Thursday, December 31, 2009

Red Fox

Nature Watch
By Susan Benson,
CNHM Director of Education

Have I mentioned lately how much fun it is to live in the northwoods? I continue to be amazed by what we can see in the natural world in one or two days. On my own property, in the last week, I’ve seen wolf tracks; a bobcat, whose tracks I searched for the next day; two red squirrels chasing each other around a tree, for what seemed like a dizzying amount of time; white-tail deer tracks, everywhere; and what appears to be a red fox bed site. In a few days’ time I had the content for several weeks Nature Watch articles.

I was exploring the forest behind my house. I found the beds on a small hill, four disc-shaped beds with fox tracks leading up to them. I smiled with such pride at having found them in the forest, probably one hundred yards away from my house. I had to find out more. Was it mostly likely a red fox or gray fox? Was it one fox returning for several nights, or two? I had to know the answers.

Was it mostly likely a red fox or gray fox? Gray fox are not as common in the northern third of the state, as Wisconsin is the northern part of its range. Therefore, I assume that the bed sites were made by a red fox.

Was it one fox or two? In December, males and females have paired up in preparation of the breeding season, which means the bedding sites I viewed are possibly from two animals. Foxes sleep while curling their long bushy tails around their body and over their nose and foot pads to keep warm. Red foxes are nocturnal, with most of their hunting taking place two hours before sunset until a few hours after sunrise. Able to run up to thirty miles per hour, they can travel up to nine miles in one night in search of food.

In the winter, red fox eat mostly meadow voles, mice, snowshoe hare, and cottontail rabbits. During other seasons they will eat squirrels, songbirds, eggs, insects, snails, crayfish, berries, fruit, acorns, corn, or grass. The red fox is a solitary hunter that searches field edges or forest while search for their prey. They have excellent eyesight, as the slight movement of an ear may be all that is needed to locate a rabbit or squirrel. They can smell eggs or young rabbits in their nests. Their large ears allow them to locate a sound within one degree of its actual location. Additionally, fox can hear mouse squeals from 150 feet away, or hear movement underground, dig, and capture their prey. From a distance, they creep low to the ground, slowly towards the correct location. Once they are close enough, they will often launch themselves up at an almost forty-five degree angle, pouncing down on the site of their prey. They can jump up to fifteen feet away! They will sometimes kill more than they can eat, and will bury food for future use.

Fox families have their own marked territories that they defend from intruders, a space that is from 150-400 acres. Scenting is an important form of staking territory, as they mark rocks and trees with their urine. When facing another fox, they may participate in a group chase or will charge and growl. They wave their tail to communicate their presence. Red foxes also have a wide range of vocalizations that peak during winter during the dispersal of juveniles as they stake out new ranges, and during the mating season. They have barks used as internal family communication, as a warning, or to convey information. They have “shrieks,” “staccato barks,” and “whines” to interact with others and establish contact. They have “wow-wow” barks for friendly communication. “Coughs” warn cubs of potential danger, and “growls” and “screams” are used in defensive positions.

If you seem me on the street, please do not be surprised if I give you a “wow-wow” bark as my hello. Also please know, if I cough, it is probably due to a cold, not a warning! Be sure to spend some of your own holiday season outdoors! Who knows what you will discover in your own back yard. Be sure to include a night listening session as well. For listening to potential fox sounds, choose cold, clear winter nights when fox prefer auditory communication. If you have your own red or gray fox story to share, please email the Museum at, or post your own stories on the Nature Watch blog at

For over 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 and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at to learn more about exhibits and programs.

Thursday, December 24, 2009

Bird Coloration

Nature Watch
By Susan Benson,
CNHM Director of Education

A blue jay darts across the yard. An American goldfinch shows its more camouflaged winter colors that are so drastically different than the summer yellow and black. Even the black and whit e of a chickadee against the snow is a striking color contrast. Color is not always what it seems in the bird world, in spite of the amazing variety of colors we see. Still, it seems to bring a gasp of pleasure when we see these colored wonders.

