Thursday, July 22, 2021

Butterflies Live in Layers

Every afternoon, the Museum’s pollinator garden draws me outside with the magnetic pull of its beauty, and the possibility of discovering something new.


I’m rarely disappointed.

This week, while following the darting flights of a calico pennant dragonfly, a weird pattern caught my eye. On a knee-high plant, a few narrow, pointed leaves had been laid up against the stem and wrapped in webbing. They looked a little worse for the wear. If the holes in milkweed leaves can tell you where to find monarch caterpillars, then this web probably held something interesting, too.

I didn’t have to get much closer to see a swarm of dozens of tiny caterpillars feeding on the leaves, with some staying protected inside the web tents. Despite their tiny size, clusters of bristles erupting from nodes all around the caterpillars’ body segments made them seem rather stand-offish. In translucent shades of cream and brown, they weren’t much to look at.






Still, after a few photos and a visit to iNaturalist.org, I had a name for them: Harris’s checkerspot. These were the larvae of a pretty orange butterfly with black markings—smaller, and softer-looking than a monarch. In order to be sure, I also had to identify the plant they were eating. My PlantNet app, and the Minnesota Wildflowers website, both helped to confirm: flat-topped white aster, Doellingeria umbellata. This is the only food in the entire world that this species of caterpillar can eat.

These small, rough hairs on the leaf margins--so small that my fingers could feel them but only my macro camera could actually see them--were one of the key identifying factors for flat-topped white aster...especially because the caterpillars will never give this particular plant the chance to bloom! Photo by Emily Stone.


Of course, that’s not terribly unusual. Monarch butterfly caterpillars can only eat milkweed. Rosy maple moth larvae focus on maple trees. Aphrodite fritillary caterpillars munch only on violet leaves. Oil bee larvae can only develop on a diet of floral oil and pollen from loosestrife flowers.

Adult Harris’s checkerspots are not nearly so picky. They sip nectar from a bounty of blossoms. In contrast, hairy-banded mining bees (who were featured in our Bee Amazed exhibit a few years ago) specialize in foraging on goldenrod flowers. They won’t even emerge from the ground nests where they overwintered until their favorite flowers bloom in August.

With all of these picky eaters and close relationships in the world of pollinators, the diversity of native flowers in our pollinator garden is what really makes the difference. Each insect can find something it needs as both a larva and adult, and each flower can attract someone to move its pollen. Plus, with so many different flowers, we have something blooming all the way from early spring into late fall.

This week, something else caught my eye. Heather Holm, author of “Pollinators of Native Plants,” and an expert advisor on our bee and pollinator exhibits, posted two new graphics to Facebook. One of the beautifully drawn, four-paneled handouts talks about keystone species, which means plants like oak trees that are food for at least 940 species of caterpillars.

The other graphic introduces the concept of “soft landings.” Heather’s website explains that, “Soft landings are diverse native plantings under keystone trees (or any other regionally appropriate native tree). These plantings provide critical shelter and habitat for one or more life cycle stages of moths, butterflies, and beneficial insects.” She’s advocating for people to use the tree’s own leaves to build up soil and duff around its trunk, and add shade-tolerant native plants to create a cradle for those caterpillars to fall into when it’s time for them to pupate or overwinter. “It’s a great place for a beginner to start making a difference in their own yard,” Heather told me.

Funded by a grant from Wild Ones Minnesota. ©2021 Heather Holm and Neighborhood Greening. Developed in consultation with Desiree Narango, Ph.D.; artwork by Elsa Cousins. * For more on creating soft landings under trees, visit: www.PollinatorsNativePlants.com/softlandings.html


If you’ve been to our Mysteries of the Night exhibit, you know that this habitat could benefit fireflies, too!

I’ve been learning about and teaching about leaf litter and “messy” yards as good habitat for a while, but this was the first time I really saw the life of butterflies and other insects in layers. First there’s the canopy of flowers that provide nectar for the adults, and pollen for baby bees. Then there’s the understory of leaves—which might actually be overhead—that the caterpillars need to eat. And finally, the ground layer of loose soil, dead leaves, and rotting logs is essential for these insects to complete their life cycles and survive the winter.

“Plant diversity will yield butterfly and moth diversity,” Heather reminded me. And that includes the dead and rotting plant parts, too! For example, the Harris’s checkerspot caterpillars that first caught my eye this week overwinter as large caterpillars in the duff under their favorite aster—ready to resume feeding again in the spring, before pupating and emerging as a butterfly in late June.

I’m going to make sure that our “messy” pollinator garden continues to attract a diversity of life, and provide all the layers of habitat they need to live.



Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Mysteries of the Night exhibit. Connect with us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

Thursday, July 15, 2021

Sparkling droplets of baby food and Tyvek

As I wheeled my bike past the front gardens at the Museum, the heady perfume of common milkweed flowers swirled in the deepening shade of late afternoon. A monarch butterfly landed, sipped nectar from the pale pink flowers, and then rose easily with flaps of its enormous, orange wings. Little black ants crawled industriously over the blossoms, too. Tonight, after I’d sunk into bed, these pale, sweet smelling flowers would likely send out their beckoning signals to the night shift—moths looking for a sip of sugar-filled nectar on their way to find a mate.




Ten miles later, as I entered the dim tree tunnel of my town road, I smiled at a patch of yellow stars twinkling from the gravely shoulder. The five-petaled flowers belong to fringed loosestrife, a native plant that seems to be on the increase along roads where I ride my bike.

Fringed loosestrife is a native plant with yellow flowers. It often grows in damp soil. Photo by Emily Stone.


If you live on a lake or pay attention to invasive plants, the name loosestrife might send a shudder down your spine. Purple loosestrife is an introduced species that is listed as “Restricted” in Wisconsin, which means that “it has the potential to cause significant environmental or economic harm” when it fills in wetlands, replaces native plants, and disrupts habitat for fish and wildlife.

