A Cornell University study that asserts dwindling milkweed is not the main cause of an alarming decline in the monarch butterfly population has rekindled debate about what is affecting the insects and how best to save them. The study, based on two decades of population data, argues the monarch’s numbers fall during its southward migration and at its winter habitat in Mexico. It coincides with news of a fresh threat to that habitat: plans to reopen a gold, silver and zinc mine in a village in Michoacán state just five miles from the mountain tops where monarchs winter. Led by Anurag Agrawal, a Cornell professor of ecology and evolutionary biology, the study analyzes the size of the population of the monarch (Danaus plexippus) at different... [Log in to read more]
