How animals survive the winter

Guest post by April Vaos

Living in Illinois, we’re lucky enough to enjoy a change of seasons. Though I often find it difficult to switch from the crunch of fall leaves to the crunch of snow, it can be a peaceful time to head outdoors. Recently, I went walking in Independence Grove in Libertyville, part of the Lake County Forest Preserves in northern Illinois. As I looked around in the quiet, contemplative landscape, I thought about the life that teemed all around me, and how it was now hidden from view or departed on a migration.

While leading winter walks, I’m often asked, “Where are all the animals?” It depends on the animal. Each employs different survival strategies that help it adapt and even thrive in winter. What, exactly, do animals do to make it through the challenges of cold temperatures and a lack of food? Well, I like to say they have MAD strategies: migrate, active and dormant.

When cool temperatures arrive in northern Illinois, so do dark-eyed juncos (Junco hyemalis). Not only do they visit Illinois, they migrate into all of the lower 48 states to spend a milder winter than where they’re from: Canada. Stock photo.
When cool temperatures arrive in northern Illinois, so do dark-eyed juncos (Junco hyemalis). Not only do they visit Illinois, they migrate into all of the lower 48 states to spend a milder winter than where they’re from: Canada. Stock photo.

Migrate: Many animals in Lake County migrate, or travel, from one place to another over short, medium or long distances to survive winter. It isn’t so much about the cold as the lack of food in winter. Food sources such as insects, plants and fish—which can’t be reached when waterbodies are frozen over—are largely unavailable.

Birds, butterflies and even bats are common migrators. Though we often think of animals migrating across hundreds or thousands of miles to different states or countries, they can also migrate short distances vertically. For example, some amphibians and insects burrow further down the soil horizon below the frost line to stay warm.

Lots of folks marvel over the long migration of monarch butterflies (Danaus plexippus), but hoary bats (Lasiurus cinereus) make extended flights, too. It’s believed that Illinois’ hoary bats migrate to southern California or Mexico for the winter, a 1,200-mile trip each way!

Hoary bats (Lasiurus cinereus) migrate to warm, southern locales for the winter. Photo © Merlin Tuttle.
Hoary bats (Lasiurus cinereus) migrate to warm, southern locales for the winter. Photo © Merlin Tuttle.

Active: Some animals remain active during winter. Doing so means they need to find food continuously to survive. To endure the weather, they may grow extra fur or build winter homes. Examples of animals that stay active include white-tailed deer (Odocoileus virginianus), coyotes (Canis latrans) and even channel catfish (Ictalurus punctatus).

Northern cardinals (Cardinalis cardinalis) are both the Illinois state bird and a great example of an active winter animal. Cardinals are permanent residents, forgoing southward migration. Due to the cardinal’s varied diet of seeds, fruits and insects, they can find enough food in Lake County year-round. While often called warm-blooded, a better term is endothermic, meaning cardinals can produce their own body heat.

Northern cardinals (Cardinalis cardinalis) are red year-round. They get their color from carotenoid pigments in the seeds and fruits they eat. Stock photo.
Northern cardinals (Cardinalis cardinalis) are red year-round. They get their color from carotenoid pigments in the seeds and fruits they eat. Stock photo.
During winter, red foxes (Vulpes vulpes) practice a hunting technique called mousing. Fox ears are sensitive to the quiet sounds that prey animals make as they chew or move around beneath the snow. When a fox locks on to a vole or mouse, it pounces, punching through the snow headfirst, trying to snap up its prey. Stock photo.
During winter, red foxes (Vulpes vulpes) practice a hunting technique called mousing. Fox ears are sensitive to the quiet sounds that prey animals make as they chew food or move around beneath the snow. When a fox locks on to a vole or mouse, it pounces, punching through the snow headfirst, trying to snap up its prey. Stock photo.

Dormant: Dormancy describes a period when an animal’s metabolic activity is minimal and development is temporarily suspended to conserve energy. This allows species to prosper in environments where they might not otherwise be able to survive.

There are varying degrees of dormancy. Hibernation is full winter dormancy, which can last all season and includes decreased body temperature, heart rate and metabolic rate. Groundhogs (Marmota monax) and thirteen-lined ground squirrels (Spermophilus tridecemlineatus) are hibernators. On the other hand, torpor, a deeper sleep than normal—as seen in black-capped chickadees (Parus atricapillus) and deer mice (Peromyscus maniculatus)—may only last a few hours. These animals are active in warmer weather but may enter torpor daily or during bouts of extreme cold.

Groundhogs (Marmota monax) are skilled at surviving winter through hibernation—but contrary to popular culture, they don't have the ability to predict weather or the severity of the winter. Stock photo.
Groundhogs (Marmota monax) are skilled at surviving winter through hibernation—but contrary to popular culture, they don’t have the ability to predict the severity of the winter. Stock photo.

Wood frogs (Lithobates sylvaticus) have an almost zombie-like adaptation. In fall, a wood frog finds a safe spot under a log or leaf litter. When the temperature in its home falls below 32 degrees Fahrenheit, the frog starts to freeze. This prompts its liver to convert glycerol into glucose, forming a sort of antifreeze. If you were to find a frozen wood frog, there’d be no heartbeat or breathing motion to tell you it was alive. But come spring, this hardy critter will thaw and hop away as if it never became a frog-sicle.