Luckily, these two plants are unrelated by both taxonomy and ecology. They are in two completely different plant families, and fringed loosestrife does not become invasive. The shared name doesn’t seem to have any botanical significance, since it’s a literal translation of Lysimachus, the name of a friend of Alexander the Great.

There were no butterflies flitting in their unsteady way among these flowers, though, and neither would fur-covered moths drink from sweet chalices by night. A closer look at the blossoms—through the macro setting on my camera—revealed hundreds of tiny, jewel-tipped hairs crowding onto the pale yellow stalks of the anthers, cascading down onto the red centers of the petals, and scattering outward like glass beads spilled on a silk cloth.

Flowers in the genus Lysimachia, like this fringed loosestrife, have gland-tipped hairs that exude oil instead of nectar as a resource for specialized bees. Photo by Emily Stone.



The sparkling droplets weren’t diamonds, of course, but to one local species of bee, they were even more valuable—as their only options for baby food and Tyvek.

Female bees in the genus Macropis collect oil from flowers in the genus Lysimachia, lured in by a special scent that no other pollinators can detect. The bees spread that oil on the walls of their nests, where it keeps the tiny soil tunnels dry in the summer and humid in the winter. They also mix the oil with pollen to make bee bread as food for their babies. Many of our solitary, native bees who nest in the ground need to line their tunnels with waterproofing, but they secrete wax and oil from their own bodies to do the job. And they mix nectar with the pollen to make bee bread.

Just one species of oil bee lives in Wisconsin (Macropis nuda). Their days begin mid-morning, as the males wake up in the cozy embrace of a buttercup or other nearby flower. Females sleep in their shallow ground nest, and seem to rouse a little deeper into the warmth of day. Both males and females perch on leaves to bask in the sun and venture out to non-loosestrife flowers to drink nectar for their own energy. By noon, females begin to visit loosestrife flowers that are receiving full sun, and males—with black bodies and yellow foreheads—patrol nearby in search of mates.

When a male wants to mate, he skips all formalities and simply pounces on a female. If she is receptive, they tumble together for a second or two, and then fly off separately. If she objects, the female bee kicks out her hind legs and dislodges him. She may then continue to forage with her hind legs held high as a reminder of her rejection. This gesture is even more effective because the female bee’s hind legs are lushly furred with white hairs that contrast with her black body.


Macropis nuda female. Photo by
The Packer Lab - Bee Tribes of the World.

 


The fur serves another purpose, too. Short, finely dissected hairs hold oils like a sponge and stiffer hairs support the sodden mat. Using hairy pads on their front legs, females scrape oil from the flower onto her hind legs. She can also collects oil and pollen simultaneously, and carry them mixed together in a ball.




The mother bee places this bee bread inside a small nest cell that she dug into soil and lined with oil. She lays a single egg and closes the cell. The larva hatches, feeds for 10-14 days, and spins a cocoon that completely fills the cell. The cocoon is so waxy and waterproof that the larva must leave a small hole for gas exchange as they breathe through the winter. An adult bee emerges the following spring.

This story has been playing on repeat for roughly 100 million years. The oldest known fossil of a bee is in the same family as our Macropis nuda. That means they flew with dinosaurs, just as flowering plants evolved. A long history doesn’t guarantee a stable future, though. Just like the more visible monarch butterflies, these rare bees are vulnerable to the whims of habitat destruction by humans and climate.

Because I tend to bike past before and after the sun shines on the flowers, I still haven’t seen a little black bee with lushly furred legs visiting my patch of loosestrife. But I like knowing—or at least hoping—that they’re out there...my neighbors in the natural world.


Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Mysteries of the Night exhibit. Connect with us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.



Thursday, July 8, 2021

Dragonflies and Emergence

I bent down, then knelt down, then finally sat down on the sun-warmed grass so that I would be eye-level with the dragonfly. Usually they dart off so quickly that I don’t get a good look, but this female calico pennant clung to the tip of a milkweed leaf even as she was buffeted by an afternoon breeze.




Her enormous eyes were the color of sweet cherries, and light glinted off their curve in just the same way. Golden triangles marched down her ebony abdomen. Dark patches on her hind wings, laced with yellow veins, glowed like stained glass in the sunlight. Truly, she was a work of art.

Dragonflies like this female calico pennant are beautiful. They also go through an elaborate process of metamorphosis that is worth pondering more deeply. Photo by Emily Stone.



As I sat mesmerized by the dragonfly’s delicate beauty, thoughts of my to-do list melted away. Instead, a memory surfaced from an essay written by one of my students last semester when I was adjunct teaching. “Whenever I feel distance from myself or want to give up,” she wrote, “the most beautiful creature appears.” Anahi, a student at Northland College whose parents are from Mexico, had been writing about a frustrating time in her life, and how encounters in nature have a way of easing sadness and stress.

Those thoughts resonated with me, but one of her next sentences stopped me short: “We praise dragonflies for their attractiveness, but we never consider the challenges they face for us to see them.”

I saw the truth in her statement immediately. While an adult dragonfly might dart and shimmer for a few weeks of the summer, it can take years for them to get to that point.

“A dragonfly has four stages in their life cycle,” wrote Anahi. “They lay their eggs, form into larva, transition into a molt, and then become an adult. Seems simple, right? Well, that's where we're wrong.” When I first read Anahi’s essay, this sentence felt simple, too. But later, when she told me how young she was when she began translating letters from lawyers, hospital bills, and work instructions for her parents, who were still learning English, I realized that this sentence held a deep wistfulness for dragonflies’ long childhood.

Once dragonfly nymphs hatch from eggs, they may spend anywhere from six months to six years in this youthful stage, before they emerge to become flighted adults. Like tiny dinosaurs, the nymphs roam the bottom of streams, lakes, and ponds, hunting with hydraulically powered jaws for mosquito larvae, minnows, and snails. But even as fierce predators, they risk being eaten by fish and frogs, and being fed to baby loons.

