Curiosity

Bright summer sunlight trickled through the thick canopy of trees and danced across the shallow stream. Two dozen little feet clad in their oldest shoes tramped through the water, too, somewhat less gracefully than the sun flecks. This was crick stomping at its best: a hot day, cool shade, refreshing water, and a sense of adventure.

I felt like a mother hen at the center of the flock as we moved our way upstream. Instead of pecking at grain, the chicks’ hands darted out to pick up this rock or that one. I was always glad when my campers got as excited about rocks as I did. The shallow, flashy, nature of the creek meant, on most days, several shallow channels braided themselves through wide gravel bars of interesting rocks. After big thunderstorms, I loved to watch as a torrent of brown water churned and frothed down the creek, revealing an alien landscape to explore as the floodwater receded.

On this particular crick stomp, we brought an honored guest with us. A NASA scientist named Owl (a camp name chosen because she liked the nighttime) was in the creek with us. She was part of a NASA outreach program involving girls, science, and education. She led us in activities like using recycled items to create creatures that could survive in each planet’s unique habitat, dissecting candy bars as if they were types of bedrock, and stargazing.

As an astrogeologist, Owl was particularly excited to accompany the girls on a crick stomp. They were soon distracted picking up rocks, but I stuck by Owl and let my curiosity show.

“Look here,” she said, pointing to a place on a gravel bar where flattish rocks were stacked up against each other like shingles. “When we see rocks like this, we know that water once flowed there.” “Obviously,” I thought in my teenage head, “this is a creek.” Owl continued: “By learning about rocks on earth, we can also learn more about rocks on other planets. If we see rounded rocks, or rocks stacked up like this on other planets, we know that there was once water flowing there also.” “Hmmm…” I thought, and tucked that bit of knowledge away in my brain.

As I went on to take geology courses in college, Owl’s words snuck back into my consciousness time and again. In class, we often talked about how you could read the story of ancient streams in the structure of the bedrock they had become. Knowing this gave me new eyes for observing flowing streams and the rocks they move.

This summer, I was barely aware of NASA’s latest project – the Mars rover “Curiosity,” until a friend (also a geology major) posted a news article on Facebook. The headline read: “NASA's Curiosity Finds Water Once Flowed On Mars.” The detailed photos showed rounded pebbles and streambed characteristics that could only have been formed by running water.

Scientists gathered enough data to estimate that the stream was between ankle and hip deep, and flowed about three feet per second. The characteristics of this Martian stream are preserved in a conglomerate, the type of rock formed when pebbles and sand become cemented together. You can find earthly conglomerate nearby at Copper Falls State Park.

Reading NASA’s report, I was immediately transported back to crick stomping with Owl in our shallow stream. “By learning about rocks on earth,” she had said, “we can also learn more about rocks on other planets…we can know that there was once water flowing there also.” Thanks to Owl, and a little Curiosity, the alien landscape of Mars seems a lot more familiar.

At the time Owl visited, finding evidence of surface water on Mars was a lofty goal for the future of space exploration. Now that the future is here, I wonder what the next generation of space exploration will look like, and if any of those crick-stomping girls will join the adventure.

Sumac

Natural Connections

Sumac

Emily Stone

Naturalist/Educator at the Cable Natural History Museum

 

As tree leaves stop gathering sunlight for food and prepare for the winter, it seems like that extra light is reflected back to our eyes in the brilliant colors of fall foliage. Green chlorophyll has faded away, and sugars it produced all summer are stored deep within the tree as starch.

 

In some trees, the fading chlorophyll reveals yellow and orange pigments. In other trees, red pigments are created in bright sunlight. While I appreciate the golden light that filters through an aspen stand in fall, it is the red leaves that make me really love autumn.

