Warm temperatures and drought have likely contributed to fewer butterflies in their wintering grounds of Mexico, but experts say the subspecies is resilient.
A migratory monarch butterfly feeds on native flowers in Zapalinamé State Park in Coahuila. Mexico, during the fall migration. Drought and warmer temperatures can kill off the flowers that the insects rely on for survival. travel up to 3,000 miles from southern Canada and the Great Plains of the United States to spend their winters in, according to a new report released this week by the Mexican government and other groups.
That said, in the case of eastern monarchs,"the overall trend has been to decrease, so we need to act very quickly and very strongly to build conditions for them to bounce back," says Rickards, for instance by reducing pesticide use in Mexico. Eastern monarch populations have declined by about 80 percent since the 1980s, mostly due to the growth of agriculture, which has killed off vast amounts of milkweed.