Monarch butterflies are as American as apple pie, having once been found in backyards across the country. Generations of schoolchildren have reared monarchs in classrooms, watching in wonder as striped caterpillars transform into large orange-and-black adult butterflies. The monarch’s multigenerational migration is legendary — a journey of more than 2,000 miles from Mexico to Canada, undertaken by animals weighing less than a single gram. The monarch plays a unique and prominent role in the imagination of our country, especially considering it’s an insect. These creatures are ambassadors of nature in people’s gardens and symbols of summertime outdoors.
Yet these butterflies, once a familiar sight, are plummeting toward extinction due to landscape-scale threats from pesticides, development and global climate change. In their overwintering groves there were once so many monarchs that the sound of their wings was described as a rippling stream or a summer rain. Early newspaper descriptions described branches breaking under the weight of so many butterflies and depicted the masses of butterflies as “the personification of happiness.” The 2016 monarch count showed that over the past 22 years, these butterflies declined by 68 percent, with the population at 150 million butterflies — not the most devastating of declines, and wonderful news considering the truly alarming count in 2015 of just 42 million, the second-lowest ever since surveys began in 1993.
But consider also: That 42 million number meant the butterfly had declined by 80 percent over a 20-year average, meaning that if all monarchs from the population high in the mid-1990s were grouped onto football fields, the area they covered just two years ago had been reduced from 39 fields to an area barely larger than one field.
Also butterfly experts expected monarch numbers to rise, as they did, in 2016, due to favorable summer weather conditions in the species’ U.S. breeding areas, since butterfly populations fluctuate widely with changing weather. And monarchs need a very large population size in order to be resilient to threats from severe weather events, pesticides and climate change. To put things to scale: A single storm in 2002 killed an estimated 500 million monarchs.
The heart of the monarch’s range is the midwestern “Corn Belt,” where most of the world’s monarchs are born on milkweed plants growing in agricultural fields. Because of the ubiquitous spraying of Roundup on corn and soy that have been genetically modified to resist herbicides, the monarch is in bad trouble in the core of its range, where its sole host plant, milkweed, is disappearing. In a one-two punch, climate change is undermining the stable weather conditions and predictable flowering seasons that monarchs need to complete their migration. Climate change also threatens these butterflies’ overwintering habitat in the mountain forests of Mexico. Just as Joshua Tree National Park will soon no longer support Joshua trees, the International Monarch Reserve in Mexico is expected to become climatically unsuitable for monarchs by the end of the century.
Because of all this and more, in August 2014 the Center and allies petitioned to protect monarchs as "threatened" under the Endangered Species Act. In December, the U.S Fish and Wildlife Service declared the species may warrant protection. In December 2014 the Service determined that protection may be warranted, triggering an official review of the butterfly’s status that, by law, must be completed within 12 months. But by March 2016 the Service still had not issued a final decision — so the Center for Biological Diversity and Center for Food Safety filed a lawsuit against the Service over its failure to protect monarch butterflies.
Monarchs’ decline is a harbinger of widespread environmental change. The plummeting population of this familiar butterfly, along with the decline of many other butterflies and bees, threatens the wellbeing of people as well, because the food security of humans is dependent on the ecological services that pollinators provide. History shows a tragic record of the unexpected decline of abundant and widespread species. Complacency and false-positive assumptions about the resiliency of once-common species can have tragic consequences when timely action is not undertaken to safeguard their populations. The migration of the monarch butterfly is at risk of being lost unless humans take rapid action to protect it.
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Contact: Tierra Curry