Yeah, but Busse Woods isn’t connected straight through to all of the other forest preserves. AND, it’s not THAT large of an area. The Elk herd doesn’t roam free - it’s in an enclosure on the grounds.
As for a long series of rivers and lakes — it’s NOTHING like that! Maybe you’re thinking the area by Chain O’Lakes on the Fox River (which is many miles to the North and a little East)? Or perhaps the Des Plaines River which runs about 20 miles east of Busse Woods? The forest preserves that border the DP River are not very large at all, and they are frequented by too many people to have an animal like this roaming through the forests without attracting a LOT of attention... And, none of these towns border either the Fox River, or the Des Plaines River. Plus, to get to the rivers, or in between the forest preserves you’d have to go through large urban/suburban areas. Don’t get me wrong - it’s not like there isn’t any “green” left, but it doesn’t all hook up together nice and easy to provide a vast amount of land for a cougar to live off of. And, people in Elk Grove would definitely notice if the herd was thinning as well.
I grew up in the area, and trust me, cougars are NOT something that should be around there naturally at this point. And the one seen in Winnetka? I can’t even fathom that...
A 150 pound cougar was was shot to death by the Chicago Police on the north side of Chicago,near Wrigley Field in 2008. In the days preceding, cougar sitings had been reported in the Northern suburbs around Skokie, Wilmette, Winettka Stomach contents indicated cougar had been dining on deer and smaller animals.
Look at a detailed topo map of the area. There is a lot more “Greene” space than people think. And yes, the elk are in an enclosure. That’ll slow a cougar down for about 60’seconds.