Monarch Butterflies Show Hope for the First Time in Decades

In the deep forests of central Mexico, a hopeful story is emerging for the monarch butterfly. For the second year in a row, the number of these iconic insects has grown. After twenty-five years of worrying declines, this increase suggests that the population has finally stabilized. For a long time, the future of the monarch looked very dark. These beautiful American insects were flitting closer to extinction. Now, however, there is at least a small reason for hope. New data from WWF Mexico, a major conservation group, offers clear evidence that the decline of the eastern monarch population has stopped. This is true even as the insects face worsening threats across their entire range.

Each fall, tens of millions of monarchs take a miraculous journey. They live east of the Rocky Mountains and migrate all the way to a specific forested region in central Mexico. These featherweight insects are so plentiful during the winter that the tree branches often droop under their collective weight. The sight of millions of orange and black butterflies covering the evergreen trees is a rare and breathtaking event in nature.

To understand how many butterflies are surviving the winter, researchers hike into the forest during December and January. They measure the area of the trees covered by the monarchs to estimate the population size. This winter, the numbers were up. Monarchs aggregated in trees covering about 7.2 acres of forest in Mexico. This is a substantial increase from 4.4 acres the year before, and a significant jump from the 2.2 acres recorded two years ago. Despite this progress, scientists warn that the numbers are still far from what is needed for long-term survival.

While these new numbers are encouraging, they are still far below historical averages. The average from the first ten years of monitoring was about 21 acres, and scientists consider about 15 acres to be a sustainable level for the population. Despite falling short of these goals, the recent growth is still good news. Karen Oberhauser, a professor emeritus at the University of Wisconsin Madison, is one of the nation's leading monarch experts. She was not involved in the new WWF Mexico report but agrees that the data is positive.