Leopards and tigers and bears!

Post by Jen Berlinghof

Around the first frost is the best time for spotting bears in the Lake County Forest Preserves in northern Illinois…woolly bears, that is! These fuzzy caterpillars succumb to a late fall wanderlust and can often be found traversing trails and roads, as well as climbing vegetation and nibbling a last few bites before winter sets in. They belong to the subfamily Arctiinae, commonly known as tiger moths. Their scientific name stems from the ancient Greek word arktos (“bear”), for the appearance of their hairy larvae.

A woolly bear caterpillar (Pyrrharctia isabella) found along the Des Plaines River Trail. Photo © Lake County Forest Preserves.

Any ten-year-old child can probably identify the most common woolly bear larva in the area, the isabella tiger moth (Pyrrharctia isabella). It boasts orange and black bristles in a banded pattern. That same child may also try to convince you this critter can predict the severity of the coming winter by looking at the length of the caterpillar’s bands of bristles. But just as groundhogs can’t truly predict the spring, moth larvae cannot predict the winter. After each molt, a stripe of the black setae (stiff hairs) is replaced by orange setae. This makes the orange band broadest in the last instar, or stage of larval development.

The author holds a giant leopard moth caterpillar (Hypercompe scribonia) in her hand. Photo © Lake County Forest Preserves.

I found another type of woolly bear caterpillar on a recent hike at Ryerson Woods (Riverwoods) that might be less familiar to folks. The larva of the giant leopard moth (Hypercompe scribonia) sports shiny black bristles separated by red inter-segments. Like the isabella moth larva, this giant woolly bear lacks stinging spines and doesn’t bite. When alarmed, it curls up into a tight ball, displaying its setae like little swords that can irritate the skin and mucous membranes of potential predators. This defensive posture also makes its bright red inter-segments prominent, a literal “red flag” to warn predators they’re unpalatable.

In its defensive posture, a giant leopard moth caterpillar displays its stiff setae and red inter-segments. Photo © Donald W. Hall.

Once these woolly bears have gorged themselves on asters, milkweed, sunflowers, violets, and even dandelions—and almost finished growing as larvae—they ramble on to find a suitable spot under leaves or logs to wait out the winter. Unlike most moth larvae that spend our freezing months tucked inside a pupal “sleeping bag,” in general tiger moths overwinter as nearly full-grown caterpillars, pumping glycerol through their bodies to keep their cells from freezing solid. They then emerge in spring to munch a bit more before creating a cocoon and completing metamorphosis.

The familiar orange-and-black woolly bear caterpillar emerges in spring as an adult isabella tiger moth. Photo © Patrick Randall.

An adult giant leopard moth. Photo © Christopher J. Williams.

As the sun sets earlier in the final days of fall and winter approaches, take these last moments to try to find these fascinating larvae before they hide away and press pause on their development. Discover new trails with our Hike Lake County Challenge before it ends on November 30. Then, come spring, look for the adult moths when both larvae and people emerge to explore the new season.

Happy New Year!

Video

Happy Winter from the Lake County Forest Preserves!

Video by Brett Peto

Whether venturing outside for fresh air and exercise, or finding a gorgeous spot to sit quietly and reflect on the past year, we find great peace in the Lake County Forest Preserves.

Thank you all for following along on our adventures this year. We encourage you to find a quiet spot to just breathe—perhaps the still woodlands of Captain Daniel Wright Woods:

Cheers to a new winter and peaceful new year!

Snowflake anatomy

Post by Jen Berlinghof

My family and I spent the beginning of the new year in the Northwoods. We wanted quiet. We wanted nature. Most of all, we wanted snow. As we started out on a snowshoe trek to a nearby river, tiny snowflakes settled on my son’s navy blue parka. They seemed to freeze on contact for only a few seconds, forming miniature constellations, before melting into temporary teardrop stains. The filigree of each flake in those hushed, fleeting moments fascinated both of my boys.

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Nature at night

Post by Jen Berlinghof

This winter’s lack of snow has made enjoying the winter woods a little more difficult for me. So, when a scant few inches of snow fell last week I made my way to Old School Forest Preserve at dusk to explore one of the Lake County Forest Preserves solar-lit trails.

Inky black branches of old oaks played in contrast to the white-washed sky before the blush of an orange sherbet sunset took over. The woods were still and quiet as I searched for any signs of crepuscular creatures that capitalize on the twilight. Continue reading

Des Plaines River Trail—Route 22 to Lake-Cook Road

Post by Jen Berlinghof

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It was a new year and a new trail, as we completed the last leg of our Des Plaines River Trail journey to hike the entire length of Lake County, Illinois. We began this hike just south of Route 22, which led us south through the recently completed trail section and beyond to the southern border of the county. We left our tracks upon the trail, just as the animals do along this greenway. Along the way, we found fresh signs in the snow that mice, squirrels, small birds, raccoon, deer, fox and even some intrepid fat-tire cyclists had all traversed the trail before us, taking advantage of a balmy 40-degree day in January. Continue reading

Stories in the snow

Post by Jen Berlinghof

As the thermometer dipped to -8 degrees Fahrenheit this week, one thing was clear: the snow and cold are entrenched for a while longer. So are the stories of the animals, as told by the tracks etched in the frozen landscapes that sweep across the Lake County Forest Preserves. We may not see the animals themselves. However, each track, pile of scat, bit of hair clinging to a branch, hole in the snow and chewed acorn is an element of the tale from their winter excursions.

How do we decipher these stories? When trying to identify which animal made a particular track, it is important to look not only at the individual track but the overall pattern. Also, scan the surrounding habitat for clues.

Let’s see if you can figure out what happened in each of these nature vignettes:

mouse tracks

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Surviving in the subnivean

This winter has been harsh in Lake County, Illinois, causing many of us to wish we could migrate to South America like some birds do, or hibernate in a cozy underground den like the groundhog.  Alas, most of us just stick it out in the cold. It may offer consolation to know we are not the only animals active during these record-breaking cold, snowy days. It turns out there is a whole ecosystem teeming with life right under the snow.

Recently, scientists having been taking a closer look at life in the subnivean, which literally translates to “a place under the snow.” The space between the snow and the ground acts as a seasonal refuge for invertebrates, birds, and small mammals. Snow affords these small critters with remarkable insulation, and temperatures around 32 F regardless of the temperature above the snow. Biologist Bernd Heinrich explains the science underlying these insulating properties in the book Winter World: The Ingenuity of Animal Survival. “As long as both ice and water exist side by side, they constitute a thermostat keeping temperatures constant.” When water converts to ice crystals, heat releases. When ice turns into water, the process uses up heat.

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