Monarch Conservation Science Partnership

Science Center Objects

The Challenge

Over the last two decades, the Eastern migratory population of monarch butterflies has declined by about 80%, leading many scientists to consider how to best conserve and rebuild monarch populations. Conservation efforts can be challenging to design and execute because of the multi-generational migration of monarchs that spans North America. Conservationists must consider many challenges while trying to reach their conservation goals, including: 

• Coordination across the range of the monarch between Canada, the United States, and Mexico

• A lack of national-level monitoring and gaps in current data regarding monarch butterflies and their habitats

• Many factors that influence population decline like herbicides, insecticides, climate change, and land loss

The Monarch Conservation Science Partnership was formed to address these challenges.

Time series of monarch butterfly overwinter abundance in Mexico, as described by Zylstra et al. (2021)

Zylstra and colleagues (2021) published a re-analysis of historical studies of monarch butterfly overwinter abundance, predicting a time series of historical abundance for monarch butterflies before systematic surveys began. For more information, see Zylstra, E. R., W. E. Thogmartin, M. I. Ramírez, and E. F. Zipkin. 2020. Summary of available data from the monarch overwintering colonies in central Mexico, 1976–1991: U.S. Geological Survey Open-File Report 2020–1150, 10 p. https://doi.org/10.3133/ofr20201150

(Credit: Wayne Thogmartin, USGS. Public domain.)

Who We Are

The Monarch Conservation Science Partnership (MCSP) is a group of scientists, managers, and conservation organizations from across North America who perform science that will help meet the challenges of monarch conservation. Led by USGS, members come from federal agencies, non-profit organizations, and academic institutions across the United States, Mexico, and Canada. Meetings of the MCSP have been hosted by the USGS John Wesley Powell Center for Analysis and Synthesis in Ft. Collins, Colorado. Principal Investigators include Darius Semmens and Jay Diffendorfer with the Geosciences and Environmental Change Science Center (GECSC) and Wayne Thogmartin with the Upper Midwest Environmental Sciences Center (UMESC). 

Monarch on Joe Pyeweed plant

Monarch butterfly on a Joe Pyeweed plant.

(Credit: Emily Weiser, USGS. Public domain.)

The Approach 

To address conservation challenges, MCSP has followed the Strategic Habitat Conservation framework to help identify target population sizes, create conservation plans, and monitor the state of monarch butterflies in North America. The framework works in four steps:

  1. Biological planning
  2. Conservation design
  3. Conservation delivery
  4. Outcome Based monitoring
Strategic Habitat Conservation: a Business Model for Conservation

The U.S. Fish and Wildlife Service employs a four-step iterative process for conducting conservation. This process perpetually moves sequentially from one step to another, guiding and refining the decision making necessary for sound conservation.

(Credit: Wayne Thogmartin, USGS. Public domain.)

 

 

1. Biological Planning: How many monarchs do we need? 

Researchers with MCSP first identified how many monarchs are needed in the population to avoid extinction. Semmens et al. (2016) used extinction modeling to determine the population size at which monarchs would avoid extinction. This population target serves as the goal for conservation and has implications for how much habitat is required to restore a population at that size. 

For more, see, Semmens et al. 2016.

4th instar monarch caterpillar

Monarch caterpillars proceed through 5 instars (i.e., larval stages) before forming a chrysalis, at which point they develop into adults. 4th instar caterpillars spend 1-3 days in this developmental stage, depending on temperature, voraciously consuming their host plant, milkweed (Asclepia spp.).

(Credit: Emily Weiser, USGS. Public domain.)

2. Conservation design: How can we increase population size? 

Achieving the target population could involve two different approaches – decreasing monarch deaths or increasing fecundity (the number of new monarchs each female produces). With no clear path for decreasing monarch deaths, conservation design focuses on increasing female lifespans by increasing nectar availability and creating more breeding opportunities by increasing milkweed. MCSP-led studies determined that: 

  • Conservation efforts need to occur across the entire monarch range, not just in particular areas
  • Within the North Central region of the U.S., milkweed must be planted in all land uses, including agricultural and marginal cropland areas, to reach a goal of restoring ≥1.3 billion stems of milkweed 

For more, see, Oberhauser et al. 2016 and Thogmartin et al. 2017.

