Four Wings and a Prayer (17 page)

“Don’t you have these at home?” she asked as I took a seat beside her and we watched the white monarch chase an orange out to sea, and seemed pleased for herself and sorry for me when I told her we did not. A gust of wind came off the ocean, lobbing the white monarch shoreward, and it lay for a long time in the grass.

The woman told me bits of her story—worked at the flower shop at the Mauna Kea Beach Hotel, used to live up in Volcanoes, raised potatoes, was a retired lei maker. She wanted to feed me, to give me things, to show me pictures, to explain things about natural history. “The monarchs like crown flower because it is syrupy,” she said. “Doesn’t matter if caterpillars eat my plants. They need food, too.” She wanted to know about me, too, who just wandered into her yard the way a butterfly might, blown in with the wind.

And then there was nothing to say, so we sat there watching the white monarch going nowhere and the ocean chasing some surfers back to the beach. What is passion? I asked myself again. It is the collapse of space between two or more
bodies, I decided as the woman’s face drew close to my own. It is strangers meeting in trust because, though their physical histories are unknown to each other, they are connected by what moves them. It is a cliché to talk about love that binds, but love does bind, and that is why passion, especially passion for a thing, is a way of knowing that comes before epistemology.

“My nephew will continue to feed the insects when I am gone,” the woman said at last, answering a question that had not been uttered. No; answering a question that had not been uttered out loud.

Chapter 7

F
EBRUARY CAME
, and March, and instead of slinking away, winter socked into the mountains like a thick fog. It snowed on March 14, a heavy, wet snow that clotted the roads, making them impassable. When the sun came out we put on skis greased with blue wax and flew through the woods as if those skis were wings. Up one hill, down another, stomach to follow, while the chickadees and goldfinches, their feathers mottled as if, having dressed for one season, they were now deciding better of it, moved overhead, no more graceful than we were.

The air was still frigid, topping off at freezing most days, and thoughts of the tropics and of tropical butterflies were overwhelmed by the drifts of snow hugging the kitchen windows and the prowl of sanding trucks moving slowly across the frozen pavement. Ice still lay across our pond, a big, un-breachable
pane of it, and on sunny days it was possible to look through it like glass and see last summer’s weeds and misthrown tennis balls and other lost treasures.

It was disconcerting to tune in to Monarch Watch and hear Chip Taylor exclaim about spring and the impending breakup of the Mexican colonies. From where I sat, it was neither warm enough nor green enough to imagine butterflies’ being able to head north. If there was a human equivalent of the switch that turned off diapause, enabling one’s imagination to range beyond the present, mine was disengaged.

Throughout the winter, as the butterflies huddled under the canopy of oyamel trees and the traffic on D-Plex slowed, I kept track of another migrant crisscrossing the Mexican border with the regularity of a commuter. By my count, Bill Calvert had been back to Mexico four times since I said good-bye to him in Contepec the previous November. Now here he was again, as the snow was flying in the Adirondacks, writing from Mexico that the spring exodus from El Rosario had begun.

“The monarchs again put on a sterling performance last week!” he reported on March 16. “During our last day in the area, we witnessed a massive flow of tens of thousands of butterflies flying out of the colony down across a pasture. All of the butterflies within three meters of the ground were flying in the same direction, giving the impression of a massive sheet of orange-and-black-colored creatures streaming slowly downward. At the middle of the pasture there was a seep of water. Thousands of monarchs were at the seep drinking water from the water-soaked mud and from open pools, but the majority were flying on past the seep. Above three meters fewer butterflies
were flying in the opposite direction back toward the colony.

“This colony was the Rosario ‘bud colony.’ It was the lower part of the Rosario colony that had budded off from the main colony, which occupied a site in the same drainage, but at a higher elevation. Each day more butterflies left the upper (original) colony and joined the bud colony. At this point in time (March 11), it was hard to tell whether the bud colony or the main colony had more butterflies. The bud colony was stopped from descending to even lower elevations by fields and pastures that came all the way up to three thousand meters’ elevation. Monarch colonies always descend the mountain during the course of the [winter], accelerating during late February and March when the combination of intense sunshine and lack of clouds and moisture in the air warms up the ambient considerably. The descent is almost always associated with a particular arroyo or drainage.

“At Rosario they usually follow the drainage called Arroyo Los Conejos. However, this year they used another drainage about 1.5 kilometers to the northwest of Los Conejos, called the Rio Grande by the locals. When we were there (well into the dry season), there was only a little water flowing in it.

“The lack of forest at the field edge did not stop them entirely, however. During the day butterflies poured out of the bud colony and over the ridge at the little community, La Salud, toward Angangueo. These butterflies are undoubtedly part of the return migration to the United States and Canada. Each day tens of thousands pass through the town of Angangueo. They are all going in the same direction—northward. Back toward Rosario, many thousands are taking nectar from
flowering plants, especially eupatorium and senecio along the road to Angangueo. Many of these do not return to the bud colony mentioned above. Instead they bud again, forming smaller aggregations in remnant pieces of woods along the Angangueo-Rosario road. These small remnants of woodland may be very important to them in offering nighttime shelter from cold and predators.”

C
ALVERT’S MESSAGE APPEARED
not on D-Plex but on Journey North, an educational Internet site dedicated to tracking the northward progress of a number of spring migrants, monarch butterflies included. Every week from the end of winter to the beginning of summer, migration updates were posted and maps drawn. Texas, Louisiana, Missouri, Kansas, Illinois, Ohio: it was like a national wave cheer as the monarchs swept through.

