Wednesday, November 23, 2011

Crossbills and Irruptions

Winter often brings interesting things down from the North.  Snow, for one, floats in on cold arctic air that sweeps down from Canada. Earlier in the fall we saw many migrating birds on their way south for the winter.  They often stop in our wetlands and forests to eat and rest. We may also notice retired “snowbirds” migrating on the same routes, zooming along in motor homes and refueling at the nearest Holiday station.  Many birds, and snowbirds, migrate along the same routes every year, and their timing is so precise that phenologists can predict the arrival of the first and the departure of the last of each species to within a few days.

Other species are not so orderly, and seem to migrate helter-skelter in regards to date and location. Snowy owls, redpolls, and crossbills are a few examples of these “irruptive species.” To irrupt means to enter an area suddenly, in contrast to the lava erupting out of the volcano suddenly. We don’t see these irruptive species every winter, at least not in any quantity.  Most migrations are driven by food availability, and these are no different.  Have you ever noticed that our fair-weather bird friends are the ones who eat a lot of insects, especially flying insects?  Think of all those warblers, flycatchers, and robins! They skedaddle about the time I put away my insect repellant.

Our year-round residents tend to eat seeds or meat, which are easier to find in the winter than mosquitoes. Goldfinches and house finches are seed-eaters that we can enjoy all winter long. Chickadees must eat the energy-equivalent of about 250 sunflower seeds per day in winter! They don’t just eat seeds, though.  You may have seen them at your suet feeder or pecking at the fat on road killed deer.

Crossbills are finches that can survive almost anywhere and nest in any season, as long as they have plenty of spruce or tamarack seeds.  They are a classic irruptive species, which is why Katie Connolly, the Museum Naturalist (and my house mate), was so excited to see a white-winged crossbill in our yard this last weekend!  A quick check on the Wisconsin Birding List (, where lots of birders post their sightings, revealed that a hundred or more of these red birds with black and white wings were seen on the Bayfield Peninsula around the same time. 

Crossbills are fascinating creatures that I love to show visitors in the Museum’s Collections Room. In the cabinet of drawers that says “Please Open,” where we keep our study skins (dried bird skins stuffed with cotton), there lie two red birds with funny bills.  Just as their name suggests, their bills are crossed. The lower mandible curves under the upper mandible. They can be either “right-beaked” or “left-beaked,” but just as in humans, right-beaked birds are more common.

To eat, the crossbill slips its beak under the tightly shingled scales of spruce cones and then twists its head, using the curved tip to provide leverage. The scale is lifted just enough for the crossbill to grab the seed.  Crossbills often twist a cone off the tree and take it to a perch.  They extract seeds while holding the cone in one foot and rotating it like an ear of corn. A single crossbill can eat up to 3,000 seeds a day!

During this time of year it is common for flocks of humans to irrupt as well, often congregating in large and gregarious flocks where there is plenty of food. As winter closes in, we are reminded about what it means to share the bounty of this beautiful Earth, and to give thanks for all we have. Happy Thanksgiving!

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,

Thursday, November 17, 2011

Flashes of Red

Now that the trees are stark and bare, the leaves nowhere except, as poet Mary Oliver writes, “underfoot, moldering in that black subterranean castle of unobservable mysteries…” things hidden from us all summer become visible again.  The angles of twigs are drawn precisely against the gray sky, with hornet nests, vireo nests and gouty oak galls as their only adornment.  Withered ferns settle down to reveal the subtle shapes of the forest floor.  Steel gray glimmers of open water weave their way through the trunks and remind me of places I have yet to explore. 

The beauty of “stick season” as I learned to call it in Vermont, is subtle to say the least. After leaf-off and before snow the landscape seems more melancholy.  It’s easy to develop tunnel vision and stop noticing the woods. If we let them, these days of gray skies and brown ground can make us appreciate the bursts of color even more.  Have you seen the winterberry holly in the swamps!?  Bright red berries adorn every inch of every twig on female Ilex verticillata shrubs.  The male flowers occur on separate plants, and can’t produce fruit themselves. Botanists and Greeks call this characteristic “dioecious,” meaning “two houses.”  Being low in fat, the berries last until late winter for two reasons: they don’t go rancid quickly, and they aren’t eaten until other more energy-dense fruits are scarce.  Forty-nine species of birds eat the berries, from bluebirds and catbirds to our old friends the cedar waxwings. 

I’ve seen other flashes of red lately, too -- on my chilly cheeks, in holiday decorations, and on the crests of pileated woodpeckers.  It’s always thrilling to hear their wild laughing call, and see the brilliant flash of their white wing linings as they swoop through forest clearings. My ornithology professor called them “monkeys of the Northwoods” because of their raucous call. Twice last week, (when I was still braving twenty-degree dawns to bike to work,) I saw a pair darting across Highway M, and another pair on Garmisch Road. 

