Mysteries Abound

Studying nature, the answers we find lead often to more questions. Mysteries abound, such that naturalists and ecologists frequently act as sleuths in pursuit of clues. Observations feed our curiosity, leading to speculation, reflection, and inquiry.

So I was naturally curious when one of our canoe-program volunteers mentioned that he had seen some unusual markings along the bank of the Kishwaukee River in the Deer Run Forest Preserve. He said it looked like someone had dragged something out of the brush and into the river. When he told me about it, he was helping out with our youth canoe camp, Blazing Paddles. We were going to be paddling that very section of the river and he wanted to know if I could help interpret what had made the marks.

As good fortune would have it, he was able to point out the place along the bank shortly before we directed our pod of teenaged paddlers to pull ashore for a lunch break.

striations, etched like scratch marks into the sloping riverbank

striations, etched like scratch marks into the sloping riverbank

With a small band of curious campers in tow, I hiked back along the shore to investigate. The markings fanned out from a small opening in the vegetation, as if someone had combed or raked the surface. But this was no Zen garden and there were no trails near this section of shoreline. I ducked into the willows to investigate further.

There, behind the edge of the brush line, the answer was apparent. Sharp stumps of willow, a couple of inches in diameter, bore the grooved channels formed by sharp rodent teeth. Beavers apparently had been taking down willows and dragging them toward the water, stump-first with the upper leaves and branches trailing, raking the surface of the soil.

The adolescent paddlers in my company were impressed, never before having seen for themselves that sort of evidence of beaver activity—and they also were impressed with the beavers’ famed industriousness. We knew that the work must have been recent, as we found additional evidence farther along the bank:  A length of willow trunk, gnawed at the base and bearing the tell-tale tooth marks, still had a few green leaves at the tip. Those leaves would have wilted within days of the stem having been severed.

evidence of beaver activity; adolescent human for scale

evidence of beaver activity; adolescent human for scale

Beavers (Castor canadensis) are the largest rodents in North America, with bodies reaching 30 inches or more in length. A typical adult beaver may weigh between 35 and 65 pounds, although specimens weighing up to 85 pounds have been reported. Beaver teeth are formidable: the front incisors are oversized and appear orange in color, as iron replaces calcium in the enamel, making the incisors exceptionally strong—capable of gnawing through hardwood trees.

a stump exhibiting the grooved marks left by a beaver’s tough incisors

a stump exhibiting the grooved marks left by a beaver’s tough incisors

Further adaptations of these aquatic mammals include webbing between the toes of the hind feet and the distinctive paddle-like tails. When startled, a beaver may slap its flat tail in warning as it disappears beneath the water’s surface. Beaver fur was prized by the trappers who were among the first Europeans to explore this area. The outer guard hairs are long and glossy while the underfur is very fine and dense, protecting and insulating beavers’ skin from the water. Oils secreted through glands are distributed and combed through the fur while grooming to enhance the waterproof qualities of the fur. Such musky oils are also used to mark territorial boundaries.

Physiological adaptations like webbed feet and a flat tail enable beavers to thrive in aquatic environments.

Physiological adaptations like webbed feet and a flat tail enable beavers to thrive in aquatic environments.

Beavers are monogamous and live in extended family units, typically spanning three generations. Their preferred diet consists of herbaceous vegetation, although they will browse on woody stems when necessary.

Of course, we seldom see beavers. Not only are they generally restricted to riparian and pond-side habitats, they also are generally nocturnal, spending the daylight hours in lodges built of branches and accessible through underwater entrances. So, like much of the wildlife with whom we share this little corner of the planet, they may remain unseen, but can be known by their effects.

And beavers can have amazing effects on the environment. They are nature’s environmental engineers; their dams and lodges my redirect the flow of streams and rivers, flooding vast areas and influencing plant communities and habitats over long periods of time.

Nature is endlessly fascinating; collecting evidence, we are drawn deeper into explorations of interrelated phenomenon. Threads lead to nodes that branch off to other threads. One of the things that I find satisfying about studying nature is that we can devote a lifetime of study there and never get to the end of it all. Mysteries abound and there is always more to explore.

