Thursday, February 25, 2021

Curiosity, Perseverance, and Life

There’s a space kid inside almost every one of us. That fact is made clear to me by the nation’s giddy response to NASA’s most recent accomplishment—a successful landing of the Perseverance rover on Mars. The rover used a heat shield, a parachute, cameras, and a rocket-powered jetpack to land. Actually, the jetpack allowed the main contraption to hover while the rover was lowered gently to the surface on a cable. Whaddya wanna bet that next summer there will be kids making rocket noises while they drop the requisite bucket-on-a-rope out of their treehouses?

Perseverance Touching Down on Mars (Illustration): An illustration of NASA’s Perseverance rover landing safely on Mars. Hundreds of critical events must execute perfectly and exactly on time for the rover to land safely on Feb. 18, 2021. Credit: NASA/JPL-Caltech.

While that bucket is probably hoping for a delivery of cookies, Perseverance is looking for signs of life. Its landing area includes a delta—which is a place where a river carrying sediments from its entire watershed flowed into a lake, slowed down, and dropped most of its load in a fan-shaped landform. If there was life on Mars, surely signs of it would have been collected by the river and deposited here. The shoreline of the lake could be another hotspot, based on what we know about life and fossilization here on Earth.

Using another trick straight out of our 10-year-old dreams, scientists can tell the rover to shoot a laser beam at any promising rock and then analyze the chemical composition of the dust cloud that rises. If the rock warrants a closer look, then an x-ray beam and another laser will take a peek at the chemicals present. In the most promising spots, the rover will drill down and collect a piece of the planet. What then? The sample will be stored in a box full of neat rocks (who among us doesn’t have one of those in the basement or garage?) that a future mission of the European Space Agency will bring back to Earth.

Signs of life could include minerals that don’t tend to form on their own, or structures that often form in the presence of critters. There’s an example of one of those structures on Old Grade Road northeast of Lake Namakagon. The Grandview Boulder is taller than a person, and under the moss you can see thin, convex layers in the rock. These layers are the fossilized remains of colonies of photosynthetic microbes. The algae and cyanobacteria excreted mucus, which trapped sediment and eventually built their own rock—called a stromatolite.

The Grandview Boulder near Lake Namakagon exhibits thinly layered structures that scientists are now looking for on Mars. Photo by Emily Stone.

Stromatolites are common in the fossil record on Earth, but rare to find still living. And while discovering a rock with this pattern on Mars would be exciting, it isn’t a sure thing. Stromatolites can also form without the help of life.

So, it’s going to take something pretty special to give scientists complete confidence that they’ve discovered extraterrestrial life.

There’s another problem, too. What if life on Mars looks so different from life on Earth that we don’t even recognize it?

I tackled this problem myself once, as a middle schooler at Girl Scout Camp. The Girl Scouts had a partnership with NASA, and one of the activities they provided was a variation on an activity often called “Create-A-Creature.” Each girl was assigned to a different planet and given a description of the habitat there. All rock, all gas, no atmosphere, crushing gravity, toxic chemicals—there was a stunning array of characteristics among our planets and their moons. Next, we were given a box full of bottles, cans, yogurt cups, and all manner of random stuff scavenged out of the recycling bin, plus glue, pipe cleaners, and other standard craft supplies. The goal? Create a creature with adaptations that allow it to survive on our assigned planet.

Our assemblages of detritus didn’t look like much in fact, but in our minds they had rock-crushing teeth, sulfur-digesting guts, and all sorts of fantastical adaptations that have not yet evolved on Earth. That combination of crafts, space, and tons of imagination was a winning combination for the child that was me. Honestly, the space part wasn’t why I loved it, but the other two ingredients won me over.

I have since led this activity with my own students in many forms. On “Tidepool Day” in California, for example, we built sea creatures using both trash and natural objects scavenged from the wrack line left by high tide. And yesterday, just hours before the Perseverance landed, I led 5th graders in creating their own special fish during a Virtual MuseumMobile visit.

Because we don’t really know what life on Mars would look like if it did, in fact, exist, those NASA scientists need a special combination of skills and imagination. Waddya wanna bet that those NASA scientists and engineers were once kids who created things out of the recycling bin, made rocket sounds in treehouses, collected buckets of neat rocks in their garage, and crick stomped in rocky streams?

Waddya wanna bet that the NEXT generation of NASA scientists is doing those things right now?

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at Or order it from our friends at to receive free shipping!

