This sprawling IBA includes open lake waters, coastal wetlands, Lake Erie Islands, a large bay, sand beaches, numerous river mouths, deciduous woodlands, and shrublands. It represents the shallow backwater and associated marshes of Lake Erie. Onshore woodlands and shrublands populate ancient beach ridges, remainders from the reduction over geological time of Lake Erie. Between these ancient beach ridges lie the marshlands. The islands include an important nesting island for waterbirds (West Sister Island NWR) and migratory stopover sites for land birds (Bass Islands, Kelleys Island). Sandusky Bay is an important Bald Eagle fall/wintering area. Open waters surrounding the islands and in Sandusky Bay are important waterfowl staging areas.

Various public agencies including U.S. Fish and Wildlife Service and Ohio Department of Natural Resources (Division of Natural Areas and Preserves, Division of Parks and Recreation, Division of Wildlife) administer much of the habitat. Among the more significant sites are Maumee Bay State Park, Mallard Club Wildlife Area, Metzger Marsh Wildlife Area, Cedar Point NWR, Ottawa National Wildlife Refuge, Darby Unit ONWR, Navarre Unit ONWR, West Sister Island, Magee Marsh Wildlife Area, Toussaint Wildlife Area, Little Portage Wildlife Area, Kelleys Island, the Bass Islands, Sandusky Bay, Medusa Marsh, Sheldon Marsh State Nature Preserve, Old Woman Creek National Estuarine Research Reserve, Pickerel Creek Wildlife Area, Willow Point Wildlife Area, Resthaven Wildlife Area, and Castalia Pond. Also included are large expanses of privately managed marshland including Winous Point Marsh Conservancy, Ottawa Shooting Club, and Toussaint Shooting Club.

West Sister Island NWR provides nesting habitat for 40% of the breeding herons and egrets within the U.S. Great Lakes Basin. The Western Lake Erie Basin IBA holds the largest concentration of waterfowl anywhere in Ohio during migration. Sandusky Bay and surrounding areas provide refuge for one million waterfowl during fall and early winter staging, with the bay hosting a peak of 290,000 at one time, including up to 67,000 American Black Ducks and over 170,000 Red-breasted Mergansers. Among the other species found there, with maximum counts, are Canvasback (23,700), Redhead (9,300), Gadwall (13,100) Green-winged Teal (15,525), Northern Pintail (14,800), American Wigeon (8,500), Blue-winged Teal (12,400), Common Goldeneye (3,500), Ruddy Duck (3,300), American Coot (7,000), Mallard (100,200), and scaup species (50,600). The state record of 2,285 Bufflehead was recorded around Kelleys Island on 16 Nov 2002(T. Bartlett-Ohio Cardinal). It is increasingly utilized as a wintering area for Tundra Swans (1,000 max. season) and Snow Geese. Thousands of Canada Geese also occur. More than 45,000 waterfowl pass through Ottawa NWR during spring and fall migration. Large concentrations of waterfowl are present in spring with maximum numbers in the 100,000s. April staging in Sandusky Bay totals typical numbers of 25,000-30,000 Lesser Scaup (maximum 40,000), 9,000 Canvasbacks peak daily, and 3,000-5,000 daily Ruddy Ducks (V. Fazio).

Over 100 Bald Eagles regularly concentrate in Sandusky Bay in fall and winter with fall staging numbering as many as 200 in the region. The historical beach ridge bridged by the Magee Marsh Wildlife Area boardwalk is a major conduit for migrant land birds. A second historical beach ridge 7 miles southeast of Magee is the site where Black Swamp Bird Observatory annually bands thousands of neotropical migrants. Over 250 species of birds are recorded annually in the region.

The marshes are the largest breeding and migratory area for rails and bitterns in the state. This includes what may be the only viable population of King Rails in the state.

The northwest Ohio and southeast Michigan marshes are important migratory resting and feeding habitat for shorebirds. The Lake Erie marshes qualify as a Site of Regional Importance in the Western Hemisphere Shorebird Reserve Network.

Thirty-eight species of shorebirds have been recorded within the marshes since 1993. Spring migration stopover sites include controlled-level marshes and flooded crop fields. In fall, shorebird migration can be concentrated, especially on the Crane Creek estuary. As many as 15,000 shorebirds are recorded during peak days in fall migration. The Crane Creek estuary and several associated marshes comprise the only known eastern U.S. site for Long-billed Dowitchers to stage and molt in fall over the course of several weeks (500-600 max. season in November). Includes federally-designated habitat for Piping Plover. Over 100,000 shorebirds have been documented visiting the northwest Ohio and southeast Michigan marshes annually during northward and southward migrations, with total stopover population estimates ranging from 500,000 to 1 million.

Over 100,000 Double-crested Cormorants have been counted during late summer staging in western Lake Erie.

Migrant land birds pass through the region in the millions according to some estimates. The region is a significant area for breeding of many species including Yellow Warbler, Marsh Wren, and Willow Flycatcher.