For most birds, color comes from pigment, which are chemical compounds located in the feathers or skin. Pigments absorb part of the white sunlight as it hits, and then reflect just part of the color spectrum, which is what the observer’s eye sees. For example, a cardinal has pigment that absorbs all the wavelengths of light except the ones that, when they enter our retina receptors, appear red. When we see black color, no light is reflected. When we see white color, all wavelengths are reflected. Melanin pigments produce blacks, browns, grays, and beige colored feathers. The pigments that produce yellows, reds, and oranges are called carotenoid pigments. These carotenoids are not produced within the bird’s body, however. Birds of these colors rely on their food – pink flamingos depend on carotenoid-rich crustaceans for their color, and the yellow goldfinches get their pigmentation from seeds they eat.
The blue of a jay that we see is not coloration based on pigments. In fact, blue and iridescent colors are "structural colors," produced in special cells in the feather barbs. For us to see “blue,” there are microscopic box-shaped cells that scatter the light, favoring the shorter blue wavelengths. Iridescent colors are produced by from modified barbules that cause wavelength changes based on the angle of reflection. These special cells split the sunlight, making iridescent colors dependent on the angle of the light. A ruby-throated hummingbird aligned just right makes a shimmering sight, but when turned wrong, the color goes black.
Many of our camouflaged birds exhibit what is known as "countershading.” These birds have dark backs with gradual lighter shading until the belly is white. Countershading tends to eliminate an abrupt shadow, absorbing bright light from above while reflecting light below where light is dim. “Disruptive coloration” is the use of patterns that break up the outline of the bird to avoid detection. Killdeers are an excellent example of this disruption, allowing the bird to blend in with the color of its background.
Why is coloration important? The earliest theory made by Darwin regarding bird coloration was that the bright coloration of males evolved through female choice of the most attractive male plumage. Another “color” theory is that bright colors can intimidate predators. Or, if we consider the bright coloration some species, such as monarch butterflies or coral snakes use to warn predators, it could be that the more colorful the bird the more unpalatable. It is believed that birds identify themselves to other flock members through color patterns visible in flight. Bright colors might help to deflect predator’s attention away from nesting sites. Colors inside of mouths of open chicks may stimulate parental feeding and help guide them to where “x marks the spot.” These are all interesting examples of how birds use their coloration.
Perhaps bird songs did not evolve for our human enjoyment, nor did bird colors evolve to delight our eyes. In spite of this, we benefit greatly from the joy they bring. Millions of dollars are spent every year as humans attempt to draw them closer to their homes. Birds are a part of many people’s regular conversation. We even bring their sounds and bright colors into our homes as pets. Whatever their color, they are an integral part of our human lives.
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 and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at to learn more about exhibits and programs.

Thursday, December 17, 2009

What do they do for Christmas?

Nature Watch
By Susan Benson,
CNHM Director of Education

While I watched students in a classroom writing their letters to Santa, I began to think about how different animals spend their Christmas. Where do the birds go? What about the frogs or turtles? Are the black bears already hibernating? What kind of “Christmas” do they have?

Where do some of the birds go for Christmas? For this answer, I had to go to my favorite bird field guides. The common loon leaves our lakes to enjoy the eastern and gulf coast, as well as the south-eastern part of the United States. Banded great blue herons from Canada have been found in Mexico, Honduras, Cuba, Colombia, Venezuela, and Ecuador’s Galapagos Islands. Some of my favorite forest-loving birds have just the right idea – red-eyed vireos end up in the western Amazon, hermit thrushes in the Bahamas, Guatemala, or El Salvador, and the black-throated green warbler in the Bahamas, Cuba, Jamaica, or Panama. The northern oriole heads to central Mexico or northern South America. Finally, the winter wren (how does it get that name anyway?) winters in the southern United States.

If we take a look at bald eagles of the Great Lakes region, they do not always migrate, though these resident eagles may travel significant distances in winter to seek food. Ruffed grouse stay with us, growing fringes on their toes in the winter to act like natural snowshoes and spending cold nights using the snow as insulation – imagine using the snow to stay warm. Next we can look at the resident bird that carries a bit of Christmas red color, the pileated woodpecker. These birds make deep, oval excavations in trees to find ants, especially carpenter ants, and wood-boring beetle larvae. These woodpeckers apparently have the “spirit of giving” year-round, as their large excavations often become feeding stations for other woodpeckers, wrens, or other birds.

Frogs have an interesting Christmas. Wood frogs, for example have no heartbeat. They do not breathe. Their blood does not circulate. Their nerves barely register electrical impulses. They are essentially frozen solid, yet their vital organs are not damaged. Spring peepers, gray tree frogs and upland chorus frogs also may freeze and thaw several times during the course of a winter. How do they do it? The answer is antifreeze. When ice begins to form on a wood frog’s skin, the frog’s liver releases a high level of blood sugar, enough to fill the blood vessels in all vital organs, creating a type of antifreeze. Other frogs will burrow into the soil or a lake bed to keep from freezing. Leopard frogs sink to the bottom of a water body, where they sometimes unfortunately become food for a fish.

Where do turtles go in the winter? All but one of Wisconsin's eleven turtle species spend Christmas under water. A few turtles bury themselves while others remain motionless on the bottom. Some scientists believe that they hibernate, their blood changing to function like antifreeze, with their body temperature dropping to only a few degrees above freezing. Other scientists believe that they don’t hibernate, but are semi-active, although this activity can take a toll on their body reserves.

