Plants and Animals
Vertigo pygmaea Crested vertigo
Key Characteristics
This is a tiny land snail with a chestnut brown-colored cylindrical (beehive-shaped) shell that is 1.8 - 2.0 mm in height and 1 - 1.1 mm in width with 5 whorls. The last whorl has a strong, pale crest just behind the aperture lip.
Status and Rank
US Status: No Status/Not Listed
State Status: SC - Special Concern (rare or uncertain; not legally protected)
Global Rank: G5 - Secure
State Rank: S1S2 - Rank is uncertain, ranging from critically imperiled to imperiled
Occurrences
| County | Number of Occurrences | Year Last Observed |
|---|---|---|
| Chippewa | 1 | 1998 |
| Mackinac | 3 |
Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.
Habitat
The crested vertigo is found in a calcareous coastal fen dominated by sedges, especially near the shore. It also is often found thriving on roadsides and other disturbed habitats, including urban centers.
Natural Community Types
For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.
Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.
Management Recommendations
The crested vertigo is vulnerable to foot and vehicle traffic. Hydrological changes should be strictly avoided. Use of prescribed fire in occupied sites should be avoided, if possible, or prescribed fire should be applied very conservatively, leaving multiple refugia and using a burn interval of at least 15 years.
Active Period
Active from first week of June to fourth week of September
Survey Methods
Surveys can be conducted anytime during the growing season, but are most successful in spring and fall following rain showers or when the soil is moist, and during higher relative humidity conditions and cooler temperatures. Visual surveys consist of looking for individuals crawling on the ground, in moist leaf litter, and on or under woody debris. Litter sampling consists of collecting soil and leaf litter samples in the field and drying, sifting and looking for snail shells in the litter samples in the laboratory.
Litter sampling
Survey Period: From first week of June to fourth week of September
Humidity: Humid
Precipitation: Just after rain
Visual surveys
Survey Period: From first week of June to fourth week of September
Humidity: Humid
Precipitation: Just after rain
References
Survey References
- Nekola, J.C. 1998. Terrestrial Gastropd Inventory of the Niagaran Escarpment and Keweenaw Volcanic Belt in Michigan's Upper Peninsula. Small Grants Program, 1998 Nongame Wildlife Fund, Natural Heritage Program, Michigan DNR, Lansing. 133pp.
- Schilthuizen, M. and H.A. Rutjes. 2001. Land snail diversity in a square kilometer of tropical rainforest in Sabah, Malaysian Borneo. Journal of Molluscan Studies 67:417-423.
Technical References
- Hubricht, L. 1985. The Distributions of Native Land Mollusks of the Eastern US. Field Museum of Natural History. Fieldiana: Zoology, No. 24.
- Nekola, J.C. 1998. Terrestrial Gastropd Inventory of the Niagaran Escarpment and Keweenaw Volcanic Belt in Michigan's Upper Peninsula. Small Grants Program, 1998 Nongame Wildlife Fund, Natural Heritage Program, Michigan DNR, Lansing. 133pp.
- Nekola, J.C., T.A. Smith and T.J. Frest. 1996. Land snails of Door Peninsula natural habitats. Final report to the Wisconsin Chapter of The Nature Conservancy. 55pp.