Friday, May 15, 2015

Return of the Ruby

After clicking on one of the bookmarks in my browser, I anxiously waited for the page to load. Slowly, a map of the continental United States appeared, and the animation started. White, yellow, and orange dots progressively filled the southern tier of states, until finally, a layer of dark red dots reached the level of central Wisconsin, just south of Cable.

“Hurry up, they’re almost here!” I admonished (jokingly) to Elsa Hansen (the Museum’s new Naturalist/Curator) who was scrubbing out our old hummingbird feeder at the sink.

Every spring I watch the migration maps (check them out at JouneyNorth.org) and eagerly anticipate the arrival of migrating birds. First it’s the loons (who have been yodeling on my lake for a few weeks now), and then the ruby-throated hummingbirds.

A non-technological indication of the hummers’ impending arrival is the return of yellow-bellied sapsuckers. Sapsuckers’ squeaky-toy calls filter through the forest about two weeks before the first hummingbird buzzes in. My journal entry from April 13th includes the note, “FOY sapsucker,” so it’s about time! (FOY is birder-speak for “first of the year.”)

Why the connections between sapsuckers and hummingbirds? They have a special relationship. Sapsuckers drill tiny holes into trees. These sapwells provide them with a variety of nourishment. Sweet liquid comes first, followed by sugar crystals as the leaking sap evaporates. Finally, insects who come and feed at the sapwells become protein-packed snacks.

Hummingbirds know this, too. The males – who must arrive early to claim a territory – have the challenge of finding food before many flowers are blooming.  Curiously, they will seek out sapsucker trees as a source of tree “nectar” and insects. Since hummers are relatively small, sapsuckers seem to act charitably toward their tiny dinner guests. Freeloaders they are not, though. Male humming birds are extremely defensive of their food sources, and so chase off a multitude of other birds and critters who might sip more than their fair share of the sap. Thus, both the hummingbirds and sapsuckers benefit.

Of course, hummingbird feeders can also be an important source of nourishment to the early birds. Hence, our push to get the old feeder out of storage and hung up outside. From Elsa’s furious scrubbing, frustrated noises, and questions like “how do I get the black stuff out of that crevice,” it became clear that we were due for a new feeder.
While it’s not necessary to boil the sugar water to sterilize it, it is important to keep your hummingbird feeders sparkling clean, and change the water before the black stuff starts to grow. This one had been put away dirty last fall, and was now a lost cause. Sun-brittled plastic and broken bee guards finalized the decision.

Later, as I stood paralyzed by indecision in front of the vast selection of hummingbird feeders at the hardware store, something else caught my eye. Big jugs of bright red liquid sat on the bottom shelf, advertising “Ready-to-Use Hummingbird Nectar!”

“No!” I gasped in disgust, startling a customer at the end of the isle. Red food coloring is a dangerous additive to hummingbird nectar. No, it’s not the carcinogenic Red Dye No. 2 that was banned in 1976. But its replacement, Red Dye No. 40, has been banned in Europe, while simultaneously being approved by the USFDA for consumption in small quantities.

The catch is that hummingbirds don’t consume nectar in small quantities. In order to power their flight muscles (at 53 beats per SECOND) and their metabolism (at more than 1260 heartbeats per minute), hummers eat more than twice their own bodyweight in nectar and insects each day. At this rate, while including a normal proportion of flower nectar, feeder nectar, and insects in their diet, the average hummingbird would ingest 12 times the amount of red dye shown to cause DNA damage in mice. And the mice weigh four times more. While there is no money available to fund a study on the effects of red dye on hummingbirds, it is safe to say that not using it will save you money, and probably save their lives.

I shook my head and headed home, bright-red, easy-cleaning feeder in hand. With great anticipation, I poured ¼ cup of plain white sugar into a 1 cup Mason jar, screwed the lid on tight, and shook. Soon the crystals dissolved and the water cleared. I filled the feeder, hung it outside my window, and opened my laptop to check the migration map again. A red dot had now appeared in Ashland, WI, a little to my north. They’re here!

Just then, I caught a movement out of the corner of my eye. Zoom! He buzzed past the feeder, his ruby throat shimmering in the evening sun. Closing my laptop now, I scribbled “FOY hummingbird” into my journal, smiling the whole time.