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is closed, but our Mysteries of the Night exhibit is available online. Connect with us on Facebook, Instagram, YouTube, and to keep track of our latest adventures in learning.

Thursday, February 18, 2021

Subnivean Party

Kerflumpf. Mumpf. Fump. It’s difficult to describe exactly the sound that snowshoes make in 18 inches of fresh, fluffy snow. I can tell you that the soundtrack includes some huffing and puffing, and the swish, swish, swish of nylon sleeves as arms swing their assistance. At the start of our recent dive into the polar vortex, I traded skis for snowshoes and headed out into the untracked forest.

Only snow-plops blown out of treetops marred these smooth drifts of snow.
Photo by Emily Stone.

The woods felt peaceful and serene. Only snow-plops blown out of treetops marred the smooth drifts. Winter, I thought to myself, can feel pretty lonely sometimes. If only I was smaller…

Because, for the little critters at least, there is a party going on under there. Under where? In a curious space called the subnivean zone.

Do you remember the magic of hoar frost that I wrote about a few weeks ago? Water vapor in the air crystalizes directly into ice without going through the liquid phase. Under the snow, at ground level, the opposite happens. Latent heat from the earth—stored months ago during days of summer sunshine—gives snow crystals at ground level just enough energy to vaporize back into their gaseous form. Sublimation is the scientists’ term.

The vapor rises just a bit, filtering into the snow, where it changes the structures of crystals as it solidifies again. The result is a zone of airy pockets and loose, granular snow topped by an icy ceiling; and above that a thick, insulating blanket made—counterintuitively—of ice and air. Best of all, this magical space remains at or near freezing. That might not usually seem warm, but after our weeks of subzero temps, we can probably agree that 32 degrees Fahrenheit sounds fairly pleasant.

I’ve written and taught about this subnivean zone many times before. Usually my focus is on the small mammals—mice, voles, and shrews—who make their winter homes in tunnels sewn between soil and snow. And, of course, there are the charismatic carnivores who chase those warm nuggets of protein. Short-tailed weasels (who become ermine in their white winter fur) follow mice directly into their dens. Foxes and owls take another route—pinpointing supper with their ears and then plunging in from above.

But I mentioned a party going on under the snow, and these are only the most visible revelers. Jon Pauli, a winter ecologist from UW-Madison, explains that, “In this refuge, there's a complex ecosystem of interacting microbes, insects, plants and animals that we can't see but are active throughout the winter.” In fact, says one of his research papers, the subnivium is where the “majority of biodiversity in northern temperate areas spends the winter.”

For example, Pauli and his colleagues have been studying the impacts of warming winters on the energy budget of wood frogs. These cold-blooded amphibians take refuge in leaf litter and very carefully allow themselves to freeze solid while the subnivean zone forms around them. Once frozen, their metabolisms are shut down, which preserves their limited energy stores. The moderating effects of the subnivium buffer them from energetically costly freeze-thaw cycles, and also reduce the potential for lethally low temperatures.

Frozen wood frogs have a fair amount of company. One group of ants, in the genus Temnothorax, likes to set up house inside empty acorn shells. Like a colonial version of hermit crabs, they compete for a limited number of good homes. Loathe to abandon their nut hut for the winter, they simply snuggle up with about 100 workers and a few larvae and produce glycerol as an antifreeze to prevent cell damage. Unsurprisingly, colonies in acorns that are buried more deeply in the leaves and soil have higher winter survival rates. Also unsurprisingly, the little girl in me loves that nature has its own version of acorn fairies.

Temnothoraz ants are also known as “acorn ants” because their colonies live inside acorn shells. Photo by Matt Hamer, Wikimedia Commons.

A thick layer of leaf litter isn’t just important for ants. Autumn leaves provide insulation before snow accumulates, and then continue to augment our fluffy white blankets. This protects plants’ roots from freeze damage. Dead leaves also provide essential habitat for woolly bear caterpillars, mourning cloak butterflies, luna moth cocoons, the eggs of red-banded hairstreaks, bumblebee queens, spiders, snails, millipedes, mites, and more. Some of them are frozen, some of them are active. And they aren’t the smallest subnivean inhabitants.

Woolly bear caterpillars need thick leaf litter covered by insulating snow in order to survive the winter. Photo by Emily Stone.

