Thrilling

I was a little jealous a few days ago – my friends in Vermont, and my friends up in Ashland, WI, were all reporting frogs calling. Oh, to hear the spring chorus again!

To console myself, I went for a glorious bike ride along the east side of Lake Namakagon. Alder catkins dangled limply in the soggy ditches, already having released most of their pollen. The dark little female catkins, resembling tiny pinecones, have hopefully caught enough of the pollen from the wind for all of their seeds. They will remain on the speckled burgundy twigs throughout the year.

Silvery catkins, not quite ready to release pollen yet, bedeck the male pussy willow shrubs. On separate female pussy willows, the much less conspicuous female catkins begin to open. They look more like a bottlebrush than a lucky rabbit’s foot. In the plant world, this gender segregation is termed “dioecious,” from the Greek “two houses.” Plants where the male and female flowers are on the same bush, such as the alders, we call “monoecious,” meaning “one house.”

It is days like this, when the snow has melted, the sun is bright and the woods are mostly brown, that benefits of being an evergreen plant really shine. The waxy leaves of wintergreen look productive on the road bank. The white pine and cedar needles have lost their winter pall. Many non-native weeds, trying to look inconspicuous by lying flat to the sidewalk cracks and the gravel edges, are actually rejoicing in a flurry of photosynthesis.

In those brown woods, there are lacy green rosettes of evergreen woodfern lying flat to the ground. Last autumn the base of each leaf stem softened to form a hinge. This allowed the fern to overwinter in the subnivean layer. Snow cover insulated the leaves and protected them from the drying winds. Because of this protection, they can retain most of their chlorophyll and are ready to start making sugar at the first signs of warm sun. These old leaves will never stand upright again, but they do fuel the growth of a new set of lacy fronds.

As the subnivean layer is exposed, we find even more evidence of a busy winter beneath the snow. Mouse and vole runs appear in melting drifts and in thatches of dry brown grass. Delicate white fungal hyphae – the vegetative, root-like part of a fungus – are caught in the act of decomposing leaves, acorn caps, sticks, and even scat. The white fuzz reminds us that more than ferns and mice that thrive under the snow.

The subnivean layer supports a complex community of life, including vast mats of fungi and bacterial colonies—many of which were not even known to science 20 years ago. They play a hugely important role in recycling nutrients, and even in releasing and sequestering carbon dioxide.

As a soft, warm, dusk fell over the woods, I could not resist one more evening excursion. I slopped down the driveway toward a little alder swamp. I felt a thrill in the air. I stopped to listen. Sure enough, a jingle bell chorus of spring peepers rang out through the woods, punctuated by the quacks of wood frogs.

Every spring I feel the same thrill as each new thing blooms, or wakes, or returns. As usual, Mary Oliver captures the feeling for me, this time in her poem “Pink Moon – The Pond”: You think it will never happen again / Then, one night in April / the tribes wake trilling.

In the depths of winter, it was hard to believe that this would ever happen again. Now we are already a month ahead, and spring phenology just keeps happening! I would love to hear about your observations and spring discoveries. What is blooming? Who is singing? And how early are they?

Not Necessarily Pretty

The warm wind smells fresh and damp, and brings with it sunshine, birdsong, and melting snow.

In places, though, the wind carries an unpleasant smell, sometimes described as a mixture of burning automobile tires, decaying meat, and garlic. If you follow your nose upwind you may find yourself in a mostly frozen swamp. Black ash and red maple trees stand like skeletons against the sky. Dogwood and alder shrubs form thickets around the edges.

If you are brave enough to explore on the rotten ice, you may find something rotten indeed – or at least something trying to make you think it is rotten! This is the home of the skunk cabbage.

More conspicuous in summer when their large green leaves grown in tall rosettes, but more interesting right now, the blossoms of skunk cabbage deliberately smell like dead stuff to attract early spring pollinators like honey bees and carrion beetles.

The insects not only get a snack when they visit a skunk cabbage, they also get a warm place to rest. Skunk cabbages are able to bloom so early because they actually produce heat and melt their way up through the ice. The heat is released through oxidation and break-down of sugars, an essential process in our own metabolism as well.

During the two weeks that skunk cabbages flower, they consume about the same amount of oxygen as a small mammal of comparable size. In fact, one researcher has quipped that they are "more skunk than cabbage." This high metabolism allows the plant to regulate itself like a warm-blooded animal, maintaining a temperature of about 30 degrees Fahrenheit above the outside air.