It’s interesting to note that most animals don’t have just one, but multiple strategies for outlasting winter. Blanding’s turtles (Emydoidea blandingii) are cold-blooded—or ectothermic—so they depend on the sun’s rays, plus air and water temperature, to keep their body temp ideal. For the winter, a Blanding’s turtle migrates down to the bottom of a wetland and buries itself in mud. Once safe and sound, it enters dormancy.

Looking for a way to not just survive but thrive this winter? Venture out for a hike with our Animals in Winter program on January 15, 2022, 1-4 pm. Or learn to decipher animal tracks by taking our Winter Tracking and Wildlife Observation Workshop program on January 29, 2022, 9:30 am-12 pm.

Whatever you choose, I hope you get outside this winter and enjoy the serenity of the season, knowing that many animals are hunkered down for the time being—just waiting for spring to return.

Become a community scientist

Post by Jen Berlinghof

While the past year and a half has kept many of us mostly at home, nature in our backyards and beyond has provided a balm for these trying times. General use of the Lake County Forest Preserves in northern Illinois is trending 30% higher in 2021 than a typical pre-pandemic year. And in 2020, there was an astounding 70% surge in visitation. The number of folks delving into home gardening and backyard birding has skyrocketed as well, making headlines by leaving store shelves bare of birdseed and bird feeders. The COVID-19 pandemic has amplified our desire to connect to nature closer to home, and it has created space and time for local, daily observations. All of this translates to an environment ripe for community science, also called citizen science.

Community scientists flip over a cover board during a BioBlitz event held at Middlefork Savanna in Lake Forest in 2008. Photo © Carol Freeman.
Community scientists flip over a cover board during a BioBlitz event held at Middlefork Savanna in Lake Forest in 2008. Photo © Carol Freeman.
Continue reading

A native garden to call your own

Guest post by Eileen Davis

What is your earliest gardening memory? Was it planting a seed in a paper cup at school, and watching it sprout and grow on the classroom windowsill? Perhaps you gathered dandelion flowers and presented your mom with a beautiful, yellow bouquet. Or did you rake up a giant pile of leaves to jump in on a crisp fall day? You might even have visited the native garden at Independence Grove in Libertyville, part of the Lake County Forest Preserves in northern Illinois.

My earliest gardening memory is helping my aunt and uncle in their garden. I was only about four or five years old, but I clearly remember the prickly feeling of the cucumber vines scratching my forearm as I helped pull weeds. No matter the memory, we are all doing the same thing—tending to our little piece of the Earth. It’s something humans have done for thousands and thousands of years. We are and always have been dependent on our environment for survival.

The author's daughters playing in a backyard leaf pile. Photo © Eileen Davis.
The author’s daughters playing in a backyard leaf pile. Photo © Eileen Davis.
Continue reading

The cunning of cowbirds

Post by Jen Berlinghof

Bird migration is well underway, and the nesting season is upon us at the Lake County Forest Preserves in northern Illinois. I watched last week as an American robin (Turdus migratorius) plucked dried grasses from the yard, nudging them into place with her beak and wings, readying her cup-shaped nest for the azure eggs that are synonymous with spring. From the nearby American sycamore (Platanus occidentalis) tree, I heard the gurgling chatter of a flock of brown-headed cowbirds (Molothrus ater).

I thought about how while the robin might’ve seemed completely absorbed in her nest building, she was probably wearily listening to the cowbirds, too. Brown-headed cowbirds are North America’s most common avian brood parasite, forgoing nest building altogether. Instead, they lay their eggs in the nests of more than 200 other species of birds, leaving the incubation and rearing of their young to these unwitting foster parents.

A female brown-headed cowbird (Molothrus ater) spotted at Rollins Savanna in Grayslake. Photo © Phil Hauck.
A female brown-headed cowbird (Molothrus ater) spotted at Rollins Savanna in Grayslake. Photo © Phil Hauck.
Continue reading

The curious courtship of the American woodcock

Post by Jen Berlinghof

March is the demarcation of spring. This new season is brewing now as snowmelt percolates through the thick mats of leaves on the forest floor into swollen creeks. Sap is rising in the sugar maples (Acer saccharum), with its promise of sweetness after a harsh winter. The purple, mottled crowns of skunk cabbage (Symplocarpus foetidus) peek out of the thawing mud, surging toward the sun. And the quiet of winter is replaced with the cacophony of western chorus frogs (Pseudacris triseriata) accompanied by the “peent” and “whir” of American woodcocks (Scolopax minor) in the Lake County Forest Preserves in northern Illinois.

The American woodcock (Scolopax minor) is a curious species to study. Stock photo.
The American woodcock (Scolopax minor) is a curious species to study. Stock photo.
Continue reading

The feathered friends of fall migration

Guest post by Ken Klick

Fall bird migration is happening now at the Lake County Forest Preserves in northern Illinois, and each day (and night) brings tens of thousands of newly arrived birds. Yet finding fall migrants can be challenging. Their subdued palettes of brown, tan, and olive feathers hide in sharp contrast to their resplendent springtime colors.

