Passport to Nature

Winter in a Frost Pocket

Kevin chirps loud and convincing greetings to the swamp’s birds, speaking the languages of blue jay, chickadee and Eastern screech owl.

By Lindsay Renick Mayer

It has been a tough winter to enjoy the outdoors. I got in one January hike to Sky Meadows State Park with my family and lasted an hour on Maryland’s Catoctin Mountain during the polar vortex. So my wildlife viewing has been largely restricted to the posters of amphibians and paintings of cephalopods lining my office walls.

But then I venture out for a snowy trek at The Nature Conservancy’s Cranesville Swamp Preserve — a “frost pocket” that runs several degrees colder than the surrounding area. Now I regret not having layered on the long underwear more frequently this winter.

Pocket Protectors

The Nature Conservancy has purchased 1,744 acres at Cranesville since 1960 to protect the abundance of rare species that call the swampy expanse home.

Many of Cranesville’s plants and animals aren’t found anywhere else in Maryland, yet are common in colder climates. Boreal larch trees and winterberry, for instance, along with wildlife such as the fisher, Northern saw-whet owl and bog copper butterfly inhabit Alaska and Canada.

Maryland’s Department of Natural Resources describes the swamp as a “boreal peat bog relic.” Formed 15,000 years ago during the last Ice Age, Cranesville keeps its cool due to its unique geology and location nestled in a mountain valley.

Searching for Signs of Life

On a recent morning with temperature in the mid-20s I set out with Deborah Landau, conservation ecologist for the Conservancy in Maryland/DC; Kevin Dodge, wildlife professor at Garrett College; and Jonathan Wilson, environmental reporter at WAMU 88.5 in Washington, D.C.

We’re in search of critters that thrive in wintery conditions that drive many of us under the covers with books and hot chocolate in hand. Even in the middle of the coldest winter in 30 years, signs of life are all around us.

Kevin calls our attention to the edge of a small stream where he sprawls flat on his stomach over a snow bank. “It’s a little tough because you’ve got some snow cover on top of them, but I think we’re seeing mink tracks here,” he says.

“In the winter, we can see the tracks of everybody who’s out here,” Kevin adds. “If you wander around enough, you’re going to see signs of mink, otter, fisher, long-tailed weasel, bobcat, coyote, red fox and gray fox.”

While we don’t see any of these animals in the flesh, we see plenty of evidence of their adventures: scat, urine, paw prints of differing sizes, even a semi-circular depression where a mink or otter had clearly slid into the water.

Finally, after trekking through nearly three feet of snow to make our way deeper into the swamp’s conifer forest, we see our first wildlife. But not without some coaxing from Kevin.

Kevin chirps loud and convincing greetings to the swamp’s birds, speaking the languages of blue jay, chickadee and Eastern screech owl. Within a few minutes, curious chickadees and blue jays hop from branch to snowy branch in the hemlock and spruce overhead. On any given day, Kevin says, he may also call in the winter wren, alder flycatcher, Northern water thrush and magnolia warbler.

Keeping Conifers to Keep Cranesville Cool

Had The Nature Conservancy not protected Cranesville Swamp nearly 55 years ago, there’s a good chance that we wouldn’t be standing among conifers. Historically, these evergreen trees with needle-like leaves — primarily spruce, pines, hemlocks and larch — covered most of western Maryland, West Virginia and Pennsylvania.

But logging in the late 1800s and early 1900s, followed by massive wildfires, has transformed these diverse conifer forests largely into hardwoods. Cranesville has maintained much, though not all, of its coniferous forest cover, so The Nature Conservancy has planted 18,000 red spruce and 1,150 white pines across 300 acres. 

A new challenge, the invasive hemlock woolly adelgid, has started to ravage the preserve’s hemlock trees over the last two years.

“Hemlock is the remaining native evergreen that wasn’t logged as extensively as the other tree species,” Deborah says. “If we lose hemlocks at Cranesville, it will be absolutely devastating. It’s our last significant stand of conifers out here.”

Because conifers stay green throughout the year, they block the sun and keep already-cold temperatures in the frost pocket even lower. So deep snow cover sticks around longer than the normal winter season, sometimes even extending into mid-May, according to Deborah.

This year she suspects the snow is here to stay for at least another month. Once the snow thaws, Cranesville will be well worth another trip.

“It’s a wonderful place to go in all four seasons,” Deborah says. “You’ll see something completely different every time. A visit here is a good way to get right into a swamp, right into a hemlock forest, without having to muck around.”

The trail and boardwalk are open to the public year round and come with a downloadable audio tour.

Listen to WAMU’s story about our visit to Cranesville Swamp Preserve.


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