The migratory monarch butterfly (Danaus plexippus plexippus) was added to the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species this week. Categorized as Endangered, these insects have just a Critically Endangered classification to pass before being considered Extinct.
With the addition of the migratory monarch butterfly, the IUCN Red List now contains 147,517 species, with over 41,000 of them being threatened with Extinction.
Environmental changes, habitat destruction, and the use of pesticides are thought to be the cause of the dramatic reduction in their numbers, which has seen a population decrease of between 22 and 72 percent in the last decade. Droughts and wildfires have limited the growth of milkweed, a primary source of food for monarch caterpillars, and deforestation has stripped these butterflies of their nesting grounds.
This dramatic fall in numbers raises concerns about the species' ability to maintain the population and prevent a further decline in numbers. Despite the evident population decline, and the efforts of organisations like IUCN to raise awareness of the insect’s plight, the United States has not yet listed the migratory monarch butterflies under the Endangered Species Act.
The migratory monarch butterfly, a subspecies of the monarch butterfly (Danaus plexippus), are identifiable by their iconic black and orange wing patterns. These insects undertake a nearly 5,000 kilometer (3,000 mile) migration across North America, flying up to 160 kilometers (100 miles) per day, making this the longest migration of any known insect species.
Unlike their adventurous cousins, the species of nonmigratory monarchs do not face the same risk of extinction, and for now, their Central and South American habitats seem to sustain their numbers.
In 2008, the El Rosario Monarch Butterfly Reserve in Mexico was designated a UNESCO World Heritage site, with the aim of protecting overwintering monarchs, but despite best efforts, the site also saw a reduction in occupied acreage between 2019 and 2020. Threats from illegal logging are putting both the roosting sites and those protecting them at risk, after two butterfly activists were killed trying to protect the forest in 2020.
Despite the discouraging statistics, organizations like the El Rosario Monarch Butterfly Reserve and other overwintering sites are working tirelessly to protect these dwindling numbers.
By planting milkweed, reducing pesticide use, protecting roosting sites, and contributing to community science by helping monitor populations, we can all be involved in encouraging a resurgence of this iconic species.