Copperhead snakes ("Agkistrodon contortrix") are also present in the park. The Copperhead ("Agkistrodon contortrix mokasen") and Timber rattlesnake ("Crotalus horridus") are venomous. Agkistrodon contortrix mokasen is a venomous pit viper subspecies found in the eastern United States. Northern copperhead ("Agkistrodon contortrix"), timber rattlesnake. This enzyme is present in the venom of the southern copperhead snake ("Agkistrodon contortrix contortrix"). They are not closely related to the American copperhead, "Agkistrodon contortrix".