Snails living in the Upper Peninsula are among rarest
in U.S.
GREEN BAY -- Animals that lived side-by-side with mastodons during the Ice Age have been discovered alive in Michigan's Upper Peninsula.
The animals are tiny snails, and although mastodons became extinct after the Ice Age, small pockets of habitat remain in the Upper Peninsula that allow the snails to survive. The discovery results from a study conducted by Prof. Jeffrey Nekola of the University of Wisconsin-Green Bay, and supported by the Small Grants Program funded by the 1998 Nongame Wildlife Fund of the Michigan Department of Natural Resources.
The study discovered a dozen snail species never before documented living in Michigan. Researchers also found 65 of the 71 species of snails known to occur in the Upper Peninsula.
"Some of the species we found are among the rarest land snails in eastern North America," says Nekola.
But warns Nekola, people walking through likely areas in the Upper Peninsula shouldn't expect to just "stumble" upon rare snails: these creatures are small. "All of the 12 species we added to Michigan's list are somewhere around the size of Lincoln's nose on a penny," he explains.
Nekola and student researchers collected samples along Lake Superior from Ironwood to the tip of the Keweenaw Peninsula and north of Lake Michigan from the Garden Peninsula to Drummond Island. The two areas are very different geologically but, explains Nekola, the bedrock in both offer the ingredient-lime-that makes for good snail habitat.
The mastodon's surviving "neighbor" is Vertigo nylanderi and until Nekola's studies found the species in the Upper Peninsula and Wisconsin, no one had seen the snails alive since specimens were collected in Minnesota in 1949. The habitat required by Vertigo nylanderi-widely scattered tamarack trees on sedge prairie-was also the habitat required by mastodons at the close of the last Ice Age. The UW-Green Bay researchers found living snails in four such remnant sites stretching from Delta County to Chippewa County.
"This tells us an important story about how animal size affects its resource needs and its ability to adapt to global climate change," says Nekola. He explains that when climate change after the Ice Age caused the demise of large tracts of tamarack-sedge prairies, the mastodons died, too. "There wasn't enough habitat for them, but for snails, the small remaining areas were enough."
Vertigo modesta is another Ice Age relic that Nekola and students found living in tiny soil pockets between boulders at the base of cliffs in Keweenaw County's Cliff Range. The snail is a northern species known only as a fossil in the Midwest. It normally lives from Alaska to Newfoundland and in other cold places like high in the Rocky Mountains.
"About three-quarters of the new Michigan 'finds' are Ice Age relics, the other quarter are southern species that nobody knew lived this far north," says Nekola.
An example is Guppya sterkii, normally found from the Ozarks to the Appalachians. UW-Green Bay researchers not only identified live specimens in a warm, west-facing site near Lake Michigan close to the Delta-Schoolcraft County line, but found what may be the largest colony known in the upper Midwest.
Over the summer, UW-Green Bay researchers collected samples from 75 sites in the Upper Peninsula. The gallon-sized bags of soil and leaf litter were taken back to the lab where the painstaking part of the work takes place. Researchers wash the soil away through fine sieves, dry the remaining litter, spread it on trays, and carefully sort with fine sable brushes to find the snails. The tiny shells can only be identified through microscopes.
The snail research illuminates several issues for Nekola. Preservationists typically focus on the large animals that need big tracts for survival-such as grizzly bears and wolves-to the exclusion of smaller creatures, says Nekola. "As humans dig, dredge, cut, and pave, things that can persist in small areas are in trouble, too," he says.
He often reminds listeners that the term "wilderness" is relative. A wilderness area doesn't have to be big enough to support wolves: for a snail, a rocky ledge the size of a saucer is a wilderness. "This tells me that no landscape should be discounted," says Nekola. "It changes our perspective on what areas need to be considered priorities for protection."
Nekola is intrigued, too, by the idea that animals and plants that lived with Ice Age creatures live on today. It isn't necessary to go to the rain forest to experience exotic things, he says, "It's in our own back yards."
(98-126 / 12 Oct. 1998 / VCD)