Monarch Butterflies Join the Red List of Endangered Species

Kristen A. Baum • August 2, 2022

...Thanks to habitat loss, climate change, and pesticides

On July 21, 2022, the International Union for the Conservation of Nature placed the migratory monarch butterfly on its Red List of threatened species and classified it as endangered. Monarchs migrate across North America each year and are one of the continent’s most widely recognized species. The Conversation asked Oklahoma State University biologist Kristen Baum , who has studied pollinators for more than 25 years, to explain the listing’s implications for the monarch butterfly in the U.S.

What is the IUCN, and what does its action mean?

The IUCN is a network of public, private and nonprofit organizations that work to conserve nature worldwide. The Red List, which was developed in 1964, provides a standardized approach for assessing the extinction risks of species. Listing the monarch butterfly draws attention to its status and to areas where more research is needed to understand factors contributing to its decline.

The IUCN listing applies to the migratory subspecies of the monarch butterfly, or Danaus plexippus plexippus. There are two migratory populations: one east and one west of the Rocky Mountains.

The eastern population migrates thousands of miles from overwintering sites in central Mexico to breeding grounds in the Upper Midwest and southern Canada. The western population migrates from overwintering sites along the Pacific Coast in California and Baja California in Mexico to breeding grounds west of the Rocky Mountains. Monarchs in other locations throughout the world, such as in Europe and many Pacific Islands, don’t migrate and are not part of the listing.

Map of North America showing monarch butterfly fall migration routes.
In fall, eastern North American monarchs fly south using several flyways that mostly then merge into a single flyway in central Texas that leads to their overwintering sites in central Mexico. Western monarchs migrate from the Rocky Mountains to overwintering sites on the Pacific Coast. USFS

What are the main factors threatening monarchs?

There are many factors contributing to monarchs’ decline. One of the most serious threats is habitat fragmentation and loss. Habitat fragmentation occurs when urban development or agricultural expansion break up large areas of habitat into smaller, often isolated patches. This leaves fewer areas for monarchs to find the nectar-rich plants that adult butterflies feed on , or milkweed, the sole food source for monarch caterpillars.

Other threats include pesticides , disease , climate change and invasive species. Providing more suitable habitat for monarchs in more places could help them tolerate these stresses.

Monarchs are particularly susceptible to threats during the parts of their annual cycle when many millions of them cluster together. For example, a winter storm in March 2016 killed 31%-40% of the monarchs in some overwintering colonies in central Mexico. Winter storms also blow down trees, which can reduce habitat for overwintering colonies in subsequent years.

Temperature and precipitation can influence monarchs’ spring and fall migrations and breeding season success. For example, spring weather is an important factor influencing the size of the summer monarch population. Slightly warmer and drier springs produce more monarchs on the summer breeding grounds.

Scientists send a hummingbird-shaped drone to film swarming monarch butterflies in Mexico at close range.

Are monarch butterflies protected in the US?

Not yet, although the U.S. Fish and Wildlife Service recognizes that they are at risk.

The agency received a petition in 2014 to list the monarch butterfly as threatened under the Endangered Species Act. It concluded in 2020 that listing the monarch was warranted but precluded. This means that while monarchs are at risk of extinction, they are less at risk than other species that are currently higher priorities, such as the rusty patched bumblebee.

That decision put monarchs on the candidate list, where the agency reviews their status every year. Only a subset of species on the IUCN Red List is also protected under the Endangered Species Act. For insects, that number is less than 20%.

The IUCN report estimates that the eastern monarch population has declined by 22%-72% over the past decade, and the western population has declined by 66%-91%. Evaluating trends for insect populations can be challenging because they tend to fluctuate from year to year.

Another challenge for measuring the populations of migratory species is that patterns can differ depending on when in the annual cycle they are evaluated, such as breeding versus overwintering. To estimate how many eastern monarchs overwinter in central Mexico, scientists measure how many hectares of trees are covered with monarchs and convert that number into an estimated number of butterflies.

Many factors influence how densely monarchs cluster together in trees on their overwintering grounds. Estimates based on data from the summer breeding grounds are also challenging because monarchs go through multiple generations per year and breed across a large area.

Would an ‘endangered’ listing in the US help monarchs?

Migratory monarchs have a huge range that extends from southern Canada to central Mexico and includes all of the contiguous U.S. They use many types of open habitats, from prairies to urban parks. This makes it challenging to implement and enforce regulatory actions.

The IUCN report points out that the decline of the eastern migratory population seems to have slowed, or even stabilized, over the past 10 years. The 2014 petition to list monarchs under the U.S. Endangered Species Act spurred many actions to support monarchs that likely contributed to slowing their decline, from planting milkweeds and nectar plants in home gardens to large-scale restoration projects.