Anahi, too, faced challenges. She watched I.C.E. agents arrive to take away her father. She endured racial slurs, stereotypes, and unkind words and looks. She traveled to Mexico alone to connect with cousins, while her parents remained at home and tried to share the experience vicariously. And, she navigated the college selection and application process largely alone, as the first person in her family to attend college.

Now in Ashland, she often seeks out a bench down by Lake Superior, where she can watch dragonflies and escape for a few minutes from the pressures of her life. She wrote, “Dragonflies have survived for 300 million years because they have strategies to adapt into new environments.”

As a biology major, manager for the lacrosse team, and center of a close-knit group of friends she treats like family, Anahi has metamorphosed into an active young adult. Soon she’ll graduate and spread her wings. Which is why, I think, when she wrote a research paper about dragonflies for her entomology class, she saw the similarities, and the metaphors, in their life cycle.

After having read a semester’s worth of heart-felt essays filled with emotion and wisdom, and having sat across from this soft-spoken young woman while she told me about a life both like and unlike my own, I see the world a little differently. And I read her essay a little differently, too.

“Before they're transformed during last molt in the nymph stage, the dragonfly walks to dry land and sits near the edge of the water,” wrote Anahi. “Once they find a secure spot, away from predators, the thorax begins to slip. The dragonfly begins to ease itself out the nymph exoskeleton. During this step, they also must wait for their legs to gather strength. While they are waiting, the legs and the abdomen start to expand. That process is called emergence.”

“Even if the legs start to gain some strength, they must be careful because they can get tired while waiting, since developing takes time. They end up feeding close to the water or on anything that is close by. Once they are ready, they slowly start moving and flying farther and farther away.”

The calico pennant that had captured my attention finally darted to a perch on the far side of the garden. “Beautiful,” I thought, and also so much more.




Author's Note: This Natural Connections was written in partnership and with approval from Anahi Gill.



Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Mysteries of the Night exhibit. Connect with us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.




Thursday, July 1, 2021

The Myths and Mysteries of Sphagnum moss


Cool water welled up around my ankles, and my feet reveled in the soft, woven texture of the bog mat as I set my muck boots next to a hummock of leatherleaf. As a kid in Iowa, I loved squishing my toes in silky mud. Now I prefer the clean, spongy mosses of a northern bog. I gave everyone along on the “Field Trip to a Poor Fen” the option to go barefoot, but most kept their boots on. They’d already had enough of an adventure just crossing the moat on a fallen log!




The Namekagon Fen State Natural Area is a true gem of beauty and diversity. I’m sure it’s no coincidence that it’s also difficult to access. Over the thousands of years since the glaciers melted away, the basin where the fen sits has been filling with vegetation. Initially, the wiry stems of leatherleaf, an evergreen shrub, would have reached out in a tangle from the sandy shoreline. Those plants formed a sort of scaffolding, and mosses, grown from spores blown in on the wind from refugia where they’d survived glaciation, soon grew thickly, too.

As moss threatened to bury it, the leatherleaf grew taller and reached wider. Dead plants built up, and more species arrived on the wind or the feet of ducks. Eventually the basin filled in, with peat (poorly decomposed plants) forming a thick-but-floating mat across the surface of the pond. Along the edges, with the influence of warm rainwater trickling in, the vegetation decomposed, leaving an 18-foot-wide moat of open water between upland and mat. That’s what we crossed on the log.

I could barely contain my excitement once the group gathered next to one of 7 large pools of open water that dot the mat. The open water indicates the presence of springs, and that groundwater influence is what makes this peatland wetland a fen instead of a bog. A true bog only gets water from rain and snow.

Both fens and bogs are filled with fascinating plants.

Pitcher plants, for instance, have dealt with the lack of nutrients in bogs by becoming carnivorous. They trap insects in their water-holding leaf, and then a large community of small aquatic creatures breaks down the meal, each taking their share of the spoils before the plant itself absorbs nitrogen and phosphorus straight out of the water. (You can read more about this and other carnivorous plants in my archived columns here on my blog. Just type "fen" into the search box.) (You can also watch a video of one of the critters in a pitcher plant eating an ant here.)




Bog laurel, bog rosemary, and black spruce, on the other hand, conserve nutrients by holding onto their tough, narrow leaves for more than one year.

And then there’s Sphagnum moss, the plant that makes those adaptations necessary.

Sphagnum moss grows quickly, and is overtaking this pitcher plant leaf!



Sphagnum is a keystone species—one that has an outsized influence on its habitat. First it clambers out onto the leatherleaf scaffolding, and then it starts sending hydrogen ions into the water. These positively charged atoms (H+) displace positively charged nutrients (potassium K+, and calcium Ca2+) so that the moss can claim them for its own growth. This also increases the acidity of the water. Did you know that pH stands for the “power of hydrogen”?

The dead cells of Sphagnum  moss, which make up all but the uppermost leaves of the plant, also hold water like a sponge. The wet, acidic environment that Sphagnum  creates slows down decomposition in bogs, and the lack of recycling leads to a lack of nutrients available for new growth, partly because few bacteria can be active in such a habitat.


The tops of these Sphagnum mosses were did photosynthesis when alive, while the stems have been dead for a while, and their purpose is to have empty cells that hold water and bacteria. 

As a young naturalist, I was taught that Sphagnum  was used for diapers and wound dressings because of its absorbency, and because its acidity made it sterile. Science has proved that only the first fact is true. With the new DNA sequencing techniques available to scientists, we now know that the hollow cells of Sphagnum  moss are host to a thriving and unique community of microorganisms—bacteria mostly—who carry out a suite of essential functions.

Some bacteria get carbon from methane in the water and thus provide the moss with 20% of its carbon needs. Other bacteria grab nitrogen out of the air, and share it with their host. Many, if not most, of these bacteria are still virtually unknown and poorly understood. Plus, each of the 380 species of Sphagnum around the globe likely hosts its own distinctive microbial community.