Ruby-throated hummingbirds are attracted to the red of your feeder. Adding red dye to the water is completely unnecessary and dangerous to the birds. Photo by my nephew, Isaac Stone, age 6. (With help from Grandpa Larry.)

Friday, May 8, 2015

“…what is lovely, and will not last…”

The flute-like notes of a hermit thrush wafted through my bedroom window. “Whyyyyy don’t you come with me?” he sang in a rising scale. I didn’t even open my eyes in the pre-dawn gray, but I did smile to myself. Spring has felt slow this year, because of the long period between snowmelt and green-up, but it is finally here.

My favorite way to celebrate spring is with a hike up St. Peter’s Dome in the Chequamegon-Nicolet National Forest. Gentle slopes, plentiful moisture, deciduous trees, and interesting rocks enrich the soil, which supports an amazing array of wildflowers. In comparison, the sandy hemlock grove near my house is a barren desert. The evergreen shade there doesn’t allow enough of the sun’s energy through to the forest floor to support much of a ground layer.

I suspected that I might still be a little early for the majority of blooms, but I just had to see what was up. Cut-leaved toothwort, blue cohosh, wood anemone, bloodroot, and wild leeks all poked their little leaves and buds out of the floodplain of Morgan Creek. The pale, fuzzy leaves of wild ginger were just beginning to sprout from its horizontal stems (called rhizomes) that snaked along, half-buried in the rich, moist soil.

The wild ginger caught my eye because its rhizomes were more bare than usual, with just a few cloaks of leaves here and there. Crouching down for a photo, I wondered if it was the foot traffic of people avoiding a mud puddle, or some other culprit that caused this exposure. Then I moved a little clump of dead leaves, and the tiny, pinkish point of an earthworm shrank away from the sunlight. Ah ha!

While European earthworms (brought here with ship ballast or in root balls) are wonderful at breaking down organic matter and mixing the soil in our gardens, they are just too efficient for the plants in our woods. Our northern forests evolved in the absence of earthworms, after the glaciers froze them out. Many plants here need thick, slowly decomposing leaf litter to grow, and for their seeds to sprout. In this exposed patch of ginger rhizomes, with the continued possibility for nighttime frosts and a lengthening drought, it is easy to see why fallen leaves are important.

Repercussions of the worms’ voracious feeding extend throughout the forest. The three-leaved clumps of trilliums unfurling themselves along the trail, with white buds that will be open by the time you read this, decline in worm-infested habitats. Other common summer plants (just now emerging!), like arching stems of Solomon’s seal, the thickets of wild sarsaparilla, and even sugar maple seedlings—the next generation of maple syrup—are also at risk. In their place, a lovely, green lawn of Pennsylvania sedge fills in among the trees.

With the lower diversity of plants on the forest floor, ovenbirds (a vociferous, ground-nesting warbler) are much more susceptible to nest predators like squirrels and other birds. One study, conducted in the Chequamegon-Nicolet National Forest just a few years ago, found that ovenbird numbers decline by about 25% in worm-infested maple forests. Happily, the same research project also found that three other species of ground-nesting birds—the hermit thrush (who woke me up), black-and-white warblers, and veery—are not affected by earthworm invasions.

As I put more space between me and the trailhead, the signs of worms faded quickly. Tiny, white, pants-shaped buds of Dutchman’s britches readied themselves for opening next to pink-striped spring beauties that were already attracting bees. Tiny leaves at the tips of chokecherry twigs glowed crimson in the sunlight. We all warmed up in the strengthening sunlight and on the steepening trail.

Spotted salamanders have already returned to a vernal pool just under the top of the Dome. Their clusters of round eggs—clear with black centers—rest among films of algae, layers of leaves, and tiny, wiggling larvae. I didn’t see any signs of worms up that high, which is fortunate. One study looked at the response of salamander populations to earthworm invasions, and found that “Salamander abundance declined exponentially with decreasing leaf litter volume.” Salamanders need lots of leaf litter to house the tiny critters that they eat.

These woods are changing – by the century, the year, and the hour. Some changes – like the graceful unfurling of petals, the delicate emergence of leaves, and the lyrical return of warblers—are welcome. Other changes may be more troubling.

Oh, to love what is lovely, and will not last! What a task to ask of anything, or anyone, yet it is ours, and not by the century or the year, but by the hours.” –Mary Oliver, Snow Geese.

