“Prairie Rattlesnakes are the only venomous snakes in South Dakota.” National Park Service
Size
Usually about 3 to 4 feet; Montana gives 15 to 60 inches and NPS says up to 5 feet. Arizona gives a maximum of 28 to 64 inches (excluding rattle) depending on subspecies; in Colorado it is rarely over 39 inches.
How to recognize it
Rattle (or a button in newborns) at the tail tip
Head much broader than the neck, many small scales on top of the head, heat-sensing pit between eye and nostril
Vertical (cat-like) pupils
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46 records by month.What the sources say
Venom: “Prairie Rattlesnakes are the only venomous snakes in South Dakota. … South Dakota’s only species of venomous snake.” (National Park Service)
Habitat: Although these snakes enjoy open grasslands and prairies, they may also seek out forested environments. (National Park Service)
The bullsnake has no rattle, an oval or rounded head and large round pupils; the prairie rattlesnake has a triangular head, slit pupils and a rattle. Bullsnakes are often mistaken for rattlesnakes: when threatened they may coil, flatten the head, hiss and vibrate the tail in dry leaves to sound like a rattle, so do not judge by behavior or by head shape alone.
Give rattlesnakes plenty of space and do not try to handle them. National Park Service
How to report
SDGFP: [email protected] (hunting/fishing and wildlife questions); report a suspected aquatic invasive species with a photo to [email protected]; report a tick photo to SD DOH via the South Dakota Tick Survey; report wildlife violations at 1.888.OVERBAG. South Dakota Game, Fish and Parks
Venom labels come only from official sources and link to them; "Not stated" never means harmless. How labels work.
Sources
Contact Us. South Dakota Game, Fish and Parks. undated page; checked November 3, 2026.
Amphibians and Reptiles checklist. South Dakota Game, Fish and Parks (Wildlife Action Plan website checklists). undated page; checked November 3, 2026.
“Prairie Rattlesnakes are the only venomous snakes in South Dakota.”
“Prairie Rattlesnakes are the only venomous snakes in South Dakota. … South Dakota’s only species of venomous snake.”
Prairie Rattlesnakes in the Badlands. National Park Service (Badlands National Park). updated April 16, 2021; checked November 3, 2026.Quoted passages (5)
“If you are bitten by a rattlesnake, please call 911 immediately.”
“One of the best ways to prevent a bite is to give these animals plenty of space and not try to handle them.”
“Snakes typically come out of hibernaculums and return to their summer activity in April or May when the weather is warm enough.”
“Female rattlesnakes give birth to 8-17 baby snakes in the late summer. … they are born venomous.”
“In the winter, ground temperatures are too cool for snakes to be active.”
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