Acknowledgements
We are grateful to S. Altizer, C. Edwards, D. James, and N. Warchola for allowing us to reinterpret data from their past and ongoing research in support of this essay, and to M. Power for comments on an early version of this essay. K. Dooley participated in three surveys. Our ideas have benefitted from conversations with the community of biologists and policy-makers working with monarch butterflies. Both authors acknowledge support from NSF DEB 19-20834 and DOD SERDP RC-2700.