Monarchs and California golden poppies...Color them orange...Color them bold...Color them beautiful...

And color them natives...

The California golden poppy, Eschscholzia californica, California's state flower, is popping up all over, while monarchs, Danaus plexippus, are winging their way inland from their overwintering sites along the California coast.

The overwintering population in California dropped this year by 30 percent as compared to last year, according to the Xerces Society for Invertebrate Conservation. The stormy weather didn't help.

"The 27th annual Thanksgiving count ran from November 11 through December 3, 2023, totaling 233,394 butterflies across 256 overwintering sites in the western United States," Xerces reports on its website. "This tally is slightly lower than last year's (330,000), yet similar to the 2021 count. The overwintering population of western monarchs remains at approximately 5% of its size in the 1980s."

Overall, habitat loss and increased use of pesticides and herbicides continue to be key factors in the decline of the monarch population.

Interestingly enough, both monarchs and California golden poppies are toxic. "All parts of the (California golden poppy) plant have toxic properties if ingested," according to the State of California Capitol Museum website. And, as we all know, monarchs are toxic. As caterpillars, monarchs sequester or store toxins from milkweed, and those toxins help protect them from predators. The coloring is also a deterrent. 

Two natives, toxic, but beautiful...

It's Wednesday afternoon, Nov. 1 and a female monarch butterfly flutters into our Vacaville pollinator garden.

Me: "Welcome Ms. Monarch! Aren't you a little late for the migration?"

Ms. Monarch: "No, I'm just a late bloomer,. so to speak. I'm heading to Santa Cruz to join my buddies for the winter and then we'll return in February. Right now, I need some nectar, a little flight fuel, to make it to Santa Cruz, if you don't mind." 

Me: "Help yourself, Ms. Monarch. Right now we have several plants blooming, including Mexican sunflower, tropical milkweed, zinnias, blanketflower, catmint, roses, foxgloves, and evening primrose. One of your sisters passed through here Oct. 21 and she laid eggs on the tropical milkweed, Asclepias curassavica. She ignored the native milkweed, Asclepias fascicularis, and the other natives we planted."

Ms. Monarch: "Thank you for giving us a choice."

Me: "You're welcome. But watch out for the spiders and praying mantises."

Ms. Monarch: "Hope they won't catch me!"

Me: "I'll check to see where they are. No, don't see them, but that doesn't mean they're not there." 

Ms. Monarch, sipping nectar on the tropical milkweed: "This is delicious. You don't mind if I stay 'n sip, sip 'n stay, or awhile?"

Me: "We planted it for you and your brothers and sisters. Well, for other insects, too, like honey bees and syrphid flies, but mainly for you. There's talk, you know, about being endangered."

Ms. Monarch: "Will my sister's eggs survive?

Me: "Well, between the spiders, ants, wasps, lady beetles and milkweed bugs, we can't promise.  Hey, even monarch caterpillars will eat the eggs. But we do know this: only 5 percent of the eggs make it to adulthood. So, the odds aren't good. Oops, gotta go. 'Bye for now."

Bohart Museum Open House on Saturday, Nov. 4

Want to talk to a scientist about monarch butterflies? Then you'll want to attend the Bohart Museum of Entomology open house on Saturday, Nov. 4 from 1 to 4 p.m. in Room 1124 of the Academic Surge Building, 455 Crocker Lane. Scientists will be there to answer your questions.

The event is free and family friendly and a great opportunity to learn more about Danaus plexippus.

The scientists will include:

• UC Davis distinguished professor emeritus Art Shapiro of the Department of Evolution and Ecology, who has studied butterfly populations in central California since 1972 and maintains a research website, Art's Butterfly World.
  
  
• UC Davis emeritus professor Hugh Dingle, a worldwide authority on animal migration, including monarchs.  He is the author of Migration: The Biology of Life on the Move (Oxford University Press), a sequel to the first edition published in 1996. See news story on the UC Davis Entomology and Nematology website.
  
  
• UC Davis professor Louie Yang, who does research on monarchs. Due to parental duties, he may be able to attend only the last part of the open house. See news story about his work.
  
  
• UC Davis professor Elizabeth Crone of the Department of Evolution and Ecology, formerly of Tufts University, who researches monarchs. See news story about the declining monarch population on the UC Davis Entomology and Nematology website.
  
  
• UC Davis postdoctoral fellow Aramee Diethelm of the Elizabeth Crone lab. She holds a doctorate from the University of Nevada, Reno.  Both her Ph.D. and postdoctoral work are on monarch butterflies.  

