Fall Colors

Nature Watch
October 8, 2008

By Susan Benson,
CNHM Director of Education

Every autumn we revel in the beauty of the fall colors. The mixture of red, purple, orange and yellow is the result of chemical processes that take place in the tree as the seasons change from summer to winter. During the spring and summer the leaves have served as factories where most of the foods necessary for the tree's growth are manufactured. This foodmaking process takes place in the leaf in numerous cells containing chlorophyll, which gives the leaf its green color. This extraordinary chemical absorbs from sunlight the energy that is used in transforming carbon dioxide and water to carbohydrates, such as sugars and starch. Along with the green pigment are yellow to orange pigments, carotenes and xanthophyll pigments which, for example, give the orange color to a carrot. Most of the year these colors are masked by great amounts of green coloring.

Chlorophyll Breaks Down
In the fall, because of changes in the length of daylight and changes in temperature, the leaves stop their foodmaking process. The chlorophyll breaks down, the green color disappears, and the yellow to orange colors become visible and give the leaves part of their fall splendor.

At the same time other chemical changes may occur, which form additional colors through the development of red anthocyanin pigments. Some mixtures give rise to the reddish and purplish fall colors of trees such as dogwoods and sumacs, while others give the sugar maple its brilliant orange.

The autumn foliage of some trees show only yellow colors. Others, like many oaks, display mostly browns. All these colors are due to the mixing of varying amounts of the chlorophyll residue and other pigments in the leaf during the fall season.

Other Changes Take Place
As the fall colors appear, other changes are taking place. At the point where the stem of the leaf is attached to the tree, a special layer of cells develops and gradually severs the tissues that support the leaf. At the same time, the tree seals the cut, so that when the leaf is finally blown off by the wind or falls from its own weight, it leaves behind a leaf sear. Most of the broad-leaved trees in the North shed their leaves in the fall. However, the dead brown leaves of the oaks and a few other species may stay on the tree until growth starts again in the spring. In the South, where the winters are mild, some of the broad-leaved trees are evergreen; the leaves stay on the trees during winter and keep their green color.

Weather Affects Color Intensity
Temperature, light, and water supply have an influence on the degree and the duration of fall color. Low temperatures above freezing will favor anthocyanin formation producing bright reds in maples. However, early frost will weaken the brilliant red color. Rainy and/or overcast days tend to increase the intensity of fall colors. The best time to enjoy the autumn color would be on a clear, dry, and cool (not freezing) day.

Enjoy the color; it only occurs for a brief period each fall.

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 13470 County Highway M or on the web at http://www.cablemuseum.org/ to learn more about exhibits and programs.

Fall Trees & Birds

Nature Watch
October 2008

By Susan Benson,
CNHM Director of Education

Are the pines dying? When did the hummers last leave the feeders? These are some of the questions that have filtered into the Museum in the last two weeks. Read on for more answers.

Using the term “evergreen” to describe our conifers is not quite right. It is normal for some needles on our area’s conifers to fall off the trees. This occurrence, called fall needle drop, is a loss of the oldest and innermost needles shed from our pines, spruce and fir. Some fear that this is a disease, insect, or other warning sign, but is natural this time of year. Pines shed their oldest needles in the fall, and white pines usually shed their needles every two years. Sometimes the needle drop occurs in a short period of time, rapidly browning and falling, and other years, it’s almost unnoticeable because the discoloration happens over a longer time period. Environmental stress conditions can also affect this event, as root stress from extended dry periods, excess soil moisture, or poorly drained soils can impact this phenomenon, creating a greater needle loss. By the end of the needle drop, the trees may look bare, having lost approximately a third of their needles, and if the current season’s needle growth was a good one, there can be a greater fall needle drop. The needles on the tips of the branches are the newest growth, and if they were brown, this would be a larger concern and indication that something might be wrong with a particular tree.

What is happening in the bird world? Yellow-rumped warblers and sparrows are still migrating through. Migrating raptors and geese are still observable as is the occasional thrush in the forest. The ruby-throated hummingbirds appear to be gone. As requested in a previous article, last day reports came into the Museum from several people: September 16, September, 13, September 13, September 15 - all observed in the Cable area. Another report from Cable shared the past three year’s data: 2006, September 9; 2007, September 8; 2008, September 13. Thanks to those who shared this information! Ruby-throats do not do well in temperatures below the mid-20s (F), so this, mixed with the photo-period (shortening day length,) sends them south. A larger contributing factor driving migration is when there is the greatest food abundance. Banding studies have shown that those we saw in mid-September were not necessarily the same individuals we saw throughout the summer. Stumpy and the others we may have named at our feeders (this name comes from one of the Cable bird reports) might already be gone. The number of birds migrating south could be double that of the spring migration with the addition of immature birds. The immature have no memory of past migrations, and so follow an urge to gain weight and fly; once their flight is established the first time, it is possible that this becomes the route that bird retraces throughout its life. Some recommendations for those of us who have hummingbird feeders are to keep them out two weeks past the last day sighted, just in case there is a later migrant looking for food. At the same time, it is suggested to not keep your feeders out in conditions where they might freeze.

