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For information on Wisconsin's rare vertebrate animals, contact:
Rich Staffen
Conservation Biologist
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Jay Watson
Conservation Biologist

Cherrystone Drop (Hendersonia occulta)



Cherrystone Drop (Hendersonia occulta) State Threatened, have a thick 6-8mm wide shell that is wider than it is high, usually reddish or yellowish in color, and lacks an opening in the center of the base of the shell. Inhabitants of small areas of algific habitat or the similar cool, moist, shaded sites of cliffs where algific conditions occur without substantial talus or ice. The species is most often found on wooded alluvial-soil banks and bluffs.

State status

Status and Natural Heritage Inventory documented occurrences in Wisconsin

The table below provides information about the protected status - both state and federal - and the rank (S and G Ranks) for Cherrystone Drop (Hendersonia occulta). See the Working List Key for more information about abbreviations. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. The map is provided as a general reference of where occurrences of this species meet NHI data standards and is not meant as a comprehensive map of all observations.

Note: Species recently added to the NHI Working List may temporarily have blank occurrence maps.

Documented locations of Hendersonia occulta in the Natural Heritage Inventory Database as of July 2015.
Summary Information
State StatusTHR
Federal Status in Wisconsinnone
State RankS2S3
Global RankG4
Tracked by NHIY

Species guidance

Note: a species guidance document is not available at this time. Information below was compiled from publication PUB-ER-085-99 (now out-of-print).

Identification: The shell is thick, wider than high, reddish or yellowish in color, marked by fine spiral lines across the surface of the whorls, and about 0.25 inches (5-8 mm) in diameter. The domed shaped spire (top part of shell above the aperture) has 6 whorls with the sutures (seams between the whorls) unimpressed. The base is rounded and without an opening, the umbilical area covered by a callous pad. In adults, the outer lip is greatly thickened forming a heavy projecting ridge.

Habitat: Inhabitants of small areas of algific habitat or the similar cool, moist, shaded sites of cliffs where algific conditions occur without substantial talus or ice. The species is most often found on wooded alluvial-soil banks and bluffs along the Lake Michigan shore. Driftless Area sites are on north-facing slopes supporting oak-maple woodland. This snail is found in the soil and leaf litter along cliffs, soil-covered ledges on cliff faces, and on talus and soil and leaf litter near the cliff base.

State Distribution: Occurs in Brown, Door, Kewaunee, Manitowoc, Sheboygan, Ozaukee, Milwaukee, Sauk, Crawford, Iron, Vernon and Grant Counties of Wisconsin.

Management Guidelines: The location of the snails in soil and leaf litter at the base of the cliffs makes them vulnerable to trampling. Preservation of habitat along the Lake Michigan shoreline will be a decisive factor in the long-term status of the snails in Wisconsin.



Cherrystone Drop

Photo by Ryan O'Connor, WDNR.

Cherrystone Drop

Chicago Field Museum Specimen. Marks are mm.

Photo by Terrell Hyde and W.A. Smith, WDNR.

Cherrystone Drop

Live Hendersonia occulta at site 162-Coon Creek

Photo © James Theler.

Cherrystone Drop

Photo © James Theler.

Wildlife Action Plan

Wisconsin Wildlife Action Plan graphic

Natural community (habitat) associations

The table below lists the natural communities that are associated with Cherrystone Drop. Only natural communities for which Cherrystone Drop is "high" (score=3) or "moderate" (score=2) associated are shown. See the key to association scores for complete definitions. Please see the Wildlife Action Plan to learn how this information was developed.

Ecological landscape associations

The table below lists the ecological landscape association scores for Cherrystone Drop. The scores correspond to the map (3=High, 2=Moderate, 1=Low, 0=None). For more information, please see the Wildlife Action Plan.

This map shows the probability of Cherrystone Drop occurring in each of Wisconsin's Ecological Landscapes.  Actual scores can be found in the table to the left.

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Landscape-Community combinations of highest ecological priority*

Ecological priorities are the combinations of natural communities and ecological landscapes that provide Wisconsin's best opportunities to conserve important habitats for a given Species of Greatest Conservation Need. The 10 highest scoring combinations are considered ecological priorities and are listed below. More than 10 combinations are listed if multiple combinations tied for 10th place. For more information, please see the Wildlife Action Plan.

* Ecological priority score is a relative measure that is not meant for comparison between species. This score does not consider socio-economical factors that may dictate protection and/or management priorities differently than those determined solely by ecological analysis. Further, a low ecological priority score does not imply that management or preservation should not occur on a site if there are important reasons for doing so locally.

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Issues/threats and conservation actions

Conservation actions respond to issues or threats, which adversely affect species of greatest conservation need (SGCN) or their habitats. Besides actions such as restoring wetlands or planting resilient tree species in northern communities, research, surveys and monitoring are also among conservation actions described in the WWAP because lack of information can threaten our ability to successfully preserve and care for natural resources.

Threats/issues and conservations actions for rare animals

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Last revised: Thursday, October 08, 2020