Take this for what it's worth, but last deer season I was sitting in a tree stand in McDonough County IL and I saw something moving at 300 yards that was too big to be a feral cat and too small to be anything else, definitely feline. It was on an alfalfa field for about 5 minutes before it went back into the timber. I say take it for what it's worth because at the time I was looking head on into a freezing rain and a 20mph wind so I couldn't make a positive ID.
With that said there was a bear roaming Northern IL counties earlier this year, a tail cam pic of a Cougar in Yorkville, IL last year, and feral hogs in Fulton County, so I have no doubt there are bobcats roaming throughout the state............and per prior posts they are all specifically protected by the hunting regs (X feral swine during open gun seasons)