BENTON HARBOR, MICHIGAN - Forty-eight insects are currently included on the U.S. Endangered Species List, and the only way any insect has ever come off the list is through extinction. This is especially troubling for the world’s butterfly populations, which have declined by 20% over the last decades.
This time of year, Nate Fuller can often be found counting butterflies. The director of the Sarett Nature Center in Benton Harbor, Michigan, needs an accurate count of Mitchell’s satyr butterflies, to help preserve one of their last known habitats.
“They’re very particular in the kind of habitat where they can live, which is part of what makes them so rare and amazing indicators for our water quality,” he said.
Hard to spot
Emerging into a vast wetland of soupy ground covered in shoulder-high grasses and sedges, dotted with poisonous sumac trees, it’s slow going, but a cell phone app helps keep track of where butterflies have been spotted as well as when and how many, all important data for better understanding Mitchell’s satyr populations.
Finding the small brown butterflies with golden-ringed eyespots on their wings can be difficult. There just aren’t many around. They also rest with their wings closed to blend in with their surroundings.
“We can step over this way, there’s a chance we might stir up a Mitchell’s satyr,” Fuller said.
The Mitchell’s satyr was placed on the Endangered Species List in 1991. Initially it was thought that the loss of wetlands contributed to their decline.
Why the decline?
“We knew them to be where spring fed wetlands were,” Fuller said. “The assumption was it was a case of invasive plant species, humans destroying wetlands, draining them, dredging them.”
But, as habitats were restored, the Mitchell’s satyr continued to decline. Fuller says environmentalists realized something more complicated was at work.
“The clues seem to suggest that it’s not just habitat availability,” Fuller said. “It’s ground water and the amount and the quality of ground water coming into these wetlands seemed to be a challenge for the butterflies.”
While the decline is likely the result of a combination of factors, the fact that water quality might contribute is unsettling because the wetlands are the headwaters for the Midwest’s rivers and streams.
Toledo Zoo breeding program
A captive breeding program was started four years ago at the Toledo Zoo to get to the bottom of the mystery. Ryan Walsh is its director.
“We’re actually doing two things with these guys,” Walsh said. “We’re starting a captive colony. We’ll occasionally collect them to add new genetics to the captive population. We can really breed a large number of the butterflies. The rest of them, the ones that won’t be left back for captive breeding will be released out into the wild.”
The caterpillars spend the winter in a special weather-controlled chamber. That helped determine the Mitchell’s satyrs don’t do well below 4.4 degrees Celsius, the temperature at which hard freezes in the fen wetlands will kill the insects.
With that knowledge, the program produced 1,300 new eggs this year, something that may go a long way toward restoring the population. And may, one day, earn the butterflies a ticket off the Endangered Species List.
Meanwhile, back at the Nature Center, our luck isn’t so great. In two hours, we’ve spotted only three Mitchell’s satyrs. But Fuller says if anything, that’s a good reason to continue to build the breeding program.
“We should care because they’re indicators that there’s something wrong with our landscape, whether it’s water quality, water quantity or habitat? But sort of the bigger picture, do we care about creation? Do we care about the world we live in? It’s the idea of caring about the land, so that the land can care for us in return,” he said.