 
Trilliums decline when earthworms invade their habitat. Happily this one is still surrounded by a healthy carpet of leaf litter. Photo by Emily Stone.
The rhizomes of this wild ginger plant lay exposed to the elements because earthworms ate their blanket of leaves. Photo by Emily Stone


Friday, April 24, 2015

The Wolves of Isle Royale and Michipicoten Island: "Very different trajectories..."

Still jittery from the excitement of the day, I headed out of Ashland, WI, along the lake. A glimmer of twilight still lit the sky, and a bright planet hung above the road. The calm waters of Lake Superior reflected the heavens with a magical, luminous beauty. My imagination skittered out across the glassy surface, landed briefly on two almost mythical islands, and then back to the events of the day.

Rolf O. Peterson had just concluded his keynote address at the Midwest Wolf Stewards Conference at Northland College. Hearing him speak for the first time was a thrill. I grew up without much of an interest in wolves, but Rolf changed all that. After reading his landmark book, “The Wolves of Isle Royale,” while preparing to teach winter plant identification for a wolf ecology course, I became captivated by the incredible stories and valuable knowledge generated by his long-term research project on Isle Royale. Wolves protect plants by controlling herbivores, he revealed. With that, I was hooked.

The story still fascinates me. Moose swam the 15-20 mile expanse to Isle Royale in the early 1900s. With their hollow, buoyant hair, large paddle feet, and huge, warm, biomass, moose are excellent swimmers. Almost anything else needs wings, an ice bridge, or a boat to get to the island. For fifty years, the moose population boomed and busted in response to weather conditions and food abundance. Then, in the 1940s, wolves crossed an ice bridge and “introduced a new management plan,” joked Rolf.

The wolves also initiated a new human interest in the island – research. Wildlife biologist Durward Allen worked for years to get funding and permission to research the newly arrived wolves. He finally succeeded in 1958, and pioneered the project. Rolf Peterson was his final graduate student. Through their efforts (and the many people who help them), we’ve all had access to the incredible drama unfolding on Isle Royale.

As the numbers of both wolves and moose fluctuated widely over the years, our mythical beliefs of a system in balance were challenged. The wolf population on the island rose to the highest density ever recorded in nature, and then plummeted dizzyingly with the introduction of canine parvovirus. The moose population took off, while the wolves struggled, now handicapped by genetic anomalies caused by severe inbreeding.

With the fluctuation in the numbers of charismatic megafauna came ups and downs for vegetation on the island, too. After the huge wolf crash due to parvovirus in the early 1980s, moose exploded and ravaged the trees. Rolf showed horrific photos of young balsam fir trees stripped bare up to their tips. But, as the wolves recovered, so did the trees. 

After a wolf from the mainland—M93, “the old grey guy”—brought new genetic fitness to the island wolves, the vegetation recovered even more. Rolf observed tens of millions of new trees sprouting on Isle Royale, and aquatic plants (a favorite food of moose,) returning to the lakes. While the wolf reintroduction in Yellowstone National Park (YNP) has put these carnivore-herbivore-vegetation “trophic cascades” in the news lately, the vegetative recovery in YNP is only along the lines of tens of thousands of trees.

This winter, Rolf and his research staff found that the wolf population had decreased from nine wolves to only three, while moose had risen to 1,250. One of those three wolves has so many genetic anomalies from inbreeding, that Rolf suspects it may already be dead. Two new wolves came and explored the island for a few days, but traveled back to the mainland just a few days before the ice bridge melted.

With the moose management that wolves brought to the island effectively gone, what might happen in the future? The moose are on track to double their numbers in a few years. The remaining mature balsam fir trees are nearing the end of their lives, with little hope for their seedlings to escape browsing. The National Park Service is conducting an Environmental Impact Statement for various management options, but that process may take years.

As the future of wolves on Isle Royale seems to teeter at the brink, a thrilling new story is emerging on another island in Lake Superior. During the morning session at the Wolf Stewards Conference, Brent Patterson, of the Ontario Ministry of Natural Resources and Forestry, reported on three wolves who have just arrived on Michipicoten Island in northeastern Lake Superior. This little Provincial Park is the third largest island on Lake Superior, and sits about ten miles offshore. Caribou were reintroduced to the island in the 1980s, and they have been doing well.

