Matt Forister, myself, and our collaborators at the Xerces Society and the USFWS have a new paper out titled "Host Plants and Climate Structure Habitat Associations of the Western Monarch Butterfly" which is published in the journal Frontiers in Ecology and Evolution. In this paper we model the habitat associations between monarch butterfly, their milkweed host plants, and a number of climatic, topographic, land use, and soil variables. We also perform habitat modeling for 13 of the most common milkweed species in the western U.S. Our study is the first large-scale habitat modeling study focused on the western population of the monarch butterfly which overwinters on the California coast and migrates inland towards the Rocky Mountains. Our paper is open access meaning that anyone can read and download it. You can go to it by clicking HERE.
To facilitate this kind of modeling we used an online citizen-science mapping tool called the Western Monarch and Milkweed Mapper. You can use the WMMM to upload your photos of monarchs and milkweeds in order to help us build better models in the future! The WMMM also flags recent monarch sightings so that you can see when the monarchs are arriving in your area. The WMMM also has great resources for learning how to identify the different species of milkweeds. You can access the Western Monarch and Milkweed Mapper by clicking HERE.
Our habitat modeling work was also made possible by the tremendous amount of legwork by Madeline Steele and Joe Engler (USFWS) who completed a first version of these habitat models in 2016. Most of the variables that we used were originally compiled by Madeline, and the methods that we used followed Madeline's approach.
Finally, we should note that we have made high-resolution maps as well as details about the methodology available in the supplementary material. I would encourage you to check out these resources. For GIS users we have GeoTIFF versions of our maps available. Please contact me and I will send you a link to these files.
Citation: Dilts, T.E., Steele, M.O., Engler, J.D., Pelton, E.M., Jepsen, S.J., McKnight, S.J., Taylor, A.R., Fallon, C.E., Black, S.H., Cruz, E.E., Craver, D.R., & Forister, M.L. (2019) Host plants and climate structure habitat associations of the western monarch butterfly. Frontiers in Ecology and Evolution, 7, 188.