3. Conservation Delivery: How to transform the land? 

Executing the plan across multiple land uses requires the help of many organizations, working groups, and associations. Important efforts informed by the conservation design principles of the MCSP include:

  • The Midwest Association of Fish and Wildlife Agencies (MFWA): thirteen states and three Canadian provinces who work to deliver the Mid-America Monarch Conservation Strategy
  • Rights-of-Way as Habitat Working Group: partners from many transportation and energy industries working on the Monarch Candidate Conservation Agreement with Assurances (CCAA) which encourages brush removal, mowing, and seeding strategies that support monarch habitat 

4.  Monitoring

Numerous monitoring programs across North America continue to track information about monarchs. The Integrated Monarch Monitoring Program (IMMP) is one such program established by USGS and the U.S. Fish and Wildlife Service. The national program collects milkweed, nectar plant, and monarch use data from many land-use types to help understand monarch ecology and conservation efforts. 

Scenarios of habitat conservation for recovering monarch butterflies

 More than 200 scenarios of habitat conservation for recovering monarch butterflies to levels sufficient for reducing risk of extinction were evaluated. These scenarios identified different levels of milkweed restoration needed to fulfill deficits in the amount of milkweed needed for restored populations of monarchs. Only a handful of scenarios satisfied the full amount of milkweed required, and all successful scenarios but one entailed participation from all sectors of society participating in monarch conservation, a "All Hands on Deck" approach. For more, see Thogmartin, W. E., L. López-Hoffman, J. Rohweder, J. Diffendorfer, R. Drum, D. Semmens, S. Black, I. Caldwell, D. Cotter, P. Drobney, L. L. Jackson, M. Gale, D. Helmers, S. Hilburger, E. Howard, K. Oberhauser, J. Pleasants, B. Semmens, O. Taylor, P. Ward, J. Weltzin, and R. Wiederholt. 2017. Restoring monarch butterfly habitat in the Midwestern U.S.: “All Hands on Deck”. Environmental Research Letters 12:074005.  
https://doi.org/10.1088/1748-9326/aa7637

(Credit: Wayne Thogmartin, USGS. Public domain.)

 

For more, see, Cariveau et al. 2019, Pleasants et al. 2017, Weiser et al. 2019, and Weiser et al. 2020

Tools for Decision Making

 

Participants in the Monarch Conservation Science Partnership

The Monarch Conservation Science Partnership is a consortium of government, non-government and academic scholars and policy analysts gathered to address science information needs pertaining to the monarch butterfly.

(Credit: Jill Baron. Public domain.)

Further Reading

Diffendorfer, J. E., L. Ries, J. B. Loomis, K. Oberhauser, L. López-Hoffman, B. Semmens, B. Butterfield, D. Semmens, K. Bagstad, J. Goldstein, R. Wiederholt, J. Dubovsky, B. Mattsson, and W. E. Thogmartin. 2014. National valuation of monarch butterflies indicates an untapped potential for incentive-based conservation. Conservation Letters 7:253‒262. https://doi.org/10.1111/conl.12065

Semmens, B. X., D. J. Semmens, W. E. Thogmartin, R. Wiederholt, L. López-Hoffman, J. E. Diffendorfer, J. Pleasants, K. Oberhauser, and O. Taylor. 2016. Quasi-extinction risk and population targets for the Eastern, migratory population of monarch butterflies (Danaus plexippus). Scientific Reports 6:23265.  https://doi.org/10.1038/srep23265

Oberhauser, K., R. Wiederholt, J. Diffendorfer, D. Semmens, L. Ries, W. E. Thogmartin, L. López-Hoffman, and B. Semmens. 2017. A trans-national monarch butterfly population model and implications for regional conservation priorities. Ecological Entomology 42:51–60. https://doi.org/10.1111/een.12351

 Thogmartin, W. E., J. E. Diffendorfer, L. López-Hoffman, K. Oberhauser, J. Pleasants, B. X. Semmens, D. Semmens, O. R. Taylor, and R. Wiederholt. 2017. Density estimates of monarch butterflies overwintering in central Mexico. PeerJ 5:e3221.  https://doi.org/10.7717/peerj.3221

 Thogmartin, W. E., L. López-Hoffman, J. Rohweder, J. Diffendorfer, R. Drum, D. Semmens, S. Black, I. Caldwell, D. Cotter, P. Drobney, L. L. Jackson, M. Gale, D. Helmers, S. Hilburger, E. Howard, K. Oberhauser, J. Pleasants, B. Semmens, O. Taylor, P. Ward, J. Weltzin, and R. Wiederholt. 2017. Restoring monarch butterfly habitat in the Midwestern U.S.: “All Hands on Deck”. Environmental Research Letters 12:074005.   https://doi.org/10.1088/1748-9326/aa7637

