October 19, 2007
By Susan Benson
Director of Education
Cable Natural History Museum
We continue our march toward winter! One sure sign is that when we step outside mornings and evenings, we can see our warm, moist breath condense in the chilly, drier air.
The same thing happens as plants and the ground itself “exhales” at night. All air contains moisture, which is called water vapor. The moisture in the air close to the ground comes from the soil and the plants; when this air cools at night, the moisture condenses to form water droplets on the grass and plants—what we call dew. When the temperature falls below freezing point, the moisture in the air freezes into ice crystals and settles on grass and plants—this is frost. Unlike dew, frost damages plants because the water inside the cells of a plant freezes and breaks the cells’ walls, resulting in the death of the affected part of that plant.
This cool fall air is still full of birds; many songbirds have already left the region, but you can still see ducks, Canada geese, woodcock, and snipe on the move, migrating south. Start watching for winter visitors arriving from Canada, like the dark-eyed junco and white-throated sparrow.
Another unmistakeable bird you might chance to see this fall is a wild turkey. The largest game bird in North America, turkeys were historically abundant in central and southern Wisconsin, and provided an important food source for Native Americans and early settlers. Wild turkeys were nearly eradicated from the state, but a successful reintroduction program begun in 1976 has led to healthy populations found throughout the southern two-thirds of Wisconsin.
It was thought that turkeys would not be able to survive in the northern part of the state, because long periods of snow cover would keep them from finding food. However, during the winter of 2003-04, 164 turkeys were released onto six sites in Bayfield and Ashland Counties, and due to a combination of the hardiness of this species, plus our recent mild winters, the turkeys have thrived and expanded their population and range in our region.
Out on Lake Superior, anglers have been pulling on their insulated waders and heading out around the mouths of tributary streams and rivers, hoping to catch coho salmon. At this time of year, cohos migrate from the lake and upstream to spawn.
This popular sport fish, sometimes called a silver salmon or sea trout, is not native to the Great Lakes, but was intentionally brought here to help reduce the populations of alewives (also not native) in Great Lakes waters. By the late 1960s, coho were regularly raised in hatcheries and stocked into the Great Lakes, and now for better or worse have become part of the lakes’ ecosystem.
Become a phenologist! Jot down on a wall calendar each day you see or hear geese outside, then note the day they finally all depart. Keep track of the date of the first snowfall, or the first subzero night, then compare those notes from year to year to make your own record of winter’s arrival.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.