Richard Ellis/Alamy Stock Photo

Harsh winter storms set back monarch recovery

Monarch butterfly populations seemed to be fluttering back 2 years after hitting an all-time low, but the butterflies have suffered another setback. The monarchs’ bright orange wings (seen above) were observed across just 2.91 hectares of forest in their wintertime habitat in Mexico this year—a 27% drop relative to last winter, researchers from the Mexican government and the World Wildlife Fund (WWF) Mexico reported last week in a study released by WWF Mexico. The butterflies travel from Canada and the eastern United States each year to the pine and fir forests of central Mexico, where researchers measure the forest area they cover as a proxy for their population. The 2013–2014 season suggested dire population numbers, with the butterflies spread across a mere 0.67 hectares, but they seemed to be rebounding since then. However, strong storms at the tail end of last season destroyed 54 hectares of monarch habitat in Mexico, and the loss of milkweed habitat for monarch caterpillars in the United States continues to threaten the migration. With the butterfly population already far below the high of 18.19 hectares in the mid-1990s, the dip underscores how fragile the migration is in the face of extreme weather and habitat loss.