Friday, January 20, 2012

Seeing Things

As I came around the corner, a dark blob at the edge of the road caught my eye.  You know how we are always seeing things that aren’t there?  Mailbox reflectors turn into deer’s eyes in our headlights. Tall stumps look like black bears.  Clumps of leaves take on the shape of an owl.  The dark blob was less than three feet tall.  It had pointy ears and a sloped back.  It was black against the bright mid-day sunlight and white snow.  Then, in an impossible moment, it went leaping back into the tangled fir thicket.

Bobcats aren’t rare in Wisconsin, but I’ve only found one set of their tracks in all the miles of trails I’ve hiked and skied in Wisconsin.  Actually seeing an animal make tracks is an excellent learning opportunity, so of course I stopped the car in an open stretch of road, put on the blinkers, and went over to check out the disturbed snow.  Since the flakes were light and fluffy, none of the four toes were visible in the tracks.  I could tell generally where the wild feline had walked calmly up to the edge of the road, sat down for a bit, and then hurried off with big poufy bounds. 

If I hadn’t seen the actual cat, I don’t think I could have identified its tracks.  I could tell, by the size of the body and size of the tracks, that this was not a lynx.  Canada Lynx, with their four-inch wide, snowshoe-like feet, have never been abundant in Wisconsin, since they prefer the deep snow and thick conifer habitat of their favorite prey—snowshoe hares.  Some years, when the snowshoe hare population in Canada crashes, lynx will wander down to Wisconsin to find food.  There hasn’t been a sighting in Wisconsin since 1992, and only 28 verified records since 1870.  Because lynx are so rare here, they are listed as a Protected Wild Animal, but not as a State Endangered Species.  They are on the federal list.  Bobcats can be trapped and hunted.

A few weeks ago in Minnesota’s Cascade River State Park, I watched as a bobcat walked up the trail toward me. It chose a soft place in the pine needles and laid down for a catnap, or perhaps it was waiting in ambush for a squirrel.  Some minutes later it stood and stretched.  Maybe it wasn’t hunting as much as digesting, since it paused then to squat and deposit a long, dark hair-filled scat.  With that business taken care of, it walked daintily down the trail.  A string of oval tracks just smaller than my lip balm were pressed into the light dusting of snow.

Don’t you believe me?  I watched it happen, just like a movie, in my mind’s eye.  The body print was just so on the pine needles, the four tracks of a squatting position had an extra sharpness due to added pressure and time.  The scat was positioned exactly where you’d expect it to be.  Poet Mary Oliver tells a similar tale from deer tracks in The Pine Woods, and challenges us, saying “But I don't believe only to the edge of what my eyes actually see in the kindness of the morning, do you?” 

Was I seeing things?  Absolutely, and that is the very essence of tracking.

Constructive Interference

“Oh wow!  Look at the size of that turkey!  I never realized how beautiful their feathers are – check out the iridescence.”

The mount of a wild turkey in flight is one of the most-exclaimed about objects in the Museum’s Collections Room.  The 5,000 feathers on a turkey are worth noticing, with their rich browns, shimmery copper, iridescent blues and greens, and elaborate black designs.  Some of the colors are a result of pigments, those molecules that absorb certain wavelengths (colors) of light and reflect others.  Melanin is a common pigment in nature, and does more than make things appear brown.  It can also protect against bacteria and fungus, UV radiation, and high temperatures.  A certain type of fungus appears to be able to use melanin to capture the energy of gamma rays for photosynthesis!

Melanin can’t make a turkey, or a seashell, or a butterfly, or a soap bubble shimmer, though.  The vivid, shifting, enchanting colors of these objects are caused by the structures themselves, not a type of pigment. Remember that light travels in waves, and the color of light is determined by its wavelength.  Red light has longer wavelengths, while purple light has shorter wavelengths.  The rest of the colors fall between in rainbow order. 

When light passes through a thinly layered substance, the light bounces off the back surface toward your eye, and joins light bouncing off the upper surface toward your eye.  Where the waves of light overlap, they interfere with each other. The interference can be either destructive, where the waves cancel each other out (so you see black on an iridescent object), or constructive, where the waves amplify each other.