 

The staghorn sumacs around here are particularly colorful as their leaves morph through a rainbow of color, ending on crimson. They are also fast growing, short-lived, and tolerant of a wide variety of soil types and moisture levels. I am thrilled that sumacs like road ditches, because admiring their lively colors can improve almost any long drive. Sumacs are interesting beyond just their colors, too. Did you know that they are a member of the cashew family? This family also includes mangos, pistachios, and poison ivy!

 

Even while the leaves are still green, sumacs start to show red.  Large conical clusters of red-furred fruits sit at the ends of branches, giving a good show of color from June-September. Not every clump of sumac produces fruits, though. This observation troubled me off and on for years, until I realized two important parts of sumac’s biology: it is dioecious, and it reproduces vegetatively by rhizomes. Let me explain…

Dioecious (which means “two households” in Greek) indicates that each individual plant has reproductive units that are either only male or only female. Most flowers you encounter are monoecious, which means they have male and female parts in the same flower (“one household”). For sumac, this means that some trees are only male, and do not produce fruit. Ah!  That is one part of the equation.

Rhizomes are modified stems that creep underground and send out roots and shoots from their nodes. If you chop a rhizome up, a new plant could grow from each piece. Asparagus is a great example of a plant we propagate by its rhizome. In a clump of sumac, the rhizomes stay connected, and new plants grow outward from the center.  Since the oldest, tallest plants are in the center, clumps of sumac are often attractively dome-shaped.

As the sumac grows new shoots from its rhizome, it is actually producing clones of itself. If the parent plant is male, all the offspring will be male, too, and that clump will not produce fruit. Mystery solved!

To reward yourself for this new knowledge or for a bit of refreshment as you enjoy the fall foliage, why don’t you make a pitcher of sumac lemonade? Gather a half-dozen berry clusters and steep them in a pitcher of cold water for an hour or so. Strain out the seeds, hairs, and bugs through a cheesecloth. Add sugar or maple syrup to taste (remembering that these sweeteners were made by plants using sunlight), then chill and enjoy the rewards of a summer well-lived!

 

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, STAR POWER: Energy from the Sun, opened in May 2012 and will remain open until April, 2013.

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/

 

Sharpies at Hawk Ridge

Natural Connections

Sharpies at Hawk Ridge

Emily Stone

Naturalist/Educator at the Cable Natural History Museum

 

A blustery northwest wind cut right through two layers of wool as I stepped out of the car at Hawk Ridge in Duluth, MN. Binoculars, bird books, hot tea, and windbreakers in hand, my parents and I set up our watch with about fifty other birders and volunteers. Bright sunshine alternated with shadows cast by hurried gray clouds. Up on a wooden platform, several experts peered through spotting scopes, intently searching the sky. Their quarry: hawks.

 

Each fall, about 82,000 raptors pass over Hawk Ridge on their southern migration. Understandably reluctant to cross a large body of water, the birds funnel southwest along the shore of Lake Superior. The high, rocky outcrop of Hawk Ridge Nature Reserve makes a great viewing platform, and people from all over (like my parents from Iowa) come to watch the migration here.

 

Under some conditions, hawks will fly low over the ridge, zooming just above the heads of excited birders. Today, most of the raptors were tiny black specks in the distance, only visible by scanning the wild blue yonder with our binoculars.

 

Raptor biologists here have a special trick for getting close-up views of the hawks – bait. Using a technique a lot like fishing, researchers pull the string on a lure to make it look like an injured bird. When a raptor swoops down for an easy meal, it becomes tangled in one of a series of nets. Researchers carefully extricate it from the net, take a variety of measurements, and attach a numbered band to its leg. About three percent of birds banded here are recaptured. Based on the data collected from recapturing banded birds, sharp-shinned hawks migrating over Hawk Ridge generally head southeast to Illinois, and then southwest toward east Texas and Mexico, following the prevailing wind pattern.