The microbes that Pauli mentioned are important here, too. Fungi and bacteria take advantage of the microclimate of the subnivean zone to slowly break down dead stuff throughout the winter. They release their nutrients in spring—just in time to fuel the growing season. In contrast, invasive earthworms decimate the leaves too quickly. Both insulation and nutrients diminish.

As I was saying, the soundtrack above the snowpack is pretty quiet. That allows me to cock my ears like a fox and focus my listening toward a hidden world beneath the snow. What do I hear? A wild party in that magical place we call the subnivean zone.

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at Or order it from our friends at to receive free shipping!

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is closed, but our Mysteries of the Night exhibit is available online. Connect with us on Facebook, Instagram, YouTube, and to keep track of our latest adventures in learning.

Thursday, February 11, 2021

Patterns of Life: Galls

Summer in the Northwoods can feel like a painting—broad sweeps of green and blue provide the backdrop for highlights in all colors of the rainbow. Winter, though, can feel like a pen and ink sketch, where shapes, textures, and patterns rule. I enjoy these shifts in perspective, since they can help me spot new things.

A little while ago I found myself in a weedy strip of vegetation between my friend’s driveway and a field. The colors of summer had all but drained from the thicket of goldenrod plants. Where once there were sunny yellow flowers tossing above a sea of green leaves, there now stood a sepia-toned jumble of fuzzy seed heads, crinkled leaves, and leaning stems. In this winterized sketch, I scanned the lines, looking for a particular pattern.

Goldenrod galls are small, round lumps that appear near the tops of the growing stems in response to the chewing action of insect larvae. Every year I collect a couple gallon bags full of these galls to use in our MuseumMobile lessons. With kitchen shears in-hand, I had soon accomplished my goal.

Many of the galls were the typical, spherical homes of goldenrod gall fly larvae. But as I started sorting through and cutting them open, I found one that didn’t match. It wasn’t much different—only slightly taller than wide, with some raised ridges. I knew that its real differences were hidden inside. A sharp knife around the equator of the gall soon revealed a hollow center with a shiny brown shell rattling around. The shell was the dried out puparium (like a chrysalis) of the goldenrod gall moth—Gnorimoschema gallaesolidaginis—whose larva created this elliptical gall.

An elliptical gall formed by a gall moth on a goldenrod plant. Photo by Emily Stone.

As I rolled the thin, mummy-like shell in my fingers, it cracked open. The split did not reveal a metamorphosing moth pupa changing from larva to adult. Instead, dozens of tiny, white, translucent larvae—each only about 2 mm long—spilled out of the hollow cylinder. Any normal person would have been grossed out. I was thrilled! The moth larvae are parasites on goldenrod, and they themselves are victims of many different parasites. I wrote about this in 2017, when all I found was a hollow, hole-riddled shell, cleaned out by the larvae of a tiny wasp.

The shiny shell of a gall moth puparium—only 2 mm in diameter—cracked open to reveal a mess of tiny parasitic wasp larvae that ate their host. Photo by Emily Stone.

Based on some research and inquiries, these translucent larvae probably belong to a different species of tiny, parasitic wasp. While wasps like these can’t sting us—their ovipositors are just for depositing eggs—they do play an enormous, and largely hidden, role in our ecosystems by keeping the populations of other insects in check.

I currently have some of the larvae tucked away in a Mason jar with a damp paper towel in the hope that they will metamorphose into adults and give us more clues as to their identity.

In the meantime, I found another curious pattern in the lines of my winter woods.

On several snowshoe hikes recently, I’ve gazed up at the lace of bare branches silhouetted against the sky, and found one tree among them covered in lumps. While these woody balls persist through the summer, they are out of sight and out of mind—hidden by that wash of green.

Like the lumps on goldenrod stems, I figured that these were probably galls. Plant galls are simply abnormal outgrowths triggered by everything from viruses, fungi, bacteria, insects, and mites, to other plants. Which of those parasites could trigger such persistent, woody galls?

Rounded galls caused by a fungus dot the branches of a northern red oak tree. Although a red maple’s twigs are intertwined, it does not seem to be infected with the fungal parasite. Photo by Emily Stone.

The answer, according to a fact sheet from the Wisconsin DNR, is that these galls are caused by a fungus in the genus Phomopsis. While little is known about how the fungus spreads, it seems to start on the smallest twigs before moving to larger branches. Often, only a single tree or a small cluster will be impacted. Some twigs or branches may be girdled and die, but the main tree will survive for many years. There is no treatment available, or even needed, although you can cut off infected branches if you find them unsightly. I find them whimsical!

