A comprehensive mapping of the North American migration patterns of the iconic monarch butterfly could help preserve a species threatened by loss of habitat and food sources, a team of international
researchers says. In a study conducted across 17 U.S. states and two Canadian provinces, from southern Texas to Alberta, biologists from Canada, the U.S., and Australia tracked the northward migration of the monarchs, documenting five generations in a single breeding season. By analyzing a chemical signature found on the adult butterflies’ wings that reveals their specific birthplace, scientists were able to track the different generations of butterflies as they migrated north to the U.S. Midwest, from which many butterflies then traveled to Alberta. According to Tyler Flockhart, a Ph. D. student at the University of Guelph in Canada and lead author of the study published in the Proceedings of the Royal Society B, the decline in milkweed and a surge in genetically modified crops might be affecting monarch survival.