Geothermal

Chippewa Nature Center is growing greener! By now, hopefully you’ve heard about our fantastic new Nature Preschool (see diagram) and upcoming expansion of the Visitor Center. The expansion will add additional space for more classrooms, an auditorium for large groups and enough office space to finally fit our entire staff. During the design of our new facilities, CNC staff worked closely with Kubala-Washatko architects to make our expanded facilities as energy efficient and environmentally friendly as possible.

One way to greatly reduce energy consumption is by using a geothermal heating and cooling system. Geothermal pumps use the stable temperatures of the ground as a heat source to warm buildings in winter and as a heat sink to cool them in summer. If you’ve ever explored a cave or been in a tunnel, you may know that the temperature deep underground stays amazingly stable throughout the year (about 55-60 degrees F). By boring vertical wells underground (typically 100 to 400 feet deep), we’re able to borrow some of this stored energy to use for heating and cooling the building.

A geothermal heat pump doesn't create heat by burning fuel, like a furnace does. Instead, in winter it collects the Earth's natural heat through a series of pipes, called a loop, installed below the surface of the ground. Fluid circulates through the loop and carries the heat to a compressor unit in the building. This electrically-driven device acts as a heat exchanger to concentrate the Earth's energy and release it inside at a higher temperature in winter.

In summer, the system draws heat from the building and transfers it into the earth through the loop. Cool liquid then runs from the Earth back into the building. Inside the newly-constructed portions of the building, plastic pipes will run underneath poured concrete, forming a “water-to-water” radiant slab system. In current portions of the building, a “water-to-air” system will use forced air in order to heat and cool the building.

Geothermal systems aren't just for big places! Many people have discovered the energy-saving benefits of geothermal right in their very own homes. For a great introduction to everything about geothermal energy, check out this Energy Kids Website.

Autumn Photo Journal

Leaves of gold, migrating birds and squirrels getting ready for winter.

Fallen leaves on the forest floor and a crisp chill in the air.

Oh Autumn, if you could only linger!

Squirrels at the Feeder

I sometimes wonder if the Gray and Fox Squirrels feasting on millions of pounds of sunflower seeds at America’s backyard bird feeders ever think about the “good ole days.” Do they remember burying acorns and other nuts throughout the forest, and scrounging all winter, using their fine noses to rediscover the vast majority of

their cache? (Or perhaps someone else’s cache – 85% of buried nuts are found and eaten, but not necessarily by the original owner.) Do they remember days on end of not having food because a thick layer of ice made digging through the snow impossible? Do Gray Squirrels in particular have family legends of the great emigrations, when thousands of them periodically deserted food-scarce forests, drowning by the hundreds as they tried to swim swollen rivers?

Squirrels have always eaten a varied diet, including not only the nuts they are famous for burying, but the buds, blooms, sap, and inner bark of trees, as well as fungi, insects, galls, bird eggs, and fruit. They know their resources well. Gray and Fox Squirrels, for instance, learn in just one season to snip out the seed embryo from a white oak acorn before burying it, else the acorn will germinate and grow a large taproot, which squirrels aren’t keen on eating. Red oak acorns, on the other hand, are buried “as is,” because they go dormant after falling from the tree, and will store nicely for the whole winter.

Fungi are stored for winter eats as well, though more commonly by Red Squirrels than by the two larger squirrel species. Fungi are not just buried; they are first snipped off at the base or in bite-sized chunks, and left to dry on a stump or in the fork of a tree.

The cynic in me sometimes believes squirrels no longer have need for these basic survival skills, because they simply eat at bird feeders on demand. In reality, though, I know this isn’t true. I get too many calls from people upset about squirrels stripping the bark from maple trees in the spring. (We aren’t the only ones who know about the sweetness of maple sap.) On nearly any walk in the fall woods, I find at least one mushroom drying on a stump. And just to prove how savvy they are (or how little I know), a young black squirrel ran by my window as I wrote this article -- carrying a walnut he was obviously intent on burying!

-Janea Little, Senior Naturalist

Map-Free Travel

Most people stop and check a map when they take a long trip, or even on a short trip into a new area. You first double-check that you are where you think you are, then look at the route ahead to see what to expect in terms of route changes, distances, and obstacles.

In comparison, the map-free travel plans of birds have long been a mystery. How do they know where they are going, how far to go, or what route to take? Year after year, ornithologists have answered many questions about how birds get oriented.

They have learned birds use stars to navigate by. They have learned that birds have a built-in compass to orient by the magnetic poles of the planet, although they can’t tell magnetic north from south. (A very significant point for long-distance migrants that cross the equator.) And they know that birds can see polarized light, which enables them to orient by the position of the sun even on a fairly cloudy day.

In 2004, another piece of the migratory puzzle was solved. A team of scientists from the Illinois Natural History Survey, Princeton University, and Germany’s Oldenburg University, followed a series of Swainson’s and Gray-cheeked Thrushes that were tagged with radio transmitters and released at sunset for their nocturnal migratory flight. Some of the birds were simply “tagged” and released, while others were first exposed to artificial magnetic fields that were “off” by 80 degrees.

Control birds, as expected, flew due north when released. The birds whose magnetic “readings” had been skewed flew west for the first night, then rested during the day. The next evening, however, the control birds all corrected their course and headed north.

So what does it mean? Apparently birds are able to calibrate their internal compass using the location of the sun, and probably do so every evening before they take flight. It’s a significant factor for those long-distance migrants, who can re-orient after crossing the equator. Question #312 answered, two-and-a-half million to go!

-Janea Little, Senior Naturalist