Home Sweet Home

Home. Such a simple, yet evocative word. So essential to our sense of security and wellbeing. Most of us rely pretty heavily on the comforts of home to help us endure the vicissitudes of life out there in the wide world. Faced with daunting challenges and fearful prospects, dangers, difficulties and dilemmas, the child within cries, “I wanna go home!”

We are not alone in finding safety and comfort in the nest, in the den, in the burrow. Our animal compatriots in the wild need their space also. Educators here at Severson Dells explain to school groups that organisms “Have to Have a Habitat” and we explore the many ways in which they find their respective niches in nature. Every organism needs shelter, nourishment (food and water), and space. If any of those needs is withheld, the organism cannot thrive and may not survive—at least not for long.

I was reminded of these essential truths recently when setting up a photographic plot to record progress in restoration here at The Dells. Along the crest of a low ridge, I came across a spoil pile:  light-brown glacial till unearthed from below the surface by an animal digging a burrow or den. Evidently, the animal had taken up residence there some time ago:  the soil was worn and lightly weathered; new plants had taken root there.

Outside this burrow, the spoil pile has been colonized by new plants.

Outside this burrow, the spoil pile has been colonized by new plants.

Just a few feet away, however, was a second excavation, one that apparently was quite fresh, looking as if it had never seen rain. What impressed me about it was the size of the stones that had been dragged or pushed out of the hole. Some were rough-hewn, several inches in diameter, and must have weighed a few pounds.

a new spoil pile of glacial till featuring large stones unearthed from below

a new spoil pile of glacial till featuring large stones unearthed from below

It can be difficult to tell with certainty which local mammal would have dug a given burrow. For denning season, coyotes may dig holes to occupy while giving birth and caring for their young pups, although such dens are generally abandoned by early July. Opportunistic as they are, coyotes are more likely to use a den that was excavated, and subsequently abandoned, by another animal. Red foxes typically leave scraps of bone and hide around a den entrance. Woodchucks (groundhogs) are well known for their excavation expertise and their dens often feature a “dirt porch.” A woodchuck would be capable of pushing a fairly large stone up and out of its burrow.

Curiously, a number of local animals may occupy a single burrow, either consecutively or—reportedly—even at once. Skunks, opossums, badgers, coyotes, raccoons, and groundhogs are said to be among those known to cohabitate from time to time.

Hollow trees, of course, offer another familiar form of shelter for wildlife. A large oak near the underground burrows presented an ample opening into an interior chamber; a walnut husk on the lip of the opening hinted at the chamber’s occupancy.

another residential address for local wildlife

another residential address for local wildlife

In addition to the many bird species known to be cavity nesters, the following mammal species also are known to occupy hollow trees:  raccoons, opossums, fox squirrels, gray squirrels, flying squirrels, bats, white-footed mice, bobcats, and gray foxes. (Yes, gray foxes do climb trees!) Given the walnut husk, it seems likely that one of the squirrels calls this place home.

Home. It means much more than the house (or den or burrow or nest) that we live in. Home embraces the wider environment. Our community. And when we care deeply about the natural environment, we come to realize and respect the fact that our home includes at least a portion of the natural world. And we associate our sense of comfort and wellbeing with that local environment. This is what it means to have developed a sense of place. And this is what it means to come home to nature.

Juneberries!

 Every year in June I enter into a fresh round of negotiations. No, it’s not an annual contract; I am just trying to come to terms with some of my avian colleagues. You see, it is in June that the ripening fruits of serviceberry shrubs turn dusky purple and invite us to partake of the berries, luscious and delicious.

In fact, Juneberry is another common name for serviceberry, as is shadblow.

Robins are among the first birds called to raid my trees; Cedar Waxwings follow soon after. I have two serviceberry trees (shrubs) at my house and in most years they offer up an ample harvest; there’s plenty to share with my avian neighbors. The trouble is that the trees have grown tall enough that I can only reach the lower tiers of fruit, so only a portion of the produce can be harvested by me while the Robins and Waxwings have access to all.

Ripening Juneberries attract birds (and people).

Ripening Juneberries attract birds (and people).

