Least bittern

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Ixobrychus exilis

Type: bird

Status:

Species Guide

Least bittern

Ixobrychus exilis

Species Type: bird

Conservation Status:

IDENTIFICATION

The least bittern is the world’s smallest heron with a length of 13 inches and a wingspan of 17 inches. It is a stocky, small-sized wading bird. The neck is buffy-white with brown streaking. Their belly is white while the upper portion of their body, their crown, and tail are black on males and dark brown on females. There is also a large bright buff wing patch. Their eyes and bill are yellow while their legs are greenish-yellow.

Like its larger cousin, the American bittern, it lives in marshes with dense vegetation. They have thin bodies. This allows them to move easily through thick reeds and grasses. Their camouflaged feathers and shy behavior often allow them to go unnoticed. When frightened, bitterns take on a reed-like position. They point their head skyward and move their body back and forth, imitating a blade of grass blowing gently in the breeze.

Bitterns fly with stiff, laboring wing beats that are quicker than other herons. Bitterns fly low with their legs trailing behind the body.

Least bitterns may be quite vocal, both during the day or at night. The male’s call is a soft coo-coo-coo. Other calls include a rail-like tut-tut-tut or kek-kek-kek-kek which can be heard year-round.

Distribution & Habitat

DISTRIBUTION AND HABITAT

The least bittern is a widespread species with a large breeding range consisting of the entire eastern half of the U.S. as well as several additional local sites as far west as California and Oregon. It winters in portions of Mexico and Central America and is a year-round resident in southern Florida, the Caribbean, Mexico, Central America, and portions of South America as far south as northern Argentina.

Least bittern habitat is largely tall emergent vegetation within freshwater marsh, although they may occasionally occupy coastal brackish marsh as well. They will use artificial wetlands as well as wetlands near lakes, rivers, or estuaries. During migration or in winter, bitterns may be found in wetlands, marshes, and grassy fields.

Diet

DIET

Least bitterns prey on small fish, amphibians, mollusks, crustaceans, insects, and some small mammals.

Hidden by its camouflaged feathers, the bittern stalks prey, standing motionless before striking with its spearlike bill. Bitterns hunt alone. They search for food within marshes or along the shorelines of creeks during the day or at night. They may also cling to reeds and other emergent vegetation in order to forage over deeper water.

Life Cycle

LIFE CYCLE

The breeding season for the least bittern in New Jersey is between mid-May and late August. A platform nest is built in a dense stand of emergent vegetation over shallow water, about a foot above the water. Both sexes construct the nest out of dried plants among live stalks. 4 to 5 eggs, sometimes as many as 7, are laid in May or June and incubation lasts 16 to 19 days. The young are semi-altrical and are tended to by both parents. The young can leave the nest 4 to 5 days after hatching but normally leave at 13 to 15 days. They are capable of flight at 25 days after hatching.

Scientific Classification

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Aves
  • Order: Ciconiformes
  • Family: Ardeidae
  • Genus: Ixobrychus
  • Species: I. exilis