Discus Macclintocki - Size

Size

The shell of this snail is no bigger than a shirt button, with adults ranging in size from 5 to 7 millimeters in diameter. They live in the leaf litter preferring a diet of birch and maple leaves. The snail shares its habitat with a host of rare and disjunct plants and animals associated with cool habitats. Balsam fir (Abies balsamea), Canada yew (Taxus canadensis) and yellow birch (Betula alleghaniensis) are common to algific talus slopes. The threatened Northern monkshood plant (Aconitum noveboracense) also grows on these sites.

The 775-acre (3.14 km2) Driftless Area National Wildlife Refuge was established in 1989 to permanently protect populations of the Iowa Pleistocene snail and threatened Northern monkshood. These species’ habitat cannot be restored if it is damaged and lost, and the primary objective of their respective recovery plans is providing protection for remaining colonies. The invasion of garlic mustard (Alliaria petiolata) onto algific talus slopes has emerged as a threat in recent years.

The Refuge consists of scattered tracts of land in northeast Iowa ranging from 6 to 208 acres (0.024 to 0.84 km2). Algific talus slopes range in size from a few square meters to perhaps a 1⁄₂-mile (800 m) in length. More than just the algific talus slope is targeted for acquisition. Sinkholes that feed the system can occur some distance away from the slope and need protection to ensure long term integrity of the site. Buffer areas around the slope are included when possible. The Refuge contributes to lands already protected by The Nature Conservancy, the Iowa Department of Natural Resources, County Conservation Boards in Iowa, and publicly owned sites in Ohio and New York.

At least eight other snail species, considered glacial relicts, are also protected on these sites. Some of these species like the midwest pleistocene vertigo (Vertigo hubricti hubricti), are even smaller and perhaps more rare than the Iowa Pleistocene Snail. Protection of algific talus slopes may help prevent the need for threatened or endangered status for these snails and plants like the golden saxifrage (Chrysosplenium iowense).

• Appearance - These small land snails are only about 1⁄₄ inches (6.35 mm) in diameter. Their shells are brown or greenish white.
• Habitat - The snails live in the leaf litter of special cool and moist hillsides called algific talus slopes. Cool air and water, from underground ice, flow out of cracks in the slopes and keep the ground temperatures below 50 °F (10 °C) in summer and above 14 °F (−10 °C) in winter.
• Reproduction - Iowa Pleistocene snails breed from late March to August. Two to six eggs are laid among the leaf litter and hatch in about 28 days. The snail's life span is about five to seven years.
• Feeding Habits - The snails eat the fallen leaves of birch and maple trees and dogwood shrubs.
• Range - These snails have only been found at about 30 sites in Iowa and Illinois. Fossilized shells indicate they were once much more widespread during cooler glacial periods.