AMES, Iowa – The size of the U.S. monarch overwintering population underscores the continued need for conservation in the Midwest and North America.

That’s according to the World Wildlife Fund, Comisión Nacional de Áreas Naturales Protegidas and the Monarch Butterfly Biosphere Reserve in its recently released 2020-2021 overwintering monarch population report.

On Dec. 1, 2020, the United States Fish and Wildlife Service determined that adding the monarch butterfly to the list of threatened and endangered species is warranted.

However, they precluded an immediate listing due to their workload on higher-priority listing actions, said Steve Bradbury, Iowa State University professor of entomology. “With this decision, the monarch becomes a candidate species for listing under the Endangered Species Act,” he added.

At this time, the United States Fish and Wildlife Service recommends continued implementation of voluntary conservation efforts within the Upper Midwest, he said. Conservation efforts that establish new breeding habitat are of prime importance.

The report said adult monarch butterflies covered approximately five acres of forest canopy in Mexico, an area about two acres smaller than last year. Moreover, scientists estimate a long-term average of 15 acres of occupied forest canopy is needed to sustain the eastern North America monarch population and its continental migration.

The report added that loss of habitat in the United States, forest degradation in Mexico and extreme weather events have contributed to the population decline over the last 25 years.

Currently, Iowa is the epicenter of the U.S. monarch’s summer breeding range, and roughly 40 percent of all monarch butterflies that overwinter in Mexico are estimated to come from Iowa and neighboring states in the Midwest.

“As a candidate species, there is no immediate, direct regulatory oversight of public and private landowners under the Endangered Species Act,” Bradbury said. “The Fish and Wildlife Service indicated they will address the listing decision in 2024.

“Leading up to 2024, the Fish and Wildlife Service will undertake another in-depth analysis of the monarch’s population status, and the nature and extent of progress made by voluntary conservations efforts, such as those undertaken by the Iowa Monarch Conservation Consortium,” he added.

Facilitated by Iowa State University, the Iowa Department of Natural Resources, and the Iowa Department of Agriculture and Land Stewardship, the Iowa Monarch Conservation Consortium is leading voluntary conservation efforts in the state.

This is based on a strategy developed by the consortium’s 50 organizations, which include agricultural and conservation associations, agribusiness and utility companies, universities and federal agencies.

Kayla Lyon, director of the Iowa Department of Natural Resources, said the consortium supports habitat improvements in rural landscapes that do not conflict with agricultural production, are sufficient in scale to support improved monarch breeding success and strive to complement other conservation programs.

“Now is a critical time for us to recognize the importance of providing habitat for monarchs to help minimize the decline in population,” she said. “Together, we can all do our part to provide the necessary habitat for these butterflies by simply planting milkweed or other native wildflowers not just on large landscapes, but even in our backyards and planters. “We are proud of our continued partnerships that focus on providing this habitat on a larger scale on our publicly-managed lands.”

According to Iowa State entomologists, the monarch butterfly faces many challenges, including the loss of milkweed and nectar plant habitat in its spring and summer breeding ranges. In addition, female monarchs lay eggs exclusively on milkweed plants, and caterpillars also feed solely on milkweed leaves, although adult monarchs feed on nectar from a variety of flowering plants.

“Consequently, monarch observations will fluctuate from year to year in a given habitat patch,” Bradbury said. “In addition, observations of monarchs in a given habitat patch is also a function of the number of habitat patches in the surrounding landscape (the more, the better). 

“As more habitat gets established in the landscape, it will take less time for females to find habitat patches to lay their eggs,” he added. “In turn, this will result in a greater number of eggs laid in the landscape, and more adult monarchs in the next generation.”

Iowa State entomologists said habitat restoration and reconstruction should include a diverse array of milkweed and blooming species to provide nectar for adult monarchs throughout their full life cycle, including spring and fall migrations.

The Iowa Monarch Conservation Strategy has laid out a 20-year plan for establishing approximately 480,000 to 830,000 acres of new habitat in Iowa from 20018-2038.

“We’re working with public and private partners to ramp up conservation efforts around the state to improve the health of our soils, protect our water sources and preserve the monarchs that play a critical role in our ecosystem,” said Iowa Agriculture Secretary Mike Naig.

“I encourage everyone to look for opportunities to layer conservation practices, like buffer strips and milkweed to maximize the environmental benefits, while creating habitats for monarchs and other wildlife,” he added.

Bradbury said, however, “We’re at the front end of implementing the conservation strategy, hence it’s too early to assess changes in monarch populations as a function of new habitat,” he said. “In addition, habitat established in the past two or three years is just starting to support perennial, native forbs and milkweed.

“Over the last several years, Iowa State, with the support of Iowa Monarch Conservation Consortium members, and the USDA Conservation Innovation Grant program, established about 30 habitat demonstration sites in 2016 across the state,” he added. “Results from these projects helped inform habitat establishment practices.” 

In March 2017, the city of Cedar Rapids, Iowa, donated 1,000 acres of unused land to the Monarch Research Project’s 10,000 Acre Initiative.

Under the Iowa Renewable Fuels Association’s own initiative, 16 monarch fueling stations with over 48 acres planted have been established, to date.

“Habitat sites have been established by 11 of the association’s members, including nine biofuel plants and two associate members,” Bradbury said.

Bruce Trautman, who recently retired as director of the Iowa Department of Natural Resources, said the number of Iowa ethanol and biodiesel companies constructing monarch fueling stations throughout the state is increasing as millions of butterflies continue to migrate to Iowa, which has become one of America’s premier spots for these kinds of habitats.

“Iowa is perfectly situated to lead the way in conservation efforts for the monarch butterfly,” he said. “Since Iowa is located within the monarch’s core breeding range, every patch of milkweed habitat added here counts toward national monarch conservation efforts. The recovery cannot succeed without Iowa.”

Daniel Robison, holder of the Endowed Dean’s Chair in Iowa State’s College of Agriculture and Life Sciences, said research at Iowa State “has improved our understanding of what it takes to establish and enhance habitat to sustain the monarch.

“Our research findings and on-going extension efforts, in coordination with other state and national partners, helps ensure science-based information guides our conservation practices in Iowa, and the greater Midwest.”