While I’ve mostly noticed Phomopsis galls on northern red oaks, they also occur on maples, hickories, and other species in Wisconsin. Around the world, the fungus causes galls on trees in Italy, Poland, Spain, Portugal, Switzerland, England, India, Russia, Tunisia, and more. (This list is gleaned from the titles of scientific journal articles written about the fungus, but could also serve as my post-pandemic travel goals.)

The austere sketch of winter reveals many patterns. We see lines…and lumps where lines should be. We see the patterns of lives interwoven.

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at Or order it from our friends at to receive free shipping!

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is closed, but our Mysteries of the Night exhibit is available online. Connect with us on Facebook, Instagram, YouTube, and to keep track of our latest adventures in learning.

Thursday, February 4, 2021

Like a Rifle to my Dreams

I opened my garage door and gazed out toward the setting sun over an expanse of snow-covered ice. Strange, I thought. The lake level must have risen, since the ice was now level with the sill. Turning to the right, my heart jumped when I saw two young polar bears playing in the snow just meters away. They were white, fluffy, and cute. Although their body shape was wrong. Maybe they were albino black bears? In any case, they paid me no mind, and seemed to present no danger. But, where was their mother? Then CRACK! A sound like a rifle shot reverberated through the air.

I awoke with a start and opened my eyes to the dark room. The bears had been in my dream (where did that come from!?), but the sound was from real life. I fumbled through a sleepy haze to understand the noise. Was the house falling apart? No, there were no other sounds of destruction or chaos. Then, obviously, it must have been a tree cracking open in the cold.

I checked my phone: 3:30 a.m. I opened my weather app and checked the temperature: -13 degrees Fahrenheit and falling. Outside, a full moon cast shadows in the brittle cold. “Sweet,” I thought to myself as I rolled over, “now I know what to write about this week.”

The thermometer read -18 degrees when I came downstairs to make coffee. This had been one of the coldest nights of the winter so far, and it followed on the heels of a really lovely, clear, sunny afternoon. At one point I had turned my face to the sun and reveled in the warmth I felt—even though the high temperature only reached 11 degrees above zero.

My face wasn’t the only thing absorbing warmth. The low-angled rays of afternoon sun were beaming their energy onto the southwest sides of trees. This heats up the bark and the inner wood. When things warm, they expand.

The other side to that, of course, is that as the Earth’s heat escaped into a cloudless night and temperatures plummeted, the wood contracts rapidly and unevenly, with the outer layers showing the most dramatic change. The contrast is divisive, and the sound of wood ripping apart is loud.

Even as it burst into my dreams, the past night’s crack had sounded close. So, once the temperature rose above zero, I layered up and decided—without much hope—to see if I could find the tree who split. Standing under my bedroom window, I turned to look northeast—at the southwest sides of the trees—the side that usually cracks. Sure enough, there were at least a half a dozen narrow scars snaking lengthwise up trunks. On ashes, maples, and hemlocks, these cracks had all been trying to heal themselves for years if not decades. These were good evidence of past frost cracking.

On snowshoes, I took a little tour of the scars. They were filled with rough bark, old mushrooms, beetle-hole-riddled wood, piles of sawdusty larval frass, crusty specks of wound-healing pitch, and the messy webs of now-frozen spiders. Wonderful stuff, really. These old tree scars are fun to explore!

The scar from an old frost crack.

Old mushrooms

Beetle larvae frass (poop) that is basically sawdust.

Spider webs

Want to learn more about these and other Unsung Heroes of Nature? I'm giving a talk on February 11, 2021, for the Master Gardeners, and everyone is welcome! 
Find more info and the registration link here.

As I came full circle, though, the black stripe of a narrower crack caught my eye. It was on the southwest side of a young basswood tree—less than a foot in diameter—and just beyond my bedroom wall. Close up, I found none of the scar tissues or evidence of age I’d seen in the other scars. Instead, I found the warm brown colors of bark that hasn’t been weathered. I found small slivers of creamy wood—freshly exposed. And I found a deep crevasse filled with glittering crystals of hoar frost—assembled from moisture recently released from damp wood.

Some previous injury weakened this young basswood tree, and then plummeting temperatures caused it to crack open with a sound like a rifle shot. Photo by Emily Stone. 

Freshly exposed wood and hoar frost in this crack give clues to just how recently the fissure opened. Photo by Emily Stone.

