Dangerous Migration: One of Nature’s Most Impressive Migration Phenomena is at Risk

By William Rapai

 

*The following story appeared in the Fall 2017 edition of Michigan Nature Magazine

monarch - Wendy Caldwell, Monarch Joint Venture

Many flowers—especially native plants—are terrific sources of nectar for monarch butterflies. Photo by Wendy Caldwell, Monarch Joint Venture

It’s September at the Michigan Nature Association’s Goose Creek Grassland Sanctuary.

Even though asters and goldenrod are in bloom, most plants that grow here—including the three species of milkweed—are in decline. 

Hanging from the underside of a leaf, a Monarch butterfly emerges from its chrysalis, with an urge to do only one thing: fly to Mexico.

Five generations of Monarchs have hatched already during this calendar year, but this individual is different. Always synchronized to the lifecycle of the milkweed, this Monarch inherently understands that fall is approaching and it must go. 

FWS_Monarch_Migration_Map_5.24.17

Monarch butterflies are not able to survive the cold winters of most of the United States so they migrate south and west each fall to escape the cold weather. They travel much farther than all other tropical butterflies, up to 2,000 miles. They are the only butterflies to make such a long, two-way migration each year. Map courtesy U.S. Fish and Wildlife Service

There are no roadmaps or guideposts for the Monarch and there will be no adults that have made the journey before to show the way. There is only an inner drive that guides the butterfly on a 2,000-mile journey south and west, across the corn belt, the hot, dry plains of Oklahoma and Texas, across the Rio Grande, and over the mountains of Mexico to a place it has never been before—the Monarch Butterfly Biosphere Reserve west of Mexico City—where it will spend the winter in hibernation.  

There are Monarchs all across the United States and the southern tier of Canada and biologists split them into two populations. The western population winters in southern California and spreads out across the west coast and the Great Basin in the summer. But the eastern population—those butterflies east of the Rocky Mountains—return to Mexico in the fall in one of the most astonishing natural phenomena on this planet. Other butterflies migrate—both north in the spring and south in the fall—but the Monarch’s journey is unique because of the distance and the entire population somehow finds its way to one location in the mountains of Mexico after being spread out across half of North America. 

 

Reason for Alarm

This eastern migratory population is in jeopardy, however. The Monarch’s population is in trouble, caught in the crossfire of changing land use and habitat loss, drought in the southern plains, dangerous pesticides, and extreme storms. In the early 1990s, the eastern population of the Monarch was estimated at more than 500 million individuals. By 2014, that number had fallen to about 34 million. The population has rebounded somewhat since then—to an estimated 56 million in 2015, according to Chip Taylor, the director of Monarch Watch at the University of Kansas.

Even though the numbers have perked up, there is still much reason for concern. A 2016 study of this population by the Scripps Institution of Oceanography at the University of California at San Diego and the U.S. Geological Survey concluded that it could go extinct sometime in the next two decades. In fact, the eastern Monarch population decline has become such a concern that in 2014 President Barack Obama issued an executive order to create the National Pollinator Task Force to develop an action plan to save declining populations of honeybees and restore the eastern Monarchs to about 225 million. 

The Monarch’s population crash has increased the importance of sanctuaries like the Goose Creek Grasslands. This 70-acre sanctuary is just a postage stamp on a landscape dominated by agriculture, but it has everything a Monarch needs: flowering plants that provide nectar and plentiful milkweed, which is the only food source for Monarch larvae. This place also has sanctuary manager Rachel Maranto and many generous volunteers who work hard to remove glossy buckthorn, an invasive plant that would grow property line-to-property line and quickly dominate the entire landscape if not controlled. 

The on-the-ground work at the Goose Creek Grasslands is representative of the commitment the Michigan Nature Association has made to the Monarch. MNA has been working with the Michigan Department of Natural Resources and other government agencies, non-profits, and citizens to promote the health of the Monarch by promoting the planting of additional nectar plants and milkweeds.