Pileated woodpeckers mate for life, and hold their territory year-round.  The female that startled me out of reading yesterday morning by swooping in for lunch at the base of an oak tree is the same one I eagerly photographed from a second-story window last spring.  You’ve probably noticed their large, rectangular holes in both softwood and hardwood trees.  They’ll drill anywhere they can find carpenter ants, which they extract with their sticky foot-long tongue.  Sometimes the hole is so large and the tree is so small that the trunk snaps right off! 

It’s no surprise that scientists and wildlife managers consider them “ecosystem engineers.”  Especially beneficial is their aversion to using the same nest cavity twice.  Every spring the pair will hollow out a new tree, often with two entrance holes, and the abandoned cavities are quickly re-purposed by ducks, squirrels, owls, bats, other woodpeckers, and wasps.  Pileated woodpeckers are the main source of large tree cavities in the forest!  It’s as if one family in the housing development built a new house every year and gave their old one away.

During the period of heavy logging near the turn of the last century, the populations of these crow-sized woodpeckers declined   As forests have recovered, so have the birds.  Though their numbers are slowly increasing, they still face hazards.  In younger forests, pileateds tend to use the oldest, largest trees for their roosts.  These taller trees are lightening rods, and can be dangerous to the young families.

Once snow falls it will be easy to track the woodpeckers’ eating habits.  Fresh woodchips around the base of a tree, or in the ski tracks, are a good reminder to look up.  Not only might you see a striking bird or their fresh excavations, you will jolt yourself out of tunnel vision and be ready to notice the next burst of beauty.

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,

Thursday, November 10, 2011

Treasures of the Secret Bog

As a young girl I loved the story of the Secret Garden.  I wished for a secret place all my own, where I could watch things grow and change.  At that time, roses and other cultivated flowers seemed romantic.  These days I still love to find out-of-the-way places where I can watch the seasons come and go, but I much prefer native wild plants to roses.  Instead of a Secret Garden, I visit a secret bog!  Tucked away down a 100+ year old logging road, to get to this bog you must push through thickets of balsam fir and climb through tangles of birch and aspen deadfalls.  You must brave ticks, wipe spider webs off your face, and get your feet wet.  The treasures I find are worth every stick in my eye. 

Last weekend was my first visit to the bog in a couple months.  Gone were the spring peepers and wood frogs, gone were the slender green leaves of fen sedge, gone were the mosquitoes and black flies!  Present were the tamaracks with their golden glow, the fluffy Truffula Tree-like seeds of cotton grass, and the gracefully-twisted dried seed pods of blue flag iris.

Bogs are unique natural communities.  In Wisconsin, they have been forming for 10,000 years in sandy bowls left by the glaciers.  The bowls were formed when huge chunks of ice broke off of the main glacier ice and were buried in sand and gravel by the many streams draining the melting ice mass.  The sediment insulated the ice for a while, but it still melted slowly, eventually leaving a low area where the ice had been.  Geologists call these glacial kettles.  The high mounds of sand and gravel around them are known as kames.  It’s this process that helped create the rolling topography we love on the ski and mountain bike trails all around the Cable area!
Their unique formation has a big impact on the hydrology of bogs, or the way that water flows in an out.  Basically, it doesn’t.  True bogs don’t have inlets or outlets, and are perched high above groundwater influence, too.  All their water comes from rain and snow.  Rain and snow are both slightly acidic, and as dead leaves soak in the water, more acids are released.  The process is very similar to your morning cup of tea.  (In fact, several bog plants make delicious tea!) Without flowing water, there is little oxygen.  Organic matter decays slowly or not at all, forming black soil called peat.  Sphagnum moss, leatherleaf and many other plants build up a thick mat of vegetation until the bog is almost dry.  Sometimes the mat quivers like a waterbed and hides open water underneath. 
Some nutrients and oxygen do reach the margins of the bog through rainwater runoff.  This causes a narrow band with higher decomposition rates, allowing open water in a ring around the bog.  Last May the moat was deep and squishy, and a class of seventh graders almost didn’t make it across (due to squeamishness, not danger).  Now the moat is mostly solid and grassy.
As I step out into the golden-brown heath, my mission is to find treasure.  Not silver or diamonds, they don’t taste very good.  Today, I’m seeking cranberries!  Displayed attractively on emerald mosses, the ruby-red fruits do look like jewels.  And a hunt it is for this treasure!  I scour each hummock for fruit, sometimes finding none, sometimes one, sometimes a dozen.  With bent back I nose on to the next mound of moss and twigs.  The high places around small tamarack trees seem to be productive.  I find one patch of berries tangled in the dried thatch of grass.  Some of the little globes have fermented, and burst between my fingers.  Others, buried so deep in moss they haven’t been frosted, are still only pale cream with red speckles. 
The picking goes slowly.  This is partly because the cranberries are few and hidden.  It is mostly because I get distracted easily by the other treasures I find!  In one flat mossy patch there are about a dozen dried flower spikes, each about eight inches high.  Dry weed ID is a fun challenge, so I poke around their bases looking for clues.  I find a tiny cluster of mini leaves.  Curled tightly like fern fiddleheads they can only be the hibernaculum of a sundew.  Sundew are carnivorous plants, well-adapted to the nutrient-poor habitat in bogs.  In summer, tiny drops of “dew” glisten on the tips of hairs that cover small spoon-shaped leaves.  The sticky mucilage “dew” traps insects and then digests them.  Essential nutrients (especially nitrogen) are absorbed through the leaves.  Just like trees have prepared for next year by forming leaf buds that will weather the winter, these sundew are ready and waiting for next spring.
Pitcher plants, the other carnivorous plant in our bog, have also shut down for winter.  I split open one bright-red leaf (they change colors for fall, too!) and find a bug-cicle inside!  The insects caught in the sweet-smelling digestive juices of the pitcher-shaped leaf will have to wait until next spring to be digested.  Ice fills every leaf in the cluster of plants. 
After about two hours of searching, I have one quart of cranberries, and two cold feet.  Back at home, I warm up quickly as a cake bakes and the cranberries simmer with honey and cinnamon.  That was the stated goal of my expedition: chocolate cake with cranberry sauce.  I could have just gone to the grocery store, but I found so much more than fruit in my secret bog.

