Time series of monarch butterfly overwinter abundance in Mexico

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.