Illinois: An Introduction
Illinois is a state rich in natural history, natural resources and scenic beauty. The variety of life is a result of the state’s special geographic position and geologic history. The great natural boundary between the moist forests of the eastern United States and the drier prairies of the West passes through Illinois. Along its north-south axis, Illinois is one of the longest states in the Midwest. Its northern reaches have cool summers and cold winters, while southern areas of the state have mild winters and hot summers. This mixture of temperature and moisture conditions supports a rich diversity of year-round wildlife residents and also meets the needs of many animals that are seasonal or wayward travelers.
Illinois generally receives abundant precipitation, although the state has experienced long dry periods. Woodlands occur along moist river valleys, and grasslands are found in the plains. Patches of plants more commonly found in the northern part of the United States take advantage of the cool temperature climate of the northern part of Illinois. The border of the coastal plain passes through the southern extreme of the state. There, Illinois more closely resembles the forests and swamps of Mississippi than the prairies and woodlands of the north.
Geologic events have been important in creating Illinois’ habitats. In the northwestern areas of the state, rivers have sculpted the landscape without interruption for tens of thousands of years and now course through steep wooded valleys and hollows. To the east, rivers drain glacial lakes and flow through areas renovated by the last glacier. Some lake beds are becoming marshes. In central Illinois, hundreds of miles of streams drain the rich farmlands that once were the vast grasslands and wetlands of the tallgrass prairie. In the southernmost part of the state, the Shawnee highlands were formed by the uplifting of an ancient seabed. Water running off these forested slopes cut deep canyons in the sandstone. Climatic and geologic activity together created a patchwork of habitats with different moisture, temperature and soil conditions that meet the needs of Illinois’ native plants and animals.
Illinois has also been shaped by its people. As a territory rich in natural resources, Illinois has always attracted people who have harvested its animals and plants, cultivated its rich soils, mined its mineral wealth and built great cities. Although altered by the scale of modern agriculture and industry, Illinois remains rich in native wildlife and plants. Nearly 3,000 species of plants and 600 species of vertebrates exist in Illinois. In addition, dozens of species of birds pass through during spring and fall migration, while others spend only winter months within the state. Many of Illinois’ parks and conservation areas harbor more types of plants and animals per square mile than national parks such as Yellowstone or the Grand Canyon. Best of all, Illinois’ natural heritage is located close to its people. This intersection of people and nature creates some of the best wildlife and nature viewing in the United States. We invite you to join with thousands of others who know and share the joy of wildlife and nature viewing in Illinois.