Earlier in the week it was raining pine needles. Today the sun shines. Our glorious fall weather and events continue. Get outdoors and enjoy it more, and please email any unusual observations to info@cablemuseum.org.

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 13470 County Highway M or on the web at http://www.cablemuseum.org/ to learn more about exhibits and programs.

Day in October

Nature Watch
October 15, 2008

By Susan Benson,
CNHM Director of Education

What do birds do on a rainy, overcast day in October? I found out this weekend on a bike ride. Almost every day this fall I have gotten outdoors on my bike for a ride along the Namakagon River. Last Sunday, the maples were at peak. This week the aspens were at peak. Today, the maple I’ve watched change colors daily, was barren of every single leaf. Each day I stop along the route some place to make new observations. During this week’s bike ride, I watched and heard two bald eagles, an adult and juvenile calling; heard their wing beats above my head; and watched the adult fly swiftly and impressively as it followed along the Riverway. Slate-colored juncos were madly darting after each other through the brush. Black-capped chickadees and white-breasted nuthatches were flitting about. White-throated sparrows and many warblers were also foraging along the river.

Earlier in the week I was astounded by the numbers of migrating robins. They were everywhere, flying through the river valley, but in many other places around the region as well. I stopped long enough to find their favorite places, and discovered a chokecherry tree that had been almost completely stripped of all berries – in its upper branches the fruit stalks were empty. It was evidence that as our ground chills in the fall, robins do adapt their diet away from earthworms and more towards berries.

Robins form loose flocks for both feeding and flying during migration. By traveling in greater numbers, they are more able to notice predators and warn the others. Another advantage of their large flocks is that some individuals who have more experience and familiarity with an area can show others feeding or roosting areas. Their migration is patchy, with individuals spread throughout a bigger range to ensure that they will not deplete available food sources. Robins migrate mostly during the day, although move occasionally at night. They can fly up to 36 miles per hour, so can accomplish up to 200 miles per day. Robins often move ahead of warm fronts, arriving just before or along with rainy weather. Mixing these high pressure systems with northwesterly winds are good conditions for migration.

Migrate yourself outdoors this coming week, and enjoy all that fall still has to offer!

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 new facility in Cable at 13470 County Highway M or on the web at http://www.cablemuseum.org/ to learn more about exhibits and programs.

Children Outside

Nature Watch
September 24, 2008

By Susan Benson,
CNHM Director of Education

Take A Child Outside Week is September 24-28 this year. This initiative is a program designed to help break down barriers that keep children from discovering the natural world. The goal is to help children across the country develop a better understanding and appreciation of the environment in which they live, while increasing their enthusiasm for its exploration.
If you are looking for a beautiful place to spend an afternoon, look no further than the Cable area to the Forest Lodge Nature Trail. There exists a loop of trails with a wonderful blend of northwoods habitat. The terrain is perfect for an afternoon stroll, and the trails range in length from 1.2 to 2 miles, making it enjoyable for any level of hiker. The trails are located on the right side of Garmisch Road, left off of County Highway M.

When you arrive at this little gem, the sun beats warmly across tall grasses and recent wildflowers (asters, yellow coneflower, and goldenrod) that border the first stretch of trail. Here, chipping sparrows fly up before your feet, the heady scent of sweet fern reaches your nose, and the soft hum of pines meets your ears. Further on, you will reach the cool shade of a hardwood forest. Here, migrating birds weave through the sturdy trees, and mischievous squirrels and chipmunks dance about the branches. The trail passes a bog, where labrador tea bursts from the deep sponge of sphagnum moss, a vital element of a bog. Tenacious tamarack trees erupt from the sphagnum; the needles of these unusual evergreens are turning yellow, soon to drop to the ground. If you look closely you may see the unique blooms of pitcher plants, the bright red of cranberries hiding along the trailside. As you travel away from the bog, hardwoods become interspersed with hemlocks, whose branches are covered in soft, flat needles. If you look down you will see the dark, shiny leaves of wintergreen, the springy shapes of club mosses, like little Christmas trees. Flanking the trail will be several species of ferns: the semi-circular whorl of leaves that make up maidenhair, the long brown spores trailing from interrupted, the hairy stems of lady, and the three-pronged branch of bracken fern. A little bit further, the hemlocks dominate, the sun filtering through them and patterning the forest floor with golden lace. On the last leg of this journey, the trail lightens as birches and aspens begin to replace the hemlocks. You then return to the open prairie, spreading out before the parking lot from which you came.

