Much of the land in Northern Illinois which once supported typical prairie flora is now used for the cultivation of crops, roads and suburban lawns. Forests that remain include typical trees like the black oak, sugar maple, beech, black walnut, sweet gum, cottonwood, black willow, and jack pine. The leafy prairie-clover was listed as endangered in 2003. Among the state's fur-bearing mammals are opossum, raccoon, mink, red and gray foxes, and muskrat. More than 350 birds have been identified, with such game birds as ruffed grouse, wild turkey, and bobwhite quail especially prized. Except for the carp and catfish, most of native fish has been eliminated because of heavy industrial and sewage problems. In 2003, the US Fish and Wildlife Service listed 19 Illinois animal species as endangered or threatened.