Monarch butterflies cluster on tree branches in the Amanalco de Becerra sanctuary, on the mountains near the extinct Nevado de Toluca volcano, in Mexico, Thursday, February 14, 2019. For years park rangers and conservationists working around Mexico’s Nevado de Toluca volcano chased rumors of a monarch butterfly colony that wintered high in a forest of oyamel firs in some corner of the 132,000-acre national reserve. (Photo by Marco Ugarte/AP Photo)
