COS 75-3 - Effects of seasonal light and climate on butterfly community abundance and behavior

Background/Question/Methods

Communities undergo seasonal changes in species composition and abundance, but determining what environmental factors drive these changes can be difficult. Behaviors of animals in communities also can change seasonally and are crucial in shaping ecosystems. Butterflies provide a valuable service through their pollination behavior and exhibit species specific preferences for different colors and flowers. Characterizing diversity in butterflies’ responses to environmental change is important for pollinator health. To assess seasonal variation in butterfly abundance and taxonomic diversity, we conducted transect walks once monthly from July 2017 through December 2021 at a botanical garden and a restored prairie in Fayetteville, Arkansas, US. We also surveyed every other week from May into November in 2018, 2019, and 2020 at three prairie sites to obtain more fine-grained abundance data. To identify seasonal variation in butterfly behavior at a community scale, we recorded behavior during our biweekly transect walks in 2019 and 2020. Butterflies were identified to lowest tax possible; for this analysis we grouped them into families Hesperiidae, Lycaenidae, Nymphalidae, Papilionidae, and Pieridae. We then correlated abundance and behavioral data with time of year, light irradiance data recorded during each survey, and temperature and precipitation data obtained from a local regional weather station.

Results/Conclusions

We observed seasonal changes in abundance and behavior that correlated with family status and environmental conditions. Butterfly abundance increased with total irradiance and decreased with weekly precipitation and depended on the month of the survey. Behavior was also affected by total irradiance, as observations of resting and basking increased as irradiance decreased. Though environmental conditions interacted with family status to affect abundance and behavior, not all interactions that affected abundance also affected behavior. Total light irradiance affected butterfly abundance, impacting nymphalid numbers to a greater degree than abundance of butterflies from other families. Behavior however, was not affected by interactions between total irradiance and family status. By including light irradiance recordings we were able to better discriminate how seasonal factors such as light environment, temperature, and precipitation affect butterfly abundance and behavior. Furthermore our results indicate that butterflies, while often treated as a monolithic group of pollinators, display diverse patterns of behavior. An understanding of how environmental conditions differentially affect butterfly communities is important, as it informs efforts to protect prairie ecosystems.