When this frost crack opened, humid air inside the wood made contact with frigid temps, and hoar frost crystals grew. Photo by Emily Stone.

Freshly exposed wood and hoar frost in this crack give clues to just how recently the fissure opened. Photo by Emily Stone.

Radial cracks like this one—fissures that dive inward to the tree’s core instead of just separating inner bark from outer bark—are associated with injuries sustained in the tree’s youth. Did some piece of equipment scrape against this young basswood 20 years ago as the house was being built? The injury creates an area of weakness, and an entry for decay. Bacteria and fungi move in, and as they decompose the wood it absorbs extra moisture. The defective wood doesn’t expand and contract as well as healthy wood, and rapid freezing finally bursts open a significant crack. CRACK!

Warm weather will allow the wood to relax and close the crack again. The tree will begin to build scar tissue around the injury. And maybe, with quieter nights, I’ll get to enjoy the antics of those polar bear cubs.

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at Or order it from our friends at to receive free shipping!

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is closed, but our Mysteries of the Night exhibit is available online. Connect with us on Facebook, Instagram, YouTube, and to keep track of our latest adventures in learning.

Thursday, January 28, 2021

The Demise of the Monarch

Last week, the peaceful transfer of power in our Capitol was a symbol of how—for 245 years—we’ve prevented the rise of a western monarch. This democracy was founded in opposition to the idea of monarchies, and the functioning of democracy can be a source of pride.

But I’m not here to talk politics. I only mention the inauguration to make a bit of word play. Because, an invertebrate species of Western Monarch is currently being vanquished by accident. And that should be cause for alarm.

Monarch butterfly populations have dropped to critically low numbers. Photo by Emily Stone. 

Earlier last week, the Xerces Society (an international non-profit focused on the conservation of invertebrates), announced that the population of monarch butterflies who spend the winter along the California coast is nearing collapse. For the past few years, volunteer counters have found fewer than 30,000 butterflies overwintering in the groves. Those were record lows, and cause for alarm. This year, the community scientists counted a mere 1,914 monarch butterflies. That’s 99.9% fewer butterflies than were found in the 1980s. And still, there exists no legal protection for them or their essential habitat. 

Western Monarchs aren’t all of the monarchs, though. The black-and-orange beauties who spend summers with us in the hot and humid Midwest have migrated to remote oyamel fir tree forests in the mountains west of Mexico City. They are enduring an unusually cold winter there, and official counts have not yet been completed. We can only hope that their numbers won’t show the same precipitous decline as their western counterparts. 

The odds are not in our favor.

Last year, the monarchs overwintering in Mexico exhibited a 53% drop. 

The details of each population’s decline are slightly different, but the big picture holds true: their demise is driven by loss of habitat for overwintering, breeding, and migration; and by pesticide use.

In the past, it was easy to blame our southern neighbor for the declines. Illegal logging in the mountainous butterfly preserves of Mexico was a major problem, but that has largely been addressed by the Mexican government. There is still more to be done with supporting the region’s economy so that the locals won’t need to extract resources from the protected forests, but the biggest challenge to the monarch’s struggle for survival is no longer across an international border. It is right here in the US, in the ever-more-productive Corn Belt where I grew up. 

In early spring, monarchs will head north again—hoping to lay their eggs on fresh milkweed plants in Texas before they breathe their last butterfly breath. 

But what if there isn’t any milkweed? Drought, cold weather, and habitat loss have all caused its decline. And the challenges continue as generations of monarchs leap-frog north into the Midwest. Farming practices have changed a lot since my Grandpa Warren hunted pheasants among habitat-rich fencerows and pastures in southern Iowa. 

Since the first genetically modified (GMO), herbicide resistant soybeans were introduced in 1997 (with GMO corn following shortly), there has been an 80% decline in milkweed in the Midwest, and a concurrent 81% decline in monarchs. In Iowa, one biologist estimates there has been a 98% reduction in milkweed on the landscape. While GMO products have garnered support among some scientists, the changes that GMOs have caused in our farming practices and the subsequent habitat loss for many organisms (not just monarchs) are a significant bit of collateral damage. 

Although habitat loss is the biggest problem, it’s one that you can help address! Now is the time when eager gardeners start making plans for spring. Every additional back-yard milkweed plant and un-sprayed flower garden could host one more caterpillar, and provide nectar for hundreds of pollinators. 

