Let’s suppose you are a monarch butterfly flitting around the fields and forests of North Carolina on a hot summer day in late August. What are you likely to get the urge to do? Find some flowers and drink some nectar? Maybe. Hook up with some cute monarch flutterers of the opposite sex? Maybe. How about taking a road trip? A long road trip. Like maybe taking a couple of months to fly over a thousand miles to the mountains of central Mexico where you can spend the winter clutching a tree along with several million other monarchs who have also migrated down from the north? Bingo. In the late summer and early fall, monarchs across the United States start fluttering south on a migration that is simply amazing.
Although I’ve always liked butterflies, I really hadn’t thought much about them since becoming an adult. So I was minding my own business on a hot day in July, reading a Seasonal Guide to the Natural Year: A Month by Month Guide to Natural Events in the Carolinas and Tennessee, by John Rucker. I had noted on page 70, that manatees once were common in the waters at the mouth of the Cape Fear River, and that a few American chestnuts still survive in North Carolina, at page 169. But I wasn’t getting terribly excited until I reached page 228. And there it said that, at Milepost 415.6 of the Blue Ridge Parkway, “[t]housands of monarch butterflies pass through Tunnel Gap in September as they migrate to central Mexico.”” And it said no more. Well, okay. Little, fragile butterflies. Alighting on flowers and opening and shutting their paper thin wings. These guys are winging it from North Carolina to central Mexico? Like over a thousand miles or so? And they are starting off by flying through a 4,325 foot gap in the Appalachian Mountains? Hmmmm. Now that was something I needed to learn more about. And I really felt the need to spend a warm September afternoon sitting in the grass at Tunnel Gap, gazing east toward the North Carolina flatlands. And watching the monarchs flit by me on their long way west, and wishing them Godspeed on their incredible journey. Assuming it was all true, of course.
I had a couple of months until Tunnel Gap would be filled with migrating monarchs, so I had some time to research the matter.
I’d always known that monarchs are those bright orangey-yellow butterflies with black outlines on their wings. They are about 10 centimeters wide and weigh about half a gram. Little things. I knew they flitted about blooming flowers, and I guess I knew they ate nectar from the blooms. But I knew nothing about their travels. For a long time, science didn’t know much more than I.
In the early part of this century, it was thought that the monarch butterflies disappeared from sight in North America in the winter by hiding in hollow trees or other sheltered spots - essentially hibernating. In general, butterflies were not thought to migrate. But some thought that the monarchs might travel to warmer spots to escape the winter’s cold - but no one had ever found their overwintering territory. Then in the early winter of 1974, a volunteer researcher found several battered and beat-up monarchs on the side of a road west of Mexico City. Driving further up into the mountains, the researcher came upon a concentration of millions of monarchs clinging to all exposed parts of a grove of pine, fir and cypress trees. Further research revealed that about 14 million monarchs had gathered in these trees covering only a few acres at an elevation of about 10,000 feet in the Mexican state of Michoacan - about a three hour drive west of Mexico City. This was the long sought after winter home of the monarchs. The entire population of monarch butterflies that would repopulate most of North America in the spring and summer were roosting at this site (and a few other nearby sites). The monarchs would roost there all winter, attached to the trees, without eating, in a state of semi-dormancy. This huge concentration of roosting monarchs is said to be the “greatest butterfly show on earth.”
Sometime in March, as the days grow warmer and longer, the monarchs stir from their winter perch, stretch their wings, and start their journey north. As they travel north, they mate and lay their eggs on milkweed plants - and only on milkweed plants, which are the only thing the newly emerged monarch caterpillars will eat. When these caterpillars turn into monarch butterflies, they will continue the monarchs’ repopulation of their breeding range in North America - for the monarchs that overwintered in Mexico do not usually survive for long after beginning the spring migration. There will be several generations of monarchs in the spring and summer - the average life span of these seasons’ monarchs is about six weeks. But these are the monarchs that will spread throughout the United States and southern Canada, traveling north and east as far as they can go until the milkweed supply ends.
The year’s last generation of monarchs, i.e., those born in the late summer and early fall, are different from those born earlier in the year. These monarchs will have a life span of more than six months and they will not breed until the last month of their lives - in the early spring of the new year. Instead they will heed the shortening daylight and cooler fall weather, and they will turn their backs to the north to fly south (and west) to somehow find there way back to the few forested acres in the mountains of central Mexico - and maybe even to the same tree - where their great-great grandparents spent the previous winter. The complete monarch migration thus requires several generations. No individual monarch butterfly ever actually returns for a second winter in Mexico. But somehow the descendants always know when and where to go to complete their own leg of the migratory path.
How do the monarchs navigate? No one really knows. Do the monarchs follow the same routes during each year’s migration? No one knows for sure but they do use the same overwintering sites year after year. How far can monarchs fly in a day? They probably average forty to sixty miles, although one tagged monarch butterfly was located 265 miles from where it had been released the previous day - monarchs may be able to use air currents at different altitudes to speed them on their way.