Serviceberries (Juneberries, shadblow) are woody shrubs or small trees in the genus Amelanchier. There are about 20 species that occur in North America. Authors Gerould Wilhelm and Laura Rericha describe eight species and one hybrid in their 2017 tome, Flora of the Chicago Region. Of the eight species listed, six are presumed to be native to the region. (Neither the nonnative species nor the hybrid cultivar are considered to be invasive here.)

Four serviceberry species have been recorded from Forest Preserves of Winnebago County:  eastern Juneberry (Amelanchier arborea) is listed from Rockford Rotary Forest Preserve; low Juneberry (A. humilis) can be found at Blackhawk Springs and Seward Bluffs; inland serviceberry (A. interior) has been reported from Colored Sands, Sugar River, and Sugar River Alder; Allegheny serviceberry (A. laevis) is at Blackhawk Springs, Kishwaukee Gorge, Severson Dells, and Seward Bluffs.

For a variety of good reasons, serviceberries have become popular landscape plants in both commercial and residential settings. Their bark, smooth and gray, with spiraling dark streaks, offers distinctive winter interest. The leaves are small, oval, and with lightly toothed margins. In April and May, these members of the rose family (Rosaceae) are bedecked in flowers, each bearing five white, strap-like petals, longer than they are wide. The flowers yield abundant fruits, edible berries (actually pomes, fleshy fruits that form from an inferior ovary, i.e., below the other flower parts) that ripen in June. The fall foliage turns richly to tones of apricot and orange with hints of red. Some serviceberries tend toward a tree-like growth form, but attaining a height of only about 25 feet; others, especially those sold in the landscape or nursery trade, are predisposed toward expression as multi-trunked shrubs. Serviceberries are the larval host of Red-spotted Purple butterflies.

Amelanchier  in autumn splendor

Amelanchier in autumn splendor

The common name of shadblow (or shadbush) comes from the eastern region of the country, where the blooming of shadblow was said to coincide with the running of the shad to spawn in New England rivers. The name serviceberry is said to have derived from the resumption of certain “services” in the spring, whether the performance of marriage ceremonies (wedding services) or the ability to dig graves in newly thawed ground (burial services). Juneberry, of course, refers to the ripening fruit, the cause of my conversing with birds.

My negotiations with the foraging birds goes something like this. I’ll go out to my serviceberries with a small basket to collect the fruit, flushing a few birds out of the trees. The Cedar Waxwings may quickly disperse to regroup out of sight; the Robins squawk in protest as they fly off to the nearby crabapples or perch on the edge of the gutter and eye me with suspicion.

If I approach slowly and quietly, the Waxwings may linger so that I might reason with them. I explain that they are welcome to all the berries at the top of shrubs, while those situated within my reach are reserved for me. The Waxwings are generally agreeable to these terms and seem to show admirable restraint.

The Robins, however, laugh at me. They dismiss me with derision, as if to say, “Hah! What are you going to do about it?” Once I am back inside the house, the Robins are back in the lower branches.

I suppose there’s nothing for it but to plant more serviceberries.

Glow

Of all the eagerly anticipated phenomena that mark the spiraling dance of the seasons, few are as sweet, or received with such delight, as the appearance of lightning bugs in June.

Perhaps you call them fireflies. I grew up calling them lightning bugs. In fact, they are neither flies nor bugs. They are winged beetles, in the order Coleoptera. And for many of us who grew up the Midwest, these seemingly magical insects provided an early-childhood introduction to the joyful exploration of the natural world. Many of us have fond memories of dashing across the lawn, big glass jar in hand, chasing flickering points of light and squealing with anticipation of the capture. And we always knew that we could catch these harmless little insects in our bare hands, examine them closely—in rapt fascination of their eerie rhythmic glow—keep them for a time in our clear glass jars (breathing holes punched in the metal lids), and release them once more into their habitat before we were tucked into bed.

Random Factoid:  A Jamaican term for lightning bug is, “blinkie.”

Random Factoid:  A Jamaican term for lightning bug is, “blinkie.”

Adaptation in nature is nothing less than amazing. Why would a little insect evolve in such a way as to regularly emit such a bright, distinctive glow? The short answer is that they use the light to communicate. And most of that communication is about finding a suitable mate.

