Thompson Lake is one of the magical birding spots in Illinois. The number of rarities and unusual species found here in recent years is too big to list here. Breeding or summering species include up to 16 species of ducks and geese, Black-necked Stilt, Black Tern, American White Pelican, Common Gallinule, Cattle Egret, Black-crowned Night Heron, Snowy Egret, Little Blue Heron, American Bittern, Least Bittern, Sora, Virginia Rail, King Rail, Marsh Wren, Northern Harrier, Bald Eagle.

Shorebird numbers depend on the water levels. During migrations Thompson Lake is an excellent place to look for unusual shorebirds including American Avocet, Marbled Godwit, Hudsonian Godwit, Willet, Piping Plover, Western Sandpiper, Sanderling (always difficult to find away from Lake Michigan), Red-necked and Wilson’s Phalaropes. Franklin’s Gulls can usually be found here dring spring and fall migration, along with Common, Forster’s and Caspian Terns. White-faced Ibis have been seen here regularly, especially in fall. The scrub and weeds south of the observation tower can be very good for sparrows and other migrants September—November, including LeConte’s Sparrow, Nelson’s Sparrow, Sedge Wren. After breeding, hundreds of Eurasian Tree Sparrows often congregate near the observation platform.

In November and December Hundreds of thousands of waterfowl rest at Thompson, and flocks of 10,000 or more Snow Geese are frequently encountered. Ross’ Goose, Greater White-fronted Goose and Cackling Goose can usually be found here as well.

At the Clark Rd. hunter’s access, many scrub and prairie species can be found, including Henslow’s Sparrow, Yellow-breasted Chat, White-eyed Vireo, Bell’s Vireo, Willow Flycatcher, Red-headed Woodpecker. Walking the half-mile trail to the water’s edge can often be very productive. Note that the access is simply a mowed path in the grass, and may not be accessible to all vehicles.

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