Beloved for their striking orange and black beauty and their annual trek across the Golden Belt, monarch butterfly numbers have plummeted in recent years. But, they will have to wait for increased federal protection, the U.S. Fish and Wildlife Service announced Tuesday.

The agency determined the insect’s addition to the list of threatened and endangered species is warranted. But, the listing is precluded by work on higher-priority listing actions. 

With this decision, the monarch becomes a candidate for the Endangered Species Act, and its status will be reviewed each year until it is no longer a candidate. Instead, the feds encourage voluntary efforts to restore habitats for these important pollinating insects, whose annual transcontinental migration takes them over central Kansas.

The service’s action was not unexpected, said Pam Martin, Department of Wildlife, Parks and Tourism education specialist at the Kansas Wetlands Education Center in Barton County. The Center holds a butterfly festival and monarch tagging event each fall.

“One thing’s for certain, if habitat isn’t restored soon, we could lose the migration, resulting in the loss of one of nature’s most amazing journeys – the 2,000-plus mile flight of a creature that weighs less than a feather to a specific area it has never seen,” Martin said.

“Everyone has a monarch story,” she said. “What a shame it would be for our children and grandchildren not to share in that story.”

“The warranted but precluded decision for monarchs is the right one at this time,” said Chip Taylor, founder and director of Monarch Watch and an emeritus professor at the University of Kansas. “It acknowledges the need for continued vigilance due to the numerous threats to the population while emphasizing the need to continue support for programs that create and sustain habitats for monarchs.”

Why is this important?

Adult monarch butterflies feed on nectar from flowers, making them important as pollinators. 

Pollinators are crucial, Martin said. Ranging from butterflies to bees to slugs, they transport pollen from plant flower to plant flower which is essential the plants’ reproduction process.

This can include wild plants as well as domestic plants, including agricultural crops.

Habitat conservation efforts are needed across the Americas to address threats to the monarch and to bolster milkweed abundance and other habitat needs, according to the Fish and Wildlife Service. Monarchs lay their eggs exclusively on milkweed, the sole source of food for monarch caterpillars.

Also threatening the monarchs, as well as other insects, are certain insecticides and climate change, Martin said.

“So, the question becomes: what are we going to do to sustain the monarch migration?” Taylor said. “To me, it’s clear. We have to do all we can to restore and sustain monarch habitats, and we have to support initiatives that favor the reduction of greenhouse gases.”

Two long-distance migratory monarch populations occur in North America; the largest is east of the continental divide and overwinters in the mountains of central Mexico.

Monarchs west of the continental divide overwinter primarily along coastal California. Monarchs also inhabit about 90 other countries, islands or island groups around the world, but these monarchs are believed to have originated from the North American population.

The numbers are falling

Over the past 20 years, scientists have noted declines in North American monarchs overwintering in Mexico and California, where these butterflies cluster. Numbers in the larger eastern population are measured by the size of the area they occupy.

At a density of roughly 8.5 million monarchs per acre, it is estimated that the eastern population fell from about 384 million in 1996 to a low of 14 million in 2013. The population in 2019 was about 60 million. The western population, located in California, saw a more precipitous decline, from about 1.2 million in 1997 to fewer than 30,000 in 2019. 

Monarchs are known for their phenomenal spring and fall migrations, traveling across the continent to and from wintering sites. In eastern North America, monarchs travel north in the spring, from Mexico to Canada, over two to three successive generations, breeding along the way. 

Western monarchs continue to occupy and breed in warmer climates throughout the summer. The final generation in the fall makes the return trip to wintering sites in Mexico and coastal California. 

“The Western monarch numbers have plummeted in a very short period of time,” Martin said. She recently read an article that placed the current population at only 2,000. 

The Eastern population did not experience a large migration this fall, she said. 

“No one knows what the numerical threshold is for the cessation of the migration behavior,” Martin said. But, experts have made estimates.

By taking the size of the roosting area in Mexico measured in hectares (about 2.5 acres), they can extrapolate the monarch population. Ideally, scientists want to see an area covering about 14 hectares, but six is large enough to support an adequate population.

The six-hectare threshold has been reached once since 2007, researchers have noted.

How was the decision made?

“We conducted an intensive, thorough review using a rigorous, transparent science-based process and found that the monarch meets listing criteria under the Endangered Species Act. However, before we can propose listing, we must focus resources on our higher-priority listing actions,” said U.S. Fish and Wildlife Service Director Aurelia Skipwith. “While this work goes on, we are committed to our ongoing efforts with partners to conserve the monarch and its habitat at the local, regional and national levels.” 

“The Monarch Joint Venture is committed to continuing its conservation efforts for monarchs. Each of our partners, and many other stakeholders, come to the monarch conservation table with different approaches, audiences, strengths and opportunities to make a difference. There is a role for everyone in monarch conservation,” stated Wendy Caldwell, executive director, Monarch Joint Venture. 

“The Association of Fish and Wildlife Agencies has been working side-by-side with the U.S. Fish and Wildlife Service on voluntary monarch butterfly conservation since 2014,” said Sara Parker Pauley, director of the Missouri Department of Conservation and president of the Association of Fish and Wildlife Agencies. “We’ve made great strides, including raising awareness and restoring key habitat, but we still have a long way to go for a sustainable, long-term impact.”

The service evaluated threats to the monarch, including habitat loss, climate change and exposure to pesticides, and used a model to create simulations of future conditions to estimate the risk of extinction. The agency launched a monarch conservation database and gathered quantities of data which was then peer reviewed.

This led to the service’s conclusion. It added the monarch to the candidate list, assigning it a listing priority number of eight. This priority number indicates the magnitude of threats is moderate and those threats are imminent.

The ESA provides for a warranted-but-precluded finding when the service does not have enough resources to complete the listing process because the agency must first focus on higher-priority listing rules. Warranted-but-precluded findings require subsequent review each year until the agency undertakes a proposal or makes a not-warranted finding. 

Currently, listing actions for 161 species on the work plan, 64% are a higher priority than the monarch. These species include plants, insects, freshwater mussels, fish, birds and mammals. Obligations to meet court orders and settlements due to litigation can affect when the agency works on some species.