ARBORETUM NEWS (NATURALISTSNOTES)

Winter Water

SUNDAY, JANUARY 20, 2013

Utterly appropriately for the day before Inauguration Day, we bracketed Sunday’s tour with glimpses of our national birds – the actual, well-known one, and the one Benjamin Franklin unsuccessfully nominated for the honor.

Moments after we started out, a juvenile bald eagle soared high above us. Always a thrill to see, eagles have been spotted in the Madison area fairly often of late. They don’t live here year-round, but do hang out from time to time when conditions—mainly food supply and open water—are adequate. This one was mostly dark-colored with some mottling. It did not yet display the pure white head and tail which mark the mature bird.

And skipping ahead to the end of the tour, what should we see in Longenecker Gardens but a small group of wild turkeys! Meleagris gallopavo is a very popular Arboretum resident. In a 1784 letter to his daughter, Benjamin Franklin said this of the species: “For in Truth the Turkey is in Comparison [to the bald eagle] a much more respectable Bird, and withal a true original Native of America… He is besides, though a little vain & silly, a Bird of Courage … ”

Nice to witness national symbols “in the flesh” on the eve of a very important political occasion in our country.

Our stated tour topic was “Winter Water”. I found significant changes in that water, and also in trail conditions, between my Saturday scouting expedition and Sunday’s tour. What a difference 24 hours and a 20+ degree temperature drop can make! What had been slushy on Saturday was frozen hard a day later.

Arboretum trails have, to borrow a phrase from the highway department, “slippery spots and stretches”. Caution – and good footwear – are advised.

So about water. Like all matter, it has 3 states: liquid, gas, and solid. The first two forms are simple to describe and identify: liquid water, and vapor or steam. But water’s solid or crystallized state can take many different forms, depending on the conditions in which it takes shape.

Ice is certainly one, although even not all ice is created equal. We hear of “black” ice, clear ice, white ice and so forth. And then there is snow, frost, hoarfrost or rime, freezing rain … it seems that winter water is not a simple thing.

Since I’ve mentioned snow, I want to invoke Wilson Alwyn “Snowflake” Bentley. The 148th anniversary of this Vermont bachelor farmer’s birth is coming up on Feb 9th. Bentley was the first person to photograph individual snowflakes, and in his lifetime would immortalize over 5,000 of them, using a microscope attached to a camera and working in an unheated shed on his family’s farm. He considered each snowflake to be a thing of almost unbearable loveliness, which if not documented for posterity would vanish forever.

To use Bentley’s own words: “A snowflake is an idea dropped from the sky, a bit of beauty incomparable, that if lost that moment is lost forever to the world.” In that thought he found his life’s work.

The incomparable Henry David Thoreau was also a great admirer of snowflakes. “How full of creative genius is the air in which these are generated!” wrote he, adding, “I should hardly admire them more if real stars fell and lodged on my coat.” Try and remember that the next time you are shoveling “tiny stars” off your walk and driveway.

For the purposes of our tour – since it wasn’t snowing—I wanted to contrast still with moving winter water. To that end, we hiked first to Teal Pond, a small runoff-fed pond east of the visitor center. This body of water is shallow and freezes solid in winter, making it especially good habitat for frogs and toads. With very rare exceptions, fish cannot survive freezing, so they are not present to prey upon the tadpoles, and herptile species can flourish.

On our way between Teal Pond and Gallistel Woods, we noted white-birch seeds on the snow. Birch catkins open in the winter, scattering their small, tan, star-like seeds. Spring snowmelt will soften these seeds, preparing them to germinate and grow.

Making a long loop through forested land, we traversed Gallistel, crossed the Arboretum road, and entered Wingra Woods. One of the best places to see our springs – water which stays unfrozen no matter how cold it gets – is where the foot of the Wingra Woods slope meets the lake.

But first, we paused to admire another birch – yellow birch – which if I had naming rights, would be called “golden”. This species grows on Wingra’s hillside amongst the hemlocks; particularly in afternoon sunlight, its bark has a metallic glow, almost iridescent. On Sunday, the intermittent sun cooperated, and we were treated to a lovely sight.

At the smaller Wingra spring, there was another of the weather-generated changes I mentioned earlier. On Saturday afternoon, when the air temperature was at least 40, I had noted the usual bright-green watercress growing in the stream. But on Sunday, when it was much colder, frost crystals had appeared on the plant leaves – a beautiful, sparkling edging of “lace”, formed when the vapor rising off the moving water met very cold air and quickly froze onto the first surface it encountered.

When this phenomenon happens on a wider scale, we call it “hoarfrost”. Crystals sparkle from dried prairie grasses, shrubs, and trees. It’s usually seen in the morning. Like Bentley’s snowflakes, hoarfrost doesn’t last long, but it is breathtaking.

Our final stop before heading back toward the visitor center was at the Big Spring overlook. Big Spring is a larger example of moving winter water – bubbling up from warmer territory underground and making its way toward the lake.

One final outdoor observation, not related to water: the trails of meadow voles are prominent right now in grassy areas near the visitor center. Look in the lawn north of Curtis Prairie, or by the little pump house building opposite the wigwam frame. You will see winding paths in the dried, matted grass; they’re the remains of tunnels created when voles moved about under cover of snow. I’m sure the hawks and owls are glad the snow has mostly melted away. It’s a different story for the voles and mice, who are now exposed to their predators.

Stay warm, safe, and most of all dry!

Kathy Miner, Arboretum naturalist

Located between Lake Wingra and the West Beltline Highway at 1207 Seminole Highway, the University of Wisconsin-Madison Arboretum features the restored prairies, forests and wetlands of pre-settlement Wisconsin. This 1,260-acre arboretum also houses flowering trees, shrubs and a world-famous lilac collection. Educational tours for groups and the general public, science and nature-based classes for all ages and abilities, and a wide variety of volunteer opportunities for groups, families and individuals are available.