Supporting these efforts could provide more benefits than a listing under the Endangered Species Act. When a species is listed, the federal government produces a recovery plan that often includes restrictions on actions that threaten the species, such as hunting or land development. Studies have found that private land owners often become less willing to participate in conservation activities , such as allowing researchers to monitor the species on their property, after a species is listed.

It’s hard to say whether listing monarchs would have this effect. People love monarch butterflies, and community science projects that involve activities like monitoring eggs and caterpillars and tagging monarchs are very popular. Data collected by citizen scientists has expanded what researchers know about monarchs. Many of these efforts have taken place over large areas and long time spans that would be hard for scientists to replicate.

I see community scientists as critical for informing monarch conservation efforts, and hope the IUCN’s action will inspire more people to get involved.The Conversation

Kristen A. Baum , Professor of Integrative Biology and Associate Dean for Research, Oklahoma State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Common Sense for the Eastern Shore

By Friends of Megan Outten July 29, 2025
Megan Outten, a lifelong Wicomico County resident and former Salisbury City Councilwoman, officially announced her candidacy recently for Wicomico County Council, District 7. At 33, Outten brings the energy of a new generation combined with a proven record of public service and results-driven leadership. “I’m running because Wicomico deserves better,” Outten said. “Too often, our communities are expected to do more with less. We’re facing underfunded schools, limited economic opportunities, and years of neglected infrastructure. I believe Wicomico deserves leadership that listens, plans ahead, and delivers real, measurable results.” A Record of Action and A Vision for the Future On Salisbury’s City Council, Outten earned a reputation for her proactive, hands-on approach — working directly with residents to close infrastructure gaps, support first responders, and ensure everyday voices were heard. Now she’s bringing that same focus to the County Council, with priorities centered on affordability, public safety, and stronger, more resilient communities. Key Priorities for District 7: Fully fund public schools so every child has the opportunity to succeed. Fix aging infrastructure and county services through proactive investment. Keep Wicomico affordable with smarter planning and pathways to homeownership. Support first responders and safer neighborhoods through better tools, training, and prevention. Expand resources for seniors, youth, and underserved communities. Outten’s platform is rooted in real data and shaped by direct community engagement. With Wicomico now the fastest-growing school system on Maryland’s Eastern Shore — and 85% of students relying on extra resources — she points to the county’s lagging investment as a key area for action. “Strong schools lead to strong jobs, thriving industries, and healthier communities,” Outten said. “Our schools and infrastructure are at a tipping point. We need leadership that stops reacting after things break — and starts investing before they do.” A Commitment to Home and Service Born and raised in Wicomico, Megan Outten sees this campaign as a continuation of her lifelong service to her community. Her vision reflects what she’s hearing from neighbors across the county: a demand for fairness, opportunity, and accountability in local government. “Wicomico is my home; it’s where I grew up, built my life, and where I want to raise my family,” Outten said. “Our county is full of potential. We just need leaders who will listen, work hard, and get things done. That’s what I’ve always done, and that’s exactly what I’ll continue to do on the County Council.” Outten will be meeting with residents across District 7 in the months ahead and unveiling more details of her platform. For more information or to get involved, contact info@meganoutten.com
By John Christie July 29, 2025
Way back in 1935, the Supreme Court determined that independent agencies like the Consumer Product Safety Commission (CPSC), the National Labor Relations Board (NLRB) and the Merit Systems Protection Board (MSPB) do not violate the Constitution’s separation of powers. Humphrey’s Executor v. United States (1935). Congress provided that the CPSC, like the NLRB and MSPB, would operate as an independent agency — a multi-member, bipartisan commission whose members serve staggered terms and could be removed only “for neglect of duty or malfeasance in office but for no other cause.” Rejecting a claim that the removal restriction interferes with the “executive power,” the Humphrey’s Court held that Congress has the authority to “forbid their [members’] removal except for cause” when creating such “quasi-legislative or quasi-judicial” bodies. As a result, these agencies have operated as independent agencies for many decades under many different presidencies. Shortly after assuming office in his second term, Donald Trump began to fire, without cause, the Democratic members of several of these agencies. The lower courts determined to reinstate the discharged members pending the ultimate outcome of the litigation, relying on Humphrey’s , resulting in yet another emergency appeal to the Supreme Court by the administration. In the first such case, a majority of the Court allowed President Trump to discharge the Democratic members of the NLRB and the MSPB while the litigation over the legality of the discharges continued. Trump v. Wilcox (May 22, 2025). The majority claimed that they do not now decide