There are many types of animals present in Illinois today. Compared to dinosaur times, today's larger animals are not very big.
White tail deer are the largest animals found in Illinois, weighing up to several hundred pounds.
There are several ecosystems in Illinois, with different types of animals found in each one. Ecosystems include forests, farmland, prairies, wetlands, lakes, urban areas, and rivers.
Many animals that live in Illinois today do well if they like habitat that is a mixture of short vegetation, brushy areas, and small areas of timber. Cottontail rabbits and white tailed deer are two examples of animals that use several types of vegetation for food and shelter.
Most native(natural) ecosystems in Illinois are very small compared to what they were several hundred years ago. Prairie areas make up less than one percent of their original area in the state and can only be found in very small plots. The number of wetland ecosystems is also less. There is much less of the state in woodland compared to 150 years ago, but there is more woodland today than in the 1930's.
Agricultural areas make up a large portion of the state. Farmland ecosystem dwellers, such as rabbits, must use cropland, fence rows, and timber that may be next to cropland for food or shelter.
When prairies, wetlands, and forests have been changed to farmland, a new ecosystem has been formed. As with other types of ecosystem changes that have occurred, animals had to adapt or move. If they could not do either one, they died out.