It’s obvious to anyone who manages to cross the moat that the Namekagon Fen is a gem of beauty and diversity. Hot pink orchids glittered among lawns of pod grass and beak rush. Dragonflies and damselflies in a rainbow of colors darted among the plants, too. It’s now strange to know, though, that some of the greatest diversity is probably in the sun-warmed, rain-soaked moss that squished up between my very happy toes.

Calopogon orchid

Rose Pogonia orchid

pitcher plant flower




Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Mysteries of the Night exhibit. Connect with us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

Thursday, June 24, 2021

A Heat Wave Makes the Caterpillars Grow

The temperature on the bank in Cable read 94 degrees when I returned from a field trip on June 4. It was only a short walk from the air-conditioned van to the dark, cool lobby of the Museum, but the heat shimmered and blazed beyond its usual Northwoods intensity.

“I just watched through the front doors as a monarch butterfly laid eggs,” were the first words our docent, Carol, spoke from behind the front desk, even before my eyes had adjusted. I turned to look at the small patches of milkweed we’ve let spring up on either side of the Museum’s front walk. No black-and-orange monarch butterfly flitted among them now. No eggs were visible either, but since they are the size of a pin head, I’d need Superman’s vision to spot them from a distance. I did go out the next day—before the temperature rose to another record high—to snap photos of the tiny, translucent domes. One photo even revealed the pale yellow silhouette of a developing larva inside.

Monarch butterfly eggs are tiny and translucent. They are deposited on milkweed leaves, because that’s the only food that the caterpillars can eat. Photo by Emily Stone.



I’ve read that monarch butterfly eggs can take anywhere from 3-6 days to hatch, so I wasn’t quite sure when I should expect to see caterpillars. I figured it would be soon, because warmth speeds up their development process, and we’d had more than enough heat recently.

At temperatures below 52 degrees Fahrenheit, monarch eggs and caterpillars don’t grow or develop at all. On a cool night, their bodies simply pause. Extreme heat isn’t helpful, either. As temps approach 91 degrees, caterpillar growth slows and then stops. They seek shelter on the underside of leaves, or crawl down into the leaf litter to find relief.

If nighttime temperatures are on the cool side, caterpillars once again find refuge underneath milkweed leaves, shielding their body heat from the cold pull of the stars. On days that are not quite warm enough, caterpillars bask on the top of the leaves, orienting their body broadside to the sun, for absorbing maximum solar radiation. Caterpillars who grow up in cooler temperatures may also have wider black stripes, which helps to absorb heat from the sun. Temps between 59 and 84 degrees Fahrenheit seem to be their happiest range, where they can grow the fastest.

A few days after I wrote this article, temperatures plummeted and we hit an overnight low of 40 degrees. These were some cold caterpillars! Photo by Emily Stone



Staying warm hasn’t been a problem this year! [Edit: of course, right after I wrote this article we had a short cold snap!]

Just four days after Carol watched the butterfly lay eggs, I paused on my way into the Museum after my weekend. A little searching revealed a caterpillar or two, and after zooming in on the macro photos, I could even determine that these little critters were in their second instar already.

Monarch caterpillars shed their skin five times between when they emerge from their egg and when they develop into a pupa, each time revealing a larger skin waiting just beneath. Each stage is called an instar. The first instar, when a caterpillar emerges from the egg, is almost translucent, and lacks the distinctive black, white, and yellow stripes we expect. The caterpillars I spotted—just 4 days after eggs were laid—were distinctly striped, and also sported tiny black tentacles on both their head and their rear.




Over the past two weeks, I’ve kept track of these little dudes almost daily. Well, maybe not the exact individuals I first spotted. By my last count there were 30 caterpillars in all stages of development on our small patch of milkweed. I have no idea which ones were my first two friends! With all the bad news about monarch populations in decline, this is a little spot of hope.

Having lots of caterpillars in a single place doesn’t equal a species no longer on the brink of extinction, though. Jan Sharp, a Museum volunteer who also monitors monarchs for the Monarch Joint Venture, noted that in 2012 we had a similar early spring and big first crop of caterpillars. Then, when those caterpillars grew into adult butterflies and began laying their own eggs, danger moved in.

Parasitic wasps lay their eggs on monarch eggs, and the wasp larvae eat it from the inside. A different wasp lays eggs in a newly formed chrysalis, with the same deadly effect. Tachinid flies lay eggs on caterpillars. Lacewing larvae, like tiny crocodiles, devour eggs at lightning speed. And mites, spiders, ants, wasps, and bugs attack the smallest instars.

Caterpillars get safer the bigger they get, and their growth is truly amazing. From freshly hatched to entering their pupa, caterpillars increase their body mass anywhere from 200 to 10,000 times (depending on which source you read) in just two weeks—less if the weather is warm.

I’m not a fan of this season’s heat, but I do love monarchs. Maybe I’ll just watch from my air-conditioned refuge as I cheer “Grow little monarchs, grow!”


Caterpillars eat almost constantly, and can increase in size by 200 to 10,000 times before they become an adult! Photo by Emily Stone.



Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Mysteries of the Night exhibit. Connect with us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

Thursday, June 17, 2021

Singing Praise for Caterpillars


Rosy maple moths spend their childhood as caterpillar feeding on maple trees.
Photo by Emily Stone.


“Check out these pretty moths!” The Museum’s new office manager, Hayley Matanowski poked her head in the office door as I was firing up my computer for the day. On the cool concrete patio were two moths with pink-and-white striped wings and fuzzy yellow bodies. As we each scooped one up for relocation, I noticed that even their legs were covered in pink fuzz.