whether Humphrey’s should be overruled because “that question is better left for resolution after full briefing and argument.” However, hinting that these agency members have “considerable” executive power and suggesting that “the Government” faces greater “risk of harm” from an order allowing a removed officer to continue exercising the executive power than a wrongfully removed officer faces from being unable to perform her statutory duty,” the majority gave the President the green light to proceed. Justice Kagan, joined by Justices Sotomayor and Jackson, dissented, asserting that Humphrey’s remains good law until overturned and forecloses both the President’s firings and the Court’s decision to award emergency relief.” Our emergency docket, while fit for some things, should not be used to “overrule or revise existing law.” Moreover, the dissenters contend that the majority’s effort to explain their decision “hardly rises to the occasion.” Maybe by saying that the Commissioners exercise “considerable” executive power, the majority is suggesting that Humphrey’s is no longer good law but if that is what the majority means, then it has foretold a “massive change” in the law and done so on the emergency docket, “with little time, scant briefing, and no argument.” And, the “greater risk of harm” in fact is that Congress provided for these discharged members to serve their full terms, protected from a President’s desire to substitute his political allies. More recently, in the latest shadow docket ruling in the administration’s favor, the same majority of the Court again permitted President Trump to fire, without cause, the Democratic members of another independent agency, this time the Consumer Product Safety Commission (CPSC). Trump v. Boyle (July 23, 2025). The same three justices dissented, once more objecting to the use of the Court’s emergency docket to destroy the independence of an independent agency as established by Congress. The CPSC, like the NLRB and MSPB, was designed to operate as “a classic independent agency.” In Congress’s view, that structure would better enable the CPSC to achieve its mission — ensuring the safety of consumer products, from toys to appliances — than would a single-party agency under the full control of a single President. “By allowing the President to remove Commissioners for no reason other than their party affiliation, the majority has negated Congress’s choice of agency bipartisanship and independence.” The dissenters also assert that the majority’s sole professed basis for the more recent order in Boyle was its prior order in Wilcox . But in their opinion, Wilcox itself was minimally explained. So, the dissenters claim, the majority rejects the design of Congress for a whole class of agencies by “layering nothing on nothing.” “Next time, though, the majority will have two (if still under-reasoned) orders to cite. Truly, this is ‘turtles all the way down.’” Rapanos v. United States (2006). * ***** *In Rapanos , in a footnote to his plurality opinion, former Supreme Court Justice Scalia explained that this allusion is to a classic story told in different forms and attributed to various authors. His favorite version: An Eastern guru affirms that the earth is supported on the back of a tiger. When asked what supports the tiger, he says it stands upon an elephant; and when asked what supports the elephant, he says it is a giant turtle. When asked, finally, what supports the giant turtle, he is briefly taken aback, but quickly replies "Ah, after that it is turtles all the way down." John Christie was for many years a senior partner in a large Washington, D.C. law firm. He specialized in anti-trust litigation and developed a keen interest in the U.S. Supreme Court about which he lectures and writes.
By Shore Progress, Progessive Maryland, Progressive Harford Co July 15, 2025
Marylanders will not forget this vote.
Protest against Trumpcare, 2017
By Jan Plotczyk July 9, 2025
More than 30,000 of our neighbors in Maryland’s first congressional district will lose their health insurance through the Affordable Care Act and Medicaid because of provisions in the GOP’s heartless tax cut and spending bill passed last week.
Farm in Dorchester Co.
By Michael Chameides, Barn Raiser May 21, 2025
Right now, Congress is working on a fast-track bill that would make historic cuts to basic needs programs in order to finance another round of tax breaks for the wealthy and big corporations.
By Catlin Nchako, Center on Budget and Policy Priorities May 21, 2025
The House Agriculture Committee recently voted, along party lines, to advance legislation that would cut as much as $300 million from the Supplemental Nutrition Assistance Program. SNAP is the nation’s most important anti-hunger program, helping more than 41 million people in the U.S. pay for food. With potential cuts this large, it helps to know who benefits from this program in Maryland, and who would lose this assistance. The Center on Budget and Policy Priorities compiled data on SNAP beneficiaries by congressional district, cited below, and produced the Maryland state datasheet , shown below. In Maryland, in 2023-24, 1 in 9 people lived in a household with SNAP benefits. In Maryland’s First Congressional District, in 2023-24: Almost 34,000 households used SNAP benefits. Of those households, 43% had at least one senior (over age 60). 29% of SNAP recipients were people of color. 15% were Black, non-Hispanic, higher than 11.8% nationally. 6% were Hispanic (19.4% nationally). There were 24,700 total veterans (ages 18-64). Of those, 2,200 lived in households that used SNAP benefits (9%). The CBPP SNAP datasheet for Maryland is below. See data from all the states and download factsheets here.
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