Scanning the forest’s belly, I paused for a second look at some distant branches sagging with the weight of what looked like hives. No, not hives, I thought. Are those nests? Beyond my footsteps, mahogany-colored clumps dripped from the branches of scattered trees. They shimmered in the sparse light, nearly indistinguishable from the tree trunks and pine needles.

Wait, are those . . . ?

Puzzled, I ambled closer. Through squinting eyes, I began to see the details made clear by the light and shadow that grazed each wing and defined each butterfly. Not just any butterflies, and not just one. Millions. Millions of monarch butterflies. Known to scientists as Danaus plexippus and to Spanish speakers as la mariposa monarca; to me they were simply spectacular. I stood, enchanted. I had seen pictures and videos, but now I was finally among them. Millions­—clinging to the trees like shelved books waiting to be read, their stories of adventure painted on their wings. Each had flown thousands of miles to escape the freezing winters of the United States and Canada. Each had the potential to travel many more miles back north in the spring. As did I.

Soon, as had happened for so many springs before, the monarchs would leave the protection of their canopy shelter and launch north. Unlike all the springs before, however, I would go with them: the first person to ever attempt to bicycle the entire route of the monarch butterfly migration. I stared up at my future traveling companions. They huddled in silent bundles on the branches and coated the tree trunks in stilled wings. Those trees, wearing butterfly wings, would function as the start and finish line of my upcoming adventure. When warmer weather nudged the monarchs to the sky, I would begin.