William Marengo, Regional Report Compiler
In the recent geological past, glaciers profoundly shaped nearly the entire region. The most obvious result of this is the Great Lakes, which provide the region’s three states with nearly 4,300 miles of shoreline. They also allow for impressive waterfowl migration, provide habitat for overwintering “sea ducks”, and regularly produce rarities with a “pelagic” flair. Consistent vagrant hotspots are well known, but rarities can turn up anywhere along the shore, which forms natural barriers that funnel migrant raptors and songbirds. Three of North America’s prominent and long-running raptor census counts can be found here: Michigan’s Detroit River Hawk Watch, Michigan’s Whitefish Point, and Minnesota’s Hawk Ridge. Depending upon one’s definition, the region has over 37,000 lakes. Countless ponds, wetlands, and sloughs also provide impressive habitat for migrant and nesting waterfowl and other water-dependent birds.
Three major river systems run through Minnesota and Wisconsin. The Mississippi River’s backwaters host thousands of swans and ducks in early spring and late fall, as well as providing a migration corridor for passerines. Northward, the St. Croix River, and westward, the Minnesota River, likewise act as excellent migrant corridors. Many species of birds, for example, Acadian Flycatcher, Louisiana Waterthrush, Prothonotary, Cerulean, Yellow-throated, and Kentucky warblers, reach the northern edges of their breeding ranges following these river valleys.
Prairie grassland in the western third of Minnesota and some limited areas in Wisconsin, although largely fragmented due to intensive agriculture, greatly adds to the region’s avain diversity. Species using this habitat include Smith’s Longspur, Short-eared Owl, Greater Prairie-Chicken, Sharp-tailed Grouse, Marbled Godwit, Upland Sandpiper, Nelson’s Sparrow, and LeConte’s Sparrow.