The number of monarch butterflies spending this winter in Mexico has gone up — way up.
According to the U.S. Fish and Wildlife Service, the amount of butterflies that fluttered their way to Mexico from Canada and the United States jumped 255 percent from last year.
“There was unusually good weather during migration,” explained Brian Brown, curator of the entomology section at Los Angeles’ Natural History Museum.
Brown said that every winter, the butterflies migrate to Mexico and cluster in large numbers in the forest where it’s warm, just like monarchs do on California's coast.
Despite the good numbers, the insects aren’t in the clear yet. Recent years saw a 90 percent dip from their peak population in the mid-1990s. The culprit: loss of habitat and the milkweed they feed on.
“Agriculture has become more and more intensive and urbanization has taken out a lot of habitat,” said Brown. “The milkweeds that they feed on are kind of weeds that grow in scruffy areas regenerating pastures… places like that are becoming few and far between.”
Climate also plays a role. For more about the effect of cold spells on the monarchs' migration and efforts to revive the population, listen to the full conversation above.