After we released the moths into the shady trees at the edge of the Museum’s outdoor classroom, I uploaded a photo to the SEEK app, which is useful for identifying all types of living things. Rosy Maple Moth popped right up on the screen. When I posted the photos to Facebook, eleven people commented on seeing them recently. Believe it or not, their striking colors are good camouflage among the ripening seed clusters on maple trees, which are often tinged with shades of red and yellow.

My heart soared.

It’s not just that these moths are beautiful. They are an important part of our local food web, and I was happy to hear of these observations. A few weeks ago, when I wrote about whip-poor-wills, I talked to Mike Ward, a professor at the University of Illinois. His words are still ringing in my ears: “Throughout the Midwest there are lots of birds that eat mainly moths and aren’t doing well.”

Moth numbers have gone down in many areas, and that’s bad for more than just the moths themselves. They are on the menu for many species of birds, bats, shrews, frogs, toads, spiders, and other insects.

And that’s just the winged adults.

Moths begin their lives as caterpillars, just like their more visible cousins, the butterflies. Butterflies and moths are both in the order Lepidoptera, which comes from the Greek words for “scale wing,” but butterflies are classified into one subgroup, and moths fall into several. Moth species outnumber butterflies species 10 to 1!

The soft, juicy, caterpillars of butterflies and moths are food for even more critters than their parents. As they munch on plants, caterpillars transform into plump snack packs that are full of fats, proteins, and chemicals called carotenoids, which are the pigments that turn bird feathers yellow. Even much-maligned forest tent caterpillars are food for 60 species of birds and 155 species of insects, plus frogs, mice, bats, reptiles, squirrels, skunks, and bears. Nicknamed army worms for the way they march from tree to tree in a line, they are actually the larval stage of a drab, brown moth.

While groups of forest tent caterpillars are highly visible, there are far more caterpillars hidden away in the bushes than you might expect. Chickadees know how to find them, though! With their super color-sensitive eyes, a pair of chickadees will nab between 6,000 and 9,000 caterpillars each summer, just to feed to their nestlings. And chickadees are just one (adorable) example. Scientists estimate that 95 percent of nesting birds feed their babies insects, with caterpillars being a big part of that group.

This black-capped chickadee has a mouth full of caterpillars ready to feed to a nest full of hungry chicks. Photo by Emily Stone.



So if moths are in decline, that means caterpillars are in decline, and it’s no surprise that many birds (including, but not limited to, whip-poor-wills) are in decline, too. That’s just how the food chain works.

At this point, I bet you’re wondering what you can do to help. Thanks for asking!

There are a few things you can do right in your own yard. The first is to plant native flowers and trees. Native insects are closely tied to native plants. As hungry as baby birds are, caterpillars are even more ravenous. Some caterpillars increase their body mass by 2,000 times between hatching from their egg and entering their pupa for metamorphosis to an adult. That takes a lot of food. And it has to be the right food.

Oaks, poplars, willows and cherry trees are host to a huge number of insects. But many species of caterpillars require a certain type of plant. Monarchs and milkweed are a well-known pair. I recently discovered the larvae of dogwood sawflies, on dogwood shrubs of course. On the other hand, most imported plant species don’t provide good habitat. Many websites have lists of region-specific native plants that support pollinators, birds, and other wildlife.

No matter how many native plants you have in and around your yard, if you also have bright yard lights that confuse the moths, bug zappers (which kill more moths than mosquitoes), and you use pesticides, you won’t be providing good habitat. Treatments that claim to kill only mosquitoes can actually kill caterpillars, bees, and fireflies. That deprives the birds and other critters of their favorite foods and has impacts both up and down the food chain.

With the many environmental issues facing us today, making sure that my yard provides good habitat seems like an easy step in the right direction. I see timely and tangible benefits in the form of lovely native plants, cute caterpillars, pretty pink moths, and well-fed chickadees. Together, the birds and I will sing the praises of moths and their caterpillars!



Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Mysteries of the Night exhibit. Connect with us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

Thursday, June 10, 2021

The Season for Northwoods Babies

Summer is the season of babies. Loon chicks ride on Mom’s and Dad’s backs, fox pups play outside their den, and caterpillars munch on milkweed leaves. These critters don’t look or act anything alike, but they do have one thing in common: they are Northwoods babies. And when you stop and think about it, there are many different ways to be born, be young, and grow up in the Northwoods!

Loon chicks get a ride on Mom or Dad. Photo by Emily Stone.



Some babies, like the loon chicks and fox pups, benefit from two devoted parents who share the duties of feeding and protecting their young. Butterflies and moths provide no parental care. They simply lay their eggs on the food plant of their caterpillars—and then fly off! They’ve protected their caterpillars with adaptations like camouflage, bad-tasting chemicals, and the instinct of how best to hide. With many mammals, like deer, bats, porcupines, bobcats, and otters, females care for their young alone.

Lately I’ve been paying even closer attention to the wild babies in my woods, because they are the subject of the Cable Natural History Museum’s 2022 exhibit. Since every living thing is young once (it’s hard to imagine a baby house fly or beetle, but they exist!), there’s a lot to pay attention to! And I’m asking for your help!

This summer, the Museum is hosting a Northwoods Babies Photo Contest. It’s pretty simple: kids and adults of any age are invited to submit their digital photos of baby or young animals, and their hard-working parents. All animals must be Northwoods natives, and may include mammals, birds, reptiles, amphibians, fish, and insects. The photos don’t even have to be from 2021. If you got a great photo last summer, you could enter that, too!

The submission portal isn’t quite set up yet, but you can start taking photos now, and then visit our website, www.cablemuseum.org, for the details later. The deadline for entering the contest will be September 1, 2021. After that, we’ll award prizes for first, second, and third place winners in both the under-18 and the over-18 categories, and also let the public vote in a People’s Choice award! Plus, every photographer will be entered into a drawing for more fun prizes. Big thanks to James Netz Photography in Hayward for sponsoring the contest!

