Why are monarch butterflies disappearing and what can be done about it?

In late December, the US Fish and Wildlife Service (FWS) announced that it was opening hearings into the status of the monarch butterfly.

“The Service has determined that a petition from the Center for Biological Diversity, the Center for Food Safety, the Xerces Society for Invertebrate Conservation and Dr. Lincoln Brower to list a subspecies of monarch (Danaus plexippus plexippus) presents substantial information indicating that listing may be warranted,“ according to a statement from the agency.

The Center for Biological Diversity (CBD), in a press release, stated that over the past 20 years the species has lost one-third of its habitat, roughly 165 million acres of land.

The organization states that the population has declined from roughly one billion in the mid nineties to 35 million last winter which represents a decline of 90 percent over 20 years. They claim that the population needs to be very large to stand up to the rigors of severe weather and numerous natural predators.

“The Endangered Species Act is the most powerful tool available to save North America’s monarchs, so I’m really happy that these amazing butterflies are a step closer to the protection they so desperately need,” said Tierra Curry, a senior scientist at the CBD.

It is not immediately clear what steps the FWS might take to protect the monarchs. The animals range extends from southern Canada through the United States and Mexico and into northern areas of South America.

According to the CBD, the species faces a range of threats including climate change, logging, drought and heat waves, pesticides and, most especially, herbicides. According to the organization, Monsanto’s roundup herbicide which is frequently used with genetically modified crops, kills milkweed which is the primary food source for the monarchs.

It may be difficult to convince farmers to preserve milkweed. According to the U.S. Department of Agriculture milkweed is thought to be poisonous to sheep and cattle and is considered a ‘noxious weed‘ in some areas. Laws vary by state but in some areas farmers are required to remove noxious weeds where they are found. Milkweed is also considered an invasive species in some areas.

There is also little, in the short run, that the FWS can do about climate change or the current multi-year drought in the southwest. According to recent reports the southwest is facing an increasing risk of a megadrought, lasting 10 years or more.

The FWS will collect information until March 2 to determine whether a change in the status of the monarch butterfly is warranted. Evidence from scientific, commercial and other sources will be considered. Officials will consider the biology, habits, range, population and habitat of the species as well as current and proposed conservation efforts.

While the FWS considers its next steps, organizations such as the David Suzuki Foundation are encouraging individuals to do what they can to help the butterflies. Primarily they are encouraging people to reduce their use of pesticides and herbicides, to plant milkweed and to create local habitats for monarchs in gardens, parks and other public areas.