To accomplish this energetically costly feat, skunk cabbages prepared way last summer by storing lots of starch in their roots. They also pre-formed their flower bud, and it overwintered as a tightly closed bundle a few inches tall.

The purple and yellow apostrophe-shaped flowers are not really pretty, but then, not much is this time of year. Museum visitors are reporting robins, timber doodles (woodcocks), and moths. Still, the woods are drab and wet.

With more sunshine and warm days, that will change quickly. The drab, stinky skunk cabbage will be replaced by vibrant yellow marsh marigold, delicate purple hepatica, and the sweet smell of honeysuckle. In the wisdom of Mary Oliver: “Ferns, leaves, flowers, the last subtle refinements, elegant and easeful, wait to rise and flourish. What blazes the trail is not necessarily pretty.”

Magical Things

I am constantly amazed by how much I do not know about the world. There are many things that are dauntingly mind-boggling.  For instance: I was reading up on quantum theory this winter to get ready for our new exhibit about energy from the sun. I learned that the characteristics of the tiniest particle – which is smaller than I can ever imagine – impact the characteristics of the entire universe – which is larger than I can ever imagine.  As the English author, Eden Phillpotts said: “The universe is full of magical things patiently waiting for our wits to grow sharper.”

On a much more human scale, I have just discovered that Common Redpolls, those brown-streaked, red-foreheaded finches, are not as common as I had thought.  If you feed the birds, you have probably noticed sizable flocks of Redpolls moving frenetically, foraging determinedly, and then swirling away at the slightest thing. You have likely observed that they prefer tiny thistle, or nijer seeds.

This is an example of the specialized beaks of the finch family.  Darwin’s Finches are the classic model for this, with beaks that are quite varied in order to be highly adapted to their diverse food sources. Other local examples include Crossbills, which are finches with curved bills that can pry open tightly closed spruce cones; and Rose-breasted Grosbeaks, which have robust, cone-shaped beaks that can crack bigger seeds and catch bigger insects. 

The tiny beaks of the Redpolls are much better suited for thin thistle seeds than they are for big sunflower seeds. While not at your feeder, Redpolls feast on the tiny seeds of birches, alders, willows, spruces, pines, grasses, buttercups, and mustards. In warm weather, they eat quite a few small insects and spiders.

Birches, willows, and spruces are some of the farthest-north-growing trees, so it makes sense that Redpolls, who breed in the taiga and tundra, prefer their seeds.  Food is not the only issue when you are a circumpolar species, though. And this is where I think they get interesting. I just learned that Redpolls can survive temperatures of negative 65 degrees Fahrenheit.  That’s cold!

Redpolls have several physiological and behavior adaptations to living in the cold.  First, they increase their insulation.  Just like you dig your down jacket out of the closet each fall, Redpolls grow about 31% more feathers by November. Then Redpolls take a hint from the Subnivean Chronicles – they sometimes tunnel into the snow to stay warm during long winter nights.  Their tunnels can be over a foot long and four inches under the surface.  For such a tiny bird, that is impressive!

Redpolls share a behavioral adaptation with another Subnivean resident, too.  Just like chipmunks stuffing their cheeks full of seeds, Redpolls have a pocket in their neck, called an esophageal diverticulum, where they can store seeds.  The extra seeds allow them to “feed” while huddling in a protected place, overnight, or during a storm.  These seeds fuel the birds’ metabolism, and allow them to maintain their body temperature.

Enjoy watching these gregarious flocks of finches while you can!  Soon they will swirl away north to their breeding grounds.  Although we are happy to see ten, twenty, or a hundred in our yard, their global population is estimated in the tens of millions.  Yes, the Universe really is full of magical things.

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 www.cablemuseum.org to learn more about our exhibits and programs. Also discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/

Shrike!

The heavy snow brought a carnival of birds into our feeders.  Starting at 6:57 a.m., with a black-capped chickadee, there was a steady stream of goldfinches, redpolls, red- and white- breasted nuthatches, blue jays, and even a hairy woodpecker. It was fun to watch as the tiny birds flew in and out of caves in the snow-laden branches of the hemlock trees. Sometimes we could see a little flake of snow stuck to a chickadee’s head, or caught in the whiskers around its bill.

Then, in a flash of feathers, they were gone.

The reason for their quick retreat landed on top of the snow pile. Sporting a black bandit-mask on his gray head, this Northern Shrike looked the part of a feathered villain.