The Bohart Museum houses a global collection of eight million insect specimens, plus a living insect petting zoo (Madagascar hissing cockroaches and stick insects, among others), and a insect-themed gift shop. UC Davis distinguished professor Lynn Kimsey has directed the Bohart Museum, founded in 1946, since 1990. 

Want to talk to a scientist about monarch butterflies?

Then you'll want to attend the Bohart Museum of Entomology open house on Saturday, Nov. 4 from 1 to 4 p.m. in Room 1124 of the Academic Surge Building, 455 Crocker Lane. Scientists will be there to answer your questions.

The event is free and family friendly and a great opportunity to learn more about Danaus plexippus.

The scientists will include:

• UC Davis distinguished professor emeritus Art Shapiro of the Department of Evolution and Ecology, who has studied butterfly populations in central California since 1972 and maintains a research website, Art's Butterfly World.
  
  
• UC Davis emeritus professor Hugh Dingle, a worldwide authority on animal migration, including monarchs.  He is the author of Migration: The Biology of Life on the Move (Oxford University Press), a sequel to the first edition published in 1996. See news story on the UC Davis Entomology and Nematology website.
  
  
• UC Davis professor Louie Yang, who does research on monarchs. Due to parental duties, he may be able to attend only the last part of the open house. See news story about his work.
  
  
• UC Davis professor Elizabeth Crone of the Department of Evolution and Ecology, formerly of Tufts University, who researches monarchs. See news story about the declining monarch population on the UC Davis Entomology and Nematology website

Shapiro, a Lepidopterist, points out that the monarch "is NOT a focal species in my research and I am NOT a monarch expert. On the other hand, I have a unique breeding-season census data set starting in 1999. The only other census data are for the overwintering roosts on the coast. It has become apparent that the two data sets do not always agree." Shapiro said he'd talk briefly about this at the open house. 

"The iconic black and orange monarch butterfly is known for its astonishing long-distance annual migration and reliance on milkweed as its obligate larval host plant," according to a post on the California Department of Fish and Wildlife (CDFW). "Though genetically similar, there are two subpopulations of monarchs in North America, with the eastern population overwintering in Mexico and breeding in the midwestern states, and the western population overwintering in coastal California and fanning out across the west from Arizona to Idaho. Outside the U.S., there are at least 74 known populations of resident, non-migratory monarchs that have established around the world in the past 200 years, all with origins in North America (Nial et al. 2019)."

"Both North American migratory populations have declined over the past twenty years due to a suite of interrelated factors including habitat loss in breeding and overwintering sites, habitat degradation, disease, pesticide exposure, and climate change," CDFW says. "Recently the western population has experienced dramatic swings, for a low of less than 2,000 in 2020-21 to over 200,000 in 2021-22 (Xerces Society Western Monarch Count). While it is unclear which of the many factors are driving these dynamics, insect population commonly fluctuate from year to year. The overall downward trend remains concerning, particularly if the threats are not ameliorated. Though more research is needed, a stable population for western monarchs is likely closer to the historic averages in the 1980's, which are estimated to have ranged between one to four million overwintering butterflies."

"n 2014, monarchs were petitioned to be listed under the federal Endangered Species Act. In December 2020, the U.S. Fish and Wildlife Service found that listing was warranted but precluded by other listing actions on its National Priority List. The monarch is currently slated to be listed in 2024."

The monarch population is in trouble. Says the Xerces Society for Invertebrate Conservation in a post on its website: "In the 1990s, hundreds of millions of monarchs made the epic flight each fall from the northern plains of the U.S. and Canada to sites in the oyamel fir forests in central Mexico, and more than a million monarchs overwintered in forested groves on the California coast. Now, researchers and community scientists estimate that only a fraction of the population remains—a decline of approximately 70% has been seen in central Mexico and a decline of >90% has been seen in California."

Resources/Further Reading:

• Monarch Butterfly, California Department of Fish and Wildlife
• Research Permits, CDFW
• Western Monarch Mllkweed Mapper 
• Integrated Monarch Monitoring Program, Monarch Joint Venture
• Western Monarch Count, Xerces Society for Invertebrate Conservation
• Monarch Butterfly Conservation, Xerces Society
• Spreading Milkweed, Not Myths, U.S. Fish and Wildlife Service 
• Habitat Corridor Project, Views on milkweed
• Tropical Milkweed Doesn't Deserve the Bad Rap, Bug Squad blog, views on the ban of tropical milkweed by UC Davis emeriti professors Art Shapiro and Hugh Dingle, and Washington State University entomologist David James,  who studies migratory monarchs. 