There are thousands of species of lightning bugs (or fireflies—I’ll use the terms interchangeably) spread across temperate and tropical areas of the globe, classified within five subfamilies. While there are more than 200 species in North America, curiously enough there are few species that occur west of Kansas. (If you really want to impress your friends visiting here from out west, take them to a firefly show.)

Firefly behavior, color, and habitat preferences vary by species, but in general their bioluminescence is caused by enzyme-induced chemical reactions within specialized cells called photocytes. Reflector cells may intensify and direct the light emitted by the photocytes. Light cast by a firefly is extraordinarily efficient; it is what we call a “cold light” because, unlike most sources of illumination, there is no energy lost as heat.

While some fireflies may emit light to defend their territory or deter predators, what we typically see is a courtship display. Each species presents a distinctive blinking pattern that is unique to that species (although there are a few species that mimic one another as a means of interspecies trickery). Males flash their rhythmic signals in flight while females perch in low vegetation; a female may reflect the male’s flash pattern or she may, at a precise time interval, blink back to the male, signaling her whereabouts; the flashing and blinking typically continue until mating is complete.

The female lays her eggs under the surface of the soil. After about three weeks, the eggs hatch, revealing larvae that are fascinating in appearance:  segmented and armored, looking perhaps like a trilobite or some kind of spiny pillbug. The larvae persist in that form for a year or two before spending about three weeks as pupae, emerging as adults who then live for only 3 or 4 weeks—just long enough to reproduce.

A lightning bug larva is a fearsome sight—at least to its prey.

A lightning bug larva is a fearsome sight—at least to its prey.

It is pleasing to find a field or woodland edge filled with the silent twilight courtship display of fireflies. Even as adults we can be mesmerized by the flashing, dancing patterns of green or yellow points of light, swimming in the mild evening air. And yet, some neighborhoods—even some natural areas—seem to host fewer lightning bugs today than in years past. I haven’t found any published studies that compare population trends over time, but there are anecdotal reports of diminishing numbers.

Most of a firefly’s life is spent in larval form, on or below the surface of the soil where they are susceptible to environmental dangers such as drought, flood, contaminants, and predation. Some of the threats to lightning bugs are decidedly human in origin. Lawn chemicals are especially troublesome:  some can kill firefly larvae outright, and they might also kill the organisms that the larvae need to eat. Artificial lighting can reduce the ability of adult males and females to find each other, so we are encouraged to shut off our lights whenever they are not needed.

Those of us who grew up in suburban neighborhoods here in the Midwest may associate lightning bugs with lawns and the residential landscape, but of course those little beetles were here long before modern humans changed the environment, so what natural habitats would have been their haunts? Reportedly, they prefer moist environments that support low-stature vegetation. I would suppose that sedge meadows, mesic savannas, and the margins of wet prairies would have been their preferred habitats.

The ideal time to witness the firefly display is right around dusk, a little after sunset, at the onset of darkness. Firefly activity diminishes considerably about an hour or two after sunset.

Take my advice. Find a moist prairie, sedge meadow edge, or untreated old field. (If you live in a neighborhood that still has abundant lightning bugs, you can do this at home, although ambient light from the neighbors can interfere with the experience.) Perch yourself comfortably at sundown, and take in the show. Allow a soft focus to guide your steady gaze across the gloaming space in front of you. Turn off your thoughts for a few moments, quieting the internal dialog; with silent mind and open eyes, witness the play at hand… and smile like a child enchanted.

Shrewd Observatons

As one of our volunteers and I were standing at the window this morning, watching the birds at the feeders (he was hoping for some redpolls), I saw a small, dark, furry body scamper across the snow toward the sunflower seed hulls scattered on the ground.  As quickly as it appeared, it disappeared behind a pile of snow. 

“A vole!” I declared.  Then I corrected myself.  “No, a short-tailed shrew!”