Last October, a kayaker unzipped his tent to find two wolves staring back at him. Later, tracks of three wolves were discovered walking down the beach. This February, Brent and others collared three very large wolves – an adult male and adult female, and a young female. Preliminary data show that these wolves are eating “high on the hog,” and are able to subsist on only the choicest bits of the many winter-starved caribou they take down. 

Researchers are on the edge of their seats, waiting to see if the adults will breed, how the caribou will fare, and what unforeseen events will result in more questions than answers.

When asked to compare and contrast the situation on Michipicoten to the one on Isle Royale, Brent quickly listed a few ideas – they are both protected islands in Lake Superior with a single ungulate prey, and a single large predator. Unlike Durward Allen’s long delay in starting research, Brent is able to jump right in with the latest satellite tracking technology. Both islands had three wolves at our last count. “But,” Brent added with a chuckle at his understatement, “those wolves are on very different trajectories.”

As the night deepened, stars twinkled to my north over Lake Superior...over the wolves. For the humans who have lived around this lake for thousands of years, it is a source of spiritual connection to nature.  Native Americans, explorers, fur traders, sailors, and adventurers used it to foster connectivity across the landscape. For the wolves of Isle Royale, the Lake is now their prison bars, and a barrier to connection. What will the Lake mean to the wolves on Michipicoten Island? As long as we, as a society, continue to support and value research like this, we will soon be able to find out. 

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! We are currently constructing our new exhibit: “Lake Alive!” which will open May 1, 2015.

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


The last wolves of Isle Royale. Photo by Rolf Peterson.

Tuesday, April 21, 2015

The Loons are Back

Cold water and rough sand swirled around my toes as I stepped into the lake. It was a welcome caress on the cabin fever of my feet. With one last heave, I slid my goldfinch-yellow kayak into the water. Frothy gray clouds left over from scattered showers polished each ripple into a mirror as I pushed off from shore.

Easy strokes soon propelled me around the point, heading for the bay where the loons always nest. Are they back? I’ve been expecting to hear their wails slip in through the tiny crack I’ve opened in my bedroom window. A chorus of frogs has been shouting my lullaby so far, and the calls of other returning migrants fill the day. The tiny, urgent, winter wren lets forth a tinkling stream of notes in the ravine. Tireless song sparrows shout “Maids, maids, put on your tea kettle-ettle-ettle,” over and over from the highest tips of alder brush. One white-throated sparrow sang “Oh sweet Canada, Canada, Canada,” as it hurried north. The pre-historic, rattling cries of sandhill cranes. The whinny of robins. But no loons.

Scanning the waves for any speck of a loon, movement in the tree line caught my eye. I strained for a better look. Great flapping wings, with both white and black feathers, came in and out of view. “Could it be?” I hoped. And then nodded with satisfaction as the great shape swooped up to land on the utility pole where the ospreys live. Last year that nest ended in tragedy, with only one of the family of four surviving. This year, we already have new owners and a half-built nest.

Turning into a boggy bay, I startled some wood ducks, who burst out of the dried reeds in a flurry of squeaky alarm calls. Then another noise—or was it a movement—caught my attention. Either way, I turned back toward the osprey nest in time to see a flash of white on an eagle’s head as it wheeled in the sky, chasing…or chased by – I couldn’t tell – the smaller osprey.

Eagles are majestic. They are also bullies. The technical term is “kleptoparasites,” which means that they will bother an osprey until it drops a fish, then swoop down and claim the snack for their own. Eagles are also the only common predator of adult loons. Which is what triggered the sound that caught my attention. Two loons were alarming at the eagle, with harsh cries to send shivers up your spine. “They are back!” I thought, as I alternated between scanning the water in their direction and following the aerial battle. A smaller bird, probably a crow, joined in the chase. Soon it was clear that the eagle was on the run, and the osprey escorted it to some invisible boundary before swinging around and heading back to its nest.

I paddled toward the now-quiet loons. Straining my eyes, two black dots soon distinguished themselves from the distant shoreline. It had to be them.