 

Sometimes naturalists bring a recent captive down from the remote banding station so that folks on the overlook can get a better view. Moments after we arrived, two naturalists called everyone over to see a couple “sharpies” in hand. To prevent the hawks from hurting the humans or themselves, the naturalists held their wings, tail, and legs gently but firmly in the fist of one hand. The birds, both hatch-year females, looked quite calm.

 

Sharp-shinned hawks are the smallest hawks in North America, and have the biggest size difference between males and females. Females are up to one-third bigger than males, and this size difference means that they focus on different sizes of prey. Males tend to hunt smaller birds, such as sparrows, while females can concentrate on larger prey, like robins. This has two big advantages: males and females do not compete for the same food source, and chicks can get appropriately sized food as they grow.

 

During the first few weeks after hatching, the female sharp-shin broods the chicks while the male hunts and brings in small songbirds. He typically removes and eats the head before delivering the meal. As the chicks mature, the female joins in the hunting and brings larger prey for the hungry fledglings.

 

Sharp-shinned hawks are agile and acrobatic fliers, navigating dense woods at high speeds by using their long tail as a rudder. Short, rounded wings help them zip through tight spaces after small birds. During migration, they leave the dense forests of their northern nesting grounds and take to the open sky.

 

To help make the journey easier, these and other hawks will ride thermals, which are rising pockets of warmer air, formed by the uneven heating of the surface of the Earth. Thunderheads are visible thermals, where clouds of water droplets show just how high the warm air is climbing. When you see turkey vultures or other birds soaring in lazy circles without flapping, they are riding thermals. The energy in thermals comes from the Sun. You can learn more about them at our current exhibit: STAR POWER: Energy from the Sun.

 

For every mile a bird rises on this avian elevator, it can coast downwind seven miles without flapping. Still, sharp-shinned hawk’ migration from the top of this continent to the bottom takes strength, endurance, and stored energy. In order to be ready for the journey, these small hawks grow furiously—going from egg to adult size in just over 7 weeks.

 

The Hawk Ridge naturalists spent a few minute answering questions, and then asked someone to adopt the birds. For a small donation to support the research, the adopter’s name is linked with the band number of the bird, and if it is ever recaptured, the adopter will be notified. In addition, the adopter gets to release the bird. What a thrill!

 

In a flurry of feathers, the hawk left the adopter’s hand. It swooped below the cliff for a moment, giving us a spectacular “birds-eye view.” With a series of graceful circles, the sharpie gained altitude. Soon the little hawk was a mere speck in the sky, one of the many birds on an incredible journey, visible only through our scanning binoculars.

 

If you would like more information on the migration at Hawk Ridge, visit their website: www.hawkridge.org. You can also join Museum Naturalist, Katie Connolly on a Hawk Ridge field trip on October 18. Call 715-798-3890 for the details and to register.

 

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, STAR POWER: Energy from the Sun, opened in May 2012 and will remain open until April, 2013.

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 Magic of Nature

Gray mist hung in the air over Lake Namakagon, and clouds diffused the early morning sunlight. Fall colors seem deeper and richer in wet weather and half-light like this.  As I turned up County Highway D, I was dismayed to find it turned to gravel, with bright orange Road Work Ahead signs adding their own garish color to the landscape. I admit I was a little irritated that crunchy gravel, washboards, and large machinery would interrupt my early morning scenic drive.

 

At first, I traveled at about my normal speed, since the curves and scenery of this winding road encourage slow driving anyway. Then I reached the flagger, with the STOP sign showing. After a moment of irritation, I noticed a movement out of the corner of my eye. Something small, white, and furry sat quivering in the roadside grass. It scurried a few steps, then froze and looked alert on its haunches. From nose to bushy white tail, the critter was only about 8 inches long – the size of a least chipmunk.

 

Least chipmunks are the smallest and most widely distributed North American chipmunk, focusing their range in the north and west. Their larger cousins, the Eastern chipmunks, range throughout Wisconsin and the Eastern United States. Both are usually light brown, with dark brown and white stripes, live in burrows in a variety of habitats, feed primarily on seeds, and spend the winter underground sleeping and eating occasionally. They do not need special camouflage to blend in with the snow like snowshoe hares, so why was this one white?