As you step back into your car, you will take home with you amazing images, chance encounters with wildlife, and the rich, full moments that compose time spent outdoors. So, go ahead: take an hour, or even an afternoon, and explore the fabulous habitats.
Take a child outside, or just enjoy it yourselves.

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 13470 County Highway M or on the web at http://www.cablemuseum.org/ to learn more about exhibits and programs.

Black Bear

Nature Watch
September 17, 2008

By Susan Benson,
CNHM Director of Education

Do you like to eat? Probably not as much as a bear does. The black bear is a full-time, professional eater. Except during winter hibernation and a couple weeks in the summer during mating season, a bear spends all its waking hours looking for and eating food. Calorie-rich acorns from oak trees also are a favorite food for black bears. In fact, bears have been known to trek up to 50 miles to acorn-rich areas, and remember these spots from year to year. During the fall, bears prepare for upcoming hibernation by going into food frenzy -- they eat constantly and may gain up to a third of their body weight. In the fall, a hungry black bear might pack in more than 20,000 calories per day -- compare that to the average human's daily intake of 2,000 - 2,500 calories!

Black bears often are nocturnal, but may be active during the day, with activity peaks during early morning and late afternoon. In December they enter a winter den, which is frequently in a site with heavy ground cover with gathered bedding material. Black bears, unlike some mammals, are not true hibernators. They are easily aroused from their winter dormancy. Dormant black bears have a decreased heart rate and respiration, but their body temperature declines very little. They remain dormant for up to four months during the year, even when the weather is mild.
When walking outdoors, look for smooth-barked trees, such as aspen or birch, that have distinct slashes made by the bear's claws as it climbed a tree. Sometimes bears will chew on pine, spruce and fir trees, ripping off strips of bark near the base of the tree. They eat the sticky pitch inside the bark and will leave vertical tooth marks with their front teeth. Bears also mark trees to identify their territory and breeding status by rubbing themselves on specific trees and clawing the tree as high as they can reach.

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 13470 County Highway M or on the web at http://www.cablemuseum.org/ to learn more about exhibits and programs.

Wild Rice

Nature Watch
September 10, 2008

By Susan Benson,
CNHM Director of Education

One of the most important strands in the ecological web of northern lakes and streams is Zizania palustris, commonly known as wild rice. This plant is an annual aquatic grass whose nutritious seeds have long served as valuable food for waterfowl. Within its core range in Minnesota and northern Wisconsin, wild rice is eaten by mallards, blue-winged teal, wood ducks, ring-necked ducks and other species.

This important plant is more than food, however. Wild rice provides roosting and resting areas to adult waterfowl and protective cover for young birds. It also provides habitat for snails, insects and mammals, adding to the biological diversity of the wetlands where it is found.

Wild rice also helps maintain water quality by binding loose soils, tying up nutrients and slowing winds across shallow wetlands. These factors can increase water clarity and reduce algae blooms. Wildlife and water quality are not the only beneficiaries of wild rice, though — this plant has long been a staple food for Native Americans and early European explorers of the region. To the Ojibwa, the plant is called manoomin, a term derived from “Manitou,” meaning Great Spirit and “meenum,” meaning delicacy.

Wild rice flourishes best in shallow, flowing water such as rivers and flowages, and in lakes that have an inlet and outlet. The plant grows in a predictable pattern. Seeds lie dormant in the lake or river sediment through the winter, and then germinate in the spring. In late spring, the new plants grow upward, producing ribbon-like leaves that float on the water’s surface. Through the summer, shoots may reach a height of two to eight feet above water.

In August and September the seeds develop and mature and become ready for harvesting. To the Ojibwa, the August full moon is known as Rice Making Moon, signaling harvest and thanksgiving celebrations. Today’s wild rice harvest methods remain similar to those used for centuries. The ripe grain is harvested from canoes or small boats with the use of smooth, wooden sticks. Generally, two people rice as a team; one moves the canoe through the rice bed using a long push-pole while the other “knocks” the grain from the plant seed heads into the boat. The freshly harvested rice then needs to be finished, a process involving parching to loosen the grain hulls, then winnowing the rice. The end product is a grain low in fat but high in protein, fiber, vitamins and minerals, nutritionally superior to white rice, oats, wheat or rye.

