Watercolor portrait of Least Bittern (Ixobrychus exilis)

Least Bittern

Ixobrychus exilis
Breeds in summer in scattered wetlands a… Dense marshes with tall emergent vegetat… Breeding Song

Learn to identify the Least Bittern by ear. Master the "Soft coo-coo-coo" phrase and tell it apart from similar species.

“Soft coo-coo-coo”

What the Least Bittern sounds like

One of the smallest herons in the world, measuring only about 11-14 inches. It has a very slender body and a long neck and bill. Adult males have a glossy blackish-green crown and back, with rich chestnut brown wing patches and buffy-ochre neck and sides; females are similar but with dark brown (not black) on the crown and back, and overall slightly paler tones. Underparts in both sexes are whitish with brown streaks on the neck and breast. Legs are yellow-green. Adapted for clambering in reeds, it often perches with its body vertical and neck extended, appearing almost like a reed itself.

“Soft coo-coo-coo”

How to tell it apart

Listen for:The male Least Bittern's song is a low, repetitive cooing. It's usually described as a series of soft "coo-coo-coo" notes, almost dove-like but quieter. These notes carry through the marsh at dawn and dusk during breeding season. The song is easily overlooked because of its subtle volume; you might need to be fairly close to hear this gentle hooting. Often written as “Soft coo-coo-coo”.
Don't confuse with:The American Bittern — much larger (double the length) and more robust, with bold brown streaks all over and lacking any chestnut color patches.

Where you'll hear it

Dense marshes with tall emergent vegetation. Prefers freshwater or brackish marshes dominated by cattails, reeds, bulrushes, or similar plants standing in shallow water. Can inhabit extensive marshes or even small reedy ponds. Often in wetlands with a mix of open water and dense cover for foraging. Seldom seen out in the open; usually stays within thick vegetation. In winter, also uses coastal mangroves or tidal marsh edges with dense growth.

A shy, mostly crepuscular bird – most active at dawn, dusk, and nighttime. Often heard giving soft cooing calls at dusk and sometimes during the night. Breeding occurs in late spring and summer, when pairs build well-hidden platform nests in marsh vegetation. They may nest in loose colonies if habitat is good. During breeding season, territorial calls (a soft coo-coo-coo) are commonly heard at twilight. In winter, they remain quiet and solitary in dense marshes.

Similar species

American Bittern

Much larger (double the length) and more robust, with bold brown streaks all over and lacking any chestnut color patches.

Green Heron

Larger (16-18") and stockier, usually seen perched at pond edges.

Least Bittern song FAQ

What does a Least Bittern sound like?
The male Least Bittern's song is a low, repetitive cooing. It's usually described as a series of soft "coo-coo-coo" notes, almost dove-like but quieter. These notes carry through the marsh at dawn and dusk during breeding season. The song is easily overlooked because of its subtle volume; you might need to be fairly close to hear this gentle hooting. Listen for the "Soft coo-coo-coo" phrase.
How do I tell a Least Bittern from a American Bittern by sound?
American Bittern: Much larger (double the length) and more robust, with bold brown streaks all over and lacking any chestnut color patches.; American Bittern gives a booming call and is usually found in more open marsh; the Least Bittern is significantly smaller and often up in the reeds rather than on the ground..
When is the best time to hear a Least Bittern?
A shy, mostly crepuscular bird – most active at dawn, dusk, and nighttime. Often heard giving soft cooing calls at dusk and sometimes during the night. Breeding occurs in late spring and summer, when pairs build well-hidden platform nests in marsh vegetation. They may nest in loose colonies if habitat is good. During breeding season, territorial calls (a soft coo-coo-coo) are commonly heard at twilight. In winter, they remain quiet and solitary in dense marshes.