 

Two different genetic conditions result in pale animals. The most familiar is albinism. If you have been to the Museum, you probably noticed the albino deer we have on display. In albino animals like this one, two recessive genes combine and result in the loss of the animal’s ability to produce an important brown pigment called melanin. Melanin protects us from UV light, and increases as we get our summer suntan.

 

Without melanin, all parts of the animal are white or pink. The pink color, as in the eyes of a true albino, is a result of blood vessels showing through. Melanin is important for sight and eye development, and albino humans, as well as animals, often have impaired vision.

 

Another genetic condition results in animals with pale fur but normal eyes, or patches of white or pale colors. These critters are leucistic. Birdwatchers regularly report seeing lecuistic robins and other birds with unusual light patches.

 

In contrast, some animals produce far more melanin than usual. These melanistic animals are dark brown or black. Many folks comment on the black squirrel mount in the Museum’s collection. It is simply a melanistic gray squirrel. In contrast to albinism, melanism is often helpful to an animal for camouflage, and in the case of black leopards, it also gives them disease resistance.

 

People often attribute special mystical or spiritual significance to albino animals. In University of Texas tradition, seeing an albino squirrel before an exam confers good luck. In Ojibwe tradition, albino bucks represent the sacredness of all living things, and seeing one should remind us to contemplate our own spirituality.

 

I could not tell for sure which the scurrying chipmunk was – albino or lecuistic –but I knew I had to try to get a photo. I fumbled for my camera, then rolled down the window, turned off the engine, and snapped a few shots. Before long a cool breeze carrying the sweet scent of autumn leaves wafted through the window and past my nose. I took a deep breath and looked out at the sparkling water of Lake Namakagon. With the radio and engine off, my hurried brain quieted, too. This little white critter turned road construction from an inconvenience into moment of peace. Ah, the magic of nature!

 

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, STAR POWER: Energy from the Sun, opened in May 2012 and will remain open until April, 2013.

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/

 

Flights of Yellow

Yellow wings flash and click knee-high next to my bike. Up ahead, several sets of yellow wings flap quickly up to the trees. A gentle breeze releases yellow sugar maple leaves from their twigs, and they flutter gracefully to the ground. This sunny gravel road glimmers with the yellows of late summer.

The first yellow wings belong to the Carolina grasshopper. While not especially numerous, they are probably the most common grasshopper you notice. Not only do they prefer roadsides, weedy lots, and the Museum’s outdoor classroom, yellow bands along the edge of black hind wings do a great job of catching our attention.

The grasshoppers’ yellow wing bands flash briefly as they make short flights to escape from predators (or us). When flushed, they fly at a right angle to the predator’s line of travel, then hunker down and use their mottled brown body and front wings to disappear. (This seems like a better strategy than Great Blue Herons, who I have followed for miles down a river in a canoe before they flew out and around us.)

To find food, Carolina grasshoppers make lazy, bobbing flights about 2 feet off the ground, and are often mistaken for butterflies. To find mates, males rise almost vertically from the ground to heights of 3 to 6 feet, occasionally higher, and hover for 8 to 15 seconds. Then they flutter down to the ground near where they started. Late summer is their mating season, and the eggs will hatch next JuneMales, and sometimes females, produce sound in flight. The snapping, crackling, or buzzing sound is made by rubbing the under surface of the forewings against the veins of the hind wings. The short flights attract both females and other males. They remind me of frogs calling each other in to a vernal pool in the spring, or prairie chickens displaying on a dancing ground.

The second group of yellow wings belongs to Yellow-shafted Northern Flickers. As the migrating flock spooks off down the road in front of me, handsome yellow feathers are visible under their wings and tails, and yellow feather shafts show through from above and below. Their white rump patches flash brightly and give another vibrant identification clue.

