Jaime Rojo. The Forest of the Monarchs.

Streaked with sunlight and crowded together for warmth in winter, Monarch Butterflies blanket fir trees in El Rosario Sanctuary. It is cool and relatively moist at these high elevations. Monarch butterflies are adapted to the same ecological conditions as the oyamel trees and are protected by the forest canopy and by clustering against one another. Any slight changes in the forest cover can alter the delicate microclimate. I requested special permits to work outside the sanctuary's operating hours and made this photograph shortly before sunset. Jaime Rojo is a photographer and National Geographic Explorer with a background in conservation, who focuses on environmental stories about wilderness and wildlife and uses his images as tools to protect nature. He has spent 20 years documenting Monarch butterflies, and his story, "Saving the Monarchs"—a visual exploration of their migration, the threats they face, and the efforts to protect them—was featured on the cover of National Geographic