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Document Type

Article

Date of this Version

2026

Citation

Western Massasauga (Sistrurus tergeminus): A Species Conservation Assessment for The Nebraska Natural Legacy Project. Prepared by Colleen Rothe-Groleau and Melissa J. Panella, Nebraska Game and Parks Commission, Wildlife Division, 2026

Abstract

The Nebraska Natural Legacy Project recognizes the western massasauga (Sistrurus tergeminus) as a Tier I at-risk species. Provided are some general management recommendations regarding western massasaugas. Conservation practitioners will need to use professional judgment to make specific management decisions based on objectives, location, and a multitude of variables. This resource was designed to share available knowledge of this at-risk species that will aid in the decision-making process or in identifying research needs to benefit the species.

Criteria for selection as Tier I: State listed, G3

Estimated Population in NE: 1,000–2,500

Estimate based on: Field surveys

Trends since 2005 in NE: Stable

Range in NE: Very southeast portion of state; possible disjunct population in Colfax County

Habitat: Wet mesic tallgrass prairie, wet meadow/marsh/wet prairie, lower-middle tallgrass prairie, cordgrass wet prairie, crayfish burrows

Threats: Loss/degradation of tall-grass prairie habitat, woody invasion, tilling for agriculture, vehicle mortality

Climate Change Vulnerability Index: Extremely Vulnerable (NatureServe 2025)

Research/Inventory: Determine size/extent of Colfax County population; conduct surveys to assess distribution and abundance; conduct annual population monitoring

Landscapes: Lower Platte River, Sandstone Prairies, Southeast Prairies

The western massasauga is a medium-sized pit viper with a gray to light-brown dorsal base color, a row of 21–50 dark-brown to black dorsal blotches, sometimes described as ‘heart-shaped’ and three rows of small brown to black blotches on each side of its body (Ernst 1992; Dunn, et al. 2024). Western massasaugas typically have a whitish or cream-colored belly with dark lateral blotches. This species is, on average, slightly smaller than the similar eastern massasauga (Patten 2006). Western massasaugas have an adult snout-vent length (SVL) between 45–65 cm (~18–26 in).

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