Dalles Hesperian – State Wildlife Action Plan

Dalles Hesperian

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Vespericola depressus is a terrestrial land snail with a thin, depressed shell that is dull light brown or tan in color with rows of short, fine hairs on its spire. This species measures between 14 and 15 mm wide and between 8.7 and 9 mm high, with 5½ to 6 whorls.

Overview

  • Species Common Name Dalles Hesperian
  • Species Scientific Name Vespericola depressus

Ecoregions

Special needs

The Dalles hesperian appears to be restricted to lowland forests with basalt-derived soils or basalt taluses and dense understory . This species is associated with generally wet or very moist sites (e.g., riparian forests, spring and seep borders, near the bottom of a slope, moist valley, ravine, or gorge). In dry areas, association with a permanent water source such as a spring or seep is likely.

Limiting factors

Habitat loss and alteration are considered the most serious threats to this species. This species’ habitat has been fragmented and degraded by development in the Columbia River Gorge (e.g., highways, railroads, and dam construction). Grazing may also negatively impact this species in the eastern part of its range.

Conservation actions

Maintain appropriate habitat. Maintain undisturbed talus with the current vegetative cover and hydrologic regime. Monitor known populations and survey suitable habitat for new populations.

Key reference or plan

Hietala-Henschell, K. 2019. Interagency Special Status/Sensitive Species Program (ISSSSP) Species Fact Sheet: Vespericola depressus. USDA Forest Service Region 6 and USDI Bureau of Land Management Oregon State Office. 18 pp.