The Effects of Modern Urbanization on Fall Migration Patterns of Monarch Butterflies


Briana Thomas
Patrick Guerra


By Briana Thomas, Biological Sciences

Advisor: Patrick Guerra

Abstract: The mass migration of the monarch butterfly (Danaus plexippus) from Canada to the overwintering sites in the mountains of Mexico is an annual phenomenon, however, in recent years the population has been on the decline. However, there is still limited research about macro-environmental factors influencing migration. Previous research on orientation mechanisms of D. plexippus during migration has shown that solar position and magnetic compass are significant factors that influence their migratory paths. However, with the most recent changes in urbanization, other stimuli may impact their flight patterns, such as, night-time light pollution, limited canopy cover, and urban imperviousness. The objective of the study was to analyze whether the modern stressors from urbanization could impact migration routes of D. plexippus. We analyzed participatory-science data of monarch butterfly sightings with geospatial data to explore these stressors. We predicted that night-time light pollution would cause migrations to shift throughout the explored period, as the artificial light may disorient their migration routes and roosting sites. Likewise, we also predicted that with the lack of canopy cover and urban impervious would decrease the amount of shelter available, forcing the monarchs to fly further or shift their migratory pathway. Preliminary analysis shows consistency with our predictions as migration routes have shifted during the 7-year period around urbanized areas. Given the progression of urbanization, these results can provide insight into the conservation efforts of D. plexippus.


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