Now, I said before that the photo contest is pretty simple, but taking good photos of wildlife is anything but simple. For advice, I reached out to Keith Crowley. Keith has been making photos for more than 35 years, and a few years ago he nabbed some amazing shots of baby gray foxes at the Cable Community Farm.

Two gray fox pups play at the Cable Community Farm. Photo by Keith Crowley, https://www.lodgetrail.com/.



“Your primary asset is patience,” he told me, “Patience to the extreme.” For 26 days, Keith parked his vehicle a respectful distance from the fox den—which was located by the back steps of the Farmhouse—and sat for countless hours waiting for the foxes to do something interesting. He captured shots of the three cubs playing together, of the parents bringing ground squirrels for dinner, and, finally, of the cubs climbing a nearby crabapple tree. Gray foxes are pretty unique in their tree-climbing habits, so photographing that behavior was his ultimate goal.

All the while, he made sure to be respectful and ethical. “The critical thing is that you don’t disrupt the family interaction,” he told me. And that’s something for all photographers to remember. “I would prefer that the animal doesn’t even know I’m there,” said Keith. “But the main goal is not to affect their behavior. When they start noticing you, you’ve crossed the line. Then it’s best to back off, or even leave the area.”

This is especially important to remember with birds, who are almost all protected by the International Migratory Bird Treaty. It’s illegal to disturb a nest, or even possess a broken egg or lost feather unless you have the right permits. It’s also essential that you don’t get too close to a nest in the days before the chicks fledge. If you scare them out before they’re ready, their chance of survival goes way down. If you think a baby animal needs help, there are plenty of resources online to help you figure out what to do (or not do!).

Recently, Keith spotted a young fawn nursing outside his kitchen window. The photos would have been super cute, but he had no way to get his camera into position without disturbing the pair, and then the fawn would have missed a meal. That’s not ok, so Keith just watched quietly.

One way to get close to animals without disturbing them is to camouflage yourself. That could take the form of a blind, a vehicle, or camouflaged clothing like a ghillie suit. “Growing up hunting,” Keith told me, “you learn that the best camouflage is being still.”

Of course, some animals are more comfortable around humans than others, and if there’s a family in your yard, you can often sit quietly and let the critters get used to you. One of Keith’s favorite interactions was finding a baby porcupine who sat calmly at eye level in a tree at the top of the driveway for a whole week! Insect babies, like caterpillars and dragonfly nymphs, will often be cooperative models.

One of the best parts about going in search of a great photo is that it challenges you to observe nature more closely. You never know what you’ll find! So, take your camera outside, and (respectfully) enjoy the season of babies!


A tiny monarch caterpillar crawls along the midrib of a milkweed leaf. Babies are often small! Don't forget to look closely! Photo by Emily Stone. 



Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Mysteries of the Night exhibit. Connect with us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

Thursday, June 3, 2021

Whip-Poor-Will





The full moon was last week, and do you know what that means? Well, full moons signify many things to many people, but to whip-poor-wills, it means they’d better get busy if they want to give their chicks the best chance at survival.

Whip-poor-wills time their egg-laying with the phases of the moon.

I’m typically skeptical of such fanciful claims, but this one has been supported by the research, and by common sense. The brown-speckled birds become active only at dusk and dawn, and use the last and first light of day to spot insects silhouetted against the sky. Then they flutter up from their perch to scoop moths out of midair. A full moon means more light to see by, and more hours with visibility for catching bugs, which they regurgitate for their young. So, by timing mating and the laying of their two eggs just right, whip-poor-wills schedule their chicks to hatch 10 days before the full moon. Growing chicks will reach their hungriest stage just when the moonlight provides the maximum number of hours for foraging.

So if chicks need to hatch 10 days before the next full moon on June 24, and they need 19-21 days of incubation…let me count backward on my lunar calendar…that means that their parents likely mated just a few days before this recent full moon. The extra light likely helps the female admire the male as he performs his courtship display. It’s no wonder that Museum Director Deb Nelson came into my office recently and said “You should write about whip-poor-wills this week!”

“Have you been hearing them again?” I asked, already knowing the answer, since every spring since I’ve arrived at the Museum, Deb has told me how much she loves listening to the whip-poor-wills call in the woods behind her home north of Cable, Wisconsin. While their emphatic and incessant call may not be instantly recognizable, once someone has told you that they are saying their own name, it is certainly unforgettable.

Whip-poor-wills are known to call more frequently when the moon is at least 50% illuminated. This is useful information for the people who do breeding bird surveys and attempt to count whip-poor-wills on the landscape. It makes behavioral sense, too, since a nightlight means more time to be active. Plus, a male whip-poor-will needs to throw all his energy into attracting a mate and defending his territory—two activities that require him to sing loudly—in the nights leading up to the actual act of mating. Which, by my calculation above, occurs just before the full moon.

After mating, the female lays two well-camouflaged eggs directly on dry ground in a shady patch of leaf litter. Building a nest would just provide a bigger target for predators to look for. Once the chicks are about 8 days old, they hang out exclusively with Dad, while Mom often starts a second nest.

Eastern whip-poor-wills are extremely well-camouflaged and rarely seen. It’s likely you’ve heard one shouting its name, although maybe not recently as their numbers are declining. Photo by Mirko Schoenitz, posted to iNaturalist and used under Creative Commons.



“Why do they sing only at night?” was the next question that Deb posed to me. It’s a good question, and one that scientists have many answers to, none of them definitive. Maybe the birds prefer the quiet that comes with darkness. During the day, whip-poor-wills would have to compete with dozens of other bird species, plus wind noise and air turbulence.

Or maybe, since the gray-and-brown mottled whip-poor-wills spend all day hunkered down on a low limb or the ground—virtually invisible—calling during the day would alert predators to their presence and ruin their perfect camouflage. Nighttime has fewer predators, and more things to accomplish. Whip-poor-wills do their courting at night, so it’s important for the male to conduct his vociferous flirting and territorial defense when the ladies (and competing males) are also out looking for love.

