Lake Mendota froze officially on January 34, www.fishing.info/engberg_12_08_11.html2021. The median freeze date date for the lake is December 20th. With the lake freeze, the tundra swans and other water fowl left, and a new set of lake water foragers has arrived: Ice fishermen. Their arrival completes the annual cycles until spring sets in.

The deeper waters off Picnic Point are a hot spot for good sized perch. At this time, walleyes are still found in water less than 15 feet deep, but as the winter progresses, they will move to mid-lake. Also this early in the year, the fishermen catch fish attracted to the various baits throughout the day, but as winter progresses the best times are early morning and the later in the day. (see http://www.fishing.info/engberg_12_08_11 for more information on good ice fishing spots in Lake Mendota) 

​​Rime frost and its cousin hoar frost have dazzled observers with their beauty since ancient times. In his book Μετεωρολογικά, Meteorologia, Aristotle noted
"Both dew and hoar-frost are found when the sky is clear and there is no wind. For the vapour could not be raised unless the sky were clear, and if a wind were blowing it could not condense." (347a26-28)
 
The term hoar frost derives from hoary which means gray or white in medieval English of the 14th century, and was used as adjective for a person with a white beard and hair. Hoar frost forms when water vapor in moist air comes in contact with objects that are well below freezing, like trees and grass during freezing night in winter, often with starry skies above. Here the water vapor, a gas, changes its state directly into a solid, the ice on the trees and surface objects, and we have frost.
 
The term rime frost derives from the 12th century, old Norse term hrīm or rimfrost. Conditions for rime frost are less likely in Greece or in England than for hoar frost, but occur regularly in snow covered northern landscapes like ours. Rime frost can form when layers of fog or mist develop in moist air over snowfields during cold nights with temperatures below freezing. The fog consists of tiny water droplets, cooled below freezing and suspended in the cold air.

Being both a meteorologist and historian of science by training, I take pleasure in tracing how people have always been fascinated with special weather phenomena and have tried to describe and explain them. We are grateful to Steve Sentoff for providing the photos. 

After Madison’s Lake freeze, the tundra swans on University Bay will continue their migration to open waters in the Chesapeake Bay and elsewhere. During the migration period they gather in huge flocks. It is believed that the tundra swans mate for life. But after they mate and have reached their breeding grounds in the northern tundra, they fiercely defend their large territories and live as solitary pairs. ​

Will Vuyk, student Board member of the Friends, regularly visits the Preserve to observe changes of the seasons and lets himself be surprised by the beauty of nature. The heavy snowfall over the weekend drew the tundra swans from further north to the Madison Lakes. If you venture to the boat landing at University Bay, you will hear them chatter and carry on their disputes, displaying their beautiful wings and standing up tall in the water. Otherwise, they are intent on foraging, their heads under water and reaching almost a yard down with their long necks to find the choicest morsels of water plants in the University Bay.

Will writes: "The tundra swans have arrived with the snow! Lit from the west by the mid-afternoon sun, the postures and pursuits of these sociable birds are enchanting. If you are able to peel your eyes away from the swans, the Preserve itself, (while picturesque in all seasons) has been stunningly highlighted by the snow. Walk your favorite trail, enjoy your favorite spot, take in your favorite view, all accentuated in white." Enjoy Will's photos below. With the temperatures staying below freezing and no strong winds, the winter wonderland is till very much intact. 

On December 13, a wondrous snowfall brought brilliant beauty of the purest white to the Preserve. Every tree, every path, every grass blade had changed. Soft tufts of snow were clinging to every twig and branch. At the Picnic Point Marsh, tree trunks have snow packed on their north sides, which were exposed to driving northerly winds all night. Arlene Koziol is sharing her photos of freshly fallen snow on her Flicker site. 

On my weekly Tuesday morning stop at the bay, I was hoping to see some new arrivals on this crisp and sunny  1 December morning. And yes. The Tundra Swans have returned to the bay, showing off their brilliant white plumage. You can observe them from the boat landing at University Bay and close to shore along the path toward Picnic Point. Buffleheads, Common Goldeneyes, and masses of American Coots are close by. The first ice has formed along the shore rocks. Notice the strong mirage, the vertically elongated buildings on the opposite shore, resulting from cold air lying on top of still warm lake water.  Gisela Kutzbach

The Purple Martin House monitored by the Friends is located on the highest spot of the Biocore Prairie, offering a 360-view of over a large open area and a convenient high perch. Throughout the year it is visited by many birds other than Purple martins. Our monitors have observed Red-winged blackbirds, an American robin, two Baltimore orioles, Tree swallows, a Song sparrow and even a Ruby-throated hummingbird. House sparrows try to invade the nesting cavities, and once in a while the Community Garden's resident Red-tailed Hawk will perch on the very tip of the house. 

In the sequence of photos taken by Arlene Koziol on Nov 21, 2020, the hawk is watching the ground from up high, clinging to the tiny house top with its strong talons, then spotting some prey, possibly a vole or rabbit, and – with his eyes firmly tethered to the object on the ground – elegantly swooping down to capture the creature. ​See all of Arlene's photos at her Fllckr site.

Glenda Denniston spotted the rare Rusty-patched bumble bee in the Preserve, and not just one but two individuals. She reported today: "Yesterday I photographed this Rusty-patched Bumble bee (B. affinis) on a Monarda near Second Oak, Frautschi. I sent the photos to Susan Carpenter, our local bee expert, and she confirmed the ID. Susan said it was a worker and that she was engaging in “nectar-robbing” behavior (bypassing pollination of the plant to access nectar by a shortcut). This is the first Rusty-patched I’ve seen in the Preserve in quite a while, though I haven’t been looking as carefully as I once did." One big reason Glenda spends much time in the area of the Second Oak at Frautschi Point is that she has been instrumental in developing the current flowering plant communities in this area, which attract many different pollinators.

See also an interview with Susan Carpenter, Friends member and leader of our popular pollinator field trips in the Preserve, about her research on Bombus affinis in the Arboretum, as well as her Guest Blog in the Scientific American on "How to protect our disappearing bumble bees."

The Rusty-patched bumble bee's tongue is not long enough to reach the nectary at the base of a tubular flower such as Monarda or wild bergamot. Thus it did some nectar thievery by perforating the flower petals at the base and gaining quick access through the hole to the food. Wild bergamot is a marvelous forage plant for bumble bees, especially those with long tongues. It keeps its flowers open all day, replenishes nectar continuously, and replaces spent flowers with new ones over much of the summer. The gallery below features two different individuals. Notice the darker brown spot on the B. affinis shown in the two lower photos. 

That same day, Glenda also spotted another bumble bee that is currently in the decline and of Special state concern in Wisconsin: the Yellow or Golden northern bumble bee (B. fervidus). see the photos below. 

​Fungi in the Preserve grow every months of the year, but they tend to flourish in warm temperatures and in the moist conditions we currently have in the woods. From the plethora of fungi photos submitted this month to iNaturalist, a selection is shown here, many of them photographed by Friends members. The Kingdom of fungi has its own classifications of families and species, but here is a grouping by color, mainly white. It includes many common gilled mushrooms, as well as shelf fungi, bracket fungi, rust fungi, and even jelly fungi. One reason there are so many white fungi is that they have no chlorophylls. They recycle important nutrients in the forest, and they extract the energy they need from organic compounds, such as sugars or protein, in living or dead organism. These processes take place mostly beneath the surface or in the soil, and the function of the visible part of the fungi is to ensure reproduction by producing and releasing spores.