D3285: Effects of prairie restoration and management on monarch abundance

Monarch butterflies have been in decline since the 1950s, with populations decreasing by as much as 80% over the past 25 years. Research suggests that increased monarch mortality is the result of decreased floral resource availability, milkweed decline, loss of wintering habitat, and extreme weather. Current monarch conservation efforts in the United States focus on increasing milkweed abundance. Although high milkweed density may be the most effective way to help monarch recovery, floral resources are also necessary to provide nutrition for adult monarch butterflies. This study aims to gain a better understanding of which restoration efforts optimize monarch habitat. We ask the following questions: 1) Do restored tall grass prairies support healthy monarch populations? 2) Do restorations managed with fire result in larger monarch populations? 3) How does milkweed and floral resource abundance interact to affect monarch population size?



We visited 42 restored prairies throughout southern Wisconsin and measured milkweed density, floral resource availability, and monarch abundance at each life stage. All study sites had an agricultural land-use history and fell into three restoration categories: passively restored sites, seeded sites and sites that have been seeded and managed with fire. Our preliminary analyses show no significant difference in milkweed density or monarch abundance between these restoration categories. Milkweed density had a significant positive correlation with monarch abundance; however, floral resources did not. Additionally, management by fire did not seem to affect milkweed density or monarch abundance. Our data suggests that milkweed density influences monarch abundance more than restoration effort.