Ardea exilis Gmelin, 1789, Jamaica. Five subspecies.
OTHER COMMON NAMES
English: Nitlin, gaulin; French: Petit blongios; German: Amerikanische Zwergdommel; Spanish: Avetorillo Panamericano.
The least bittern is the smallest heron (11–14 in [28–36 cm]), a pale buff bird with a dark crown and back and buff-colored wing patches. The female averages larger than the male. It has chestnut, rather than black, upperparts, a less prominent crown, darker neck stripes, dark brown chest streaks, and paler wing patch. Juveniles are similar to females.
The least bittern occurs in North America, Central America, West Indies, and north, west and east South America.
The habitats typically are very dense marsh vegetation in water with both woody growth and open water patches. These include fresh water marshes, lake edges, salt marshes in temperate areas, and mangroves in the tropics.
The least bittern feeds by stalking through the reeds or along the edge of dense reed stands or on branches over the water. It walks in very crouched posture, with its neck extended and its bill nearly touching the water. It may also feed by standing in one place and may build feeding platforms. The bittern posture is often assumed as a defensive display. The least bittern is very vocal, giving a low pitched, dove like advertising call and a rattling disturbance call.
FEEDING ECOLOGY AND DIET
It feeds within dense emergent vegetation. The principal prey is small fish, but its overall diet is much broader including crabs, crayfish, insects, frogs, tadpoles, salamanders, small mammals, and even small birds.
In the north, it nests in the spring and summer and at more varied times in the tropics. Nests are placed in thick herbaceous marshes, most commonly in cattail. It nests solitarily or in small groups. The male constructs the nests and advertises with a distinctive cooing call and defends its territory. The eggs are white. Clutch size is four or five eggs, with fewer in the tropics. Unlike in the large bitterns, both sexes incubate and care for young. Chicks develop quickly, being able to leave the nest temporarily by day five, wandering by two weeks. They fledge in about three or four weeks.
Not threatened. Conservation of this species depends on marsh preservation. Water impoundments and wetland construction for various purposes increase the potential habitat for the species as it often nests in cattail marshes created by human activities.
SIGNIFICANCE TO HUMANS
None known. Least bitterns are seldom noticed, due to their small size and secretive ways. They are charming small birds that well deserve additional attention.
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