I experienced constructive interference on a macro scale last fall on a sea kayaking trip in Maine.  As we paddled along the seaward side of an island, waves bouncing off the rocky shore grew bigger and bigger as they overlapped with constructive interference. The color of my face changed from pink, to green, to white, as waves striking me from various angles tossed my kayak gawkily.  Iridescent colors also change when you alter your angle relative to the object, because the wavelength of light that reaches your eye changes.

Turkeys in Wisconsin have experienced destructive and constructive interference before, and not just in their feathers. These large game birds are native to southern Wisconsin, but were hunted almost to extinction by 1881.  Major reductions in their habitat due to logging and farming, plus diseases introduced in domestic fowl were also culprits of their decline.

In 1976, the Wisconsin DNR made a trade with Missouri to bring wild turkeys back to Wisconsin.  We gave them ruffed grouse in return. From the initial release site in Vernon County, turkeys recovered enough to move naturally and with help to other suitable habitats across the state.  Many other states have similar stories. The turkey population in United States was once down to about 30,000 birds.  Now it is over 7 million! 

It’s no surprise, then, that many Museum visitors have reported turkey sightings this winter. Their favorite times to forage are morning and evening, which corresponds nicely to most of our commutes. There are two flocks just in my 10-mile commute on County Hwy M.  After the holidays, I returned home to a whole flock of turkey tracks in my driveway and around our bird feeders.

Although northern Wisconsin isn’t their traditional habitat, we do have plenty of oaks for acorns and large white pines near water for roosting. While you might feel sorry for turkeys during harsh winters, the DNR does not advise feeding them.  To provide a turkey with enough to food to impact its survival would take a lot of food!  Any winter mortality is easily made up for by high breeding success.  Feeding can actually harm turkeys, because concentrated groups spread disease more easily, and become easy targets for predators.  If you want to help these beautiful birds, think about managing your forest for mast trees like oaks, and big pines and hemlocks for roosting.

The wild turkey was once lauded by Benjamin Franklin as a more respectable national symbol than the bald eagle, who eats road kill. Franklin wrote: “He is besides, though a little vain & silly, a Bird of Courage, and would not hesitate to attack a Grenadier of the British Guards who should presume to invade his Farm Yard with a red Coat on.”

For over 44 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. The new exhibit, The Joy of Birds: Feathers in Focus opened in May, 2011. Find us on the web at to learn more about our exhibits and programs. Also discover us on Facebook, or at our blogspot,

Monday, January 9, 2012


Finally, we're past "stick season" and snow makes it feel like true winter.The long slant of afternoon sunlight illuminatesintricate patterns of tree bark.Instead of a haze of green, trunks stand out as individuals.Some say that a tree's bark is as unique as your fingerprint.While I have yet to find a study that proves it, I have noticed that bark, even within the same species of tree, is incredibly variable.The age of a tree, its health, its growth rate, and its habitat all have an effect on the pattern of its bark.

While skiing or hiking through the forests around here,I tend to entertain myself by identifying plants while zooming down hills.Bark patterns among different species are fairly distinct once you know what to look for.In general, the fissure pattern in bark is a result of the genetics of the tree species, and the way trees grow.

Here's a riddle:If a pirate buries treasure underneath a tree and marks the tree with an X five feet above the ground, and the tree grows one inch taller per year, how high will the X be in 100 years?

The answer, of course, is about five feet, depending on local soil erosion.Trees only grow taller from the tips of twigs.Trees do get bigger around, but only by adding new layers of cells just under the outer bark.And there lies the key to bark patterns.

The center of a tree is dead; in fact, most of a tree is dead!In the trunk there are several layers of different cells.Xylem and phloem are two types of transport tissue. Xylem, which is dead at maturity, carries water and minerals up from the soil. Old xylem becomes what we think of as wood, and makes up the bulk of a tree's mass. The living phloem carries sugars down from the leaves. They have a layer between them called the vascular cambium, which creates the new xylem and phloem cells. Cambium is made of undifferentiated cells that can become anything - like stem cells. These three layers are considered the "inner bark."

Outside the phloem is the cork cambium.Just like the vascular cambium, the cork cambium produces a layer of cells inside it (living phelloderm cells), and outside it (dead, air-filled cork cells).These three layers make up what we call "outer bark."

