Whither the Migration of Monarch Butterflies?

Though the number of butterflies in general was radically down this summer, I still saw the occasional monarch. Some appeared frantic. Were they searching in vain for a mate? Other times they'd pause on a flower to take a long drink of nectar. Sometimes I'd just see a flash of orange out of the corner of my eye. No other butterfly can match a monarch's nimble power in flight. The number of sightings, maybe ten in all, wasn't much changed from previous years.

Their longterm prospects, though, are very much in question. Chip Taylor, who has tracked migrations as closely and for as long as anyone, says that monarchs as a species will survive, but their fabulous migration will not. Last year's overwintering numbers on Oyamel fir trees in the mountains of Mexico was the second lowest ever recorded. Resilient as the monarchs are, it's hard to imagine the delicate dynamic of migration surviving the rapidly increasing disruptions of climate change.

Yes, climate has changed in the past. It's said that, before humans started altering the atmosphere, the earth experienced a progression of ice ages every 100,000 years or so. During the last ice age, glaciers extended south almost to what is now NY City. What we have now is much faster change, as our machines pour a massive overdose of carbon dioxide into the atmosphere.

In a blog entry this past August, Taylor explained how extremes of weather can affect the monarchs' capacity to build numbers over the summer and migrate back to Mexico in the fall. Extended heavy rains in early summer can delay egg laying. Warmer temperatures in September and drought in October can impede a fall migration historically aided by cool winds out of the north. What we got this year was hot and dry, with three months of drought and warm weather extending into mid-November. That's a radical departure from anything I've ever witnessed.

Each year towards the end of October, I start looking for news about the migration south to Mexico. The first headline I found confirmed my suspicions: "This fall's monarch butterfly migration through Texas doesn't look promising." Then, finally, a report on-site at the roosting grounds in Mexico. Though a few had been straggling in over the past few weeks, the first largish group of 2000 monarchs wasn't reported until Nov. 21. In past years, monarchs would predictably arrive en masse in the first week of November. Then, after the monarchs had settled into their roosts, the Biosphere Reserve would be opened to tourists mid-month. This year that opening was cancelled, stranding those tourists who had traveled far to witness a unique example of nature's splendor. This is not the only destination being compromised in a world being heated in part by global tourism. There are different ways to show love for nature. Touristic love, which I was a part of in the past, becomes more ironic by the minute.

The radically dry, warm weather we've experience this fall has a lot to do with the increasing instability of the jet stream--high winds out of the west that normally feed us a steady stream of contrasting weather, but can get blocked and diverted north or south, causing weather systems to linger indefinitely. The jet stream is driven by the difference in temperature between the tropics and the arctic. As the arctic heats more quickly than lower latitudes, the temperature gradient is reduced and the jet stream becomes more malleable. 

Consider the extraordinary ambition and brilliance of the monarch butterfly's eastern migration. Huddled overwinter in the mountains of Mexico, its numbers head north in March, then each succeeding generation--usually four total--fans out from Texas to harvest the richness of flowers and milkweed foliage from the whole eastern half of the U.S. and even up into Canada, before somehow knowing how to navigate all of that embodied richness back to their little hideout in Mexico. Over the past million years, the distance flown would have contracted during ice ages, then expanded as the glaciers withdrew. I think of the monarch migration as akin to a rubber band, stretched northward by the supply of nectar and milkweed, then contracting back down to Mexico for the winter.

The vast territorial expansion each summer is surely dependent on numbers. Otherwise, how will the monarchs find each other to mate as they spread out across the continent? Though much different in behavior, the passenger pigeon was also dependent on big numbers. Its demise, more than a century ago, was due to radical habitat change and a wanton harvest and slaughter that Aldo Leopold described as "trigger-itch." Now, our itch is to take photos, and our intention is to preserve. And yet, we watch as the collateral damage of a machine-driven economy accumulates.

A post on the Monarch Watch Blog describes the Symbolic Monarch Migration that school kids in Mexico, the U.S., and Canada take part in. Kids in Mexico send paper monarchs to kids up north in the spring, and vice versa in the fall. Monarchs ignore country boundaries. They are telling anyone who takes time to listen that our interests don't stop at the border, what we do affects people and nature far away. 

One halcyon autumn day when I was a kid, walking across the broad lawns surrounding Yerkes Observatory in Wisconsin, I was astonished by the sight of countless thousands of monarchs flying above me. There was a thrilling collective energy to their flight, not dutifully unidirectional towards the south but instead more like a dance. They seemed to feed off of each other's proximity and energy--an uncanny mix of whimsy, skill, and determination. 

If the great migration were to be lost, monarchs would still persist in pockets further south. Here's a post on how the loss of migration's rigors would change them.

Still Here--A Late Fall Walk in a Desiccated Forest

On a Sunday morning in November, sipping coffee and socializing at May's Cafe in the Botanical Art Garden, 

a couple of us got to thinking: "Wouldn't it be a nice day for a nature walk in Herrontown Woods?" 

