Columbia Oregonian (snail) (Cryptomastix hendersoni)

Category: Molluscs
Ecosystems: Riparian areas
State status: Candidate
Vulnerability to climate change (More details)


If you see this species, please share your observation using the WDFW wildlife reporting form. Providing detailed information such as a photo and exact coordinates will improve the confidence and value of this observation to WDFW species conservation and management.

The Columbia Oregonian's overall abundance is low across its range. Population segments occur in fairly remote areas. Population trends have been declining; some populations have been extirpated. Snails in the Cryptomastix genus are of conservation concern because they have specialized habitat requirements. Snails do not readily disperse and populations are isolated. They are vulnerable to alteration of their habitat.

Description and Range

Physical description

The Columbia Oregonian is a medium-sized terrestrial snail in the genus Cryptomastix. The Cryptomastix species are medium to moderately large Pacific Northwest endemics.

The shell of the Columbia Oregonian measures 0.55 inch to 0.63 inches (14 to 16 mm) wide by 0.31 to 0.35 (8 to 9 mm) high. The spire is low, with 5 to 5-1/2 whorls, and the shell may show very faint ridges. The shell opening is rounded and white with a flattened lip. A whorl is the part of the shell that is one 360-degree section of the spiral; the spire consists of all whorls except the body whorl.

Ecology and life history

This species inhabits margins of low to mid-elevation seeps and spring-fed streams in an otherwise semi-arid landscape in associated talus in open, rocky prairies with few or no trees. It is typically found among moist talus, rocks and herbaceous vegetation. 

Columbia Oregonians hatch from eggs and live for more than one year, but there is little information regarding reproduction, oviposition, eggs, development, or potential longevity of Cryptomastix species. The species is likely sedentary with limited active dispersal ability.

Cryptomastix species may be herbivorous, detritivorous, or fungivorous feeding on green plants during certain seasons and microorganisms associated with decaying leaf litter, such as algae, molds, yeasts and bacteria in others.  

Geographic range

Populations of the Columbia Oregonian occur in fairly remote areas, with most locations isolated from one another by surrounding arid landscape. This species is known from both sides of the Columbia River in Oregon and Washington, from the Columbia River Gorge east and along the Snake River, through the Blue Mountains and Hells Canyon region to west-central Idaho, and is found north along the Yakima River as far as 3 miles north of Yakima. Washington counties include Klickitat, Yakima, Benton, Walla Walla, Columbia, Garfield, Whitman, Franklin and Asotin. 

Climate vulnerability

Sensitivity to climate change


There is limited information on the sensitivity of the Columbia Oregonian snail to climate change. This species is found in low-elevation seeps and streams of the Columbia River Gorge as well as mid-elevation upland habitats (782-1000 meters) in hemlock forests. In each of these locations, the snails find cover provided by herbaceous riparian vegetation in aquatic environments and large woody debris in forests. Loss of these refugia would likely alter the temperature and moisture regimes – low temperature and moderate to high humidity – upon which this species relies.

Confidence: Low

Exposure to climate change


  • Increased temperatures
  • Reduced soil moisture and/or drought
  • Altered fire regimes
Confidence: Low


This species is identified as a Species of Greatest Conservation Need (SGCN) under the State Wildlife Action Plan (SWAP). SGCN-classified species include both those with and without legal protection status under the Federal or State Endangered Species programs, as well as game species with low populations. The WDFW SWAP is part of a nationwide effort by all 50 states and five U.S. territories to develop conservation action plans for fish, wildlife and their natural habitats—identifying opportunities for species' recovery before they are imperiled and more limited.
This species is identified as a Priority Species under WDFW's Priority Habitat and Species Program. Priority species require protective measures for their survival due to their population status, sensitivity to habitat alteration, and/or recreational, commercial, or tribal importance. The PHS program is the agency's main means of sharing fish and wildlife information with local governments, landowners, and others who use it to protect priority habitats for land use planning.

Conservation Threats and Actions Needed

  • Fish and wildlife habitat loss or degradation
    • Threat: Loss of perennial flow due to diversions
    • Action Needed: Taxonomic clarification for additional taxa; delineate occupied sites
    • Threat: Habitat loss to development
    • Action Needed: Delineate and protect sites

See the Climate vulnerability section for information about the threats posed by climate change to this species. 



Applegarth, J. S. 1999. Management Recommendations for Cryptomastix hendersoni, the Columbia Oregonian (land snail) v.20, Section 2, in T. E. Burke, J.S. Applegarth, and T. R. Weasma. Management Recommendations for Survey and Manage Terrestrial Mollusks (v. 2). USFS and BLM.

Burke, T. E. 2013. Land Snails and Slugs of the Pacific Northwest. Oregon State University Press, Corvallis, OR. 344 pp.

Burke, T., J. Applegarth, T. Weasma, and N. Duncan. 1999. Management recommendations for Survey and Manage terrestrial mollusks, ver. 2.0. USDA Forest Service, USDI Bureau of Land Management. Available online at

COSEWIC. 2013. COSEWIC assessment and status report on the Oregon Forestsnail Allogona townsendiana in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xii + 87pp. (

Duncan, N. 2009. Vespericola columbianus depressa. Species Fact Sheet. Interagency Special Status/Sensitive Species Program, Forest Service, Bureau of Land Management.

Edworthy, A., K. Steensma, H. Zandberg, and P. Lilley. 2012. Dispersal, home range size and habitat use of an endangered land snail, the Oregon Forestsnail (Allogona townsendiana). Canadian Journal of Zoology 90(7):875–884.

Frest, T. J., and E. J. Johannes. 1995. Interior Columbia Basin Mollusk Species of Special Concern. Final Report, Deixis Consultants, Seattle. Prepared for Interior Columbia Basin Ecosystem Management Project, Walla Walla, WA 362 pp.

Sato, C. 2021. Conservation assessment of the Columbia Oregonian (Cryptomastix hendersoni) Mollusca. Washington Department of Fish and Wildlife, Wildlife Diversity Division, Olympia, Washington. 3 pp. 

Steensma, K. M. M., L. P. Lilley, and H. M. Zandberg. 2009. Life history and habitat requirements of the Oregon forestsnail, Allogona townsendiana (Mollusca, Gastropoda, Pulmonata, Polygyridae), in a British Columbia population. Invertebrate Biology 128:232–242.

USFWS. 2011. Endangered and Threatened Wildlife and Plants: 90-day finding on a petition to list 29 mollusk species as threatened or endangered with critical habitat: proposed rule. Federal Register 76 (No. 193, October 5, 2011): 61826-61853.

Other resources