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Least Bittern


IUCN Conservation Status: Least Concern

A tiny heron, furtive and surpassingly well camouflaged, the Least Bittern is one of the most difficult North American marsh birds to spot. Despite its inconspicuousness, however, the species can be rather common within appropriate habitat in its breeding range.

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At a GlanceHelp

Both Sexes
11–14.2 in
28–36 cm
16.1–18.1 in
41–46 cm
1.8–3.6 oz
51–102 g
Other Names
  • Blongios minute, Petit Blongios, Petit Butor (French)
  • Ardeola, Garza enana, Garcilla (Spanish)

Cool Facts

  • Thanks to its habit of straddling reeds, the Least Bittern can feed in water that would be too deep for the wading strategy of other herons.
  • When alarmed, the Least Bittern freezes in place with its bill pointing up, turns its front and both eyes toward the source of alarm, and sometimes sways to resemble wind-blown marsh vegetation.
  • The Least Bittern and the American Bittern often occupy the same wetlands, but may have relatively little interaction because of differences in foraging habits, preferred prey, and timing of breeding cycles. The Least Bittern arrives on its breeding grounds about a month after the American Bittern, and leaves one or two months earlier.
  • John James Audubon noted that a young captive Least Bittern was able to walk with ease between two books standing 1.5 inches (4 cm) apart. When dead, the bird's body measured 2.25 inches (5.7 cm) across, indicating that it could compress its breadth to an extraordinary degree.



Freshwater or brackish marshes with tall emergent vegetation.



Small fish and insects.


Nesting Facts
Clutch Size
2–7 eggs
Egg Description
Pale blue or green.
Condition at Hatching
Covered in down, rusty brown on back, whitish below; able to sit and hold head up only for brief periods.
Nest Description

A platform of marsh vegetation with a canopy made by pulling tall marsh plants over and crimping them in place. Placed in dense, tall stands of vegetation.

Nest Placement




Stalks along reeds, sometimes next to rather deep water, or climbs on reed stalks, and strikes downward into water with bill.


status via IUCN

Least Concern

Difficult to survey, so few data available. Loss of wetland habitat and the encroachment of exotic species of marsh vegetation may pose a threat.


    1. Audubon, J. J. 1840. Birds of North America. First Octavo Edition.
    2. Gibbs, J. P., F. A. Reid, and S. M. Melvin. Least Bittern (Ixobrychus exilis). In The Birds of North America, No. 17 (A. Poole, P. Stettenheim, and F. Gill, eds.). Philadelphia: The Academy of Natural Sciences; Washington, DC: The American Ornithologists' Union.

Range Map Help

Least Bittern Range Map
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