Birds - Waders
AMERICAN BITTERN (Botaurus lentiginosus)
The American bittern is BLUE-listed because of its unknown population size and its dependence on wetlands with extensive stands of tall, emergent vegetation, a habitat that continues to be lost. It is designated as NOT AT RISK in Canada by COSEWIC, but is known to be declining throughout most of its North American range.
The American bittern is a secretive bird inhabiting lush, emergent vegetation along the borders of lakes, marshes and rivers. Breeding occurs in valley bottom marshes or on flat plateau regions, from near sea level on the coast, up to 1300 m in the interior. The American bittern is almost never seen on the ground because it rarely leaves heavy cover, and its cryptic plumage provides excellent camouflage. It is active mainly at dawn and dusk, when it forages by standing motionless to capture passing prey such as insects, amphibians, crayfish, and small fish and mammals. It is most often noticed when territorial males give their distinctive call. Because of its secretive habits, it is likely more abundant and widespread than currently known.
The American bittern nests in emergent vegetation, and builds its platform nest over water or mud. Nesting marshes must have extensive stands of emergent vegetation and have stable water levels throughout the nest-building, egg-laying, incubation and nestling periods. It is a solitary breeder, and the nesting season extends from early April to mid-August. Coastal populations have suffered from the loss of brackish marshes along the lower Fraser River and its major tributaries, and the drainage of most wetlands in the lower Fraser River valley. Interior populations are threatened mainly by drainage of wetlands and fluctuating water levels.
COM: NWC, NAB, EPR, QCL, NWL, NIM
GED: LIM, NAL, FRL
CEI: BUB, CAB, CAP, CHP, NAU, QUL, WCU
SBI: BAU, MCP, NEL, MAP, PAT, SSM
SIM: BOV, CAM, CCM, NKM, QUH, SCM, SFH, EKT, UFT
SOI: SOB, NOB, NTU, STU, THB
BOP: PEL
TAP: FNL, ETP, PEP
BG, BWBS, CDF, CWH, ICH, IDF, MS, SBPS, SBS
The American bittern breeds in the interior from the U.S. border (e.g., Creston and Osoyoos), north to the Mackenzie area, and on the coast along the Fraser River valley. Its centre of breeding abundance is in the Cariboo parklands. It probably also breeds in larger marshes along southeastern Vancouver Island, in the Rocky Mountain Trench of the east Kootenay, and in the Peace River lowlands.
The nonbreeding range includes the Fort Nelson Lowland, Babine Upland, Nass Basin, and northeastern Vancouver Island. The occasional vagrant reaches the Queen Charlotte Islands.
In B.C., a few American bittern winter in the marshes of southeastern Vancouver Island and the Fraser Lowlands. Its main wintering area is in the southern U.S. and Mexico. Migrants move as single birds, and are very secretive and seldom seen. Spring migrants arrive mainly in late April and May. Autumn migrants move mainly in September and early October.
ES, LL, ME, MR, RE, SH
2: herb - (nests are built in emergent vegetation)
The American bittern requires extensive stands of tall emergent vegetation (bulrush, Scirpus sp.; cattail, Typha latifolia; willow, Salix sp.), in sloughs, marshes, swamps, protected bays of lakes or river oxbows. Most nests are placed in water 5-20 cm in depth. Stable water levels are important for successful breeding.
The American bittern inhabits wetlands of all sizes, but tends to be more abundant on larger wetlands. In Iowa, nesting occurred only on wetlands >10 ha, and in upstate New York, they were formerly found mainly on marshes >4 ha.
Gibbs, J.P. and S.M. Melvin. 1993. Call-response surveys for monitoring breeding
waterbirds. J. Wildl. Manage. 57:27-34.
Gibbs, J.P., S. Melvyn and F.A. Reid. 1992. American Bittern. In The Birds of North
American, No. 18. A. Poole, P. Stettenheim, and F. Gill (eds.). Philadelphia: The Academy of Natural Sciences; Washington, DC: The American Ornithologists' Union.
Hancock, J. and J. Kushlan. 1984. The herons handbook. Croom Helm, Ltd., Kent,
England.
