Last week, the Kalamazoo Nature Center released 18 rare butterfly caterpillars. The Mitchell’s Satyr butterfly – “satyr” like the mythical creature – is a nationally endangered species. There are only 11 groups of the butterfly left in the entire United States.
Like some endangered species, the Mitchell’s Satyr has the disadvantage of not being very attractive.
“It’s really easy for people to love those big yellow swallowtails or the monarch.”
That’s Ashley Wick. She’s leading the Mitchell’s Satyr program at the Kalamazoo Nature Center.
“You know, it’s little, it’s brown. Some cute little eyespots on it and it likes sedges which most people think are grasses. And so to me it’s just the underdog.”
The Mitchell’s Satyr might not be very flashy, but no butterfly says “Southwest Michigan” more than this one. Almost all of them live in the southernmost counties of Michigan – a few are in northern Indiana. Why here? It’s because they live in a rare habitat. Mitchell’s Satyr butterflies live in fens – a unique type of wetland.
“We’re standing here at the Kalamazoo Nature Center looking at our fen. So a fen is a high quality wetland. It’s different from a swamp or a bog.”
“And it’s fed not by water coming from the surface around us but it’s fed through springs and groundwater.”
Wick says underground the water comes in contact with things like limestone, which makes it rich in minerals. It’s also makes the water and soil less acidic.
“In these wetlands we just get a huge variety of plants and insects and just you can see the super cool, clean water.”
According to the U.S Department of Natural Resources, Michigan is one of only four states in the country where fens make up more than one percent of the landscape. Fens may be pristine habitats for wildlife, but they’re also very sensitive. Wick says something happening to the groundwater miles away can affect a fen. That’s part of the reason why they’re few fens around anymore.
“Digging a farm pond, constructing a road, really leveling large amounts of areas, digging up wetlands. And so that is one main reason that may be particular to these types of ecosystems.”
Wick says the Nature Center originally intended to release the Mitchell’s Satyrs as butterflies – not caterpillars. But the Nature Center’s timing was a little off. You see, it takes four months for the U.S. Fish and
Wildlife Service to approve a permit to raise an endangered species in captivity. But Wick says the Nature Center submitted its paperwork early.
“So that put us in a little bit of a difficult situation – which means that our permit only gives us permission to keep them through caterpillar hood, not through adulthood.”
Thus – caterpillars. Wick says maybe the Nature Center jumped the gun a little. But the Mitchell’s Satyr species is in such a dire situation that Wick says it didn’t want to wait. Unfortunately, Wick says caterpillars are less likely to survive than adult butterflies.
“As a caterpillar you’re good bird food or a parasitic wasp or lots of other parasites may lay their eggs inside or on top and the eggs will hatch and the other insects will eat your caterpillars.”
With this in mind, Wick’s team didn’t take any chances. With the help of the Southwest Michigan Land Conservancy, they spread out the caterpillars, putting them in locations that were hard for humans – and some animals – to reach. Aside from Wick’s team, the Land Conservancy, and the Fish and Wildlife Service no one is allowed to know where these caterpillars were placed. Wick says they can’t risk the caterpillars getting squashed.
“We do want people to get excited about the butterfly and want to help protect these wetlands, but at the same time we have to be careful with those areas.”
Wick says her team hopes to release more than 50 caterpillars total this year. She says some may be ready by this week. Wick also says that the team should be able to release adult butterflies next year.
Wick says it’s important to keep an eye on sensitive species like the Mitchell’s Satyr and why they’re declining.
“Having really resilient ecosystems means that we have to have all of these species present – because every time you lose one, you’re probably losing some others because they’re so interconnected.”
The Land Conservancy recently restored a fen habitat at Sarrett Nature Center in Benton Harbor. Since then Land Conservancy officials say the butterfly has come back in numbers they haven’t seen in 15 years.