In April 2021, I wrote a piece for Harvesting Nature on what appeared to be the imminent extinction of the western Monarch butterfly population. Only about 2,000 butterflies arrived on their southern California winter range in 2020 where approximately five million once clouded the skies and trees. When a population sees decline of this magnitude, coming back from the brink is rare, particularly in one breeding season, but it seems there is more to the story on the western monarch butterfly.
The 2021 Thanksgiving monarch count saw an unprecedented number of citizen scientists eager to help collect important population data. Across 283 count sites, the western monarch population estimate was over 247,000 individuals – a 100-fold increase in the 2020 count.
Given the monarch’s astonishing rebound, population limiting factors come into question. What was it about 2021 – a severe drought year in the western U.S. – that was somehow favorable to the marked population increase? According to Emma Pelton, the Western Monarch Lead with the Xerces Society, “There are so many environmental factors at play across their range that there’s no single cause or definitive answer…but hopefully it means we still have time to protect the migration.”
Weather likely played a factor. Dry spring and summer conditions can coax first-generation monarch butterflies out of their cocoons. “Those first-generation butterflies that breed in California and at Santa Cruz landmarks such as Lighthouse Field and Natural Bridges are crucial for the species’ population numbers to sustain” reported Hannah Hagemann of the Santa Cruz Sentinel.
While the 2021 count was inspiring, the population increase should be taken with caution. The Western Monarch Butterfly Conservation Plan identifies a five-year-average winter count of 500,000 butterflies to represent a sustainable population. Additionally, the U.S. Fish and Wildlife Service is still on track to propose an Endangered Species Act listing for this iconic transcontinental butterfly in 2024.
The monarch butterfly presents a continent-wide icon of the butterfly genera. Its red-orange wings with defining black outlines and white freckles once danced over pastures, thistle and milkweed across their North American range, but land use changes since the 1980s have dramatically affected monarch populations.
Monarchs make a marvelous migration to winter “hivers” based on their summer breeding range in the U.S. and southern Canada. The Rocky Mountains, of course, divide the major migration routes. Eastern monarchs overwinter in southern Florida and Mexico, while western monarchs overwinter on the southern California coast.
Their reliance on milkweed makes for an easy classroom experiment, collecting the vibrant, yellow, black and white-striped caterpillar with a few leaves and watching it turn into a chrysalis, then mature and hatch into the adult butterfly. But, at present, the monarch population has declined more than 80 percent in the past 30 years; the western population facing extinction.
In 1997, the Xerces Society established the Western Monarch Thanksgiving Count, similar to the Audubon Society Christmas Bird Count, where “citizen scientists” document monarchs on their western winter hiver. According to Washington State University, the 10 million monarchs documented in the 1980s declined to 30,000 in 2018, and fell below 2,000 this past winter.
Dramatic loss of the western monarch population led to special interest groups petitioning the U.S. Fish and Wildlife Service (FWS) to protect the butterfly and their habitat with a listing under the Endangered Species Act (ESA). A FWS status review determined that “…listing the monarch butterfly as endangered under the ESA is warranted but precluded by higher priority actions.” In other words, there are more than 100 species ahead of the monarch in need of FWS resources and protection.
Additionally, under the ESA, an insect species cannot be segregated into subpopulations such as birds, mammals and fishes. Therefore, the FWS must consider the status of the monarch butterfly as one population across its North American range. If the western monarch were to be carved off as its own “distinct population segment”, it’s ESA listing priority would likely be much higher.
While the western monarch faces a dire future, Pheasants Forever, Quail Forever and the Xerces Society promote pollinator initiatives that benefit monarchs among other pollinator species. Many Pheasants Forever and Quail Forever chapters are willing to cost-share on pollinator enhancement projects.
Additionally, two congressional bi-partisan bills, the Monarch Action, Recovery, and Conservation of Habitat (MONARCH) Act, as well as the Monarch and Pollinator Highway Act, were recently introduced to avoid the extinction of the western monarch.
The MONARCH Act would authorize $62.5 million for western monarch conservation projects, and another $62.5 million to implement the Western Monarch Butterfly Conservation Plan, paid out over the next five years. The Monarch and Pollinator Highway Act would establish a federal grant program available to state departments of transportation and Native American tribes to carry out pollinator-friendly practices on roadsides and highway rights-of-way.
At the local level, milkweed promotion could have a positive influence for the western monarch. Various studies suggest small patches of milkweed, as small as two- to five-square-yards in area, could be affective for increasing reproduction. Patches that small area easily managed in a backyard flowerbed or garden, and the western native “showy milkweed” boasts a beautiful spiked ball of pink bloom, worthy of being added to any pollinator seed mix.
Recent conservation initiatives are late to the table for the western monarch, and the upcoming reproduction season is critical to their long-term survival. Will this iconic pollinator population boast a success story similar to species like the greater sage grouse or bald eagle? Time and a few congressional votes will tell.