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.

A foray into fall fungi

Post by Brett Peto

Until recently, I haven’t given mushroom (much room) in my head to the Fungi kingdom. It’s been an admitted blindspot in my nature knowledge for too long. I’m taking some steps to correct this, though. Reading books such as Entangled Life by Merlin Sheldrake. Looking for fungi in the Lake County Forest Preserves in northern Illinois and other natural areas. Taking photos of the ones I find and doing my best to identify them.

There’s still much I don’t know—apologies for any errors in advance—but I can claim to know a bit more now than I did at the start of 2021. With fall being possibly the best time to spot some fungi, I thought I’d write about some common species you might discover in the preserves.

Some slugs feasting on fungi. Photo © Helena Keller.
Some slugs feasting on fungi. Photo © Helena Keller.
Continue reading

Bringing back the buzz

Post by Jen Berlinghof

All summer long, swaths of wild bergamot (Monarda fistulosa) quake in the presence of thousands of native bumble bee wings beating away. These pollination dynamos use a technique called buzz pollination, vibrating their bodies to trigger nearby flowers to release pollen. At the Lake County Forest Preserves in northern Illinois, a similar buzz of excitement arrived in summer 2020 when staff spotted the federally endangered rusty patched bumble bee (Bombus affinis) at Greenbelt in North Chicago.

Fast forward to summer 2021. The hum continues to reverberate after multiple sightings of this keystone species were documented across the county from Flint Creek to Wadsworth Savanna in Wadsworth. While summer’s the height of hive activity, the shoulder seasons—usually defined as May, June, September and October—might be key to the success of the rusty patched bumble bee. This is partly due to the timing, or phenology, of the species’ lifecycle. It’s one of the first bees to emerge in spring and the last to enter hibernation in fall.

A worker, or male, rusty patched bumble bee (Bombus affinis) sits atop mountain mint. Photo © Dan Mullen.
A rusty patched bumble bee (Bombus affinis) sits atop mountain mint. Photo © Dan Mullen.
Continue reading

A thousand-mile journey on two-inch wings

Post by Jen Berlinghof

I’ve spent many days this summer living the “lake life,” from the sandy dunes of the Great Lakes to the cattail-studded coves of inland waters. The waterways found within the Lake County Forest Preserves in northern Illinois have been especially rewarding. Each shoreline has provided unique glimpses of wildlife, including an osprey (Pandion haliaetus) diving full throttle to catch a fish at dawn, and a red fox (Vulpes vulpes) pouncing on prey hidden among the beach grass at dusk.

Also present at every waterway this summer has been the jewel-hued, common green darner dragonfly (Anax junius). These ubiquitous insects effortlessly nab multitudes of mosquitoes on the wing. While the monarch butterfly (Danaus plexippus) reigns in our minds when it comes to insect migrations, recent research reveals the green darner takes a multi-generational, miles-long journey of its own each year.

Common green darner dragonflies (Anax junius) are found in the forest preserves. Stock photo.
Common green darner dragonflies (Anax junius) are found in the forest preserves. Stock photo.
Continue reading

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

On the path to recovery

Editor’s note: hello readers, Brett Peto here. Guest author Pati Vitt, Manager of Restoration Ecology at the Lake County Forest Preserves in northern Illinois, is back with the second of her three-part series about our research project to restore 180 acres of former farmland within Grant Woods Forest Preserve using a climate-adapted, regionally sourced native seed mix.

An aerial view of the 180-acre research project area at Grant Woods in Ingleside. Photo © Mike Borkowski.
An aerial view of the 180-acre research project area at Grant Woods in Ingleside. Photo © Mike Borkowski.
Continue reading

Flicking through the Flickr pool

This gallery contains 10 photos.

Post by Brett Peto

You don’t need me to tell you that 2020 has been a long year. In a pandemic, separated from routines, sometimes days go slow but months go fast, and vice versa. There are fewer anchors around which to pin our schedules like so many pieces of laundry on a clothesline. Some people have started baking homemade bread, assembling model kits, binging movies and podcasts, devouring piles of books, or playing long-distance board games over Zoom. Our strategies may vary, but I think it’s helpful to have as many coping mechanisms as we can gather this year.

One adopted or continued by many folks is spending more time outdoors. Whether in yards, neighborhoods, parks, or the Lake County Forest Preserves in northern Illinois, people are discovering or rediscovering the value of nature, even as the thermometer dips. Fresh air; sunshine; wide horizons; the sounds of wind in trees and water over rocks; birds and squirrels and foxes living their private lives; the calm curiosity to find out where a trail goes and the confidence that it’s designed to go somewhere.

"Ice Ice Baby." Photo © Michelle Wendling.
“Ice Ice Baby.” Photo © Michelle Wendling.
Continue reading