I looked for monarchs throughout July, August and the first half of September. I went to various gardens with blooming flowers, at all times of the day. I did not see very many butterflies at all. And I saw only one monarch - dead and its wings crumbling - blown up against the concrete curb at a rest stop on the Interstate. This was not good.
On the Internet I found several monarch web pages with reports of a brutal freeze that had struck the mountains of central Mexico in the previous January. Those who visited the overwintering sites soon after the freeze reported that the ground was littered with dead monarchs, several inches deep. Some estimated that 75% of the monarchs had died. The numbers of monarchs beginning the northward migration in March must have been significantly diminished. One naturalist commented that the best thing local folk can do to help the monarchs recover would be to plant milkweed for their eggs and caterpillars. I don’t even know what milkweed looks like.
Armed with my new-found knowledge of the monarch, by the third week in September I was ready to make the long drive to Tunnel Gap. I picked a warm sunny day and left early. The radio played, Greensboro, Winston-Salem, then Statesville and Morganton rolled by. Up the long hill through Swannanoa Gap, I first saw clouds hanging over Asheville. I accessed the Blue Ridge Parkway near the French Broad River and headed up toward Mt. Pisgah, paralleling the Shut-In Ridge Trail. And the clouds began to close in. I turned on my headlights. Once on top of the ridge line, a steady drizzle began. I was driving through the clouds and at times the visibility was only several car lengths. I passed Milepost 410, then Wagon Road Gap. Then Milepost 415 and soon a sign for Tunnel Gap and the turnout on the left. The rain was misting and the clouds were lowering as I hopped out of the car in mid-September - just the time to part the waves of monarchs that would be riding the breezes up the eastern face of the Blue Ridge to crest Tunnel Gap and continue on their way to Texas and central Mexico. I stood in mid-Gap, facing down the slope, and let the rain mist on my glasses. Nothing moved in the sky. No orange and black wings opened and closed on the trunks of trees or beneath the sheltering leaves of the gap’s vegetation. There were no butterflies.
I did recall from my research that monarchs don’t like to fly in the rain - that they will hold onto trees or bushes until it stops raining. But this was mostly a misting rain, and there ought to be some monarchs in a hurry to get south and so willing to test the weather. So I kept searching the skies - and checking the trees and bushes for monarchs hunkered down, wary of the weather. I did see a sign that confirmed that monarchs did indeed pass through the gap on their way to Mexico. It showed the migration pattern and had a lovely photograph of a monarch. But it was the only monarch I saw at Tunnel Gap. The rain misted, the clouds lowered and I lingered at the gap. Even in the rain it was an engaging spot to look for butterflies. But there were none to be found that day. After a long while, I returned to the car, pointed it back towards the east, and started home. Half way down the parkway, the rain stopped and the clouds lifted. Just past Black Mountain the sun peeked out. It stayed sunny all the way back home.
Later that month, back at home and back on the Internet, I read a report of a monarch sighting on the coast of North Carolina from the previous March. This monarch could not have spent the winter in central Mexico and have made it back to North Carolina by March. There had to be some other explanation. The writers speculated that the monarch may have gotten lost or been blown far off course by bad weather, and had overwintered somewhere along the Carolina or Georgia coast. If the butterfly survived the North American winter, maybe clinging to some pine tree near Charleston, by March it might have been beginning its journey to the north - looking in vain for the monarchs from Mexico who would be ready to travel and mate with it. His or hers would have been a lonely trip though. Even if the Mexican monarchs had recovered from the disastrous freeze earlier in the winter, they would have been many hundred of miles behind, never to catch up to this monarch pioneer.
I hope it was just the weather that kept the monarchs out of Tunnel Gap on the day I went to meet them there. I hope it wasn’t the big freeze or the timbering of their overwintering sites in Mexico that has reduced their numbers so that only a few flutter through the gap. I will return to the gap next September and bring a folding lawn chair and maybe a cooler with some margaritas mixed and chilled. Maybe I’ll try to be there earlier in the day - and of course I will pray for sun and calm air. But first, this spring, I will get me some milkweed to plant in my garden - and, hopefully, I’ll be able to personally observe at least a few monarchs as they head north to repopulate eastern North America before the weather turns cold. Godspeed.
Postscript: In late February of 2003, my eye caught a familiar orange and black image in my morning newspaper; a photograph of a monarch butterfly resting on a milkweed plant. What’s this, I wondered, an obituary notice? I read the headline with bated breath. “Monarch butterflies recover from freeze.” Wow. The article said that scientists were marveling that despite last year’s deadly freeze, which killed hundreds of millions of monarchs, the fir trees of central Mexico were once more covered with monarchs. The survivors from last year’s winter, started north last March and began the repopulation of North America - and apparently 2002’s several generations of monarchs flourished. Several hundred million completed the fall trip back to Mexico - twice as many as the scientists had expected. A remarkable comeback for a remarkable little bug.