Surprisingly, this skilled predator is a songbird. Being songbirds, shrikes lack the sharp talons of raptors like hawks and owls. Being songbirds, shrikes have another weapon. Like the winged Sirens of Greek mythology, shrikes sing sweetly to attract other songbirds. Once prey is lured in, shrikes attack with a solid blow, then finish the job by biting the neck, shaking, or repeated knocks to the skull with their sharp beak. Shrikes often kill more prey than is immediately needed and impale the leftovers on long thorns or barbed wire.  Impaling prey on thorns may seem brutal, but it is just a practical way to compensate for having delicate feet that cannot grip food during dinner.

The stored prey also provides the shrike with food security, and will eventually get eaten when the hunting is poor.  A male shrike with abundant prey impaled throughout his territory has a better chance of attracting mates and fathering successful nests. Breeding takes place north of 50 degrees latitude around the globe.  In winter, shrikes migrate only as far as necessary to find food, which often means they come into Wisconsin!  The visitor at my bird feeder should be one his way back home soon, to begin courtship in this month or next.

In the meantime, I hope he is finding enough to eat!  While I love my chickadees, I am an equal-opportunity bird feeder. Anyway, more than half of a shrike’s diet is small rodents like mice and voles.  Unfortunately, those tasty little critters are safely hiding beneath a foot of snow in the subnivean layer. While foxes and owls have enough mass to break through the crust and dig for tunneling mice, shrikes do not have that ability.  Thus, songbirds are a larger part of their diet now, as well as in early spring when male songbirds are distracted by courtship, and in late summer when fledglings are an easy catch. Insects, frogs, toads, and salamanders round out a shrike’s diet.

The carnival of seed-eating songbirds took their sweet time returning to my feeders. They seemed a little more skittish and a little more vigilant as we all scanned the treetops for another glimpse of our thrilling winter visitor.

Turtle Dreams

All winter long, I have been watching the most graceful swimmer. She uses her arms and legs in perfect concert, making subtle motions to move up and down, hang vertically, or even spin quickly through the water. The path of her webbed toes is similar to the sculling motion of a canoe paddle that experienced boaters use for side slipping, or the hand motions of a human treading water. It almost looks as if she is caressing the water. For many long minutes, I get lost in her movements, dreaming of spring ice-out.
 

This aquatic ballerina is Shaun, our pet turtle. She is a red-eared slider, the most common species of pet turtle in the world. Native to the south-central United States, Shaun will be active and highly entertaining all winter, especially when we have extra minnows or worms to feed her. In the wild, red-eared sliders and many other types of turtles hibernate.

Most of Wisconsin’s eleven turtle species spend the winter underwater. This is an amazing feat, since reptiles are air-breathers. Even in the summer, turtles stay underwater for long dives. Winter ice cover simply means an extra-long dive. Because they are cold-blooded, hibernating turtles cool down with the water and have a very low metabolic rate. This lowers their need for oxygen, and with their lack of movement, also reduces the production of lactic acid in their muscles.

Some gas exchange may occur directly through their thick, leathery skin, helping to provide some oxygen and release some waste gases even without breathing. To make absorbing oxygen through their skin most effective, you would think that turtles would try to hibernate in the most oxygen-rich water possible. In fact, map turtles (named for the markings on their shells) do hibernate on the river bottom where fresh water can flow over them.

In contrast, painted turtles bury themselves in the mud. Painted turtles that live in the north are better than southern turtles at surviving long hibernation dives with low oxygen. As acid accumulates in their blood, they buffer the pH by increasing basic cations like magnesium, calcium, and potassium.

Snapping turtles spend winter in a low-oxygen environment similar to painted turtles– under mud in the shallows of small ponds. While the lack of oxygen is stressful, the shallows may warm up faster in spring and reduce the length of their hibernation. As it is, turtles do not feed much when the water temperature is below 65 degrees. Up here, this means that turtles may spend the entire school year hardly feeding if at all!

Turtles have amazing strength and tenacity. For many months, their breathing, movement, and almost all heart activity stops. Then in spring, they resume life where they left off. For 200 million years or so, turtles have done this and prospered with few changes.

 

In many Native American creation myths, the turtle is a central figure. It is told: When the early world was still covered by water, Great Turtle dove deep to bring up mud on his strong back. All the continents grew from that first bit of soil.

Great Turtle’s long dive culminating in the birth of the world is not unlike our present turtles emerging from hibernation into the awakening spring.

Until then, I get to enjoy Shaun’s aquatic ballet while dreaming of summer when her relatives will emerge, and we, too, can swim!

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 www.cablemuseum.org to learn more about our exhibits and programs. Also discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/.