Nectar gardens are particularly important for the Monarch’s fall migratory generation. Weight gained by those butterflies during migration will have to sustain them because they won’t eat anything until they come out of hibernation in March, says Cora Lund Preston, a communications specialist with the Monarch Joint Venture, a Minnesota-based partnership of more than 60 organizations.

There’s one more thing unique to this fall migratory generation: for their entire migration and hibernation, they are locked in a juvenile state called “diapause,” which makes them unable to breed. Always synchronized to the milkweed, they only become adults and breed after they emerge from hibernation in March as milkweed plants sprout in Mexico and Texas. 

But all that is months ahead for this Monarch. It’s a sunny September day, and the Monarch is torn whether to leave Goose Creek. Michigan is a pretty good place for a Monarch in any generation, says Stephen Malcolm, a professor of chemical biology at Western Michigan University. The landscapes of states to the south and southwest—Ohio, Indiana, Illinois, and Iowa—are a vast monoculture of corn and soybeans that provide very little in the way of food or places to breed.  Michigan’s less agriculturally intense and more complex environmental matrix is good for Monarchs because it provides more places for milkweed and nectar plants to grow. In addition, the moderating impact of the Great Lakes limits temperature extremes. 

monarchs at Fred Dye by Adrienne Bozic

Monarch butterflies at MNA’s Fred Dye Nature Sanctuary in Mackinac County. Photo by Adrienne Bozic.

Despite those luxuries, migratory restlessness is too much to overcome and this Monarch lifts off from a goldenrod, to start a perilous journey. This trip would be dangerous for any animal let alone one that weighs only about a half a gram—a hundred times as heavy as a grain of sand. There are predators and the risk of being struck by a speeding vehicle or being caught in an early frost. 

 

Near Impossible Challenge

Like other Monarchs traveling across the Midwest, this butterfly’s first challenge is finding food on a vast landscape of corn and soybeans. Often there are flowering plants growing along rural roads—New England aster, stiff goldenrod, black-eyed Susan—but there’s also danger here. If the plants are near an agricultural field there’s a chance they have been contaminated with neonicotinoids or some other insecticide. 

Neonicotinoids are considered harmless to humans in small amounts, but to insects like butterflies and honeybees they are deadly. The pesticide is systemic, which means it reaches into all parts of the plant and kills any insect that comes in contact with any portion of the plant. Many of the corn and soybean seeds planted across the Midwest are treated with neonicotinoids, and the insecticide is absorbed as the plant germinates and grows. Other neonicotinoids are sprayed on plants or are included in irrigation water, which unfortunately allows them to spread to nearby non-agricultural plants. For a pollinator like a honeybee, even a minute amount is lethal.

For the Monarch, however, the impact of neonicontinoids will be fully felt when a new generation arrives back in the Midwest the following spring. A 2015 U.S. Department of Agriculture study showed that even if milkweeds are not treated directly, they can contain neonicotinoid compounds in levels high enough to be fatal to Monarch caterpillars if they grow near treated agriculture. (You may very well have a neonicotinoid compound in your house even if you pride yourself on not using pesticides on your garden. Have a dog or cat? If it wears a flea or tick collar, it likely has a neonicotinoid as an active ingredient.)

California monarch - Wendy Caldwell, Monarch Joint Venture

Mountains west of Mexico City are the winter refuge for most of the monarch butterflies in North America. Photo by Wendy Caldwell, Monarch Joint Venture.

As the Monarch approaches the Rio Grande, it and other migrating Monarchs from across the eastern United States funnel into a narrow corridor that parallels the Gulf of Mexico. There are two dangers here: drought and tropical storms. A four-year drought in this area earlier this decade took a severe toll, as Monarchs were unable to find food as they traveled through the area. In 2011 alone, 97% of Texas was in drought with 88% of the state experiencing severe drought. 

Mexico - monarchs on trees - Wendy Caldwell

After migrating from the United States and Canada, monarch butterflies spend the winter in oyamel firs at a few mountain forests in Mexico. Photo by Wendy Caldwell, Monarch Joint Venture.

That drought also had an impact for three straight springs: Monarchs emerging from hibernation in March went north expecting to find young milkweed plants growing so they could breed and lay eggs and for three straight years there were almost none. A wet spring in Texas in 2015 gave the migrants a bumper crop of milkweed, and the Monarch population responded accordingly. 

