July 28, 2010--Midcoast: Return of the Monarchs

We do not have to look at the calendar to know that August is fast approaching. Yes, the sun is well into its annual journey south, setting across John's Bay each day a degree or two closer to Christmas Cove from its northern-most terminus, the Miles Tower and that signals the last full month of summer. And there is a chill in the air announcing the end of each day as they inexorably shorten. But the surest sign of August is the appearance of the first Monarchs. The most familiar and majestic of North American butterflies.

I was in the garden yesterday morning preparing the ground for a new bayberry when the first Monarch of the season fluttered into view. Wobbly on its new wings, clearly having recently emerged from its chrysalis. Unlike last summer when I did not know that they begin to appear at this time each year and within a few days literally millions of them will assemble in preparation for there immense journey, their migration south where they winter. Monarchs indeed, I have come to realize, as they are large by butterfly standards (with a 4 inch wingspan) and like any other self-respecting monarch they rule a vast realm.

Again, as last year, I watched as my companion haltingly circled the garden in search of the thistle flowers upon which it feeds, tasting their nectar as it stores energy before taking off on a 3,000 mile trip to its winter mating grounds in northwestern Mexico.

I wondered again yesterday what incredible power is possessed by these creatures to ever contemplate such an adventure on such a grand scale on such unsteady wings. A migration that takes them from here in Maine to Mexico, all of which gets accomplished during the two brief months of their lives.

I have learned that the Monarch is the only butterfly that migrates, as birds do, both north and south, on a regular basis. But no single individual makes the entire round trip. Along the route back north each spring female monarchs deposit eggs for the next generation.

Their winter home is in Mexico and consists, amazingly, of only 14 scant acres. And they find their way back and forth without anything approaching a brain the size of migratory birds.

How do they get the job done? What secrets are hidden in the rudimentary ganglia that constitute all the neurological capacity they have to funnel their way to Texas, between the ridges of Mexico’s Transvolcanic Mountains, and then locate that tiny Michoacan grove?

Though we have much knowledge about the inner workings of the atom and the “creation” of the universe, though we may have landed men on the moon and perfected Smart Bombs, about how the Monarch butterflies do their thing, though this has been and continues to be carefully studied, we as yet do not know. It remains one of nature’s enduring mysteries.

Theories abound—some say they have the olfactory capacity to smell the remains of Monarchs that died along the way the previous year—sort of a charnel pathway—but that is controversial since butterfly bodies do not contain the “odiferous fatty acids” that would be required to smell last year's carcasses.

Others claim that they find their way like birds by orienting themselves to the stars, by utilizing the earth’s magnetic field, or by following familiar landmarks on the ground. But this too is disputed since they do not have the brains of birds.

So it must be that they are guided by sunlight, of course, by the direction of the sun as it moves through the angles of the seasons. This is the best theory thus far since Monarchs appear to set out on their migration when the sun in their latitude drops to about 57 degrees above the southern horizon.

Right about now. As the folks across the bay in Christmas Cove know as the sun drops on top of them this time of year.

One thing is clear. With just those very few neurons, well before homo sapiens in the 1700s developed the capacity to measure longitude, the lowly Monarch had that ability. We should have asked them how to do it.

There is a nice coda to this story—because of global warming (that is not the nice part) the season for wildflowers is shifting. This has dangerous implications for the Monarchs since as they travel, like the rest of us, they need to stop on route for nourishment—in their case by pausing to grab some thistle or milkweed. But thanks to development there are less and less of these around, friends of the Monarchs have recruited people along the flight path to plant milkweed patches. Thus far, more than 1,000 have—in private gardens, schoolyards, city parks, and even golf courses.

So as I was about to hack away yesterday at the encroaching thorny thistles, I thought again and let them stand for another season. I suspect I will do the same again next year.