Illinois is in the ‘Midwest’ of the USA, just below the Great Lakes. This is quite important because it is a relatively densely populated and intensively cultivated area of the USA. It is a state in the second tier of most densely populates states of the USA. Human population density is relevant to the survival of wild cat species: the more humans there are the less wild cats there are. Also the more farming the less natural habitat there is for wild cats.
In 2002 Mel and Fiona Sunquist writing in their wonderful book, Wild Cats of the World show a large blank hole around the state of Illinois where the American bobcat was deemed to be more or less absent at that time because of the reasons stated above: too many people and too much farming.
It is interesting to note that the IUCN Red List (the best source of information regarding the current distribution of wild cat species) tells us that the bobcat is officially present in Illinois; in around 90% of the state. This is an improvement on 2015.
No doubt occupants of that state will tell us that the bobcat is present throughout the entire state. Please report sightings in a comment.
There are no other wild cat species in Illinois according to the experts. The other American wild cat which was once found across America, the puma or mountain lion, is no longer seen in Illinois or indeed throughout the entire eastern half of the country. This super wild cat was ‘extirpated’ (eradicated) from the eastern United States by the late 1890s’ (except for a small population in Florida).
However sometimes pumas do roam from the west to the east. They can travel vast distances looking for a home range. A male puma might travel into or through Illinois.
Some people believe that small isolated puma populations still exist in remote parts of the cat’s former range. There are quite frequent sightings of pumas in the east of the USA. Even on this website there are recorded sightings in North Carolina for example.
Others argue that the sightings are of escaped captive cats or cats that have been deliberately released.
Therefore the wild cat species in Illinois are (a) the American bobcat and (b) perhaps the odd puma.
There should be no other sightings of, for example, the small wild cats such as the ocelot or the jaguarundi. These cats do not live in Illinois. Occasionally there are possible sightings of these cats in the south bordering Mexico nd in Florida but I for one have not heard of any sightings in Illinois.
See wild cats of the world map – shows where the wild cat species are found by country.