Guide to North American Birds
Conservation status Thought to have declined in many areas because of destruction of marsh habitat. Runoff of agricultural chemicals into standing marsh is another potential problem. However, still abundant in some parts of North America.
Family Herons, Egrets, Bitterns
Habitat Fresh marshes, reedy ponds. Mostly freshwater marsh but also brackish marsh, in areas with tall, dense vegetation standing in water. May be over fairly deep water, because it mostly climbs in reeds rather than wading. Sometimes in salt marsh or in mangroves.
One of the smallest herons in the world, adapted for life in dense marshes. Rather than wading in the shallows like most herons, the Least Bittern climbs about in cattails and reeds, clinging to the stems with its long toes. Its narrow body allows it to slip through dense, tangled vegetation with ease. Because of its habitat choice, it often goes unseen except when it flies, but its cooing and clucking callnotes are heard frequently at dawn and dusk and sometimes at night.

Photo Gallery

Feeding Behavior

Searches for food by clambering about in vegetation above water, and jabbing downward with its long bill to capture prey at the water's surface. Sometimes flicks its wings open and shut, which may startle prey into motion. At especially good feeding sites, it may bend down reeds to build a hunting platform for itself.


Eggs

4-5, sometimes 2-7. Pale green or blue. Incubation is by both sexes, 17-20 days. Young: Both parents feed young, by regurgitation. In response to predators near nest, adult bird may make itself look larger by fluffing out its feathers and partially spreading wings. Legs and feet of young develop quickly, and young may leave nest as early as 6 days after hatching if disturbed; ordinarily remain in nest for about 2 weeks, and near nest for another week or more. 1 or 2 broods per year.


Young

Both parents feed young, by regurgitation. In response to predators near nest, adult bird may make itself look larger by fluffing out its feathers and partially spreading wings. Legs and feet of young develop quickly, and young may leave nest as early as 6 days after hatching if disturbed; ordinarily remain in nest for about 2 weeks, and near nest for another week or more. 1 or 2 broods per year.

Diet

Mostly fish and insects. Eats mostly small fish (such as minnows, sunfishes, and perch) and large insects (dragonflies and others); also crayfish, leeches, frogs, tadpoles, small snakes, and other items.


Nesting

Nests are usually widely scattered in marsh, but sometimes in loose colonies. In one South Carolina study, Least Bitterns often nested in close association with Boat-tailed Grackles. Nest: Site is well concealed in tall marsh growth. Nest (built mostly by male) is platform created by bending down marsh vegetation, adding sticks and grass on top.

Illustration © David Allen Sibley.
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Text © Kenn Kaufman, adapted from
Lives of North American Birds

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Migration

Not well known; probably migrates mostly at night. Although its flight seems weak, some individuals travel long distances. Migrates north in mid to late spring and south in early fall.

  • All Seasons - Common
  • All Seasons - Uncommon
  • Breeding - Common
  • Breeding - Uncommon
  • Winter - Common
  • Winter - Uncommon
  • Migration - Common
  • Migration - Uncommon

See a fully interactive migration map for this species on the Bird Migration Explorer.

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Songs and Calls

A soft coo-coo-coo, easily overlooked.
Audio © Lang Elliott, Bob McGuire, Kevin Colver, Martyn Stewart and others.
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How Climate Change Will Reshape the Range of the Least Bittern

Audubon’s scientists have used 140 million bird observations and sophisticated climate models to project how climate change will affect this bird’s range in the future.

Zoom in to see how this species’s current range will shift, expand, and contract under increased global temperatures.

Climate Threats Near You
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Climate threats facing the Least Bittern

Choose a temperature scenario below to see which threats will affect this species as warming increases. The same climate change-driven threats that put birds at risk will affect other wildlife and people, too.