I happen to look out my window last winter and I noticed an odd looking bird at my feeders. It was eating on the ground near the Mourning Doves, but it was so much larger, as you can see in the first picture. I thought it was a pigeon at first, but the markings looked more like a dove.
After taking a few pictures, I got my bird book out to help identify it. It turned out to be an Eurasian Collared-Dove. Not a common guy around the midwest at all.
The birds were brought to the Bahamas from Eurasia back in the 1970's. The population has adapted and numbers are increasing. They are found further and further north in the United States every year. They prefer living in smaller towns and suburbs.
It is unknown at this time what type of impact they will have on the Mouring Doves, but so far, no changes have been detected.
I checked a national birding report and a few others have been seen in the Rockford area and at Starved Rock. Keep your eyes open, you may spot one of these too.