One of the world’s rarest butterflies, the Mitchell’s satyr seems to be a sentinel species.
Or, as Nate Fuller puts it, “canaries in the coal mine for water quality.”
In October, the Portman Nature Preserve was officially opened in Michigan’s Van Buren County by The Conservation Fund and the Southwest Michigan Land Conservancy (SWMLC). This 188-acre preserve includes wetlands, uplands and oak savanna woodlands. It borders a designated trout stream and three lakes—and provides ideal habitat for the Mitchell’s satyr butterfly, with 12 of the remaining 15 populations found in Michigan.
“Protecting this butterfly seems to be closely linked to protecting the region’s groundwater. If there are interruptions in the flow of groundwater to these fens, the whole system starts to break down—and the Mitchell’s satyrs are the first things to disappear,” says Fuller, a biologist, educator, ecologist and director with the SWMLC.
“They’re extremely sensitive to dehydration, particularly in winter, since they overwinter as a caterpillar,” he adds. “Every single place where they exist is really special. In some places, we’d count 10 butterflies on a good day. On this site, we counted 100 of them in one day. It’s exciting to see such a thriving population.”
With the addition of the Portman Nature Preserve, there are now about 2,000 acres of lands protected by various organizations in the Paw Paw River Watershed. Restoration efforts will focus on the savanna and fen, or low, marshy areas.
Fuller says he’s been looking at this piece of property for close to 15 years, and the SWMLC has had designs on protecting its natural beauty for a decade. Fuller and the SWMLC worked with the former owner of the land to conduct environmental surveys, and Mitchell’s satyr butterflies weren’t the only exciting find.
“We’ve had a botanist tell us that not only are the wetlands some of the finest in the state, but that the oak savanna is fantastic—with nearly all of the plant species still there,” says Fuller. “Some of these plants occur so rarely that I’m getting a chance to learn them as a biologist.
“In one little sunny clearing, where Mr. Portman would turn his tractor around,” he adds, “there are three different species of bush clover, all within a few hundred square feet. I didn’t even know we had violet bush clover in Michigan.”
The establishment of the Portman Nature Preserve was a $2-million initiative. Half of that came from Enbridge’s Line 6B Replacement Fund, earmarked for restoration and improvement of habitat impacted during the Line 6B Replacement Project in 2014. A combination of private and public grants and donations made up the other half.
“Often, in the conservation world, we find either a really nice wetland or upland to protect,” says Fuller. “It’s pretty rare that we can get a single parcel of land that has both.”