But gardens like these are not going to make up for millions of acres of corn and soybeans. Large conservation efforts—and sustainable farming practices—also are necessary. You can help there, too, by choosing carefully at the grocery store, by supporting the organizations doing good work, and by letting your representatives at all levels of government know that you value conservation efforts. 

Should we work hard and make sacrifices just to save a single species of butterfly? Well, yes. But we also should work to save the monarchs because in doing so we will be conserving nature for ourselves and for our kids.

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at Or order it from our friends at to receive free shipping!

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is closed, but our Mysteries of the Night exhibit is available online. Connect with us on Facebook, Instagram, YouTube, and to keep track of our latest adventures in learning.

Thursday, January 21, 2021

Observing Woodland Dramas with Lois Nestel

A bobcat stares intently at activity around my birdfeeder. The hunt was unsuccessful. But the cat's presence so close to home was thrilling. Nature observations can be made almost anywhere! 
Photo by Emily Stone. 

Each time I walk out to check my new trail camera, the moments are filled with anticipation and excitement. Who will I find today? Lately, though, the critters have become suspicious of my tracks, and of whatever tiny lights and noises emanate from the camera. Good captures have become fewer and farther between. 

A red squirrel mocks my trail cam.

On the other hand, fresh snow on my driveway and in the woods records the tracks of bobcats, otters, and weasels, in addition to the fishers, foxes, and coyotes who are also captured on camera. This bit of technology is not a replacement for paying attention. Good old observation skills may still yield the best—or at least the most plentiful—results. 

Weasel tracks bound around the edges of my driveway--just out of view of the trail cam.

Lois Nestel, the Museum’s founding director and naturalist, lived in a time before we had such technological crutches to help us spy on nature. In her weekly newspaper column in the 1970s, she wrote eloquently about the many wild events she was able to observe right in her yard, which is now the Wayside Wanderings Natural Play Area in Cable. I’m pleased to share her words with you again.

“On the night of the last full moon the winds were quiet and the sky clear following heavy snow. Awakening in the night I sat by the window gazing out at a familiar world made strange and new by moonlight and shadow.

“The trees were stark silhouettes against the sky, and their shadows were blue-inked traceries upon the sparkling snow. As I watched, one dark form and then another emerged from the shadows as two cottontails came out to eat the food scattered on the ground for them each evening.

“They fed quietly for a while before moon madness struck them and they began to leap and play as only rabbits can. From immobility first one and then the other would leap high, twisting and kicking heels into the crystal air. They would chase madly around the trees, in and out of the shadows, stop, facing each other, and then be off again, often with one leaping over the other to begin the race.

“How long this might have continued is hard to say, but suddenly, quite close by, a coyote wailed and immediately the voices of several others rose in chorus. As if they had evaporated the rabbits were gone. Several times the yipping wails of the coyotes rose and fell; then all was silent.

“The woodland dramas of life and death continue, unseen by human eyes, unheard by human ears. The night was full of life; yet filled with moonglow and shadow, there appeared only the serenity of a painting by the greatest of all masters.”

Although it’s rare for us to be awake and looking at just the right time to witness these nightly activities, curious naturalists can piece together the stories by daylight in the snow. Lois later wrote:

“Each day as daylight comes, I find it one of my more pleasant self-imposed duties to check on the outdoor activities of the preceding night.

“A cat has wandered through the yard and across the porch, its small round paw prints unmistakable. Cottontails have hopped contentedly, picking up scraps in the bird feeding areas, only to bound away in sudden fright, their leaping tracks closely followed by those of a dog. Near a woodpile the springing two-by-two tracks of a weasel trace an erratic pattern that becomes more purposeful as it merges with the tiny pattering tracks of a vole and both disappear down a hole in the snow near a clump of tall dead grass. 

A bobcat track (pictured) is a larger version of the tracks of a house cat.

“Days of soft snow will find areas around the bird feeders stitched in crazy-quilt patterns by the feet of many small birds and perhaps those of a raven or crow who, at some time, strode through to collect a choice morsel.

“These and many other signs may be found along nearly any street or roadway or in one’s own yard. Beyond those more civilized confines are tracks in endless variety. The meandering tracks of deer, of fox or coyote on the prowl for food, the skittering of squirrels from tree to tree, or the shuffling snowshoe tracks of partridge [grouse] are only a few. A streamside or frozen lake may reveal the tracks of mink or the joyful run-and-slide pattern left by otters. 

The joyful run-and-slide pattern left by otters. Photo by Emily Stone.

