8 , and records for third grown young range from Jyl 22-Aug 1.