"I am encouraged by the good news coming out of Mexico, an indication that we have the ability to save the North American monarch butterfly and with it one of the most remarkable wildlife migrations on the planet," Ashe said.
"But there is much more we need to do and it will take a coordinated citizen effort on a scale never before seen."
Ashe urged people across the region to help the butterfly thrive by planting milkweed, and reach the goal of having 250 million monarchs by 2020.
"A simple stand of native milkweed can make every backyard, school, community center, city park and place of worship a haven for breeding or migrating monarchs, and together we can bring about the greatest citizen conservation victory of our generation," he said.
But Vidal of WWF warned that herbicides are still a major problem in the United States, along with illegal logging in Mexican sanctuaries.
"The threats to the monarch remain and if they are not dealt with, if actions are not followed through, the migratory phenomenon won't recover," he said.