UC Davis community ecologist Louie Yang, a UC Davis Department of Entomology and Nematology professor who researches monarch butterflies, suggests three broad guidelines for western monarch conservation in his review article published June 26 in the journal, Current Opinion in Insect Science.

The article, “Complexity, Humility and Action: A Current Perspective on Monarchs in Western North America,” is “meant to provide a concise review of and perspective on recent western monarch research,” Yang said.

The western monarch population overwinters along the California coast. Estimated at 4.5 million in the 1980s, it has dropped significantly over the past five years, the professor related, noting an  “86% single-year population decline in 2018, an overwintering population of less than 2000 butterflies in 2020, and an unexpected >100-fold increase in 2021."

Yang defined the western monarch population as occupying "a geographically distinct region of North America west of the Rocky Mountain...Ongoing climate change has made the western monarch range warmer, drier, and more prone to heatwaves, wildfires, and winter storms  with complex effects on their ecology. Land development and changes in the structure of landscape mosaics have modified both the breeding and overwintering habitats of western monarch butterflies, changing the spatial distribution of resources and risks across their range. Shifts in agricultural and horticultural practice have changed the nature of potentially deleterious chemicals in the environment, including novel herbicides and insecticides."

Yang said the spread of non-native milkweed species has likely had both positive and negative consequences for western monarchs, and more research is needed. 

His three suggestions:

1. "First, we should continue to support both basic and applied monarch research. This includes efforts to better understand fundamental aspects of monarch biology, studies to examine the ecological factors that limit monarch populations in the West and efforts to improve more targeted adaptive management and monitoring efforts. Basic research in monarch biology and ecology improves our understanding of this complex system and can inform conservation actions in profound and unexpected ways. In turn, applied research can address recognized gaps in knowledge that would otherwise limit available strategies for conservation planning and management."
2. "Second, recognizing the limits of our current understanding, we should follow the precautionary principle to minimize the risk of counterproductive action. The complexity of this system makes it difficult to anticipate or assume future changes in behavior, species interactions or population dynamics. In practice, this may mean prioritizing efforts to better understand and facilitate existing mechanisms of ecological resilience and recovery over direct actions to manipulate or augment the population with less certain consequences. More broadly, this approach would probably emphasize common sense approaches to mitigate the widely recognized upstream drivers of global change (e.g., climate change and land use change), rather than those requiring a detailed understanding of their complex, interactive effects on species-specific ecologies further downstream."
3. "Third, we should work to improve, protect and maintain the resources required throughout the complex monarch life cycle. In part, this likely means prioritizing conservation efforts that target the times and places that are likely to have the greatest positive effects, building on the common ground of available science. In the case of western monarchs, this includes protecting current and future overwintering habitats, the resources required for population expansion in the early season, and the resources required for the fall migration. Recognizing the potentially widespread and pervasive effects of pesticides, this could also mean efforts to develop more ecologically realistic and relevant metrics for the regulation of environmental chemicals."

Yang opined that "In the broader context, many of the drivers that are contributing to western monarch population declines are likely to also be affecting other species. In turn, many of the strategies that would support monarch conservation would likely benefit other species, and many of the strategies that would benefit other species are likely to also support monarch conservation. As we build on currently available science to better understand and protect the western monarch population, it is imperative that we continue to grapple with the inherent complexity of this system and respond with appropriate humility and necessary action."

Among the 54 scientific publications that Yang referenced was a research article co-authored by UC Davis Distinguished Professor Art Shapiro, who has studied butterfly populations in Central California since 1972. The article, "Fewer Butterflies Seen by Community Scientists across the Warming and Drying Landscapes of the American West," published in Science in March 2021, covered data from the Shapiro transect, the North American Butterfly Association (NABA) community count data and the iNaturalist community observation data.  The study observed widespread declines across 450 butterfly species, including the monarch butterfly, in the American West. The authors estimated a 1.6 percent decrease in overall butterfly abundance each year over a 42-year period from 1977 to 2018.

Editors of the journal, Current Opinion in Insect Science, describe it as "a new systematic review journal that aims to provide specialists with a unique and educational platform to keep up–to–date with the expanding volume of information published in the field of insect science."

Yang's research is supported by a National Science Foundation award. He was a guest on National Public Radio's Science Friday in February 2022. Listen to the interview here.