As the cambium layers create new cells, the tree expands just under the cork layer.Since the cork is dead, it can't stretch or grow to accommodate the larger girth.The bark cracks instead, and eventually sloughs off like dead skin.I think that paper birch has such smooth bark because it peels off instead of cracking.

Why do trees need bark anyway? Outer bark is the armor of a tree, and it protects the inner bark.There is something very tasty hiding in the inner bark.Think ahead to maple sugaring season and you'll know what I mean.Insects, fugus, bacteria, yellow-bellied sapsuckers, deer, moose, snowshoe hares, porcupines, humans and many other things want the sugar created by photosynthesis and transported in the phloem.

Outer bark, like our skin, can help keep these invaders out, or scar over an injury when they break in.Also like skin, bark slows water loss, allows certain gasses to be exchanged, and protects from intense sunlight. The pigments in colorful bark, like on red osier dogwood, act as sunscreens; while greenish bark, like on aspens, can photosynthesize. Bark can also protect trees from extreme cold andheat, including fire.

One of the "active ingredients" in bark is a chemical called tannin.You may have encountered tannins in the way your mouth feels dry and puckery after drinking wine or eating unripe fruit.Tea also contains this bitter brown chemical, and the tea-colored water in bogs is the result of plants steeping in water and releasing the soluble tannins.

Tannins provide a unique defense mechanism against herbivores.Condensed tannins bind with proteins and inhibit digestion.That's one reason that animals tend to eat the newest twigs and softest bark - they have fewer tannins.The ability to bind with proteins made tannin useful to humans, too.We used it for many years (and some primitive skills buffs still use it) in the tanning of hides to produce leather.The tanning process makes leather more flexible and resistant to bacteria. Hemlock bark was once a source of tannin for the leather industry.

Bark from various species also supplies us with spices (cinnamon), medicines (quinine), resin, latex (rubber), poisons, landscaping mulch, and cork (for that wine!). We can also fashion it into cloth, rope, canoes, roofing,dyes, and baskets.

So when the sun's rays sweep through the afternoon forest, take a moment to enjoy the wonderful colors, textures, and patterns of the beautiful, protective, and very useful bark.


Tracks crisscrossed almost every foot of the path as we hiked 4.8 miles to a campsite on the Superior Hiking Trail. The large prints of snowshoe hares were most common in balsam fir thickets, and tiny mouse tracks perforated the snow in grassy areas and near fallen logs. Dainty paired weasel tracks bounded impressively through the brush exploring those same fallen logs, and the linked chains of grouse steps wandered through shrubs. I love the snow for its ability to hold information and show us just how alive the woods are, even in the depths of winter.

As the trail descended to the Cascade River, we started following the paired tracks of some member of the weasel family. At just under two inches long they were too small for a fisher, too large for a mink, and the tracks bounded up and around trees, over roots, and along logs. These were the tracks of a pine marten. I live just north of a pine marten recovery area in the Chequamegon National Forest, but I haven't seen any sign of them yet. Last year researchers in Wisconsin only found evidence for 9-10 martens, and it is a state-listed endangered species. In Minnesota, however, their population has recovered from almost zero in the 1920's to over 10,000 animals today. Biologists used to think that these tree-climbing, bird-eating weasels only lived in conifer forests. Now we've learned that they can live in deciduous forests, too, so I'm hoping that Minnesota's abundant martens will find it easier to expand their range to the southeast!

Martens are not the only animals to benefit under state and federal endangered species protection. Bald eagles were delisted in 2007, and are once again a common sight. Gray wolves were extirpated from Wisconsin after extensive bounty hunting in the early 20th Century, but Minnesota always had a small population. With the help of protection under the Endangered Species Act, wolves in the Western Great Lakes Region are fully recovered. The Wisconsin DNR estimates that around 800 wolves now live in the Wisconsin.

On December 28th, 2011, the USFWS published a document that delists wolves in Wisconsin, Michigan, and Minnesota. The rule will take effect on January 27th, 2012, after a 30-day waiting period when the public can comment. If all goes as planned, wolves will join twenty-three other species that have been delisted due to recovery. This is not the first time that the U.S. Fish and Wildlife Service has attempted to delist the wolves, but perhaps now they've tweaked enough of the details to make it stick.

