Least Bittern
Least Bittern
Botaurus exilis
At a Glance
One of the smallest herons in the world, the Least Bittern is 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 calls are heard frequently at dawn and dusk, and sometimes at night.
All bird guide text and rangemaps adapted from Lives of North American Birds by Kenn Kaufman© 1996, used by permission of Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Category
Herons, Egrets, Bitterns
IUCN Status
Least Concern
Habitat
Coasts and Shorelines, Freshwater Wetlands, Lakes, Ponds, and Rivers, Saltwater Wetlands
Region
California, Eastern Canada, Florida, Great Lakes, Mid Atlantic, New England, Northwest, Plains, Rocky Mountains, Southeast, Southwest, Texas, Western Canada
Behavior
Direct Flight, Flushes
Population
310.000
Range & Identification
Migration & Range Maps
Not well known, the Least Bittern 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.
Description
Both sexes — Length: 11–14.2 in (28–36 cm); wingspan: 16–18 in (41–46 cm); weight: 1.6–3.4 oz (45–96 g). The Least Bittern is mostly buff-colored, with a dark cap and a brown (female) or black (male) back. Large buff patches on the inner wings are distinctive, visible both when perched and in flight. Juvenile Green Herons can appear similarly brown but lack these bold wing patches.
Size
About the size of a Crow, About the size of a Robin
Color
Black, Brown, Tan, White, Yellow
Wing Shape
Broad, Pointed, Short
Tail Shape
Short
Songs and Calls
A soft coo-coo-coo, easily overlooked.
Call Pattern
Flat, Simple
Call Type
Hoot, Scream
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.
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Behavior
Eggs
4-5, sometimes 2-7. Pale green or blue. Incubation is by both sexes, 17-20 days.
Young
Both parents feed their young by regurgitation. In response to predators near the nest, adult birds may make themselves look larger by fluffing out their feathers and partially spreading their wings. Legs and feet of young develop quickly, and young may leave the nest as early as 6 days after hatching if disturbed; ordinarily, they remain in the nest for about 2 weeks, and near the nest for another week or more. 1 or 2 broods per year.
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. The Least Bittern 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.
Diet
Mostly fish and insects. The Least Bittern eats mostly small fish (such as minnows, sunfish, and perch) and large insects (dragonflies and others), as well as 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.
Conservation
Conservation Status
The Least Bittern is thought to have declined in many areas due to the destruction of marsh habitat. Runoff of agricultural chemicals into standing marsh is another potential problem. However, still abundant in some parts of North America.
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.