And then there is the danger of running headlong into a tropical storm entering Texas or northern Mexico from the Gulf of Mexico. Biologists say it’s common for Monarchs to survive the heavy rains and high winds by burying themselves in leaf litter, hiding under rocks, or taking shelter in a hollow part of a tree. 

Ten weeks after it left Goose Creek, this Monarch has made it safely to the Monarch Butterfly Biosphere Reserve in central Mexico. Technically this reserve is a tropical resort—only about 19 degrees north of the Equator—but at nearly two miles above sea level, the area has a unique microclimate and winter temperatures range between 32 and 60 degrees Fahrenheit. The butterflies cluster together on the branches of evergreen trees to keep warm.

But this clustering—the entire population in less than 50,000 acres—makes the Monarchs vulnerable. A storm in early March 2016 brought cold temperatures and high winds that knocked down about 133 acres of trees and killed an estimated 6.2 million butterflies. 

 

A Cycle Worth Saving

In March, the sun climbs higher overhead, the thin mountain air begins to warm and millions of Monarchs emerge from hibernation and search for food. No longer in diapause, they now also search for mates and milkweed plants to lay their eggs and continue the butterfly’s lifecycle. 

There will be as many as five generations during the year as the Monarch again spreads out across eastern North America, reaching Michigan and the Goose Creek Sanctuary in early May. 

And on a late summer day, with the milkweed in decline at a sanctuary in southern Michigan, a Monarch will emerge from its chrysalis, with an urge to do only one thing. 

monarch on a goldenrod - Wendy Caldwell, Monarch Joint Venture

A monarch butterfly rests on goldenrod before continuing toward its migration destination. Photo by Wendy Caldwell, Monarch Joint Venture. 

William Rapai is the author of two Michigan Notable Books: The Kirtland’s Warbler (University of Michigan Press) and Lake Invaders (Wayne State University Press). He is also the president of Grosse Pointe Audubon and has a milkweed/pollinator garden in his front yard.

Estivant Pines: A Living Museum

The Estivant Pines Nature Sanctuary, protecting the largest remaining stand of old growth white pines in Michigan, celebrates its 45th anniversary.

By William Rapai

Time passes slowly at Estivant Pines.

Nobody knows that better than Gary Willis, a forester with the Michigan Department of Bertha and groupNatural Resources and former assistant professor at Michigan Technological University. Willis knows this place better than most people. When you see this preserve through his eyes you begin to understand that the best way to truly appreciate this place is not to consider time in hours, years, and decades but in centuries, periods and eras.

Estivant Pines is the Michigan Nature Association’s 510 acre sanctuary in the Keweenaw Peninsula. Despite its remote location—down a pothole-strewn dirt road south of Copper Harbor—it is one of the organization’s most popular sanctuaries. Every summer, thousands of people from across the United States visit, wandering two looping trails to marvel at white pine trees that stand 120 feet tall.

But there aren’t many visitors to Estivant Pines in the late winter or early spring because the road that leads to the sanctuary is usually under several feet of snow or too muddy to be drivable. However, the period after snowmelt and before trees emerge from dormancy is the best time to see and understand time’s impact by looking down—not up—and closely examining what is and isn’t here.

What is here is volcanic bedrock that dates back to the earliest period of Earth’s history and carbonized tree stumps that are the remains of a cataclysmic forest fire more than 200 years ago. What isn’t here is surprising and confounding. The plant life in the understory is healthy—lots of lichens, mosses, ferns, maples, birches, cedars, spruces, and balsams. Surprisingly, there are few young white pines even though these 240-300 year-old trees have produced millions of viable seeds during their lifetimes.

img 1198Willis gained these insights when he was a forester for the Michigan Nature Association. In the late 1990s he started working at Estivant Pines at the request of Michigan Nature Association’s founder Bertha Daubendiek. Willis was given a unique opportunity to study these ancient trees after a logger accidentally trespassed on the sanctuary and cut a number of the trees along one of the boundaries.