Wild rice can be hurt by pollution, the wake from large boats, exotic species and other factors. As a result many historic rice beds have been lost. Especially damaging are changes in water levels; the lakes and rivers that support rice have often been dammed, and even small increases in water depth can destroy the plant’s habitat. Although wild rice has declined in abundance from historic levels, there is hope that this trend may be reversed. A growing effort is underway to manage and restore wild rice. Tribal, state, federal and private natural resource organizations and interested individuals are working to protect and promote this special resource.

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 http://www.cablemuseum.org/ to learn more about exhibits and programs.

Winter Preparation

Nature Watch
August 30, 2008

By Susan Benson,
CNHM Director of Education


Have you noticed mallards and other ducks migrating? Or have you run into a chipmunk scurrying across the ground, cheeks bulging twice the width of its head with hazel nuts? Or your pet cat, dog, or rabbit beginning to grow a thicker coat as the days grow shorter?

It is only early September, but winter is coming, and animals have strategies for coping. Breeding has been timed so that offspring can grow and develop enough to survive their first winter. These young have time now to grow their first winter coat. Mothers who have lost weight when nursing now have time to improve their condition before winter.

Some animals leave the area through migration. Land animals have a more difficult time with migration because walking is much less efficient than flying. For those animals that stay, there are other options. Body size determines where the animals that stay end up spending the winter. A moose, for example, with its long legs, can walk through the deep snow, but smaller animals cannot, so they have to prepare to spend winter either under the snow or in areas with little or no snow. The big brown bat will soon begin searching for a winter habitat—that may be in an outbuilding or your attic. Keep a lookout for any of the signs of animal preparation for the coming cold season.
The trigger for the change in animal physiology and behavior is the photoperiod—the relative length of light and darkness during a given day. With the relative increase in darkness, many big mammals gain fat between their internal organs and under the skin. In preparation for their long winter sleep, or hibernation, woodchucks grow enormously fat toward the end of the summer. During autumn, black bears eat more than usual to gain body fat to sustain them through their winter “slumber.” Bears do not truly hibernate, but rather fall into a deep sleep from which they can awaken quickly. During late summer, a bear will eat five pounds of food per day in preparation for winter. Imagine eating five pounds of acorns! Northern small mammals gather so-called brown fat, which generates heat very effectively. Black bears and other hibernating animals maintain this same brown fat because it has the ability to dissipate stored energy as heat.
The fur of foxes, badgers and squirrels thickens to allow them to keep their body temperature constant during the cold weather. The snowshoe hare begins growing its white fur coat, beginning with its ears and tail; the total color conversion takes about 10 weeks. The short-tailed weasel also changes its fur coat to white with the exception of the black-tipped tail, which is thought to be an adaptation so that when the weasel is being chased, the pursuer will focus on black tail tip and miss catching the weasel.
White-tailed deer are affected as well; in late summer, a gland in their brains stimulates the reproductive organs. In bucks, hormones increase and the antlers harden and the velvet is shed. The period of hard antler lasts from early September to early February. We are familiar with bucks rubbing against saplings and smaller trees, removing the outer bark, and exposing the tree’s cambium underneath. The bucks then rub the cambium with their foreheads, where a scent gland is located, leaving a sign of their presence left behind for others to discover.
Some mammals, like squirrels, mice, and beavers, gather extra food in the fall and store it to eat later. Squirrels store their food, either in centralized heaps, or buried in the ground, sometimes with just one nut or acorn in each hole. Squirrels will cover their hiding place with care; these caches are usually found within 75 feet of where the squirrel found the nut or seed. When the snow cover thickens, the squirrel digs out the hiding places, and after having eaten some of the seeds, hides them again, this time closer to the snow surface. Some squirrels even store fungi in the branches of the trees. In a good fungus year, one might see dried and darkened mushrooms hanging on the lower branches of trees. During the late summer and fall, beavers also put food away, storing branches at the bottom of their ponds in preparation for winter.
Become a phenologist! Create your own backyard winter habitat by constructing a pile of logs, rocks or leaves—ideal winter lodging for mice, shrews, rabbits, toads, frogs or other small animals. Enjoy watching the outdoor action as our mammal neighbors harvest nature’s fall treats.

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.

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