The American bittern (Botaurus lentiginosus) is a wading bird in the heron family that is best known for the unique, loud, guttural call made by the male, which has resulted in it being given several nicknames, including ‘water belcher’, ‘thunder pumper’, and ‘mire-drum’. These are well-camouflaged, solitary birds that stand motionless amongst tall marsh vegetation or patiently stalk their prey. American bitterns are fairly common over their wide range, however, their numbers are thought to be decreasing, especially in the south.
The American bittern is a large, chunky, brown bird. Its crown is chestnut brown with the centers of the feathers being black. The side of the neck has a bluish-black elongated patch which is larger in the male than in the female. The hind neck is olive, and the mantle and scapulars are dark chestnut-brown, barred, and speckled with black, some feathers being edged with buff. The back, rump, and upper tail coverts are similar in color but more finely speckled with black and grey bases to the feathers. The tail feathers are chestnut brown with speckled edges, and the primaries and secondaries are blackish-brown with buff or chestnut tips. The cheeks are brown with a buff superciliary stripe and a similarly colored mustachial stripe. The chin is creamy-white with a chestnut central stripe, and the feathers of the throat, breast, and upper belly are buff and rust-colored, finely outlined with black, giving a striped effect to the underparts. The eyes are surrounded by yellowish skin, and the iris is pale yellow. The long, robust bill is yellowish-green, the upper mandible being darker than the lower, and the legs and feet are yellowish-green. Juveniles resemble adults, but the sides of their necks are less olive.
The American bittern occurs widely across Central and North America. In the summer it is found in the north as far as Alaska, and Newfoundland and central British Columbia in Canada. In winter, these birds migrate south to Central America and the northernmost Caribbean islands. They typically inhabit freshwater wetlands that have tall, emergent vegetation. During breeding, they prefer marshlands and ephemeral wetlands, but also forage in wet meadows and along shorelines, often preferring areas with much plant cover and open water.
An American bittern is a solitary forager, standing motionless or slowly walking with outspread toes as it searches for food. It hunts during the day, especially at dawn or dusk. Possibly its most famous behavior is its stance when it feels threatened. It points its bill to the sky, stretches out its body, and will even sway with the breeze, in order to blend in with the reedy surroundings. So ingrained is this pose that it will sometimes use it even when out in the open. These birds do not socialize much except when migrating in small groups, or during mating, or facing off over territories - and this can be dramatic. Males in competition with each other will crouch down and approach one another, displaying the white plumes that are between their shoulders. These moves can escalate into a chase in the air, the combatants spiraling upwards, while trying to stab their opponent with their bill.
America bitterns are polygynous breeders. Male and female do not really interact with each other except for copulation, though a female may site her nest close to a "booming" male in order to distract predators from her hatchlings. Pair formation takes place in early May when females arrive at the nesting area. The female chooses her nest site, usually amongst dense emergent vegetation above water of a depth of 4-5 cm. The female constructs the nest out of reeds, cattail, sedges, or other emergent vegetation. The female lays 2-7 eggs in one clutch, with incubation beginning before all the eggs are laid and lasting 24 to 28 days. Only the female carries out brooding and feeding duties. The hatchlings leave their nest in one to two weeks, but receive supplemental feeding for up to another four weeks after hatching.
This bird has an extremely large range. The population of American bitterns is undergoing a major decline due to degradation and loss of habitat. Eutrophication (where an ecosystem is enriched with chemical nutrients), chemical contamination, siltation, and human disturbance have greatly reduced habitat quality due to damage to the food supply. Habitat quality has also been eroded by stabilized water regimes and changes in wetland isolation. Acid rain also damages the wetlands.
According to the What Bird resource, the total population size of the American bittern is around 3 million individuals. Currently this species is classified as Least Concern (LC) on the IUCN Red List, but its numbers today are decreasing.