Overview:
Smith College students and staff have built a man-made hibernaculum at the MacLeish Field Station as part of a habitat restoration project for native species. The hibernaculum will provide a protected shelter for Eastern rat snakes and other reptile and rodent species during the winter months. The project was co-sponsored by Mutual of Omaha's Wild Kingdom and the National Wildlife Federation through the Wild Kingdom Grant Program. The hibernaculum is part of a larger habitat restoration project at the MacLeish station, which includes removing invasive species and planting native trees and shrubs.
WHATELY — Just before going home for the holidays, Smith College students constructed a winter house for Eastern rat snakes at the MacLeish Field Station as part of a habitat restoration project for native species.
Cold-blooded reptiles survive the winter months through a form of hibernation called brumation, which slows down their metabolism, heart rate and activity to survive low temperatures. However, the animals require protected quarters, or hibernaculum, to survive during their brumation.
Snakes usually brumate in abandoned rodent burrows, between rocks or with dead tree roots. However, natural hibernacula have become more scarce due to habitat degradation, loss and fragmentation from roads. As part of the habitat restoration efforts at MacLeish, students and staff at the Center for the Environment, Ecological Design and Sustainability (CEEDS) built a man-made hibernaculum. While they hope the Eastern rat snake will be the primary resident, many other reptile and rodent species may use the winter shelter.
“This is sort of like building a birdhouse,” MacLeish Field Station Manager Paul Wetzel said. “You’re trying to expand the habitat possibilities for your species of interest, and you’re doing that in a way that provides a resource for them during a particular point in their life.”
Building a snake hotel
In November, Smith College students Alex Blaszczyk and Sarah Gygax arrived at the MacLeish station to find a hole 5½ feet deep, 10 feet long and 8 feet wide. Two facility workers used a mini excavator to carve out the hibernaculum’s foundation.
“They did so much work,” Blaszczyk said. “They also did the majority of the filling with us. The excavator would bring a bunch of rocks over, dumping them in, then we’d get in the hole and move all the rocks. We were creating pockets of air that we could then fill with straw and grasses and stuff like that.”
Those pockets, Blaszczyk explained, ensure the snakes can still breathe while brumating. The rocks act like a heating pad, keeping the cold-blooded animals warm during the winter.
“This sort of creation of a very specific type of habitat for a specific period in the organism’s life forces you to to think about how the animal thinks, or to try to imagine what they’re going to need,” Wetzel said. “It’s a good exercise for students to do that.”
Wetzel and the team of students needed to consider ways for a snake to move around the hibernaculum, especially if one of the entrances collapsed. They created tunnels using terracotta roof tiles to connect the entrances to the air holes. In case the tiles move around over time, one side of the hibernaculum is a 9-foot slope for snakes to climb out.
Despite living most of their life in solitude, dozens of snakes across different species will huddle in the same animal burrow to brumate together.
“Maybe it’s a hotel. Maybe it’s a condo. I have no idea,” Wetzel said.
Blaszczyk said Eastern rat snakes have been found within a 1-mile radius of MacLeish, but Wetzel has never seen one himself. The hibernaculum was built too late in the season to have any scaly visitors this year, but the team will set up several trail cameras in the spring to capture next year’s residents.
“I think next year might be the year we will see something or not, or maybe they just don’t find it for a couple of years,” Wetzel said. “It’s made out of rocks and logs and dirt, so it’s not really going anywhere.”
Support a species, enhance an ecosystem
Mutual of Omaha’s Wild Kingdom and the National Wildlife Federation co-sponsored the project through the Wild Kingdom Grant Program. Higher-education institutions apply for an $8,500 grant to fund a conservation or restoration project for a threatened, vulnerable or endangered animal. Kristy Jones, National Wildlife Federation wildlife and nature director, said she was pleasantly surprised by the hibernaculum project because snakes rarely get much attention.
“I really love this project,” Jones said. “It really helps that they are doing on-the-ground conservation but also education about this particular animal, and that really helps people understand how this creature is important to the ecosystem.”
Jones compares threatened and endangered species to a “canary in a coal mine” for habitat loss. These species are the first alarm bells that sound when the ecosystem is in danger. While the Eastern rat snake’s ecological range extends down to Florida, Blaszczyk said Massachusetts is at the northernmost edge of its habitat. Combined with high mortality from lawn mowers and reduction of important “edge habitat” — a natural space between two different environments — the species finds itself threatened within state boundaries.
“I don’t know necessarily, [but] with climate change, there’s a chance that they will become a not threatened species, just because their range will shift northward a little bit,” Blaszczyk said.
The Wild Kingdom grants paired well with Wetzel’s existing habitat restoration efforts at the MacLeish station. Wetlands and forestland surround the 30 acres of old agricultural fields, categorizing MacLeish as the “edge habitat” the tree-climbing Eastern rat snake prefers.
The hibernaculum is part of a larger habitat restoration project at the MacLeish Field Station, where Wetzel and a group of students remove invasive species, such as multiflora rose and Chinese bittersweet, and plant native trees and shrubs. Around the hibernaculum, the Eastern rat snake’s preferred trees and shrubs will grow in place of the harmful invasives.
“The actual restoration work itself — like the vegetation removal, reforesting the area with specific trees — will be good for the habitat of the snake, but then also just for the ecosystem as a whole,” Blaszczyk said. “That restoration work is for the good of the ecosystem, and by doing that, we hope that it’ll make the area more accessible for rat snakes to live and for their population to thrive.”
