- 11–14.2 in
- 16.1–18.1 in
- 1.8–3.6 oz
- Blongios minute, Petit Blongios, Petit Butor (French)
- Ardeola, Garza enana, Garcilla (Spanish)
- 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.
- 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.
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.
Stalks along reeds, sometimes next to rather deep water, or climbs on reed stalks, and strikes downward into water with bill.
Least Bittern populations are difficult to survey, but numbers appeared relatively stable between 1966 and 2015, according to the North American Breeding Bird Survey. However, loss of wetland habitat and the encroachment of exotic species of marsh vegetation may threaten the species. Least Bittern rate a 12 out of 20 on the Continental Concern Score and are not on the 2016 State of North America's Birds Watch List. The North American Waterbird Conservation Plan rates it a Species of High Concern.
- 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.
- Audubon, J. J. 1840. Birds of North America. First Octavo Edition.
- Kushlan, J.A., et al. 2002. Waterbird conservation for the Americas: the North American Waterbird Conservation Plan, version 1. Waterbird Conservation for the Americas. Washington, DC.
- North American Bird Conservation Initiative. 2016. The State of North
America’s Birds 2016. Environment and Climate Change Canada: Ottawa, Ontario.
- USGS Patuxent Wildlife Research Center. 2015. North American Breeding Bird Survey 1966–2015 Analysis.