Neil put up his binocs as the animal reappeared, continuing its foray toward the motherload, and indeed, it was a shrew.  Blarina brevicauda – the only venomous mammal in North America (technically there are two species, the northern and the southern short-tails, but for the purpose of the article, I shall lump them together).

shrew crop1.jpg

Now I know what you are thinking:  venomous mammals?  Really?  Truly!  There are not many worldwide:  the duck-billed platypus, the Cuban and Haitian solenodons (which are foot-long, shrew-like animals), the Eurasian water shrew, and the short-tails.  Unlike the others, the platypus isn’t going around biting and “poisoning” animals – it has a spur on its hind foot that it uses in self-defense to inject venom into its enemies; the rest of them, however, use their venom to incapacitate their prey.

If you came out to our Science Saturday last month, you would’ve seen a short-tailed shrew specimen at the table where we were talking about the subnivean zone, for these small mammals are active all winter, scurrying around between the ground and the snow layer in a constant search for food.  Their metabolism is so fast that they must eat every two or three hours or else starve to death.  Therefore, they do not hibernate, and they are constantly on the move.  Invertebrates (insects, worms) make up the bulk of their diet, but thanks to their venomous bite, they can also immobilize mice and voles, taking them into their tunnels to consume later at their leisure (if such frenetic animals are ever “at leisure”).

What kind of venom are we talking about?  Is it dangerous to people?  What if one bites my cat, my dog, my kid?

The shrew’s venom is apparently similar to that of the cobra, chemical-wise.  It contains two kinds of toxins:  a neurotoxin that causes paralysis, and a hemotoxin that decreases the prey’s blood pressure and wreaks havoc on the circulatory system.  It seems that the shrew’s “purpose” for applying the toxin is not so much to kill its prey (for it is fully equipped tooth- and claw-wise to take out most of the food it finds), but rather to allow it to put prey into storage for later consumption – a paralyzed beetle or mouse will stay “fresh in the larder” until needed later on, when perhaps a quick snack cannot been found.

Knowing all that, you might still be worried about Fluffy, Fido or Freddy.  But fear not – if your cat or dog is bitten by a shrew, it will most likely not come to any harm.  Infection from the bite is probably of more concern than any reaction to the toxin.  Ditto for your child. 

Many years ago, I took a class on Winter Mammalian Ecology, and the guest instructor was Dr. Joe Merritt, who probably knows more about short-tailed shrews than anyone, thanks to his years of research at the Powdermill Biological Station in Rector, PA.  He claims to have been bitten many times by his research subjects, and has suffered little more reaction than what one would get from a bee sting.  However, like with bee stings, some people can react more strongly than others, so it is always wise to not handle wildlife unless it is absolutely necessary, and even then, use proper care and precautions (wear gloves).

shrew crop2.jpg

But I love these little guys.  They are energetic, easy to sneak up on (I was within a couple feet when I took these photos), they sing (yes – many years ago I heard one singing in the backyard while I was sitting on the grass, writing in my journal).  They have tiny little eyes, no external ear flaps, and fur that is unidirectional – all adaptations for a life spent primarily underground.

I have found many a dead shrew just lying on top of the ground in my lifetime.  Found two within about 15 feet of each other last summer right here in Rockford while I was walking the dog around our neighborhood.  Short-tailed shrews are very common (living ones, I mean, although deceased ones seem to be quite common, too).  I have often wondered why these small morsels remain uneaten by the predators that caught/killed them, and later on by scavengers, and after a bit of research I learned that birds will eat them (owls, hawks), but not so much mammals.  Supposedly this is because the shrews taste bad (and birds, apparently, are oblivious to this).  This could be from glandular secretions (located on the animal’s belly and nether regions), which turn a tasty mouthful into something that makes the predator (say a fox, or house cat) think twice about actually consuming it.

If you didn’t get to see the shrews last month, don’t fret the missed opportunity.  I have sent all the bodies from my freezer to a taxidermist and in a couple months I anticipate having specimens on hand to share with visitors.  In the meantime, keep your eyes peeled.  Watch for small furry bodies moving along the foundation of your house, or darting out to your birdfeeders.  Look for a pointy snout and plush grey fur.  Odds are, short-tails are in your back yard and you’ve just never had the opportunity to say hello.