Every year, when Deb tells me about hearing her whip-poor-wills, my response is “Do you know how lucky you are?” Just like the golden-winged warblers I wrote about last week, whip-poor-wills are an example of a common bird that is in decline. Over the past half-century, their numbers have dropped by 75%. While they are still common in some places—like Deb’s yard and the Moquah Barrens on the Bayfield Peninsula—they have disappeared from other places. Nights are quieter now in my neighborhood between Cable and Clam Lake, and even in my parents’ patchwork of prairie and woods in northeast Iowa where whip-poor-wills kept me awake as a kid.

So what is causing their decline?

Mike Ward, a professor at the University of Illinois who has been geotagging Whips in the Moquah Barrens, emphasized the relationship between the whip-poor-will population and moths. He knows it’s a strong connection, because in his words, “the birds give us a fecal sample when we tag them,” and that sample is full of moths. He also told me that “throughout the Midwest there are lots of birds that eat mainly moths and aren’t doing well. When I drive around the Barrens at night, my windshield gets covered with moths, but that doesn’t happen in other areas where the whip-poor-wills aren’t doing well.”

The connection extends to other birds (like golden-winged warblers) who eat insects, too. It’s inevitable that humans’ war on insect “pests” has impacts far up the food chain. If we get rid of all the caterpillars chopping away on plants, they can’t metamorphose into moths. And without moths, whip-poor-wills will have trouble feeding their young.

You can make a difference in your own backyard by preserving and restoring habitat, planting native species, spraying fewer chemicals, and leaving messy areas. Together, we can help whip-poor-wills rise and grow like the waxing moon.


Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at www.cablemuseum.org/books. Or order it from our friends at redberybooks.com to receive free shipping!

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Mysteries of the Night exhibit. Connect with us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.





Thursday, May 27, 2021

Two Colors of Warblers Mix and Match

Bee-buzzzzzz. From my parents’ deck overlooking their hilltop of restored prairie and ravines of brushy woods in the Driftless Area of northeast Iowa, the buzzy call of a bird cut through the much sweeter cacophony of orioles, grosbeaks, and cardinals.

The quality of the song was strikingly similar to that of the golden-winged warbler I’d heard in Northern Wisconsin just a few days prior, but with only one longer buzzzz at the end instead of a series of buzz-buzz-buzz syllables. I walked closer, and when the bee-buzzzzz came again, I turned toward the sound and caught just a glimpse of a very yellow bird among the emerging leaves. He flew before I could focus my camera, and buzzed cheekily from out of sight.


Blue-winged warblers are moving north, and encroaching on the habitat of golden-winged warblers. Photo by Andy Wilson, used under Creative Commons from iNaturalist.com.



Had I spotted this little guy in the Bibon Swamp, I might have exclaimed in dismay instead of delight. Blue-winged warblers are moving north, and have been for several decades. At the same time, golden-winged warblers have disappeared from many places (declining by 68% since 1966), with the southern limit of their range shifting 340 miles to the north. Their northern limit has also shifted—by 500 miles—into places like Minnesota and Manitoba where they had never been seen before. Where the two birds overlap, they often mate and form hybrids like the Brewster’s warbler I spotted last week in the Bibon Swamp. [Location MAP]

Golden-winged Warbler range contraction. Source



Here's a map of both of the warblers' ranges, with the green showing areas of overlap. Source



This Brewster’s warbler is actually a hybrid between a golden-winged warbler and a blue-winged warbler. The mixing of their gene pool may have an impact on their conservation. Photo by Emily Stone. 



Some scientists worry that this hybridization may ultimately lead to the demise of the golden-winged warbler as a species. That may well be true, although it’s impossible to predict the future. The scientists I talked to all have a pretty philosophical view of the situation.

David Toews, a researcher who compared the genetics of the two species, found that these two members of the Vermivora genus share 99.97% of their genes. Even when scientists find a bird that looks completely like one species or the other, the birds’ DNA reveals evidence of past hybridization. “They could only have gotten this way by hybridizing for a very long time,” he told me. “We like to try and put nature into neat boxes,” he added, “but the distinctions between different species are not always neat and tidy.”

Since both warblers tend to use brushy habitats such as alder swamps and regenerating aspen stands, there doesn’t seem to be a way to prevent the blue-winged warblers from encroaching on their northern cousins if it suits them. “The notion that somehow we’re going to stop them from hybridizing is not within the realm of reality,” Toews added. That might be ok. He thinks we can take a nuanced view and appreciate this “cool evolutionary thing happening in our own back yard.”

Don’t get me wrong, these birds are in dire need of our help, but trying to stop hybridization probably isn’t the answer. What we should do, added Amber Roth, a professor at the University of Maine and co-chair of the Golden-winged Warbler Working Group, is make sure that we manage habitat for the entire Vermivora species complex—which includes golden-winged warblers, blue-winged warblers, and all of their hybrids.


Golden-winged warblers face a myriad of threats as their population both declines and shifts north. Sharing genes with blue-winged warblers may be part of both their demise and their future. Photo by Emily Stone.



As with most species, habitat loss is a critical cause of their decline. Beaver meadows used to provide key habitat, before we trapped them for fur. Wildfires used to create a patchwork of shrubby habitats among larger forests, before we started putting fires out as fast as possible. Even settlers clearing forest openings for farming—and then abandoning them again—in the late 1800s and again in the 1930s was good for the birds, until those openings closed in again. (Those clearings may also have been what brought the two warblers into contact and started this most recent round of increased hybridization.)

Although it often feels unsightly, allowing more aspen clear-cuts within a dynamic, forested landscape could be beneficial for both colors of warblers. Just as essential is making sure that housing developments don’t encroach on important habitat, refraining from draining wetlands, and allowing beavers to do what they do best.

