How to Identify the South American Rattlesnake (Identification Guide)
A guide to recognizing this widespread tropical rattlesnake by its dark diamond blotches, pale vertebral stripe, and open-habitat range across South America.
Read the full South American Rattlesnake encyclopedia entry →
Key identifying features
The South American Rattlesnake (Crotalus durissus) is identified by a bold series of dark, diamond or rhombus-shaped blotches edged in cream or pale yellow running down a tan to brownish body, paired with a distinctive pale vertebral stripe running down the center of the back in many populations. Combined with a well-developed rattle and occurrence in open, non-forested habitats across much of South America, this pattern is highly diagnostic.
Coloration & pattern
Base body color varies from tan, olive-brown, or grayish-brown to yellowish, overlaid with a row of dark brown to black diamond-shaped blotches bordered by lighter cream or pale edging. A notable feature in many individuals is a pale, light-colored stripe running along the spine, sometimes bisecting the diamond blotches, which is a helpful distinguishing trait not always present in other diamond-patterned rattlesnakes. Pattern intensity and background color vary somewhat across its wide range.
Head, eyes & scales
The head is broad, triangular, and clearly distinct from the narrower neck, typical of pit vipers, with a heat-sensing pit between each eye and nostril. Two dark, parallel stripes often run from behind the eyes toward the corners of the jaw, framing a lighter area on top of the head. Pupils are vertically elliptical, and dorsal scales are keeled, giving the body a slightly rough texture.
Size & body shape
This is a moderately large, heavy-bodied rattlesnake. Adults commonly reach 1 to 1.5 meters (about 3.3 to 5 feet) in length, with some individuals growing larger. The body is robust, tapering to a tail tipped with a well-formed segmented rattle used to produce a buzzing warning sound.
Range & habitat where you'll see it
This species has the widest range of any Neotropical rattlesnake, found across open, dry habitats including savannas, grasslands, and scrublands throughout much of South America, from Brazil, Venezuela, and Colombia south to Argentina and Paraguay. It generally avoids dense rainforest, favoring open or semi-open terrain, agricultural edges, and rocky or sandy ground.
How to tell it apart from look-alikes
Within its South American range, this is the only true rattlesnake, so the presence of a segmented rattle alone effectively rules out confusion with other pit vipers such as fer-de-lance or bushmaster species, none of which have rattles. The pale vertebral stripe and cream-edged diamond blotches further distinguish it from North and Central American rattlesnakes, which typically lack this central light stripe. Its preference for open habitat over forest also helps separate it ecologically from other large Neotropical pit vipers.
Frequently asked questions
What is the most distinctive marking on this snake?
A row of dark, cream-edged diamond blotches along the back, often accompanied by a pale stripe running down the center of the spine.
How can you tell it apart from other South American pit vipers?
It is the only true rattlesnake in South America, so its segmented tail rattle immediately distinguishes it from fer-de-lance, bushmaster, and other pit vipers that lack a rattle.
What habitat does it prefer?
Open, dry habitats such as savannas, grasslands, and scrublands, generally avoiding dense rainforest.
How large does it get?
Adults typically reach 1 to 1.5 meters (3.3 to 5 feet), with some individuals growing somewhat larger.
Where in South America is it found?
It has a very wide range, occurring from Brazil, Venezuela, and Colombia south through Paraguay to Argentina.
South American Rattlesnake identified by the community
Recent South American Rattlesnake specimens identified with Snake Identifier.
