At Carlyle Lk dam area, they cut down 90% of the trees in this one field area next to the old river channel to prevent raptors from perching on the trees and hunting those snakes. One time when we were camping there, there was a group of volunteers scrounging the field for nests.Only rattlesnake I've ever seen was a eastern massasauga when I was a kid. It's threatened/endangered in Illinois and is mostly a wet prairie snake. Found out years after seeing it that there is a State refuge area about 5 miles away as the crow flies that was created for the snakes preservation. It's a wet prairie of only ~ 6 acres and is fenced with no access. No public road to it, access is only by easement through privately owned property.