At this point in the season, any two loons who can be in such close proximity without yodeling conflicts must be a pair. Are these the same loons who reared one chick safely into October last year? It is impossible to tell without bands, but the research suggests that it is likely. Loons have an incredible sense of place. They will choose a territory as much like the one they were born on as possible. Once they have a territory, they prefer to keep it. The place-based knowledge they acquire each year– the best nesting spots, best fishing spots, common hazards – is invaluable. While it is possible for loons to mate for life, it is their attraction to a territory—not each other—that keeps them together.

By now I had slid close enough to see the gleaming white and inky black checkers on their backs, and the sleek swoops of their foreheads. Over the winter, loons lose all of their flight feathers at once as they molt back into breeding plumage. It is known as the “pre-nuptial” molt, and they arrive here looking their best and ready to woo a mate.

I drifted in the evening light as the loons courted nearby. The birds swam toward each other for a distance. When they got within several feet, one loon spun around and they both swam the same direction. After a moment, one dove, surfaced farther away, and the routine would start again. Their coy behavior and snazzy black-and-white garb reminded me of a blurb about Senior Prom I read in the newspaper’s events calendar.

Spring is here. With it comes young and hopeful life decked out in many styles of tuxedoes and rainbows of colorful gowns. Everyone must sing, perform, defend, watch, or choose according to their own, individual, natures. Who have you been admiring this spring?

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! We are currently constructing our new exhibit: “Lake Alive!” which will open May 1, 2015.

Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com.
Photo by Emily Stone
Photo by Emily Stone


Friday, April 10, 2015

Fairyland

It was a beautiful day for a hike in Fairyland. This State Natural Area is named for the “relatively undisturbed old growth hemlock hardwood forest” that forms its core. Stands of mature, second-growth hardwoods surround the hemlocks, and ephemeral ponds poke holes up to the sky through the hemlocks’ dense green canopy. This forest was once owned by Mary Griggs Burke, founder of the Cable Natural History Museum. Legend has it that Mrs. Burke found solace in the groves as a child, and then, as an adult, set up fairy tea parties in the woods for her young friends. The sense of magic remains.

Our chilly morning meant easy walking on frozen ground, and bright sunshine added cheer to the crisp air, as we pushed through a branchy balsam fir thicket into the open, park-like hemlock grove. We paused to breathe in the primeval atmosphere.

Patchworks of emerald, olive, and chartreuse moss draped over soft, sunken logs. Hummocks and swales in the forest floor told tales of large trees, long fallen. Their huge root masses, ripped from the ground by a strong wind, had once risen above the soil. Rain, snow, and rot had knocked down the masses, crumbled their massive trunks, and now they lay like sleeping giants under the duff.

The ground-level caverns and raised root-knees of hemlock and yellow birch trunks gave us shadowy visions of the nurse logs and stumps their seeds had sprouted on long ago. The young, growing trees had embraced their damp, fertile nurseries, only to have the old wood vanish into the soil and leave empty space behind.

We all admired the cavities in the bases of trees, and examined them for signs of habitation. A few red squirrel middens, littered with piles of shucked cone brackets, spilled onto the ground. But Vivianne Hanke, who teaches fairy house making workshops for the Museum, had other ideas. “There’s a Fairy House!” she exclaimed quietly, pulling out her camera to take a photo of a castle-like mossy stump. “Here’s another one,” she murmured into the space left beneath a yellow birch’s roots. Soon we were all joining in her search. Almost any tree, we discovered, could be quickly inhabited by our imaginations.

With her eyes on the ground, Vivianne soon found another fairy home. “I almost stepped on it,” she chuckled, handing me the papery gray pouch. It didn’t look like much. A few leaf veins were still visible, but most of the case was reinforced with fine, tan-colored silk. “Promethea moth?” I said to the little cocoon in my hand; half-hoping that it would identify itself. While we were looking into stumps for fairies, here was the winter home of a real live fairy right under our feet.

Callosamia promethea are large, beautiful silkmoths, with black, tan, pink, and redidish-brown wings. Their caterpillars attach a leaf to its twig with an extra-strong lash of silk, pull the leaf around, them, and then spin a second tough, hairy chamber inside. Within those two layers of nearly impenetrable silk, the caterpillar forms its pupa and waits out the winter.

But when I took the cocoon home to examine it, I soon noticed a long groove in the back of the pouch. This cocoon had been attached to a twig along its entire length, not just from a thin, reinforced stem. With a few more queries on Google Images (the best way I’ve found to identify insects!), I soon came to the tentative identification of Hyalophora cecropia, the Cecropia silk moth, instead.

