This month, tens of millions of monarch butterflies are ending their winter sojourn in central Mexico’s mountainside oyamel fir forests and taking flight northward. Stopping to breed on milkweed en route, they will move in fluttering orange clouds as far as eastern Canada and then, as fall approaches, their descendants—three or more generations removed—will make the trip back to Mexico. For years, monarchs have been returning each fall to less and less forest due to illegal logging in central Mexico. And for years, scientists have warned of disaster, saying that if the monarchs’ winter habitat is lost, their extraordinary transnational migration could disappear, too. But with such an outcome only recently seeming inevitable, a cautious new optimism has begun emerging among monarch-conservation... [Log in to read more]