“The knowledge of tracks is a necessity to the hunter or trapper, but it can be a great source of pleasure to those who enjoy nature for its own sake and like to speculate about the stories tracks can tell.”

Want to learn more about tracking? I’ve written about it many times on this searchable Natural Connections blog. I also recommend the Falcon Guide to Scat and Tracks of the Great Lakes, available with free shipping from our friends at Redbery Books in Cable. Enjoy! 

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at Or order it from our friends at to receive free shipping!

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is closed, but our Mysteries of the Night exhibit is available online. Connect with us on Facebook, Instagram, YouTube, and to keep track of our latest adventures in learning.

Thursday, January 14, 2021

Rime Ice and Hoarfrost Make the Hidden Visible

Winter is a season of magic. Hidden beauty becomes visible. Much remains a mystery. 

It begins with our breath.

Chilly mornings are one of the first signs that winter is on her way. We step outside, fill our lungs with a deep drink of invisible air, and send forth a translucent, swirling cloud. Sunlight—because the coldest mornings follow cloudless nights—makes it glow.

Every day of our lives, air goes in and out of our lungs at least a dozen times per minute. Air also cycles in and out of plants, animals, fungi, soil, and more. I love to think about what this means for our connection to the biosphere. The air we sip into the cradles of our lungs was—just a moment ago—part of someone else’s life. The air we return to the world may enter a tree and become maple sugar, or enter a bird’s lungs and become song. 

During the pandemic this has become a terrifying problem. But in the past, in the future, and always when we’re in the woods, this reciprocity is a gift. Nonetheless, it’s easy to forget the physical properties of our breath until cold air forces the gaseous water vapor we exhale to condense into visible droplets. They are now liquid, and while big enough to see, are still small enough to float. This is the same alchemy that fills summer skies with cottony puffs of while clouds.

As winter deepens, a lack of humidity makes our breath invisible again. Clouds, however, remain. 

Lately, an unusual combination of winter weather conditions have made visible the exhalations of the Earth herself. Fog that is dense and persistent enough to trigger weather advisories has brought its own unusual magic to the winter landscape. Snow on the ground releases moisture into relatively warm air. That humidity condenses as night falls. Calm winds fail to sweep the resulting fog aside.

Fog is simply a cloud that hugs the ground. It, too, is water in the air made visible as cold causes droplets to grow. Magically—tenuously—that water remains liquid even though its temperature drops below freezing. When these supercooled droplets collide with the solid world, they freeze instantly. The ice they form becomes another solid surface, and more droplets accumulate. As light winds push the fog along, elaborate, bizarre, thick-but-fragile rime ice builds up on the windward side of pine needles, twigs, and more. For the past few weeks, this freezing fog has accentuated the grace of our forests. 

Rime ice formed on the upwind side of these red pine needles when supercooled droplets of fog froze upon contact. Photo by Emily Stone.

Water in our breath, along with fog and rime, goes through the liquid state as it becomes visible. In contrast, hoarfrost and snowflakes materialize into solid form directly from invisible water vapor when the dew point is below freezing. When that water vapor crystallizes around dust particles in the air, we get snow. When crystals grow on twigs, pine needles, even on other bits of ice, we awaken to a lace-encrusted fairyland of hoarfrost.

Down by my lakeshore, a spring bubbles up and feeds a bit of open water under the low-hanging branches of hemlock trees. In this protected haven, on cold nights, invisible water vapor in the air feeds the growth of elaborate crystals patterned like feathers, ferns, needles, and trees. These physical structures—formed of crystal facets and six-fold symmetry—give us a peek into the inner workings of water molecules. It’s a world filled with electricity, with forces of attraction and repulsion, with crystal lattices; a world usually observable only to chemists and physicists. 

Hoarfrost crystals grow directly from water vapor in calm and humid conditions. Their structures reflect the inner workings of water molecules. Photo by Emily Stone. 

Yesterday, when I headed down to the lake, I found it ringed by trees painted white with rime ice and shining in the sunlight. Impossibly complex crystals of hoarfrost bordered the spring. And a maze of otter, fox, and coyote tracks recorded stories of my unseen neighbors in the snow. 

I filled my lungs with a deep drink of air—now with some of its secrets made visible by the magic of winter. 

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at Or order it from our friends at to receive free shipping!

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is closed, but our Mysteries of the Night exhibit is available online. Connect with us on Facebook, Instagram, YouTube, and to keep track of our latest adventures in learning.