You’d be surprised what’s alive out there

By Beth Fetterly

Winter outdoors in Wisconsin invokes a magical sense of awe, as long as you have a warm hat, coat, and pair of boots handy. Not only is it the perfect time to explore how plants and animals adapt to snow and freezing temperatures, but also to explore global warming trends, insects, and birds.  Surprised?  Read on.
 

Collect your own evidence of climate change
Stepping outside in the heart of a bitterly cold Wisconsin winter day as the wind chill takes our breath away can lead to the skeptic muttering, “Global warming, what global warming?”
Climate change is tough to grasp because we read about it on the global scale; yet did you know that our Wisconsin winters provide a strong set of data that helps scientists better understand climate change?  The Center for Limnology located at UW- Madison has tracked the dates when Lake Mendota’s surface water completely freezes over (and when the ice cover breaks) for more than 150 years. They discovered that an average winter these days provides 19 fewer days of ice cover compared to a century ago.  This easily observable occurrence also shows that most of the longest seasons of ice cover happened more than 100 years ago, and that most of the shortest periods of happened within the past 25 years.  This, combined with research from other lakes around Wisconsin, Finland, Russia and Japan is one way that scientists — and anyone else — can track climate change.

Would you like to practice being a climate scientist?  Find a place along one of Milwaukee’s rivers, lagoons or even the Lake Michigan harbor, that is convenient for you to reach frequently.  Then visit that spot as often as possible with a friend or family member, and note the date when you first see ice, first see open water after ice cover and the date when you no longer see ice.  Put these three pieces of information on a calendar and make it an annual tradition. Every year you will be able to build on your own set of data.  Maybe you can even play a guessing game each year (yep, climatologists do that, too) and see who in your group of winter explorers guesses the right day. Maybe the winner gets some hot chocolate?
 

Admire the mourning cloak
While you are out practicing being a climatologist this winter, you can entertain yourself by being an entomologist, a person who studies insects.  Yep, that’s right, insects in winter.

The amazing Mourning Cloak butterfly is adapted to survive as an adult throughout the winter. In fall it produces high levels of glycerol, which lowers the freezing point of fluids in its body, which protects it from ice damage. During the colder days of winter, it remains in a state of insect hibernation, called diapause, while nestled under a brush pile, loose bark or even the eaves of your home.  However, on the occasional warm winter day, you may be able to spot this large dark butterfly outlined in pale yellow flitting over snow-covered ground!  A butterfly silhouetted by snow is an awesome sight.  If you see one, make a note of it.  Here’s a hint on locating one: Mourning Cloaks prefer tree sap, especially sap of a maple or a birch. Try to look for a tree that may have suffered a bit of winter damage and find where the sap is leaking; this sweet treat may be just what it takes to attract one of these lovely creatures.
 

Search for snow fleas
Grab a hand lens and search for bite-less “snow fleas,” which are not fleas at all, but springtails.  Their nickname refers to their size and the way that they hop, seemingly like a flea. But they do not use legs to jump; they use a spring-like tail called a furcula.  The tail remains folded under its body, held in place by a tiny hook, until the insect releases it.  When startled, the insect unhooks its tail which smacks against the surface of the snow, propelling the bug through the air! On the next mild winter day, this is a sight worth finding. The comma-sized springtail can be found on the surface of snow, usually near trees, feeding on fungi and algae. Depending on the species (there are nearly 700 documented in North America), springtails use varying forms of “insect antifreeze” as well as heat radiating off the white snow onto their dark bodies and from nearby trees to withstand the cold.

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Listen for owls
Winter is a good time to hear a Great Horned Owl, even right in the heart of Milwaukee. Why?  It is mating season, and they are trying to attract a partner.  The great horned owl hoots with a rhythmic pattern close to the phrase, “Who’s awake? Me tooooo.”  When two owls exchange mating calls, however, the haunting hoots can turn into agitated squawks.  After the eggs are laid further into winter, owls continue to protect the nest and incubate the eggs for about four to five weeks until they hatch.  Then it takes yet another month for the young to fledge — just in time for the spring activity of their prey.

So, enjoy the winter! Collect ice information, admire a butterfly, search for a springtail or listen to the owl. It will surely be an adventure.