American Bittern (Botaurus lentiginosus) Michael A. Sanders Status: Special Concern (MNFI)
Tuttle Marsh Wildlife Area, Iosco Co., MI. May 2005 © Al Menk (Click to view a comparison of Atlas I to II)
The smallest of the Botaurus bitterns, the Geographically, American Bitterns are most American Bittern is also known as “stake- common in the UP and the eastern side of the driver,” “thunder-pumper,” and “mire-drum,” NLP, although sporadic MBBA II observations because of its strange and resounding extended to the southern tiers of SLP counties. vocalizations (Gibbs et al. 1992), which are Current breeding strongholds include the NLP’s unmistakable when encountered in Michigan Saginaw Bay and the UP’s Keweenaw during spring and summer months. The species Peninsula, Seney National Wildlife Refuge and is a secretive, cryptically-colored heron of eastern Chippewa County. freshwater marshes and coastal wetlands that breeds across the northern half of the United Breeding Biology States and the southern half of Canada, and Many basic biological aspects of the American winters along the southern coastal United States Bittern are not well understood due to the and throughout Mexico and much of Central species’ secretive nature and inaccessible America (Keller and Castrale 1998). habitats (Gibbs et al. 1992). They typically arrive in southern Michigan during the first two Distribution weeks of April, and occur statewide by late The American Bittern was historically more April and early May (Monfils 2004). American common in Michigan than it is today. Barrows Bitterns seem to prefer larger, cattail-dominated (1912) considered it “one of the most abundant freshwater marshes with water depths <10cm of our waders,” and Wood (1951) listed it as “a (Keller and Castrale 1998), and within these common summer resident.” Major changes in habitats utilize stealth rather that pursuit when its distribution and abundance occurred during foraging for insects, amphibians, crayfish, and the period 1960-1990 as populations declined small fish. Encounters with the species are statewide (Adams 1991). A four-year statewide usually vocalizing males or silent individuals survey of Michigan’s coastal wetlands detected observed in flight. American Bitterns at only 24% of 108 sites (Sanders et al. 2007). Cryptic nests are commonly placed above shallow water on elevated platforms made of
© 2010 Kalamazoo Nature Center American Bittern (Botaurus lentiginosus) Michael A. Sanders Status: Special Concern (MNFI) various emergent vegetation such as cattails, also be contributing factors (Keller and Castrale sedges and grasses, although some have been 1998). The American Bittern is currently listed documented in upland fields as far as 100 m as a species of Special Concern in Michigan, from water (Keller and Castrale 1998). Males and is considered endangered in Indiana, may be polygamous, nesting with several Illinois, and Ohio (Keller and Castrale 1998). females within a single territory (Baicich and Harrison 1997). The semi-altricial young leave Conservation Needs the nest after one to two weeks, but remain The primary factor in American Bittern declines nearby to receive supplemental feedings for would seem to be the loss of wetland habitat: another two weeks. nearly half of Michigan’s original wetlands have been eliminated since European settlement, with Abundance & Population Trends many of the remaining areas seriously degraded (Click to view trends from the BBS) (Cwikiel 1998, Monfils 2004). Consequently, MBBA II data indicate a continued decline in preservation and proper management of large American Bittern numbers when compared with freshwater marsh habitats (>10ha) with dense results from the first atlas period. Total block- emergent growth is the most urgent level occurrences dropped by 27% (271 from conservation need for the American Bittern 371) despite an increase in overall coverage (Kleen et al. 2004). Wetland protection during MBBA II. There was a decrease in programs which allocate funds for wetland American Bittern observations by township; restoration and protection on both public and 5.24% indicated the species’ presence in MBBA private lands should be supported. I while only 3.77% recorded the birds during MBBA II. A downward trend is also evident in Although little is known about the effects of block data; only 11.48% of the blocks reported contaminants on bitterns, many prey species American Bittern for MBBA II, while 16.67% including crayfish and amphibians are documented these birds during MBBA I. demonstrably vulnerable to agricultural Regionally, the greatest decline occurred in the pesticides (Gibbs et al., 1992); similarly, the SLP, where habitat loss and degradation have invasion of non-native vegetation such as purple been most frequent, and where block-level loosestrife, reed canary grass and common reed records fell 56%. Statewide breeding could very likely have negative impacts upon confirmations dropped from 23 to only nine, six the species’ habitat (Kleen et al. 2004, Monfils of which were recorded in the UP. 2004). Additional research into the biology of the American Bittern, which would better BBS data indicate a significant decline (-5.13% illuminate pathways toward effective per year, P<0.1) in American Bittern numbers conservation, is greatly needed. throughout the Upper Midwest from 1966-2007 (Sauer et al. 2008). National results showed a significant decrease of -1.9% annually during the same period (Sauer et al. 2008). Although BBS data are useful for suggesting trends and patterns, they should be viewed with caution as secretive wetland bird species are generally unrepresented in large-scale survey efforts. Habitat loss is likely responsible for much of the documented decline in bittern numbers, although pesticides and agricultural runoff may
© 2010 Kalamazoo Nature Center American Bittern (Botaurus lentiginosus) Michael A. Sanders Status: Special Concern (MNFI) Literature Cited Sciences Division, Michigan Department of Environmental Quality, Lansing, MI. Adams, R.J., Jr. 1991. American Bittern Sauer, J. R., J. E. Hines, and J. Fallon. 2008. (Botaurus lentiginosus). In Brewer, R., The North American breeding bird survey, G.A. McPeek, and R.J. Adams, Jr. (eds.). results and analysis 1966-2007. Version 1991. The Atlas of Breeding Birds of 5.15.2008. USGS Patuxent Wildlife Michigan. Michigan State University Press, Research Center. Laurel, MD. Available East Lansing. online at www.mbr-pwrc.uscg.gov/bbs Baicich, P.J. and C.J.O. Harrison. 1997. A /bbs/html [Accessed Oct 15, 2009]. Guide to the Nests, Eggs, and Nestlings of Wood, N.A. 1951. The Birds of Michigan. MP North American Birds. 2nd Edition. 75. University of Michigan Museum of Natural World, Academic Press, San Diego, Zoology, Ann Arbor. CA. Barrows, W.B. 1912. Michigan Bird Life. Suggested Citation Michigan Agricultural Experiment Station Bulletin No. 94. East Lansing. Sanders, M.A. 2010. American Bittern Cwikiel, W. 1998. Living with Michigan’s (Botaurus lintiginosus). In Chartier, A.T., wetlands: a landowner’s guide. Tip of the J.J. Baldy, and J.M. Brenneman (eds.). 2010. Mitt Watershed Council, Conway. The Second Michigan Breeding Bird Atlas. Gibbs, J.P., S. Melvin, and F.A. Reid. 1992. Kalamazoo Nature Center. Kalamazoo, MI. American Bittern (Botaurus lentiginosus). Accessed online at:
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