February brought rare cause for cheer about the fate of the monarch butterfly. The World Wildlife Fund announced on Feb. 26 that, according to its annual survey, the number of black and orange butterflies overwintering in Mexico more than tripled last year, reaching its highest point since 2010. If anybody needed a reminder of how fragile the recovery of one of the world’s most fascinating migratory species can be, however, it came less than two weeks later: A cold snap in the monarch’s mountainous wintering grounds in Mexico killed millions of the butterflies. Mexican officials said they believed the butterfly’s population had “held up” during the storm, and shared photos of clumps of monarchs clinging to trees. But they offered no specific numbers; some scientists... [Log in to read more]