Wolves haven't recovered their entire historical range, and may never do so. I can sense a difference in a forest where they are and a region where they are not. Even in the primeval redwoods of California, or the rugged mountains of New England, I feel a sense of loss because I cannot even hope to see wolf tracks.

On this recent backpacking trip I was not necessarily eager to see the tracks of a large carnivore, but there they were. Lined up down the center of the trail, going our direction, were four-inch, four-toed, four-clawed wolf tracks. My skin tingled and the little hairs on the back of my neck stood up. More tracks joined the first, and for most of our hike we walked beside them as the pack traveled, explored, split and rejoined.

Wolves elicit many different feelings in folks, from respect and awe to fear and loathing. I'm in the first camp. I never tire of measuring their large paws against my own hand, or trying to interpret their hunting strategy from their tracks. Still, I was happy to notice that the tracks did not follow the trail all the way to our campsite.

Long after dark, warm in our sleeping bags, we listened intently to the night noises as the wind picked up. Far off, on the other side of the river, a lone wolf howl rose up on the wind. I shivered nervously, happily, in my shelter of thin nylon. Aldo Leopold, a great conservationist with strong ties to Wisconsin, was perceptive when he observed that "only a mountain has lived long enough to listen objectively to the howl of a wolf."

Other Tracks

This morning I followed my fox down the hill to the lake. By "followed," I mean I walked next to his footprints, and by "my fox," I only mean the local one who lays dainty beaded necklaces of tracks all over my yard and across my doorstep. Since we haven't had much fresh snow, tracks of many ages were visible. The newest ones seemed to be the tidy foot pads pressed into the smooth snow of my Mukluk prints. Older ones, messy and deep, were made when the snow was fresh and soft. Some tracks show where he floated across the crusty snow, and those were dusted lightly with graupel snow like powdered sugar on gingerbread.

Last week, behind the garage, I found a mess of his tracks around a small lump of leaves covered in snow. Two bright yellow dabs of urine indicated that this was a scent mound, used for marking his territory. Male members of the dog family, Canidae, will use raised leg urination (RLU) to let others in the area know that this territory is taken and defended.

You may think I'm crazy, but I got down on my hands and knees and sniffed the urine. Red fox and gray fox urine each have their own unique scents. Both are slightly skunky, but the red fox smells much sharper and stronger, while the gray fox's scent is mellower. The smell test confirmed that I've been tracking a gray fox. This scent marking is also why I've been referring to my neighbor as "he." By the end of last winter I had noticed enough side-by-side fox trails to be confident that my yard housed a pair of foxes. I don't have enough evidence yet to be sure that the female is still around, but this is the beginning of mating season, so I may know soon.

Back at the lake this morning I found a gray fox highway. Perforating the snow were at least eight different sets of tracks going in many directions along the edge of the ice and up onto shore. Some could be the vixen's tracks, although I don't have a good way to tell since male and female gray foxes are essentially the same size. One of the trails was very different, definitely not a fox.

The odd trail looked like Morse Code, with clumps of dots connected by five-foot long dashes. The dots were tracks, each a little less than three inches long. Five toes dug in asymmetrically above each rounded foot pad. In the troughs, three grooves paralleled the direction of travel. This pattern embodies the playful spirit of an otter running a few steps to push off, and then sliding belly-first across the ice. The grooves were from forelegs, held tight to its sides, and its tail, which acts as rudder both on land and in water. One of the many sets of fox tracks was placed neatly down the center of each otter slide, facing in the opposite direction.

"He has no words, still what he tells about his life is clear..."

This "run, run, slide" is one of my favorite tracking stories, and the one I was hoping to find last week on the opposite shore of Lake Namakagon. I have yet to see the otter making his (or her) tracks, but I have laughed with friends trying to imitate these playful creatures. Mary Oliver also interprets Otter's life through his body language, and in her poem, "Almost a Conversation," she infers:

"He does not own a computer...
He wonders, morning after morning, that the river
is so cold and fresh and alive, and still
I don't jump in."