Behold, the Box Elder Bug

“You have bugs on your window,” a second grader said very quietly to me the other day, pointing at the windows behind me in our classroom.  I turned and looked, and she was right, the windows were crawling with red and black insects, but there were far fewer than there had been! 

Image from abcwildlife.com

Image from abcwildlife.com

Severson Dells is not alone when it comes to the annual invasion of box elder bugs (BEBs).  Members of the True Bug Family (Hemiptera), these stunningly colored black and red insects are the bane of many a home-owner when fall arrives.  Why are they here, what do they want, and why won’t they leave us alone?

Like with so many animals that have been labeled as “pests” in the eyes of humanity, our troubles with box elder bugs are ultimately our own fault.  Left to their own devices, they would be perfectly happy to leave us alone (see paragraph seven).

Box elder bugs, Boisea trivittata, are one of our native insects (bet you didn’t see that coming).  The family to which they belong, Rhopalidae, is known as the scentless plant bug family.  Its members are notorious for lacking the scent gland that is found on the hind legs of most true bugs.  However, unlike the rest of its kin, the BEB is not unscented.  In fact, it is apparently famous for its stink, which it produces only when pestered – no doubt it is part of its defense mechanism.  Biologists theorize that the production of this smell, and subsequent bad taste, is what allows BEBs to congregate in such large numbers in the fall without fear of being eaten.  The red and black coloring no doubt serves to advertise that it is not tasty, just like the coloration of ladybugs, milkweed bugs and monarch butterflies.

In the spring, the females lay their bright yellow eggs in the crevices of bark of the box elder tree.  The eggs turn red as the embryo develops, and within two weeks the youngster emerges.  Also red and black, just like its parents, the juvenile goes through several instars as a nymph before finally turning into an adult.  All the while, it is feeding on its host plant.  (Like aphids, BEBs have piercing and sucking mouthparts, designed to stab into the “flesh” of the plant on which they feed and suck out its juice.  The food of choice for BEBs is the seeds of the box elder tree, although they are also known to nip and sip from the tree’s leaves, flowers, and tender twigs.) 

So, summer arrives, the nymphs grow and eat, and eat and grow.  All good things must come to an end, however, and soon summer turns in to fall.  As the cooler weather approaches, the BEBs seek someplace new to live.  Remember I said that if left to their own devices, BEBs would happily not have any interactions with us?  It’s true.  In the wild, minus the presence of humans, these insects seek out rocks, loose bark, or hollow logs to crawl into or underneath for the winter.  If it is dry and sheltered, they will be happy.  People, however, have moved in to their habitats, and as we have altered the landscape, BEBs, like so many other animals, have had to adapt.  And lo! and behold – our houses provide dry, sheltered spaces that are just perfect for these insects to overwinter!  In they come – through cracks in the foundation, holes by utility wires or plumbing, old window screens.  They crawl under siding, and nestle by loose windows.  South- and west-facing walls are preferred real estate, for they get good and toasty on cool days when the sun is out.

BEBs are not going to hurt you and are not going to eat your wiring.  If your dog or cat tries to eat them, your pet may get sick, but I haven’t read of any accounts where a pet died after ingesting a BEB.  On the other hand, I have read that even though BEBs do not “bite people,” they have been known to inflict injury, although more as a defense mechanism (you rolled over on one in your sleep) than as a premeditated action (like a mosquito biting you for a blood meal).

So what is one to do when the BEBs seem like they are taking over one’s house?  Vacuum up the interlopers.  You could also employ a variety of sprays, from insecticides to mixtures of water and dish soap, but remember:  insecticides are poisons, and they are not often specific in their targets.  You are better off trying to prevent the insects from invading by plugging all possible entrances during the summer while they are out.  Replace old or torn screens; plug holes with tight wire mesh; put tight screens on foundation and attic vents; be liberal in your caulking adventures.

In the meantime, BEBs could make for some interesting insect studies.  Maybe you can capture and mark some – follow the daily lives of individuals.  Host BEB races for your friends and relatives.  Apply some engineering and see if you can build a better BEB trap!  Who knows – maybe you or your child might discover some previously unknown trait of BEBs that will change the world!