Came across a small timber rattler closer to Earlham than Winterset in a gravel road when I was a kid. Thats the only one I have seen. Iowa populations really fascinate me. Timber rattlers can be found in Madison county area both north and south of 92 and from western side of the county to eastern side near st charles. I dont live to far away and will occasionally go for a drive on the gravels just seeing the country side and try to keep an eye out to see one crossing a road. I'd really love to see one again and watch/take some pictures. Through different posts on different platforms I have learned of a couple specific spots that definitely have a den nearby and would be a great spot to find one. That said, snakes creep me, I just want to know its there, I have no desire to be hiking around in the brush/grass trying to find one on my own. I'd love to go with someone that knows a specific spot and they lead the way just so I could see one.
I've about scoured the internet in regards to timber rattlers in madison county, have found several good articles. Back in the 1800s when the area was being settled there use to have round ups and there was a lot more than there is today. I also found an article about snake bite deaths in Iowa and in the 1800s to early 1900s there were a handful in both adair and madison counties, among other counties. There use to be a bounty for them in Allamakee county as late as the 1960s. There are known populations in obviously madison and Allamakee, but also Winnieshiek, Clayton, Dubuque Jackson, Jones..i think maybe even Linn..really just about any eastern edge and northeast county ...and im not sure, but some sources show pops in monroe and marion, must be small in those if there are, ive not seen any confirmed photos from those, it would not surprise me as they are native to IA and use to be found throughout the state, obvioulsy as the state became settled and farming practices went into effect it destroyed the majority of habitat.
There are a few websites you can find some great documentation, herpjournal.com is one. iowaherps.com. If you google around you can find some great information on Iowa information and also the facebook page 'reptiles and amphibians of iowa'
-The Massasgua rattler can be found in just a few knows spots in southeast IA that are closely monitored.
-Prairie rattlers are knows to remain on just one small area that is in northwest IA north of Sioux City.
-Copperheads, There are a couple very small known areas that do have some copperheads in extreme southeast IA.