Unlike spring migration, most birds travel quietly in the fall, barely whispering a note to indicate their presence. In Lake County, fall migration starts in July, when our forests and prairies are green and full of blooming flowers. It’s a five-month-long period involving more than 200 species that rest and feed in our nearly 31,000 acres of preserves.

Spotting a bird can be difficult when vegetation conceals fleeting glimpses, making observations tricky and identification nearly impossible. Besides, who’s thinking of fall migration in July’s summer vacation mindset?

Either way, here are some of my favorite fall birding observations by month, over my past five decades of birdwatching.

July brings our first fall migrants: shorebirds. A visit to the Lake Michigan shoreline at Fort Sheridan in Lake Forest finds sanderlings (Calidris alba), sandpipers (Scolopacidae family), and yellowlegs (Tringa spp.) avoiding people and surf while searching for food. Many migrating shorebirds have just finished raising young in the tundra’s perpetual daylight and have embarked on a 6,000-mile round trip journey.

Solitary sandpiper (Tringa solitaria). Photo © Phil Hauck.
Solitary sandpiper (Tringa solitaria). Photo © Phil Hauck.
Continue reading

The joy of a feather found

Guest post by Nan Buckardt

I found a feather today and it stopped me in my tracks. There it was, tucked into the dewy grass—a single, beautiful feather just lying next to my sidewalk.

It’s not uncommon to come across feathers in my work at the Lake County Forest Preserves in northern Illinois. My naturalist brain immediately started to assess the discovery, analyzing it on a few key points.

The feather the author found just outside her front door. Photo © Lake County Forest Preserves.
The feather the author found just outside her front door. Photo © Lake County Forest Preserves.
Continue reading

The solace of purple martins

Post by Jen Berlinghof

There’s solace to be found in the fact that the rhythms of nature march on. This spring, the sun still rises. The wild leek (Allium tricoccum) still pulses its verdant green arms through the pulpy leaf litter of the forest floor. The birds still surge through the skies as they migrate to and through the Lake County Forest Preserves in northern Illinois. Like us, some of these birds are inclined to congregate in large communities. Over the years, the colonies of a particular species, the purple martin (Progne subis), have become largely reliant on people to provide shelter for their nesting flocks.

Two purple martins look at each other on the ledge of a martin house. Photo © Phil Hauck.
Two purple martins look at each other on the ledge of a martin house. Photo © Phil Hauck.
Continue reading

Here comes the Sun (Lake)

Post by Brett Peto

The sky to the west was robin’s egg blue, a clearing in the day’s dose of clouds. They had just sneezed a handful of snow, already melting. I drove with the radio off. I didn’t know whether to wear my regular hiking boots or a pair of Wellington boots I’d packed at the last moment. The trail could be soggy, or maybe not. I was on my way to Sun Lake in Lake Villa, part of the Lake County Forest Preserves in northern Illinois.

For this month, I decided to revisit the idea behind my February 2019 post, when I explored a new-to-me preserve and wrote up my observations as a virtual tour. Readers seemed to enjoy it, and I enjoyed circling another name on the map I keep at my desk. So, here I was, about a year later, ready to chronicle another tour. Find a comfy chair and a warm mug. Here’s a snapshot of Sun Lake as I saw it.

The view looking south from the parking lot at Sun Lake. Photo © Lake County Forest Preserves.
The view looking south from the parking lot at Sun Lake. Photo © Lake County Forest Preserves.
Always look at the trail map before you go. Photo © Lake County Forest Preserves.
Always look at the trail map before you go. I walked the trail loop clockwise. Photo © Lake County Forest Preserves.
Continue reading

Finding the right angle

This gallery contains 10 photos.

Post by Brett Peto

I keep thinking about angles. Not the kind you measure with a protractor, but those you measure with your mind. The angle of a story, a conversation, or a project. Photography, of course, uses physical angles—where’s the camera pointed? is the sun directly overhead or is it the sweet time of golden hour?—but the best photos make you want to see even more. They make you want to break open the frame and soak in every bit of the Lake County Forest Preserves in northern Illinois.

Since it’s nearly the end of 2019, I thought I’d turn 180 degrees and peruse the photos uploaded to our group Flickr pool since January 1. Suffice to say: we’re spoiled. Spoiled with the beauty of Lake County’s flora, fauna, and natural areas, and the talent of the photographers who capture it for everyone to see. Trees and shrubs in their bright fall wardrobes on either side of a trail draining into a vanishing point. A sandhill crane (Grus canadensis) with both wings up like a paper airplane as it dashes to take off. A whirlpool of stars spun around a rich blue sky over a tranquil wetland.

I’ve gathered these moments plus seven more below, but that’s only a small taste. I encourage you to browse the rest of the visual buffet as we make the turn out of the 2010s into the 2020s. And, hey! You might become inclined to upload that shot living on your phone, camera, or computer.

"Night Moves." Photo © reddog1975.
Continue reading