The 2021 MJV Monarch Research Review is a free resource that gives monarch enthusiasts of all stripes easy access to key takeaways from the latest scientific literature about monarchs and their habitat.
Each year, MJV staff and volunteers read and summarize dozens of peer-reviewed articles, which are then compiled in the annual Review. The 2021 Review includes 85 articles published between September 2020 and December 2021 on topics ranging from monarch biology and populations, pollinator habitat quality and conservation to climate change and other stressors, migration dynamics, genetic research, and more. Research and Partnership are two pillars of the MJV’s work, and the Monarch Research Review helps us share the latest scientific information to inform and support collective conservation actions across the North American monarch’s range.
The Review is a free, downloadable PDF. We encourage you to read it in full and share it widely! We’ve also summarized a few noteworthy findings here:
- Several new methods and technology for tracking monarchs offer possibilities for understanding monarchs' migratory paths and habitat use. These include a non-invasive method of testing flight direction in a flight simulator, a small transmitter that delivers locational data to a nearby receiver, and a system to facilitate collection of data from small radio telemetry tags (Parlin et al. 2021, Lee et al. 2021, Fisher et al. 2021).
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Warmer winters and an abundance of non-native milkweed in the San Francisco Bay Area likely contributed to an unusually high number of monarchs breeding in this area through the past winter. The implications this may have on the western population as a whole are unknown, though it could indicate a broad and significant shift in overwintering strategy, and is unlikely to offset western population losses overall (James 2021, Crone and Schultz 2021).
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The changing climate is impacting eastern monarchs: they migrate south along the eastern seaboard almost two weeks later than they did 30 years ago, their summer populations are more greatly impacted by breeding season weather than they were 20 years ago, and "hotspots" of population increase and decline are shifting with the changing climate (Culbertson et al. 2021, Zylstra et al. 2021, Crossley et al. 2021).
- Despite the pervasiveness of pesticides near agricultural fields, field edge habitat may have a net positive impact on monarchs, especially with Integrated Pest Management and specific practices such as applying pesticides low to the ground rather than aerially. However, new research adds to the evidence that neonicotinoids have lethal and sublethal impacts on monarchs, including failure to completely eclose from the pupa (Grant et al. 2021, Krueger et al. 2021, Krishnan et al. 2021).
In the Review, individual papers are linked in the References section, and many are open source, which means you can read the full article for free. If you’re interested in reading a non-open-source article, you can contact article authors by email to request a copy. Just follow the link in the References section; usually author contact information is given on the article’s page.
The Monarch Research Review is a collaborative effort made possible through the time and expertise of our volunteer reviewers. Thank you, MJV volunteers!
The Research Review is one of many MJV science initiatives. Learn more about the work of the MJV Science Program, and while you're here, join us for free monthly monarch conservation webinars!
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