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North Dakota Species of Conservation Priority III

Fact Sheet
Scientific Name Strophitus undulatus
General Description Shell is elliptical in shape and slightly compressed. Anterior of shell is rounded, posterior pointed. The shell is generally smooth and shiny. Juvenile color begins as green with rays and darkens with age to brown or black.
Status Year-round resident.
Abundance Rare.
Primary Habitat Streams with mud, sand or gravel bottoms.
Federal Status None.
Reason for Designation Found in low numbers during recent surveys. May be an edge of range species.


(Photos courtesy of Prairie Waters Education and Research Center - Valley City University)

Locations and Conditions of Key Habitat

Preferred Habitat

The Creeper is found from the east coast to a line extending south through North Dakota, Nebraska, Texas on the western edge. Species is found in varying stream sizes and bottom substrates throughout its range.

Key Areas and Conditions for Creeper in North Dakota

The Creeper is found in the Forest River, South Branch of the Park River, and the Sheyenne River. The Sheyenne River appears to have the largest population.

Problems Which May Affect this Species


Impoundments have changed the historic flow regime of the habitat. It has also blocked movements of fish species and in turn mussel species. Land use practices on surrounding lands have also impacted the river negatively. Chemical run-off and sedimentation contribute to deteriorated water quality.

Other Natural or Manmade Factors

Release of water from Devils Lake may negatively the water chemistry in the Sheyenne River.

Research and Survey Efforts

Current Research or Surveys

  • No current research or survey efforts are on-going in this species range.

Previous Research or Surveys

  • Cvancara conducted a state-wide survey of the mussels of North Dakota in 1978.
  • The North Dakota Game and Fish Department revisited Cvancara’s sites in 1990.
  • Valley City State University revisited Cvancara’s sites and surveyed additional sites in 2008.
  • The NDDH conducted freshwater mussel surveys for state waters as a segment of its Index of Biotic Integrity (IBI) work.

Additional Research or Surveys Needed

  • A monitoring protocol for mussel species has been developed for the North Dakota Game and Fish Department under the SWG program. Implementation of this monitoring protocol is a future goal.

Management Recommendations

  • Develop buffers along riparian areas.
  • Work with partners to reduce the use of chemical near waterways.
  • Work with partners to reduce wetland drainage.
  • Remove river impoundments where possible.
  • Work with partners to maintain instream flows.

Monitoring Plans

A monitoring protocol has been developed for the North Dakota Game and Fish Department under the SWG program. Implementation of this monitoring protocol is a future goal.

2005-2015 Progress

SWG T-24-R A Two Phase Population Survey of Mussels in North Dakota Rivers provided important information on the distribution of this species. Work to implement a monitoring protocol for mussels species will is a goal of the revised Wildlife Action Plan.

Range Map

Note: A listing of works consulted when compiling the information on this page may be found in the 2015 State Wildlife Action Plan.