Timber Rattlesnake (Crotalus horridus)
Description: 44 - 50 inches. Timber Rattlesnakes may be a brown, tan, gold, or gray, with black bands or chevrons down the length of the body. The head is shaped like a spade, and the eyes have vertical, cat-like pupils. There is usually a rusty brown stripe running down the center of the back, and the tails is usually black with a velvet like appearance and a light colored rattle on the end.
Similar Species: Prairie Rattlesnakes and Massasauga Rattlesnakes do not have black tails. Many non-venomous species of snakes in Iowa will wag their tail against grass and other ground debris to produce a rattle-like sound, but rattlesnakes will hold their tails off the ground while rattling them. All non-venomous snakes in Iowa have round pupils.