Four of Illinois' 40 native snake species are venomous, according to the Illinois Department of Natural Resources.

Illinois is home to just four venomous snakes, including the striking Eastern Copperhead and the elusive Eastern Massasauga, reminding us that outdoor adventures come with a few natural surprises.

The other venomous species found in southwestern Illinois is the timber rattlesnake. These are 36 to 60 inches long on average, IDNR reports, and have wide, flat heads.