Date: 2018 to present
Primary Contact: Priscilla Crawford
Research Location: Central Oklahoma
Monarch butterflies (Danaus plexippus) have become an iconic symbol for butterfly conservation and a focus of invertebrate conservation at the national, state, and local levels. Conservation efforts would benefit from a better understanding of the butterfly’s use of habitat along its migratory path. Oklahoma is in an important geographic position for the Monarch butterfly as a significant portion of the migrating individuals of the eastern population fly through the state in both spring and fall. However, few investigations have examined the population in Oklahoma (however, see Baum and Sharber 2015, Clement and Crawford 2020, Dee and Baum 2019 for examples). Anecdotal observations indicate the yearly fluctuation of Monarch sightings in Oklahoma from early spring until late fall. Data collected in 2019, 2021, 2022, and 2023 on small milkweed plots in Norman indicate a large variation in the number of Monarch adults and larvae observed during the growing season. At this time, no one has investigated the cause of this variation. We hypothesize that Monarch numbers are closely related to weather conditions locally and along the migratory path. In Texas, migration has been shown to be affected by weather patterns (Park 2019). By comparing weather data and butterfly observations we intend to determine what is influencing the Monarch population in Oklahoma.
In particular, we are interested in the reproductive Monarchs that are observed in late summer and early fall. On average, this is the most abundant Monarch population in Oklahoma. The caterpillars and subsequent adults during this time have been referred to as the “Fifth Generation” of the annual Monarch cycle (Brower 1996). This generation of Monarchs is not well understood or documented. Research effort has focused on early rounds of reproduction that occur during the summer in the upper-Midwest. To better direct conservation efforts in Oklahoma, it is important to understand this reproductive population. What host plants are they using and is this a limiting resource? What weather conditions are correlated with Monarch reproduction and migration?
We are also interested if different milkweed species affect Monarch migration behavior. Currently we believe that Asclepias viridis is the most common larval host plant Oklahoma, but undisturbed natural populations of A. viridis senesce by late summer when some adult Monarchs start arriving in Oklahoma (Tracy 2022). Researchers at Oklahoma State University have found that mowing and fire mid growing season stimulated new grow A. viridis, providing high quality foliage for caterpillars (Baum and Sharber 2015, Dee and Baum 2019). Citizen scientists in Oklahoma who have been working on Monarchs for years have mentioned that they find many Monarch caterpillars on Cynanchum leave, a vining milkweed that thrives in the late, hot summer and is productive until the first freeze. Additionally, the non-native Asclepias curassavica provides late summer foliage for Monarch caterpillars. This easy to grow milkweed has become popular to grow in the home setting as a way for citizens “help the Monarch.” Unfortunately, this species has been found to harbor disease (Steele et al 2023), accumulated high concentrations of toxins (Faldyn et al 2018, Agrawal et al 2021), and possibly be a reproductive sink (Batalden and Oberhauser 2015, Clement and Crawford 2020, Majewska and Altizer 2019).
Project Goals and Objectives:
We aim to:
With citizen science and meteorological data available, we will examine what weather conditions and milkweed species are correlated to Monarch abundance and reproduction in Oklahoma.
Through our observational studies, we will examine late summer and early fall reproduction and host plant usage of Monarchs in central Oklahoma.
Students who have provided valuable assistance: Abigail Cervenka, Claudia Goss, Regan Wilcox, Emily Nguyen, Marcus Hulsey, Chloe Paden, Kayleigh Clement, Josh Hughes, and Christian Newkirk.
Agrawal AA, Böröczky K, Haribal M, Duplais C. 2021. Cardenolides, toxicity, and the costs of sequestration in the coevolutionary interaction between monarchs and milkweeds. PNAS 118 (16) e2024463118. https://doi.org/10.1073/pnas.2024463118
Batalden RV, Oberhauser KS. 2015. Potential changes in eastern North America monarch migration in response to an introduced milkweed, Asclepias curassavica. In Monarchs in a changing world: biology and conservation of an iconic butterfly, edited by Oberhauser KS, Nail KR, Altizer S. pgs 215-224.
Baum KA, Sharber WV. 2012. Fire creates host plant patches for monarch butterflies. Biological Letters 8:968–971. http://doi.org/10.1098/rsbl.2012.0550
Brower LP. 1996. Monarch butterfly orientation: missing pieces of a magnificent puzzle. Journal of Experimental Biology. 199: 93–103. https://doi.org/10.1242/jeb.199.1.93
Dee JR, Baum KA. 2019. Mowing frequency influences number of flowering stems but not population age structure of Asclepias viridis, an important monarch host plant. American Midland Naturalist 182:27-35. https://doi.org/10.1674/0003-0031-182.1.27
Faldyn MJ, Hunter MD, Elderd BD. 2018. Climate change and an invasive, tropical milkweed: an ecological trap for monarch butterflies. Ecology 99:1031-1038. https://doi.org/10.1002/ecy.2198
Majewska AA, Altizer S. 2019. Exposure to non-native tropical milkweed promotes reproductive development in migratory monarch butterflies. Insects 10. https://10.3390/insects10080253
Park J. 2019. Impacts of prevailing winds on migratory patterns of Danaus plexippus (monarch butterflies) along overnight roosts in Texas. Available from ProQuest Dissertations & Theses Global. (2234466185). Retrieved from https://login.ezproxy.lib.ou.edu/login?qurl=https%3A%2F%2Fwww.proquest.com%2Fdissertations-theses%2Fimpacts-prevailing-winds-on-migratory-patterns%2Fdocview%2F2234466185%2Fse-2%3Faccountid%3D12964
Steele C, IRagonese IG, Majewska AA (2023). Extent and impacts of winter breeding in the North American monarch butterfly. Current Opinion in Insect Science 59: 101077. https://doi.org/10.1016/j.cois.2023.101077
Tracy JL, Kantola T, Baum KA , Coulson RN. 2022. Distribution and phenology of monarch butterfly larvae and their milkweed hosts in the South-Central US. Biodiversity Conservation 31, 1797–1827. https://doi.org/10.1007/s10531-022-02432-7
