Least Bittern
Ixobrychus exilis

The least bittern, the smallest heron found in the Americas, lives in marshes among thick vegetation. This bird visits the Chesapeake region in warmer months to breed and raise young.

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A least bittern sits on a branch. This least bittern does not have clear vertical stripes on its side or underbelly.
The least bittern's unique colors help them blend in to their environment. (Photo courtesy of Cornelio Chablé/iNaturalist CC BY-NC, toned and cropped)

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Appearance

The least bittern is small, growing to only about one foot in height with, at most, a 17 inch wingspan. Its crown, back and tail are a greenish black, while its neck, sides and underbelly are white and brown with a pattern of vertical stripes. Its wings are chestnut-colored with patches of paler color.

The top of the least bittern's head is slightly crested, or tufted, and its bill and eyes are yellow. Its short legs are green on the front and yellow on the back and the bottoms of its feet. Female and juvenile least bitterns have darker streaking patterns on their necks and a slight purple tinge to their crowns, backs and tails.

Feeding

Least bitterns eat small fish, invertebrates and insects. When hunting, they grasp onto emergent vegetation with their long toes and hunt prey on the surface of the water.

Predators

This bird is common prey for many species, including raccoons, bullfrogs, snakes, snapping turtles, crows and raptors. When stretching its neck into the air, the least bittern resembles surrounding marsh reeds and grasses, often making it difficult for predators to spot. It also avoids predators among the thick stands of marsh grasses by freezing when alarmed.

Flight

Least bitterns prefer moving on foot over flying when in marshes, and their flight within the marsh often appears weak with short flutters and their legs dangling. However, these birds do take flight when migrating between Central and North America.

Voice

The least bittern's call is a low pitched, quack-like, coo-coo-coo-coo.

Reproduction and life cycle

Between late May and early July, least bitterns arrive at their breeding grounds and begin forming pairs. These pairs will build solitary nests in the marsh that are close to the ground or suspended above the water on a platform made by folding over reeds and other grasses. Females lay two to seven eggs per brood and usually have only one brood per season.

Both males and females sit on the eggs to incubate them for 17 to 20 days until the eggs hatch. After hatching, chicks spend five to 17 days in the nest, being fed regurgitated food primarily by the male.

Did you know?

  • Least bitterns are so well camouflaged that, despite their abundance during breeding season, they are often very difficult to spot.
  • Because it straddles reeds rather than wading, the least bittern can feed in water that would be too deep for other herons.
  • When alarmed, the least bittern will sometimes sway to resemble marsh reeds and grasses blowing in the wind.

Sources and additional information

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