Wild Tea

This is not the season for most wild edibles -- the salad greens of spring are long gone, even the berries are either consumed or dried up.  There are still many wild teas you can gather from the winter woods.  Here is a list of my favorites that are still available this time of year:

white cedar leaves
balsam fir needles
Labrador tea leaves
wintergreen leaves and berries
Sweet gale leaves and twigs
Sweet fern leaves and twigs
yellow birch twigs

My favorite way to prepare them is to stick whole sprig in a cup, pour boiling water over it, and wait until it's cool enough to drink.  Then I fish out the leaves and enjoy the tea!  Cedar and rosehips both have lots of vitamin C, so they are excellent choices to help ward off the winter sniffles.

Friday, November 4, 2011


The vibrant colors of the rainbow were perfectly outlined against the slate gray sky. Trees across the lake looked orange and purple through the vertical leg of the rainbow that ended precisely at our boat landing. It’s so rare to actually get to see the end of a rainbow, and even more rare for it to end precisely in your own yard! Watching the liquid silver surface of the lake as it reflected leaden clouds and skeleton trees, I decided that it had been too long since I’d paddled. 

As I dug out long underwear and put on thick wool socks, I noticed a change in the sound. Looking out I could see thick raindrops falling heavy and straight. After a second they became bigger and white, and bounced when they hit the ground! I paused a moment in my dressing to check the weather radar – the storm was no bigger than Lake Namakagon itself, a tiny green blip on the screen. By the time I had my dry top, spray skirt and life jacket on, the small white chunks of graupel were melting in the grass.

Graupel is one of my favorite early winter phenomena. It must have been cold enough to form snowflakes in the upper atmosphere, and as the flakes fell they encountered supercooled water droplets. Special atmospheric conditions (don’t ask me which ones!) allow the drops to remain liquid even below the normal freezing point of 32 degrees. When the droplets contact the snowflakes, they stick on. This process is known as accretion. Although graupel looks like small hail, it is much softer and more irregularly shaped. The first snows of the year are often graupel, and it looks like millions of tiny snowballs are falling from the sky!

The maple leaves on the path were just wet, and the precipitation dwindled to a light mist as I hauled my kayak down to the shore. I bought it precisely for times like this – when I want to go out on the water NOW, without having to convince someone to help paddle my favorite canoe. Even the cold and wet aren’t a problem with a waterproof top and an insulating life jacket. The spray skirt holds in my heat and keeps out the rain. Do you have a similar scheme for independence? 

I paddled slowly out into the lake, admiring the wispy pink and purple clouds of sunset. Delicate birch twigs and feathery white pine branches reached up to tickle the underbelly of sky. The water surface was still thick with green algae. This late-season algae bloom may be caused by the lake’s “fall turnover.” During the summer, sun-warmed surface waters don’t mix much with the cold, dense bottom water. As the season cools and winds increase, the two layers start to mix again – the “turning over.” Nutrient-rich bottom waters are brought to the surface, stimulating algae to grow in the sunlight. A melon-colored birch leaf floats among the bright green film. Life and death are never-ending cycles.

Across the channel on Burgundy Point I glide into a little boggy bay. The dried leaves of Sparganium (a group of plants commonly called bur-reeds because of their spiky seed heads) stand guard at the entrance, and the ragged leaves of dying water lilies cling to the surface. The bow of my kayak slips in among the wiry stems of alder, leatherleaf, and sweet gale with its tiny cone-like buds all ready for next spring. Just beyond stands a clump of Carex lacustris, or lake sedge. Its long spikes of seeds bend gracefully among half-green leaves. Further in I can see the small spires of black spruce and golden tamaracks.  

With the nose of my kayak stuck in the weeds, my own nose is enjoying immensely the fresh, sweet, damp, cool smells of fall. “It begins/to rain, /it begins/to smell like the bodies/of flowers” (From Rain by Mary Oliver).

Despite the cold, and the wet, and the melancholy of death and dormancy, autumn is a lovely time of year. Although I barely paddled half a mile, I found plenty of treasure at the end of my rainbow. We’ve had lots of rainbows lately, what treasures have you found?