Protecting the warblers’ winter habitat in Central and South America is also critical. While there’s an alliance focused on just that, you can help by choosing bird-friendly coffee, which promotes agricultural practices that really do help birds.

Of course, no amount of habitat conservation will be enough if we don’t get climate change under control. Models predict that with a 2°C increase in temperature, much of the winter habitat in Central America will become unsuitable, and golden-winged warblers will be extirpated from Minnesota, Wisconsin, and much of their current range.

Although hybridization with the blue-winged warbler is often listed as one of the many threats to the long-term survival of golden-winged warblers, it may also provide some hope, at least for the Vermivora genus as a whole. Tom Will, now retired from the U.S. Fish and Wildlife Service, thinks that gene sharing among the two species may allow the best adaptations to surface, and provide a buffer against environmental change. He concluded our interview by advising us all to “Enjoy evolution, admire its processes, and keep birds—all birds—on the landscape!”

Want to find out more? The Working Group is working on their website, but in the meantime The Cornell Lab of Ornithology has put together some really great resources here.

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at www.cablemuseum.org/books. Or order it from our friends at redberybooks.com to receive free shipping!

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Mysteries of the Night exhibit. Connect with us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

Thursday, May 20, 2021

Golden-Winged Warbler

Bee-buzz-buzz-buzz. A dozen heads turned toward the sound as it filtered through a shrubby mess of willows and alders. Brad Gingras, a former Museum Naturalist and avid birder, pointed toward the sound as his eyes lit up. “That’s it! That’s the golden-winged warbler!”

A dozen pairs of eyes and binoculars soon found the little singer, flitting around the backside of a willow thicket. Those thickets, and this bird, are two of the main reasons that Brad leads a field trip to the Bibon Swamp almost every spring for the Chequamegon Bay Birding & Nature Festival. In this weird year, I invited him to lead that trip for the Museum.

Just a little farther down the dead-end gravel road, we heard another bee-buzz-buzz-buzz. Necks craned up, and we were soon admiring the yellow cap, black-and-white face, black throat, and yellow wingbars of our quarry as he foraged among the tiny flowers in a sugar maple tree—visible at last!


Golden-winged warblers are one of the fastest-declining birds in North America…and we found several in the Bibon Swamp!



The Bibon Swamp is prime habitat for golden-winged warblers as they seek shrubby wetlands for nesting, and then move to mature forests nearby as soon as their chicks fledge. The tangled mess of alder, muck, and tussocks may not look inviting to us, but researcher David Toews told me “they are pretty particular about the crappy habitat that they like.”

Loss of that “crappy” habitat is a big reason why golden-winged warblers are one of the fastest declining songbird species in North America. Their population has dropped by 68% since 1966, and they now have the smallest population of any bird not on the endangered species list. Wisconsin, Minnesota, and Manitoba are their last strongholds. Happily, the Bibon Swamp is protected both as a State Natural Area, and an Important Bird Area.

Even this big block of prime habitat can’t protect the birds from all perils, though, and we found one potential threat singing nearby.

The now-familiar bee-buzz-buzz-buzz song sent us scanning the thickets in the hope of glimpsing yet another individual. We found this one crooning from the dangling twig of an elm tree, while picking insects out of the flowers. Thankful to have a clear shot, I focused my camera just as Brad was getting a good look with his binoculars.

Suddenly, the excitement in his voice went up a notch. “It’s a hybrid! This is the Brewster’s!” Zooming in on the photos I had just snapped, I could see that this little guy (we knew it was a male because of the song) had the same gray body, needle-sharp bill, yellow cap, and yellow wingbar as the other golden-winged warblers we’d spotted, but this individual had only a black eyeline instead of a full mask, and no black throat.

(Here's the location of the Brewster's Warbler on Google Maps if you'd like to go see him!)


This Brewster’s warbler is actually a hybrid between a golden-winged warbler and a blue-winged warbler. The mixing of their gene pool may have an impact on their conservation. Photo by Emily Stone.


This combination of traits is a result of mixed parentage. Brewster’s warblers are the hybrid offspring of a match between a golden-winged warbler and a blue-winged warbler. Blue-winged warblers are painted in all the same colors, but in a different combination. They have a black eyeline, gray wings, and a yellow head, throat, and breast.

In 2016, David Toews (then a post-doc at the Cornell Lab of Ornithology and now a professor at Penn State) and Scott Taylor dove into the genetics of these two visually distinct birds. Toews and Taylor found that the birds are 99.97 percent alike, with only six regions on their genomes that differ significantly. Those regions code for two of the most striking differences in appearance between the two birds: throat color and body color. Just a tiny change produces a very different-looking bird.


Blue-winged Warbler by Tony Castro - Own work, CC BY-SA 4.0,
https://commons.wikimedia.org/w/index.php?curid=60519322



Remember those Mendelian genetics you learned about in high school? Gregor Mendel grew pea plants, and discovered that some traits—like purple flowers—were dominant, and others—like white flowers—were recessive. In order to produce a white flower, the plant must have two copies of the recessive gene. Otherwise the dominant trait will show through.

As it turns out, the white throat and white body of this Brewster’s warbler represent the dominant traits. The black throat of a golden-winged warbler and the yellow body of a blue-winged warbler are both recessive traits. They rarely show up in the same bird, but when they do, we call it a Lawrence’s warbler.


Lawrence's Warbler by Dominic Sherony -
CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=6856439



Our little group of birders wandered on from there, eventually identifying 40 species of birds by sight and sound. I kept mulling over what I’d read the night before, though. Some scientists worry that the interbreeding of these two warbler species, and the resulting hybrids like the one we just spotted, are a dire threat to the already-declining population of golden-winged warblers. Could there be more to that story? Find out next week! [or the week after]



Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at www.cablemuseum.org/books. Or order it from our friends at redberybooks.com to receive free shipping!

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Mysteries of the Night exhibit. Connect with us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.