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.

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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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