Cecropias are North America's largest native moth, and share a similar rich, black and reddish-brown coloration with Promethea moths. Fairies indeed. In an ideal world, a beautiful moth would emerge from this cocoon in mid-summer, cling to someone’s screen door under the porch light, find a mate, lay eggs, and then expire peacefully in the night.  

Unfortunately, this cocoon only contained the dried, crumbled remains of a parasitized pupa. I almost wish I hadn’t opened it. Like Schrödinger's cat, if I didn’t know, I could still imagine that a viable moth pupa rested inside.

Glancing down at the empty shell resting near my keyboard, my mind wandered away from the death I’d found, and returned to a series of online photographs of a plump, fluorescent green caterpillar with multi-colored spikes, spinning a similar home. A living creature had made this!

Almost anything, we discovered, can be quickly inhabited by our imaginations.

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! We are currently constructing our new exhibit: “Lake Alive!” which will open May 1, 2015.

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


 
Photo by Emily Stone

Friday, April 3, 2015

Pileated Woodpecker

Sunlight streamed through the tree trunks as we meandered into the warming woods. The Ruffed Grouse’s thumping faded into the distance as we left his territory. In its place a loud, staccato drumming echoed through the hills, followed by the wildly laughing cry of a Pileated Woodpecker. My ornithology professor nicknamed pileateds the “monkeys of the Northwoods” due to their raucous, whinnying calls.

Like grouse, Pileated Woodpeckers are not daunted by our northern winters, and maintain their mates and territories throughout the year. Activity has ramped up recently, though, with the onset of spring and breeding season. Unlike the melodious warblers who are singing their way north right now, woodpeckers use drumming to attract a mate and defend a territory. “With such energy did he hammer that his whole body shook and his wings quivered. He fairly hurled himself wildly at it,” described the naturalist Ernest Waters Vickers in 1915. They add to the pulse of the forest.

Woodpeckers beat on trees for three main reasons: to forage for food, to excavate a nest cavity, and to drum for communication. The first two are relatively quiet affairs, done slowly and deliberately. The third is as loud as possible. Woodpeckers prefer the resonant acoustics of a hollow trunk or branch on which to drum—or a stove pipe or rain gutter—to make sure that their message gets across loud and clear. Both male and females drum.

I’m not sure who was drumming the beat we heard, but as we peered through the tree trunks, one large bird swooped through the maze and landed low on a bole, followed shortly by its mate. Then again, one swooped off and the other one followed. Were they just searching for food together? Or performing their mating dance? In 1908, Francis H. Allen witnessed their ritual,

“They hopped up and down the trunk, frequently pecking at each other's bills simultaneously, now on one side of the tree, now on the other…They hopped backward and downward a great deal, and often they lifted and partly spread their wings. Their motions were limber and undulating, marked by a certain awkward grace.”

After the thrill of their mating rituals come the more domestic duties. Pileated Woodpeckers use their large, straight, chisel-like bill to excavate a new nest hole each year. The male seems to do most of the excavation of oblong hole, removing wood chips from the area as they go. Dense, mature forests tend to contain the large, dead trees that they prefer. In young forests, when old, dead nest trees are the tallest ones around, lightning can present a hazard to nesting birds.

Although there is a significant time investment – each cavity takes 3-6 weeks to complete – woodpeckers will not reuse the hole in subsequent years. This probably serves to protect the babies from parasites, or from mammalian predators who might remember the location from year to year.

In the years after the woodpeckers raise their brood of 3-5 young, a wide variety of birds and mammals will use the abandoned cavities. Other woodpeckers, wood ducks, bluebirds, flycatchers, owls, bats, squirrels, and pine martens all benefit from pre-drilled cavities. This makes Pileated Woodpeckers a keystone species for their crucial role in creating habitat.

The pileated pair leap-frogged their way deeper into the forest, and we continued hiking. Several times we noticed piles of fresh wood chips near the trail, and looked up to find a tree trunk perforated by large, rectangular holes from the woodpeckers’ foraging activities. Nest trees have no such tell-tale signs, since the birds carry away all chips, nest debris, and feces that might give away the location of eggs and babies to a nest predator.