When do black bears go into hibernation? Do they nestle in their beds for a long winter’s sleep? Technically, bears go into torpor, which is a state of reduced metabolism from which they can be awakened. Male black bears don’t always go into dens, sleeping right on the ground, or under downed treetops. These males can be more easily aroused from their “winter’s sleep.” When you add the fact that there are a lot of humans moving around in the forest during our fall hunting season, and combine it with the current feeding and baiting of deer or other animals, it is possible to see signs of bears even through November. The latest I have seen bear tracks in the snow is December 13, although most female black bears can go into torpor as early as October first.

As I wrap my presents, enjoy my lit tree, and huddle inside my warm house, waiting for a holiday season, I again find a renewed sense of wonder at the natural world. How fortunate we are to be able to enjoy this variety of wildlife all year round, no matter what the season or conditions in which we find ourselves.

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 and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at to learn more about exhibits and programs.

Thursday, December 10, 2009


Nature Watch
By Susan Benson,
CNHM Director of Education

Some weeks seem like my best natural history observations are from a car. On my way back from teaching in South Shore School District, I kept observing signs of beavers in many of the wetlands along the way. Beavers are endowed with a series of very helpful skills that express their intelligence. Beavers are flexible, learn from observation, have imagination, an ability to plan, and can be innovative in their design. Generally, mammals rarely build structures, but beavers do far more than that. They build elaborate dams and canals to control water flow, create water levels that ensure the safety of their family, and make essential transportation pathways to find food and move building materials. In their “free time,” they build artificial islands and homes we call lodges. They are probably one of nature’s best architects!

Not only are they great builders and shapers, but at a rather large sixty or more pounds, beavers make their living while eating bark. Yum. Technically, beavers eat the ring of live tissue just under the bark. Located in this area is the phloem, containing water rich in sugars. Secondly is the xylem, the plumbing that carries mineral-rich water up from the roots. Between these two “transportation tubes” is the cambium, which is responsible for making new rings of xylem and phloem as it is needed. When they are finished eating, the leftover pile of indigestible bark chips is used as nesting material, and the leftover trunks and branches becomes their “lumber” for building.

Part of what makes this species so amazing is that no situation in their world is ever alike – they must solve each hydraulic problem before them, expressing tremendous creativity to make things work. First, they build dams as a defense from predators. To build their dams, they will often put logs in the bottom of the stream across the direction of flow, pile on more logs, use stones to hold it in place, and seal this foundation with extra sticks and packed mud. Other times they will fell one tree across the stream and use its mass to hold the water back. They will drive sharpened stakes into the stream bed. Scientists have observed an amazing array of techniques that beavers use to build their dams. The longest known dam is 2,200 feet! What a lot of work!

No matter how the dams are built, they are crucial when cold weather comes. A large pond that freezes over its entire surface can make breathing for an underwater mammal a big challenge. If the ice is thin, beavers can break open breathing holes, or can return to their burrows or lodges for air. What appears to be the best method of breathing, however, is that many beavers will cut a small channel through their dam. This allows the water to drain out just below the ice, where the gap between the water and ice provides a layer of air across the entire pond.

Next, transportation of beaver food creates a continual challenge, as we know that trees are heavy! When a beaver pond first runs out of trees close to the water’s edge, building a dam floods the area, providing more food. In time, though, they reach the point at which no more food is available. Beavers then begin excavating canals into the forest, cutting down trees along the edges, eating the tasty inner bark, and floating the branches back to the pond for use in future dams or lodges.

Another important feature beavers build is a lodge. Beavers seem to always understand what is needed, and come up with a strategy. For example, sometimes they will dig a burrow to live within, and other times will build a lodge. A family of beavers can include up to eight individuals. Their front door is in their floor, and this entrance must be at least a foot under water. The “bedroom” chamber must be above the water, and must be above the highest water level that could possibly occur throughout the year. Keeping safety in mind, they will even turn their lodges into island retreats by excavating a moat around them. Even on the coldest days, their lodge is built so well that it remains at a temperature above 40 degrees Fahrenheit.

Learning about beavers certainly puts my own life into perspective. When I complain about rising costs or the economy, or about the weather, or even the amount of energy I put into my job this week, it seems like I have nothing to complain about – my life is pretty cushy. Beavers work hard, and I sound rather lazy in comparison. On top of all the hard work they do, they coexist peaceably with many uninvited guests to their home, including muskrats, flying insects, mice, or water voles. If only I could do the same!

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 and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at to learn more about exhibits and programs.