 Thogmartin, W. E., R. Wiederholt, K. Oberhauser, R. G. Drum, J. E. Diffendorfer, S. Altizer, O. R. Taylor, J. Pleasants, D. Semmens, B. X. Semmens, R. Erickson, K. Libby, and L. López-Hoffman. 2017. Monarch butterfly population decline in North America: identifying the threatening processes. Royal Society Open Science 4:170760. https://doi.org/10.1098/rsos.170760

Pleasants, J. M., M. P. Zalucki, K. S. Oberhauser, L. P. Brower, O. R. Taylor, and W. E. Thogmartin. 2017. Interpreting surveys to estimate the size of the monarch butterfly population: pitfalls and prospects. PLoS ONE 12(7): e0181245. https://doi.org/10.1371/journal.pone.0181245

Semmens, D. J., J. E. Diffendorfer, K. J. Bagstad, R. Wiederholt, K. Oberhauser, L. Ries, B. X. Semmens, J. Goldstein, J. Loomis, W. E. Thogmartin, B. J. Mattsson, and L. López-Hoffman. 2018. Quantifying ecosystem service flows at multiple scales across the range of a long-distance migratory species. Ecosystem Services 31:255–264.  https://doi.org/10.1016/j.ecoser.2017.12.002   

Cariveau, A. B., H. L. Holt, J. P. Ward, L. Lukens, K. Kasten, J. Thieme, W. Caldwell, K. Tuerk, K. Baum, P. Drobney, R. G. Drum, R. Grundel, K. Hamilton, C. Hoang, K. E. Kinkead, J. McIntyre, W. E. Thogmartin, T. Turner, E. L. Weiser, and K. Oberhauser. 2019. The Integrated Monarch Monitoring Program: from design to implementation. Frontiers in Ecology and Evolutions 7:167. https://doi.org/10.3389/fevo.2019.00167

Weiser, E. L., J. E. Diffendorfer, R. Grundel, L. López-Hoffman, S. Pecoraro, D. Semmens, and W. E. Thogmartin. 2019. Balancing sampling intensity against spatial coverage for a community-science monitoring program. Journal of Applied Ecology 56:2252–2263. https://doi.org/10.1111/1365-2664.13491

Sample, C., J. Bieri, B. Allen, Y. Dementieva, A. Carson, C. Higgins, S. Piatt, S. Qiu, S. Stafford, B. J. Mattsson, D. Semmens, W. E. Thogmartin, and J. E. Diffendorfer. 2019. Quantifying source and sink habitats and pathways in spatially structured populations: a generalized modelling approach. Ecological Modelling 407:108715 https://doi.org/10.1016/j.ecolmodel.2019.06.003  

Semmens, D. and Z. Ancona. 2019. Monarch habitat as a component of multifunctional landscape restoration using continuous riparian buffers. Frontiers in Environmental Science 7:126. https://doi.org/10.3389/fenvs.2019.00126

Taylor, Jr., O.R., J. P. Lovett, D. L. Gibo, E. L. Weiser, W. E. Thogmartin, D. J. Semmens, J. E. Diffendorfer, J. M. Pleasants, S. D. Pecoraro, and R. Grundel. 2020. Is the timing, pace and success of the monarch migration associated with sun angle? Frontiers in Ecology and Evolution 7:442. https://doi.org/10.3389/fevo.2020.00043

Weiser, E. L., J. E. Diffendorfer, L. López-Hoffman, D. Semmens, and W. E. Thogmartin. 2020. Challenges for leveraging citizen science to support statistically robust monitoring programs. Biological Conservation 242: 108411. https://doi.org/10.1016/j.biocon.2020.108411 

Thogmartin, W. E., J. A. Szymanski, and E. L. Weiser. 2020. Evidence for a growing population of eastern migratory monarch butterflies is currently insufficient. Frontiers in Ecology and Evolution 8:43. https://doi.org/10.3389/fevo.2020.00043 

Diffendorfer, J. E., W. E. Thogmartin, and R. G. Drum (eds.). 2020. North American Monarch Butterfly Ecology and Conservation. Frontiers Media SA, Lausanne, Switzerland. 10.3389/978-2-88966-118-3

Zylstra, E. R., W. E. Thogmartin, M. I. Ramírez, and E. F. Zipkin. 2020. Summary of available data from the monarch overwintering colonies in central Mexico, 1976–1991: U.S. Geological Survey Open-File Report 2020–1150, 10 p.