Daubendiek sent Willis out to write a damage report, but during the process he started to see this incident as a unique opportunity to study how these giant trees grew. As he measured the width of the stumps and correlated individual ring-widths he began to understand these trees through the prism of time.

But it’s not just the trees that are measured in time. Much of this sanctuary sits on a high ridge of volcanic bedrock that runs between Annie Creek and the Montreal River that dates back to the earliest period of Earth’s history, some 1.1 billion years ago. In fact, Willis said, other researchers at Michigan Tech have discovered the Keweenaw was once one of the most active volcanic regions on Earth.

It’s difficult to see it from the landscape level, but Willis says if you look at an aerial photo of the peninsula, you can see a series of ridges left behind from that volcanic flow. Those ridges run parallel to the shoreline and curve as the shoreline curves and narrows as it reaches the tip of the Keweenaw Peninsula.

Even though we tend to think of these trees as old, the plant community here is in its infancy, relatively speaking. Plants—trees, shrubs and grasses—established themselves only about 10,000 years ago following the withdrawal of the Wisconsin Glacier.

Tree roots - Brittany AllenMultiple glaciers over the past 2.5 million years left behind a thin layer of soil that can support plant life but generally is not deep enough to anchor a 100-foot-tall tree. To compensate for the lack of soil, most of the pines have grown roots deep into fractures and crevices in the bedrock. Some trees have been lost to windstorms but remarkably few considering that the sanctuary sits at an altitude that varies between 200 and 500 feet above lake level. That altitude leaves these trees exposed to powerful winter winds that blow across Lake Superior. In the winter, this sanctuary can get more than 275 inches of snow in a single season. The combination of heavy, wet snow and strong wind can bring even the hardiest tree down, says Donald Dickmann, professor emeritus of silviculture and physiological ecology at Michigan State University and co-author of The Forests of Michigan. Fortunately, most of the snow that blankets the Keweenaw’s rocky ridges is light and fluffy lake effect powder.

Summer brings heavy thunderstorms and gusty winds, and the trees, which tower above the hardwood canopy, are sitting ducks for lightning strikes. One of those lightning strikes more than 200 years ago might have been the spark for a fire that ravaged this area and set the stage for the Estivant Pines as we see them today.

Those carbonized tree stumps and little bits of charcoal strewn across the landscape point to a potent wildfire that swept through the area in the late 1700’s. Willis said it likely wiped out most of the white pines that had been standing on that spot perhaps for centuries. Just as the towering, mature pines today prevent the young pines from growing underneath, those earlier pines prevented any new ones from growing beneath them. It’s not that these trees are refusing to reproduce; it’s just their reproductive strategy. Barring a major fire, disease or insect threats, these pines could be here for another 300 years before they reach the end of their natural lifecycle. As that happens, the maples, birches, spruces, and balsams that make up the understory will continue to grow and mature and create a thick new canopy 50 feet or more under the tops of the pines. As those trees mature and die, fuel for a future fire will continue to build up on the forest floor, waiting for a spark.Marianne Glosenger - Estivant Pines NO WATERMARK hi res

When that fire eventually arrives, the pines’ continued existence will depend on its intensity. A moderate fire may not cause any damage because the old trees are protected by a thick layer of bark. But if the fire is intense enough the heat will fry the layer under the bark that transports water and nutrients up the trunk. That will kill the tree even if the fire does not reach the top branches. If that happens, the tree, knowing that it will soon die, will put all its energy into seed production. The year following the fire, massive amounts of seeds will cover the now-bare, ash-covered soil and thousands of new white pine trees will germinate if there is enough rain.

And the cycle will begin again.

Ancient white pine trees like the Estivant Pines once covered a good portion of Michigan. loggingIn the late 19th century, lumberjacks cut these trees to supply wood for houses, barns, and carriages needed by a fast-growing nation. At the time, it was thought that Michigan had an inexhaustible supply of white pine.

