Large shallow bay of Lake Huron extending from Au Gres to Huron City, inland 15 miles from the east side of Saginaw Bay into the thumb.

Ornithological Summary

An array of waterbird species use the Saginaw Bay Area as a migratory stopover site, wintering ground, and breeding ground. Large migratory congregations of the columbianus subspecies of Tundra Swans (as many as 12,220 individuals) have been counted in November. Other significant migrant waterfowl concentrations include 505 American Black Ducks (Nov. 2003), 1550 Mallards (Nov. 2003), 9125 Redheads (Nov. 2004), 1748 Common Goldeneyes (Nov. 2002). Merganser spp. counts as high as 25,150 and 15,570 and Scaup spp. counts of 21,570 and 22,710 have also been made. Tundra Swans forage up to 15 miles inland from the Bay, typically on the west side of the thumb in agricultural fields, making daily transits to and from the bay for roosting.

Several important waterbird breeding colonies also exist within this IBA, including the Contained Disposal Facility (CDF) offshore of Bay City which supported the following numbers of nests during 1997-1999: 234 Common Tern, 324 Caspian Tern, 28,605 Ring-billed Gull, 243 Great Egret, and 480 Black-crowned Night-Heron.

Pitcher's Reef supports a small breeding colony of Black-crowned Night-Herons.

The tip of the thumb also supports the lower peninsula's largest spring raptor migration, with at least 18 species of hawks, eagles, vultures and falcons concentrated in areas from Caseville to Huron City, up to 2 miles inland, and occasionally overwater.

Conservation Issues

Eutrophication (nutrients), various forms of pollution including toxic substances, bacterial contamination, and sedimentation. Sources include sediment bedload and transport, industrial and municipal discharges, combined sewer overflows, contaminated sediments in the river and bay bottom, urban and agricultural nonpoint source runoff, old waste disposal sites, and atmospheric deposition.

This IBA sits within an area of one of the state's largest wind power resources and is being targeted for several windfarms. At least one project is already completed (Harvest Wind Farm). Additional windfarms should avoid areas within 3-5 miles of Saginaw Bay or Lake Huron so as to lessen the threat of impacting the many large kettles of diurnally-migrating raptors concentrated there from March to May. Any windfarm within 15 miles of Saginaw Bay could potentially adversely affect the 10,000+ Tundra Swans and other waterfowl which utilize these fields during spring and fall stopovers.


Open water portions of the IBA are publicly-owned. The Saginaw CDF is owned by the Michigan Department of Natural Resources.


Mostly open water. Many of the bays are lined by extensive cattail and Phragmites-dominated marshes. The Saginaw CDF facility is host to a variety of wetland and herbaeceous cover types.

Land Use

Multiple uses depending on which portion of the IBA is in question. Waterfowl hunting and fishing are common throughout, with industrial power generation (Karn-Weadock Facility) present. Surrounded by multiple managed cattail marshes and wildlife management areas.