Photo: Hannah Meddaugh/Audubon Photography Awards

Least Bittern

Ixobrychus exilis

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.
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
  • adult male
  • adult female
  • juvenile
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.
Learn more about these drawings.

Text © Kenn Kaufman, adapted from
Lives of North American Birds

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.

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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
Songs and Calls
A soft coo-coo-coo, easily overlooked.
Audio © Lang Elliott, Bob McGuire, Kevin Colver, Martyn Stewart and others.
Learn more about this sound collection.

How climate change could affect this bird's range

In the broadest and most detailed study of its kind, Audubon scientists have used hundreds of thousands of citizen-science observations and sophisticated climate models to predict how birds in the U.S. and Canada will react to climate change.

Learn more

Read more: climate.audubon.org
Herons, Egrets, Bitterns Long-legged Waders

Least Bittern

The darker the color, the more favorable the climate conditions are for survival. The outlined areas represent approximate current range for each season.

More on reading these maps.

Each map is a visual guide to where a particular bird species may find the climate conditions it needs to survive in the future. We call this the bird’s “climatic range.”

The colors indicate the season in which the bird may find suitable conditions— blue for winter, yellow for summer (breeding), and green for where they overlap (indicating their presence year-round).

The darker the shaded area, the more likely it is the bird species will find suitable climate conditions to survive there.

The outline of the approximate current range for each season remains fixed in each frame, allowing you to compare how the range will expand, contract, or shift in the future.

The first frame of the animation shows where the bird can find a suitable climate today (based on data from 2000). The next three frames predict where this bird’s suitable climate may shift in the future—one frame each for 2020, 2050, and 2080.

You can play or pause the animation with the orange button in the lower left, or select an individual frame to study by clicking on its year.

The darker the color, the more favorable the climate conditions are for survival. The outlined areas represent approximate current range for each season. More on reading these maps.
Winter
Summer

Winter Range
Summer Range
Both Seasons
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