Only a few stands of virgin white escaped the lumberjack’s gluttony—this one, of course, one at Hartwick Pines State Park northeast of Grayling, and another stand on private property east of L’Anse are the three best known. But Don Dickmann of Michigan State says he has found small stands of them in other places in the Upper Peninsula. Those stands, like Estivant Pines, were spared through random chance and, more recently, the passion of local citizens who wanted to preserve these trees for what they represent.

nancy leonard - epines make a difference dayTwo people who have come to deeply appreciate the history represented by these pines are Bill and Nancy Leonard, who organize volunteers and stewards for the Michigan Nature Association in the Keweenaw Peninsula. They work closely with sanctuary stewards Ted and Alice Soldan to maintain the boardwalks and trails. Bill Leonard said that as he’s working he enjoys talking with visitors and is always amazed by how many people from faraway places around the country come to see these giants multiple times.

“It just pulls people back,” Leonard said.

Indeed it does. But those visitors? For now, it seems, they can take their time.

 

William Rapai is the author of three Michigan Notable Books including The Kirtland’s Warbler (University of Michigan Press) and Lake Invaders (Wayne State University Press). He is also the president of Grosse Pointe Audubon.

As seen in the feature story in the Winter 2018 issue of the Michigan Nature magazine.

From The Archives: Wilcox-Warnes Nature Sanctuary

Prior to the publication of Michigan Nature magazine, MNA sent out quarterly newsletters to members and supporters. We will be taking a look at some of the newsletter’s feature stories in our new From the Archives series. 

Every Sanctuary Has a Story: Wilcox-Warnes Nature Sanctuary

by Katherine Hollins, Regional Stewardship Organizer

Published in the July 2011 edition of the MNA newsletter

Harol Warnes

Harold Warnes

The Anna Wilcox and Harold Warnes Memorial Nature Sanctuary is a wooded oasis amidst the suburban jungle and open agriculture in Macomb County. In addition to providing important habitat for various flora and fauna, the sanctuary serves as a wonderful spot for people to take their families out for recreation or for nature enthusiasts to study species amidst the hustle and bustle of Shelby Township.

The sanctuary was originally part of an 1833 land grant from President Andrew Jackson. It never left the possession of the Wilcox and Warnes families before being donated to the MNA in 1975 by Harold Warnes. Historically, the southern two-thirds of this 44.8 acre sanctuary were never grazed and only faced selective logging. The northern portion was last farmed in 1957, and now serves as a perfect example of a successional forest. As you walk the trails, you will notice the young forest, thick with undergrowth, gives way to a more open, mature forest to the south.

“It’s an exceptionally special place,” says Kurt Jung, an MNA Trustee and nature enthusiast. After he attended a recent Wilcox-Warnes volunteer day, Kurt encourages everyone to walk through the old woods of Wilcox-Warnes “with its commanding oak and tulip trees and quiet stream.”

Margaret Moran, long-time steward of the sanctuary, fondly remembers spending time there over the past decades. “The trees are gorgeous there, and I am thrilled with the birds. I once watched a turkey vulture stalk around picking up sticks and saw a great horned owl on a nest. I especially enjoy listening for the ethereal song of the wood thrush,” she says. “I hope those things will last in the sanctuary as they last in my memory.”

Fall colors at Wilcox-Warnes. Photo by Jeff Ganley.

Fall colors at Wilcox-Warnes. Photo by Jeff Ganley.

Without Harold Warnes’ generous land donation, MNA may never have acquired a sanctuary in Macomb County.

And although the stately tulip poplars may first draw your attention, keep an eye out for American beech, red maple, white ash, various oaks, basswood, yellow birch, black cherry, shagbark hickory, sassafras, pin cherry, prickly ash, spicebush, serviceberry and flowering dogwood trees and saplings. Spring wildflowers including trillium, dwarf ginseng, foamflower, hepatica, may-apple, and showy orchis can also be found here, along with fringed and bottle gentians later in the year.

You can spend time here searching for frogs and salamanders that make their homes in the vernal pools throughout the sanctuary, or study creek ecology and rest near our excellent bridge. As our Trustees, stewards, staff and members urge, please come out to learn about this lovely forest sanctuary and the communities it supports.

For a schedule of upcoming events, visit the MNA website.