These woodpeckers spend most of their time feeding on the ground, where their smooth brown back with black bars and dots blends in well with soil and leaf litter. They catch ants and other insects (but not grasshoppers!) with their long, sticky tongues, and dig up anthills to access tasty larvae. Ants are not just food, but also pest control. Flickers rub formic acid from the ants on their feathers during preening to help prevent parasites.

When flushed, flickers make short, undulating flights up to low branches, and often perch like robins instead of clinging to the trunk like most woodpeckers. The courtship flights of the Northern Flicker in spring are noisy and lively, as three or more birds of both sexes perform a comical dance, nodding and bowing or chasing each other through the branches of a tree. Instead of the snapping sound of grasshoppers, the song of the Northern Flicker is a loud wick-wick-wick-wick or a squeaky flick-a, flick-a, often accompanied by a long continuous roll of drumming on spring mornings.

This time of year, flickers head south. (They are one of the only migratory woodpeckers.) Warblers continue on toward Central America in their mixed flocks. Soon harsh frosts will silence the grasshoppers, and maple leaves will have all made their own journey to the forest floor. The wings of fall are bringing beauty and change to our wonderful northern home.

Whose wings have you seen lately?

The Woods are Not Silent

The hermit thrush stopped singing as soon as I wrote about it a few weeks ago. All but a few birds have ceased singing even their late summer songs. While we no longer hear the lilting phrases of love and territorial defense jumbled in a cacophonic morning chorus, the woods are not silent.

 

Daydreaming on a walk the other day, I gradually became aware of darting movements and soft chip notes in the low and leafy trees. The little flock of foraging warblers engaged in a constant conversation of “companion calls.” These short chips and chirps in a regular back-and-forth rhythm indicate that everything is still okay. In this season, different species of warblers flock together, to make use of many eyes and safety in numbers. They often join with chickadees, who serve as local guides that know the best restaurants and the most dangerous neighborhoods. As they forage for tasty insects and juicy caterpillars, the small birds cannot always keep in visual contact with each other through the leaves. Companion calls help keep track of every bird in the flock.

 

Finding food right now is important for these little engines that weigh only as much as seven cents. They are on an epic journey. The black-and-white warbler, which I recognized from its striking stripes and nuthatch-like behavior, is heading for somewhere on that species’ unusually extensive winter range – anywhere from Florida to Venezuela and Colombia. Today must be a stopover day, a time to refuel for the journey ahead.

 

The other warblers in the flock were drab olive green, the standard color of young warblers and adults in non-breeding plumage. Birders know them as “confusing fall warblers.” I could not identify them to species, but it is a safe bet that they also are heading to somewhere in Central or South America for the winter. The secrets of how birds find their way on this incredible journey remain largely hidden. They appear to navigate using a variety of cues that include the stars, the earth's magnetic field, and even smell.

 

The many-mile migration of these tiny birds is triggered by a combination of factors, including a change in day length, lower temperatures, dwindling food supplies, and genetic predisposition. Since presence or absence of food is not the only or the most important trigger, you can continue feeding the birds through autumn and winter (even hummingbirds!) without fear that your food will interrupt their migration.

 

Warblers come here in the spring to find a space of their own where they can take advantage of our longer day length and feed ravenous youngsters on our plentiful crop of insects. Their songs are the soundtrack of summer. They leave in the fall when the shorter days and freezing temperatures make those same insects much harder to find. Yet the woods are not silent.

 

As amazing as it is that these tiny creatures can travel 2,000 miles or more twice a year, I also have a deep respect for the year-round residents who make do and even thrive in the bitter (and beautiful) northern winters. Chickadees, nuthatches, and downy woodpeckers find enough food to fuel their internal fires, and seem almost cheerful throughout the wintry months. Thanks to the wonderful diversity of lifestyles in nature, the woods are never silent!