These days, it seems our Pileated Woodpeckers are having good luck with reproduction. Hardly a day goes by when I don’t hear the “monkey of the Northwoods,” or catch a glimpse of this striking black-and-white bird in its undulating flight. It wasn’t always that way. Pileateds were considered rare in 1900s, due to habitat loss and hunting. When the forests rebounded, so did the birds. I like the sound of that.

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! We are currently constructing our new exhibit: “Lake Alive!” which will open May 1, 2015.

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


Photo by Larry Stone

Friday, March 27, 2015

The Pulse of a Waking Forest

Our morning dawned crisp and blue. In the woods, we knew that the trails would be firmly frozen, the mosquitoes still far from flying, and perhaps the ticks would be hunkered down, too. The novelty of this snowless, chilly spring weather is a perfect match for a hike on the North Country Trail.

As we entered the brushy, deciduous forest and strode down the leaf-littered path, I felt my heart quicken and thud in my chest. After a moment, the sensation reached my ears, too. It wasn’t my heart – it was the drumming of a Ruffed Grouse! I’m always amazed by how much I feel their sound instead of hearing it. In the thick of mating season, their incessant, accelerating beats have even caused a fleeting catch in my breath as they temporarily overpower my own body rhythms.

The grouse drummed again; thumping slowly at first, and then crescendoing into a rapid-fire blur. As his last vibrations dissipated into the still air, another grouse answered from a neighboring territory. The low-frequency sounds are audible from up to a quarter mile away.

Over the years, we’ve employed several explanations of how ruffed grouse create this sound. Because male grouse often display from atop a hollow log, perhaps they created the sound by actually hitting the log with their wings. Or, since they also display on rocks, mounds of soil, or prominent roots, perhaps the sounds comes from the wings striking together behind the birds’ back, like a spruce grouse. Those explanations were discredited in part due to some fuzzy photographs of captive Ruffed Grouse by Professor C.F. Hodge of Clark University in the early 1900s.

H.E. Tuttle spent many days in blinds observing drumming grouse from 1910 to 1918, and published his findings in the American Ornithologists' Union’s journal, “The Auk.” Tuttle examined Hodge’s photos and agreed that the sound did not come from wings beating together. He posed the possibility that rudimentary air sacs contribute to the sound (as in the displays of greater sage-grouse).

One theory he dismissed heartily was that the drumming sounds were produced the same way as grouse’s noisy flight. He described it as “an unsatisfactory explanation of that far-away throbbing challenge which steals on the ear so subtly, like the half heard beating of one’s own heart.”

As in many realms of science, as the technology improved, so did our explanations and accuracy. In the 1920s, Arthur Allen of Cornell University used a new-fangled contraption to shoot motion-picture footage of the grouse. By slowing down the movement, he ruled out every explanation except the one that we currently accept.

On the Cornell Lab of Ornithology’s “All About Birds” website today, you can read the result of their founder’s research: “The male Ruffed Grouse’s signature drumming display doesn’t involve drumming on anything but air. As the bird quickly rotates its wings forward and backward, the air that rushes into the temporary vacuum beneath the wings creates a miniature vacuum, generating a deep, thumping sound wave...”

That thumping sound wave sends “the blood sap pulsing quicker along the veins…” (Tuttle again) not only for humans, but also for the lady grouse. She can probably differentiate between different males, since the number and rate of pulses in each bout of drumming is unique to each individual.

Tuttle noted that if he rustled the leaves in his blind to sound like the dainty footsteps of an approaching female grouse, the male would drum instantly, and also flare his name-sake ruff of neck feathers. Once he’s able to attract a female with this huge output of energy, copulation lasts only a few seconds. The female then wanders off to build a ground nest and raise the chicks completely on her own.

Hiking down the trail, we found many clusters of sawdust-filled grouse droppings. Those piles marked where they had digested tree buds and catkins on sub-zero nights while buried snugly in a snowdrift. In one balsam thicket we heard – but did not see – the whirr of a grouse’s startled explosion into flight. We have to admire their tenacity of these year-round residents, even if we sometimes chuckle at their lack of grace.

Now, as the days lengthen with the promise of spring, we can also appreciate how grouse’s drumming seems to jump-start the pulse of a waking forest.

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! We are currently constructing our new exhibit: “Lake Alive!” which will open May 1, 2015.

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

Photo by Larry Stone