After mating, Erebia seeks shelter from a brief shower beneath a handy parasol, the leaf of a Parry’s primrose. Its rose-pink petals glisten with raindrops as Erebia sits snug and dry, his wings folded tight. The urge to fly and seek a partner assuaged for now, he rests as his next spermatophore recharges the costly nutrient package it will bear along with sperms. When the rain lets up, he creeps down a fissure for the night. In the morning he will resume his up and down flights over the rocks, seeking to mate as many times as he can during his lifetime. If he manages to couple with a female already mated, his spermatophore will displace the other, so his genes will be the ones passed on. So there’s no giving up just because he has succeeded once.
Of course, the same fate could befall his own germ cells, left with his first mate. Not for now, however. Since their parting on the morning after their union, she has been unreceptive to further courtship, raising her abdomen high and spreading her wings low whenever approached, until the frustrated males give up. Instead, she hops, flutters, and crawls from tuft of grass to sedge tussock to lump of stone. From time to time she taps a grass blade with her antennae, dips her body’s tip, and deposits a single egg on one surface or another, cementing it into place. More often than not, the chosen substrate is an overhang of rock, where the egg is inconspicuous but never very far from a succulent supply of grass.
Large for a satyr’s egg, more the size of a swallowtail’s, the ovum resembles an oblong vase for a petit point flower. Ribbed and creamy white when laid, it turns tan and purplish brown and in a few hours ripens to silver-gray with a Prussian blue band around the dimple on top. Finally, before hatching, it goes putty-gray against the grayer granite and fading grass. About ten days after the egg is deposited, a thrip-size larva will eat its way out, consume the eggshell, and switch to tender grass. How many times Erebia’s offspring will molt before diving into the grassroots will depend upon how many days remain before the alpine herbage dries out between summer’s last breath and autumn’s first frost.
Of all this, Erebia knows nothing. He has resumed his patrols, sometimes top to bottom and back, other times back and forth in a drunken glide path to the edges of the willow thickets and Boloria bogs below. A Clark’s nutcracker makes a halfhearted pass at the butterfly. Distracted by a checkerspot, it loses both in a classic fox-and-grapes act of indecision. The corvid settles for a fat rock spider instead, thus getting the distilled goodness of ten scree moths, two Magdalenas, four checkerspots, and a tortoiseshell, as well as various flies, caddis flies, and lacewings harvested over the orb weaver’s lifetime.
Erebia hasn’t quite the same vigor as before. Shiny chitin is beginning to show through the sparser scales on the veins of his wings, especially the big, swollen vein at the base of the forewing that sets the satyrs apart from other lineages of butterflies. Still, but for the beak brand applied by the black swift, his wings are entire. Few shrubs grow on the rockslides to tear butterflies’ wings, and nights spent safe among the lockbox of the rocks mean no scratches or tears from branches blowing on the nighttime breeze.
The most obvious sign of Erebia’s aging shows in his coloring; no longer truly black, but a rich coffee-bean brown, he has faded in the harsh ultraviolet rays of the alpine sky. Built and colored for the purpose of gathering sunbeams, those sable vanes nonetheless lose their luster in the performance of that very function.
So Erebia is a little past his prime when he meets a fresh misfortune. During a late passage, he is taken by a sudden gust and carried over the ridge to the steep snowfield that gathers, then melts annually in the lap of the mountain’s other side—a mere ghost of the glacier that carved out this cirque. Only once before has he ventured here, all the way down the north-facing slope to the protalus rampart at its base, but that was a warm day, and he sailed right back up and over to his accustomed home range. Now, as he blows over the snow-bowl, the cold-blooded insect feels its chill. A stiff, sharp shaft of upwelling air clutches him, sucking him down onto the surface of the firn. There his body temperature rapidly drops toward the danger point.
A watcher at the snowfield would notice the surface speckled and spotted with the bodies and wings of grasshoppers, butterflies, and other insects thus entrapped. This strange fallout proves a boon to foraging birds and entomologists. Rosy finches and water pipits alight in the middle of these refrigerated larders for the cold cuts they contain. Ptarmigan, leaving off their accustomed willow buds for the high-protein opportunity, work the edges. Birds draw other birds to the bonanza. Helpless when the temperature of their flight muscles drops below a critical point, most insects become easy prey when so chilled—or simply freeze to death and become immured in the snowpack. Sometimes entire strata of this snow plankton have been preserved in glaciers, and famous among scientists are the places, such as Grasshopper Glacier in Montana, where the melting feet of these ice sheets give forth their insect lodes. The lesser museum of Magdalena Mountain is about to gain one more specimen.
Instinctively, just before numbness sets in for good, Erebia lays his closed wings flat against the reflective surface of the snow. At just this time of day the sun shines directly onto the mountain’s far face, blinding birds, pikas, and passersby unless they shield their eyes. For a time, Erebia’s temperature flirts with the point of total shutdown. Then a calorie or two convects from that spread black beam catcher to his body and into his muscle fibers, the nodes of nerves. Heat gain begins to overcome loss by an immeasurable margin, but not too small for Erebia to feel and respond to. Slowly, slowly, he reclaims precious degrees. The snowfield struggled its best to drain the BTUs from his blood, but those elegantly evolved solar panels, the wings of an alpine, suck back at the sunbeams for all they are worth.
Finally, just able, Erebia rights himself and begins to crawl. In a few labored minutes he reaches the edge of the snow, struggles onto warm granite, continues to a hot black patch of lichen, and lies flat again. In seconds his flight muscles reach the takeoff temperature, well above the ambient high for the day—and he takes flight. The first patch of campion he passes over draws him like a butterfly collector to beer, and he quaffs the sugar-rich nectar for minutes.
Renewed, as the sun sinks to the ridgetop, Erebia follows another time-grooved pattern and flies to a shadowed cleft in the rockslide. Alighting on the rim of the rock, he fairly dives into the void that promises safety for the high montane night. He’ll never know how close he came to frozen death that day, but if he knows anything, it is how to pass a high-country sunset. He crawls down the fluted side of a rock chimney. At last, warm against the stone-walled haystack of a providential pika, Erebia sleeps his Stygian sleep, a black butterfly down a black hole in a black night. Thus ends the twelfth day of adult existence for one alpine resident of Magdalena Mountain.