Western Massasauga Rattlesnake (Sistrurus tergeminus) - Endangered


Description: 18½ - 30 inches. Western Massasauga Rattlesnakes are gray or grayish-brown with dark bands or blotches down the back. Blotches on the back become bands near the tail, which is tipped by a small rattle. The eyes have vertical, cat-like pupils and the head is shaped like a spade, though it is not as wide as the heads of other rattlesnakes in Iowa.

Similar Species: Eastern Massasauga Rattlesnakes are similar in appearance, but are only found in Eastern Iowa. Timber Rattlesnakes usually have a rusty brown stripe running down the back, and have a black tail. Prairie Rattlesnakes are similar in appearance but are not found within the range of Western Massasauga Rattlesnakes in Iowa. 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.

Age in years of Most Recent Record
75+ 70 65 60 55 50 45 40 35 30 25 20 15 10 5

This map is generated from data provided by the Drake University Biodiversity Center, observations from HerpMapper.org, the Iowa DNR Natural Areas Inventory, as well as other sources. Please help us keep it up to date by reporting your sightings to HerpMapper.