Because Humbug Marsh represents a significant portion of the last unaltered wetlands in the Detroit River corridor and the last mile of natural shoreline on the river's U.S. mainland, it serves as a vital habitat for a large variety of endemic fish, birds, and plants that are regionally rare and may otherwise be extirpated from the area.
In a recent survey, approximately 51 species of native fish were found within or very close to Humbug Marsh (MDNRE unpublished Data 2006). Certain forage fish species such as Lepisosteus osseus (longnose gar), the Michigan Threatened Species Luxilus chrysocephalus (striped shiner) and bullhead catfish (Ameiurus nebulosus, A. natalis, and A.melas) are not likely to leave marsh areas to travel through the Detroit River (Goodyear et.al. 1982). Opsopoeodus emiliae (pugnose minnow), a state listed endangered species, is also likely to use the protected areas of Humbug Marsh where the fast current of the Detroit River is slowed by the island and wetlands.
Over 90 native plant species are known to occur within the Humbug Marsh complex, at least 12 of which have a coefficient of conservatism value greater than 5. This means the area has maintained some of its pre-settlement character, despite the pressures of development, influx of invasive plants, and other ecosystem alterations (Reznicek et al. 2005).
Over the past several years, a number of bird surveys have taken place in Humbug Marsh. Data from Christmas Bird Counts (2004-2007), North American Migration Counts (2005-2006) and The Big Sit (2007-2008) show that at least 154 native bird species from 39 different families use the Marsh and associated upland (Bird Watcher's Digest 2007 and 2008, Craves and Fowler 2003, Craves 2006). The number of avian species increases during fall and spring migrations, when thousands of birds make their way through the lower Detroit River. In addition to supporting migratory waterfowl, Humbug Marsh is known to be part of an important flyway for at least 17 species of raptors during their annual migrations. The area is considered essential for the preservation of migrating raptor species such as Buteo platypterus (Broad-winged Hawk) and Accipiter striatus (Sharp-shinned Hawk) by the Audubon Society, and thus, was designated as an Important Bird Area in September of 2007 (National Audubon Society 2009).
Surveys conducted in 2005 showed that the number of present and potentially occurring species of reptiles and amphibians within the Humbug Marsh complex is greater than 25. Many of these species are recognized by the Michigan Wildlife Action Plan, prepared by the Michigan Department of Natural Resources and Environment, as Species of Greatest Conservation Need. Most importantly, this site supports the Elaphe vulpine gloydi (eastern fox snake), a species protected throughout its range and listed as "threatened" by the State of Michigan (Mifsud 2005).
Finally, Humbug Marsh provides habitats for a large diversity of odonates, some of which are regionally rare. A 2007 survey found twelve species of damselflies from two families and 25 species of dragonflies from five families (Craves 2007).
As loss of habitat continues to threaten endemic species of southeast Michigan, strongholds such as the Humbug Marsh will become increasingly important in preserving the ecological integrity of the Great Lakes ecosystem as a whole.
Bird Watcher's Digest. 2007 and 2008. Data from L.M. Appel.
Craves, J. A. 2007. Baseline inventory of Odonata at the Detroit River International Wildlife Refuge,
Humbug Marsh Unit. Final Report. CCS MOA #2007CCS-98. USFWS Region 3, Fort Snelling, MN.
Craves, J. A. 2006. Thirty years of the Rockwood Christmas Bird Count, 1975-2004. Report to the
U.S.Fish Wild. Ser. Great Lakes Coastal Program. East Lansing, MI. 37 pp.
Craves, J. A. and J. A. Fowler, Jr. 2003. Twenty-five years of the Detroit River Michigan-Ontario
Christmas Bird Count. Ontario Birds 21:109-128.
Goodyear, C. S., T. A. Edsall, D. M. Ormsby Dempsey, G. D. Moss, and P. E. Polanski. 1982. Atlas of
the spawning and nursery areas of Great Lakes fishes. 14 vols. U. S. Fish and Wildlife Service,
Washington, DC. FWS/OBS-82/52.
Mifsud, D.A. 2005. Michigan Herpetological Atlas Survey Report, 2005. A Report to The Michigan
Department of Natural Resources Natural Heritage Program, Lansing, MI. 55pp.
National Audubon Society 2009. Important Bird Areas in the U.S. Available at
Reznicek, A., M. Penskar, B. Walters and S. Campbell. 2005. Floristic Quality Assessment for the
Humbug Marsh Unit of the Detroit River International Wildlife Refuge. Michigan Natural Features
Click to enlarge image.