BioKIDS – Kids’ Inquiry of Diverse Species, Botaurus lentiginosus, American bittern: INFORMATION

Botaurus lentiginosus

What do they look like?

The American Bittern is a medium-sized heron with a stout body and a neck, short legs, and a white neck. The upperside of the bird is brown finely speckled with black. The undersides are heavily streaked with brown and white. There is a long black patch that extends from below the eye down the side of the neck.

• Other Physical Features
• endothermic
• bilateral symmetry

• Average mass

  600 g

  21.15 oz

  AnAge

• Average basal metabolic rate

  2.7412 W

  AnAge

Where do they live?

During the breeding season, the American Bittern ranges from the Mid-United States to northern Canada. Its wintering range stretches from the south Atlantic coast across the Gulf coast and west to southern California.

• Biogeographic Regions
• nearctic
  • native

What kind of habitat do they need?

In the breeding range, the American Bittern inhabits areas of freshwater wetlands with tall emergent vegetation, shorelines, and vegetative fringes. The bird prefers beaver-created wetlands to those of glacial origin.

• Terrestrial Biomes
• forest
• rainforest

How do they reproduce?

The American Bittern is considered monogamous; however, it is possibly polygynous under some circumstances. Pair formation occurs in early May when the female arrives at the nesting site. The female then chooses the nest site, which is usually in dense emergent vegetation over water that is 4-5 cm in depth. The nest is built by the female and is constructed of reeds, sedges, cattail, or other emergent vegetation. Egg laying is performed daily with one egg laid in the in the morning. Incubation begins before the full clutch is laid and lasts 24 to 28 days. Brooding and feeding duties are performed solely by the female. The hatchlings leave the nest after one to two weeks, but they receive supplemental feedings by the adults up to four weeks after hatching.

• Key Reproductive Features
• iteroparous

• gonochoric/gonochoristic/dioecious (sexes separate)

• sexual
• oviparous

• Average eggs per season

  4

  AnAge

• Average time to hatching

  34 days

  AnAge

How long do they live?

• Range lifespan

  Status: wild

  8.3 (high) years

• Average lifespan

  Status: wild

  100 months

  Bird Banding Laboratory

How do they behave?

Little is known about migration patterns of the species. Northern populations that occupy areas where temperatures can reach below freezing are known to migrate. Southern populations occupying regions where temperatures are milder, however, appear to be non-migratory. Members of the species appear to be highly asocial, with minimal pair bonds between the sexes. Foraging is completely solitary.

• Key Behaviors

• flies

• motile

How do they communicate with each other?

• Perception Channels
• visual
• tactile
• acoustic
• chemical

What do they eat?

The basic diet of the American Bittern includes insects, amphibians, crayfish, and small fish and mammals. When foraging, it relies mostly on stealth, waiting motionless for its prey to pass by. Its coloration adds to its ability to go undetected by prey. When its prey is in reach, the bird darts forward and seizes the prey in its bill. The prey is then killed by biting or shaking and is swallowed head first. Microhabitats for foraging include vegetation fringes and shorelines. Even-aged stands of older, dense or dry vegetation are avoided.

Do they cause problems?

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How do they interact with us?

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Are they endangered?

The American Bittern population is undergoing a substantial decline due to loss and degredation of habitat. The species was listed as a Nongame Species of Management Concern by the United States Fish and Wildlife Service in 1982 and 1987. It is listed as a species of special concern in the state of Michigan. Eutrophication, siltation, chemical contamination, and human disturbance have significantly reduced habitat quality by damaging the food supply. Changes in wetland isolation and stabilized water regimes are also eroding habitat quality. Acid rain is also another significant threat to the species due to its damaging effects on wetlands.

• IUCN Red List

  Least Concern

  More information

• IUCN Red List

  Least Concern

  More information

• US Migratory Bird Act

  Protected

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  Special Concern

Within the thick vegetation of its habitat, the American Bittern uses resounding calls to communicate. The eerie calls for which it known has won the species many nicknames: stake-driver, thunder-pumper, and mire-drum. The species remains relatively unstudied due to its secretive nature and inaccessible habitats.

Contributors

Marie S. Harris (author), University of Michigan-Ann Arbor.

References

Gibbs, J.P., et. al., The Birds of North America No.18. The Academy of Natural Sciences of Philadelphia, 1992.