Hi, I have found conflicting information as to when hummingbirds leave Northern Illinois. I thought they were hear through September, but the people at the local feeder store told me to take down my feeders. This is odd, because I still have hummingbirds here; one just drove me out of the yard. In any case, the people at the store seemed not to believe I had still seen them, but they've always been helpful and informative in the past. Who to believe?