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.