As we thought upon that thought, other thoughts sought to intrude. We are a merry crew--by habit, it would seem--finding some buoyancy even as beneath the usual merriment there has grown a deepening trepidation. The world is being rocked by disruption--politically, biologically, climatologically. These November days are discomfortingly comfortable, the woods are bone dry, the trees aching from drought. What will spring be like after a fall like this? In a world where disruption reaches into every nook and cranny, the very concept of refuge is under siege. We thought and thought, and thought some more until the answer finally came. Yes, we decided, a walk in the woods might be just what we need.

And so we set off, leaves crisp beneath our feet, down the red trail, then followed the silent cascade along the yellow. What to talk about? Beech leaf disease? Oh dear. I spoke of the color-coded forest--that special time in the fall when colors change and each species announces itself with its distinctive color. Gaze around and grasp all at once from the reds and yellows, burgundies and browns, the species that inhabit that valley. Many of the colors were made pale by drought. Some trees and shrubs had simply dropped their shriveled leaves, short circuiting the color change, but still some colors showed. 

At the second stream crossing, it occurred to me: there might actually be flowers in this desiccated forest. Native witch hazel blooms in late fall, unlike asian varieties that bloom in early spring. And yes, just off the trail, there it was, not just a sprig here and there, but a whole grove of witch hazel, massed larger than I'd ever seen or noticed, holding their countless flowers high.

One in our group, Jill Weiner, took this closeup of the curiously shaped and curiously timed blooms.

We hiked up to the cliff, to gaze out across the valley and scrutinize some interesting leaves. A white oak leaf had tiny holes--a sign of one of the hundreds of insect species that find sustenance in native oaks.

Looking out from the cliff, I saw a bright splotch of yellow, and headed down to have a look. It was a tree, though not much larger than a shrub. By the leaf shape and size, it appeared to be an American elm, a species whose grandeur I had witnessed in my youth, before it was laid low by an introduced disease. "Still here," it seemed to say. After all this, and all that, still here.

Cliff photo by Jill Weiner.

Native Fall Color and Berries in Herrontown Woods

One vision being gradually realized at Herrontown Woods through the power of incrementalism is the transformation of the long boardwalk into a native plant corridor that will be especially attractive in spring and fall. The boardwalk, given the V-ful nickname of Voulevarde because it was built by chainsaw virtuoso Victorino and leads from the main parking lot up to Veblen House, was intentionally routed past some mature examples of native shrubs.

Arrowwood Viburnum has toothed leaves (thus the latin name Viburnum dentatum) and can turn a brilliant reddish color in fall. 

We're managing the corridor for an open woodland, so that enough sunlight can reach the understory to power abundant berry making by the native shrubs. The many Blackhaw Viburnums, named after their black berries ("haw" means berry, as in hawthorn), are a dramatic example. 

The preserve's largest winterberry shrub--a holly called Ilex verticillata--greets you along a bend in the Voulevarde with abundant red berries this time of year.  

One of the preserve's large highbush blueberry bushes--they tend to be loners persisting here and there in the preserve--also grows along the route, with bright orange fall color.

The largest native swamp rose (Rosa palustris) in the preserve is also near the trail, its single pink flowers emanating a heavenly fragrance on hot summer days. Its rose hips are bigger than those of the nonnative multiflora rose. While the invasive multiflora rose is ubiquitous in the preserve, there are only two native swamp roses found thus far across 150 acres, mostly because the swamp rose needs more consistently wet conditions to compete. We've started planting more of them, in wet spots that get some sun, to see if we can increase their numbers over time. Again, the battle cry: "Incrementalism!"

Beyond the boardwalk, up towards Veblen House, is a good example of a rare native shrub, variously called Hearts a' Bustin' or strawberry bush. The deer love it so much that we needed to cage it until it was tall enough to escape their browsing. Located in a partial forest clearing, it receives enough sun to develop abundant berries.

In the fall, its leaves turn white. Hearts a' Bustin' is a native euonymus (Euonymus americanus), rarely seen due to deer browsing, while the nonnative euonymus, burning bush, is ubiquitous in the preserve and largely shunned by the deer. Notice a recurring story?

Up at the horserun near Veblen House, these look like shrubs or small trees, their fall color backlit by late afternoon sun. They are in fact trumpet vines growing on some sort of structure placed there decades ago. 

A different angle shows the trumpet vine with the bright red of Virginia creeper in the foreground. Both are native vines that can be a little aggressive, but sufficient shade deprives them of the energy to be obnoxious, allowing us to enjoy their best traits without any need to keep them in line.

Virginia creeper has five leaflets to poison ivy's three. These leaves look like they've donated some of themselves to the insect world. 

The boulders in Herrontown Woods, bedecked by mosses and lichens, are reminiscent of whales whose gray skin has collected barnacles. Sweetgum leaves are particularly creative and varied with their fall color.

Also generous with fall color is the native winged sumac, which has started to pop up in areas where we remove invasives. They seem to be part of the soil's memory of past eras when the forest was younger, before the canopy closed and shrouded the ground in deep shade. 

Another source of beauty, noticed while removing dead ash trees near the Veblen House driveway, is the combination of the old evergreen cedar trees with the deep burgundy of young white oaks rising to ultimately fill the space left by the ash.

The loss of ash trees to the emerald ash borer is a profound tragedy, but if we can take advantage of the new openings in the canopy to reawaken a diversity of native shrubs and trees, there is at least some recompense.