The butterflies were dispersing across a wide swath of the country. This was one of the main characteristics of the spring migration. Having come from that wide swath and then funneled into Mexico in the fall, the butterflies simply went out of it in reverse, leaving together through the narrow channel of the funnel, then scattering into the big wide world. We tend to think of a migration as a movement from one place to another—from Ontario, say, to Michoacán. The spring migration, from a few very concentrated places in the south to the entire eastern segment of the United States and parts of Canada, seemed less that than a random dispersal. Still, the monarchs were shifting habitats to take advantage of abundant food and places to lay eggs as spring and summer moved north through the flora—the very definition of migration.
Meanwhile, milkweed, though not migratory, was doing a wave cheer of its own, reborn at higher and higher latitudes as the soil heated up, and the air warmed, and daylight limbered, stretching, stretching, and stretching some more.

J
UST AS THE
fall migration had captured the imagination of scientists and citizens for the better part of a century, maybe more, the spring movement of monarch butterflies had also piqued their curiosity. Once the Urquharts found the Mexican overwintering grounds, they began tagging butterflies there, hoping to recapture them once the colonies had broken up. The assumption was that the butterflies went north; a recaptured monarch would be good evidence to support that hypothesis. But it was one thing to demonstrate that monarchs from the United States and Canada spent the cold months in the Mexican mountains, and quite another to say that the monarch butterflies that had wintered in Mexico spent the spring and summer in North America. It was a third thing altogether to say—to demonstrate—that the butterflies that made the trip south in October were the very same ones that flew north in March. That would mean that those butterflies were living for six and seven months or more. It would mean either that they were recolonizing the entire northern range, moving up the latitudes like a ladder, breeding and laying eggs as they went, or that they were going part of the way, breeding, and then dying. In that case no individual monarch would make the entire round trip. In that case forget bird migration—the comparison would no longer be apt.

How did the spring leg of the migration work? Back in
the nineteenth century, when Charles Riley, the Missouri state entomologist, was pondering the destination of the swarms of monarchs he was seeing each fall, another question was on his mind as well. Riley supposed that the butterflies were heading south, like birds, but then what? Worn, tattered monarchs had been found each spring in the southern United States, but they had merely raised more questions than they answered. Who could know where those butterflies had come from, and when? Even tagging data, when they were later obtained, were inconclusive. How could it be proved that a monarch butterfly tagged in Minnesota in September and found seven months later in Texas, for example, had spent the winter in the Mexican highlands, unless it was recaptured there as well? And the chance of that happening, statistically speaking, was nil.

Enter—again—Lincoln Brower. While his sometime rival Fred Urquhart was occupied with his tagging project, Professor Brower was in his laboratory at Amherst, continuing the work on chemical defense in monarchs that he had begun as a graduate student at Yale. There he had shown that monarch butterflies were distasteful to birds because of the toxicity of the milkweed they ingested as caterpillars. Now he and his colleagues turned that conclusion on its side and examined it from a different perspective. Since the monarchs stored the toxins—the cardenolides—in their bodies, and since different species of milkweed had different and specific concentrations of the cardenolides, Brower and his colleagues surmised that they should be able to determine which plant or plants a butterfly had eaten in its larval stage. And, they reasoned, since the plants were geographically specific, growing exclusively in some places and not in others, knowing which plants it had
eaten as a caterpillar would reveal where that butterfly had come from. They called the process cardenolide fingerprinting. It did have that “the jig is up” quality to it.

To test their hypothesis, Brower and his associates collected fall migrants, butterflies at the Mexican overwintering colonies, springtime monarchs from Texas, and monarchs found in the northern United States in June. As they suspected, the first group, the fall migrants, had fed on
Asclepias syriaca,
the big, broad-leaved, common milkweed that grows north of the thirty-fifth parallel. No surprise there. It was the other groups that told them things they could have only guessed before. While both the winter monarchs and the faded ones found in Texas in the spring showed the
syriaca
pattern, those that had been captured in the North, where
syriaca
was prevalent, had the fingerprint of two southern milkweeds,
viridis
and
humistrata.
To Brower this was “definitive evidence” that the successive-brood theory was right: the migration was a kind of relay race in which fall migrants passed the genetic baton in the spring to offspring whose offspring then continued moving north until they had colonized the entire range and it was time to head south again.

The evolutionary adaptation that had led to this kind of sequential migration had another interesting feature as well.
Viridis
and
humistrata
were both high in cardenolides. The monarchs that carried their fingerprints were extremely toxic to birds, while the ones that carried the
syriaca
pattern were less so. While this might seem to put the generation that left Mexico at risk, it did not. As these monarchs reached the northern tier, their predators had not yet fledged their own young; by the time that occurred, that generation of monarchs
would already have reproduced, and the new generation, born to the southern milkweeds, would take its protection from them.

A
T ABOUT
the same time that Bill Calvert was writing from Angangueo that the spring fling had begun, Chip Taylor, sitting in his office at the University of Kansas, was banging out his own assessment. His was based not on firsthand observation but on what he had learned, over years of sorting through the anecdotal information that came his way, of the monarch’s biological clock. This was the same clock that Lincoln Brower had referred to the previous year when he worried that the monarchs’ departure from the overwintering site two weeks early was a sign not of an overeager butterfly population but of habitat destruction that had served as an eviction notice.