 

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, STAR POWER: Energy from the Sun, opened in May 2012 and will remain open until April, 2013.

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/

In a Field of Goldenrod, Part II

"Imagine yourself living in a globelike room with greenish walls bulging outward and upward and then arching in to meet above your head," the naturalist Edwin Way Teale wrote. "Imagine such a room constructed of succulent, edible material, forming a house that at once provides food and shelter, plenty and protection. That is what you would find if you traded places with one of those gall insects that now live in the globular swellings on the stem of my hillside goldenrods.

Those galls began their story last spring. After a female goldenrod gall fly, Eurosta solidaginis, deposited an egg on the terminal bud of a growing goldenrod plant, the egg hatched in about ten days. The larva immediately bore down into the stem. The chewing action and the larva’s saliva, which is thought to mimic plant hormones, caused the goldenrod’s stem to thicken.

Soon, runaway cell division triggered by the larva formed a dense, round growth on the stem called a gall. This provided both food and shelter as the larva grew up. After going through three stages, called instars, the larva is ready for winter.

The larva will not leave the gall yet, though.  Instead, it will excavate an exit tunnel in the gall to use in the spring, leaving just the outermost layer as a door. The larva must chew the exit tunnel now, because once it pupates into an adult, it will not have chewing mouthparts. The larva will then retreat to the center of the gall and fill its cells with glycerol, a cryoprotectant that protects cells from damage due to freezing. This is where we are in the story right now.

I often stop to examine the dried, brown galls as I ski or snowshoe through snowy fields. If you open a gall in the middle of winter, you may find the larva, surrounded by the debris excavated from the exit tunnel. They make good fish bait, and are protein-rich snacks for downy woodpeckers and chickadees.

You can tell which bird attacked a gall by the size and neatness of the hole. Downy woodpeckers have a thin, sharp beak that neatly excavates the tough dry material. Chickadees have a blunter beak, and make large messy craters. In contrast, the larva’s own exit hole (if it makes it through the winter) is tiny, perfectly round, with no rough edges, and no concave excavation pit.

Predators help determine the size of the galls. Downy woodpeckers select larger galls to attack, probably hoping for a larger grub. In areas where downies are common, flies with smaller galls survive better, and smaller galls are more common.

Birds are not the only creatures who exploit the gall fly larvae, though. A parasitic wasp, Eurytoma gigantea, uses its long ovipositor to penetrate the gall wall and lay an egg inside. The newborn wasp larva first eats the fly larva, and then continues to feed on the gall tissue until it pupates. The wasp’s ovipositor is only so long, so they prefer to lay eggs in smaller galls. Therefore, in areas where the wasps are common, galls tend to be larger. Where both downies and wasps are common, middle ground is found.

(To see for yourself why goldenrod gall fly larvae appeal to so many predators, I recommend that you taste one for yourself! The concentration of glycerol makes them slightly sweet. I have met many middle school and college students who are willing to accept that challenge! Let me know if you decide to join this Cool Club, too!)

After two weeks as a pupa in the spring, the new adult gall fly will emerge. It will walk up to the goldenrod plant and look for a mate. After mating, the female fly will leave in search of a new goldenrod stem in which to deposit her eggs.

Female gall flies are quite picky about which type of goldenrod to lay their eggs on. Certain fly “races” prefer certain species of goldenrod. The female can tell goldenrod (genus Solidago) species apart by “tasting” the plant with chemical sensors on their feet, antennae, and even in her ovipositor! When the right plant is found, a few eggs are laid, and the story beings again.

                                                         

Once predators, parasites, or metamorphosis empties the galls, they become habitat for a variety of insects.  Springtails, wasps, solitary bees, beetles, and ant colonies have been discovered using the galls. Next time you go for a walk or a ski in a field of goldenrod, take a moment to imagine yourself spending the winter in the globelike room of a goldenrod gall.