Decline of the Monarch Butterfly Population

Nicole Ward

What’s Happening
One of the most iconic and beautiful species that we all know and love is in immense danger.   The monarch butterfly used to be seen in large numbers across North America, but over the past several decades the population has been rapidly declining.  When looking at the population of monarch butterflies in California, it went from upwards of one million in the late 1990’s, to only 27,000 in 2019.  Over the past twenty years, the monarch butterfly population has decreased by approximately 90%, and compared to thirty years ago, the population has decreased by approximately 99%. . Concerns of the species extinction are becoming prevalent in environmental circles across the United States and suggestions to list monarch butterflies  under the Endangered Species Act are becoming more frequent.

Background on Species
The monarch butterfly is known for its magnificent and easily identifiable orange, black, and white wing pattern.  The butterflies migrate across North America, from Canada, down to the United States, and then into Mexico.  Smaller populations of monarchs have been known to occupy regions such as Puerto Rico, New Zealand, as well as other regions of the Caribbean.  Milkweed is a resource that is essential for the survival of the monarchs.  They lay their eggs on it, and the caterpillars feed off of it.  Predators of the monarch are various lizard and bird species, who feed off the monarchs, in addition to insects like ants, spiders, and wasps, who consume the monarch’s larvae off of milkweed.

Cause of the Decline
There are several factors that have contributed to the decline of the monarch butterfly population, including a loss of milkweed, forest degradation, disease, and of course, climate change.  The main cause is the habitat loss of milkweed; this critical habitat of the monarchs has been degraded and lost due to the use of damaging pesticides, insecticides, and herbicides.  The loss of milkweed can also be attributed to our expansion of urban areas, and the demolition of natural habitats for urban life.  The other major cause of the decline is climate change.  Climate change is such an expansive issue that it affects nearly every ecosystem and every species on earth in some way.  Two major effects of climate change are the increase in temperatures, and the increase in intensity and frequency of major weather events.  In the case of the monarch butterflies, the increase in temperatures has immense effects as they  are very sensitive to changes in temperature, and these changes can cause them to be unaware of when to migrate and reproduce.  Furthermore, as the intensity and frequency of storms increases, it allows for destruction of forests and habitats that the butterflies rely on for survival.

What’s Being Done
There are a few ways we can respond to this issue, spanning from the individual level to the local level to the federal government level.  In recent years, there has been conversation about whether or not the monarch butterfly should be listed and protected under the Endangered Species Act.  In April, 2020, it was announced that the species will not be listed under the ESA for now, but rather a different agreement has been reached.  In this agreement, over 45 energy and transportation companies, in addition to several private landowners have accepted a proposal to develop or conserve habitats for monarch butterflies.  These companies will do this by changing how they apply herbicides, varying the times for mowing when no monarch larvae is present, replanting the land after construction projects, and using seed mixes to foster the growth of essential plants, like milkweed.

What You Can Do to Help
There are many things you as an individual can do right now to contribute to the study and regrowth of the monarch butterfly population.  

  1. Set up your own pollinator garden!  This is something almost anyone can do, even if you don’t have a large backyard.  The US Fish and Wildlife Service has put together step by step instructions on how you can start your very own pollinator garden.
  1. Help scientists study monarchs!  Citizen participation in science is essential.  Even if you’re not a highly trained scientist, you as a citizen still play a very important role in helping scientists conduct research.  Citizens have been helping scientists study the monarch butterfly since the 1950’s.  Through organizations like Journey North, you can report your sightings of monarch butterflies, and look at up-to-date migration maps and get the latest news on the migration of the butterflies.  Other organizations such as Monarch Watch, allow you to tag monarchs that you see, using small numbered stickers that you can order from them.  You can then submit your findings directly to them.  
  1. Be a politically active citizen!  Being involved and informed about politics at the local level as well as the state and federal level is important for so many reasons.  It’s important to do your research, and learn about politicians’ stance on issues regarding the environment.  You can even contact your elected officials and advocate for the protection of monarch butterflies.  Be informed about when local elections take place – do your part and vote!  It’s especially important to vote this November in the upcoming presidential election, because the two candidates have vastly different views on environmental issues.  Educate others!  Share the information you have learned about the monarch butterfly with your peers, friends, and family!  Inform others on the issue and how they can get involved.  Maybe even share your knowledge with local groups in your community to help spread information, and get more people engaged in the conversation.

Sources: Center for Biological Diversity, Eco Watch, Environmental Research Letters, National Geographic, The National Wildlife Federation, US Fish and Wildlife Service