While international efforts are underway to protect iconic monarch butterflies from disappearing, the latest population count has found their numbers have dropped by nearly one-third since last year.According to the Xerces Society for Invertebrate Conservation, in the 1990s, an estimated one billion monarchs embarked on an epic annual migration. Their journey takes them from sites in Canada and the U.S. to wintering grounds in California and Mexico, where they find shelter and warmth among oyamel fir trees in the winter.