Flight to Plight: Witnessing the Imperiled Migration of the Monarchs

BREATHING HARD IN THE THIN MOUNTAIN AIR, we reached the trail’s end at the top of Sierra Chincua, a 10,000-foot-high biosphere reserve and world heritage site in central Mexico. Stepping into a sunny clearing, we looked about in wonder. Hundreds — no, thousands — of monarchs warmed by the noonday sun were swooping and swirling around us in lazy circles.