Grassland butterflies in the Midwestern United States rely on suitable habitat within agricultural landscapes, including pastures. While grazing can degrade insect habitat, rotational grazing has been proposed as a practice that may support biodiversity. We conducted a two-year observational study on 30 cattle pastures in southern Wisconsin to evaluate how grazing management influences butterfly communities and vegetation structure. We compared butterfly abundance, richness, and diversity between rotationally and continuously grazed pastures using standardized transect surveys. Butterfly abundance was 83% higher in rotationally grazed pastures, although richness and diversity were similar across treatments. Structural equation modeling indicated that greater vegetation height and floral frequency in rotational pastures mediated the increase in butterfly abundance. Floral communities and butterfly assemblages also differed in composition between grazing types. Within rotational systems, paddocks at the end of their rest periods had significantly higher butterfly abundance and floral resources than recently grazed paddocks. However, rest period duration (20–60 days) was not predictive of butterfly metrics, suggesting a flexible recovery window may suffice; pollinator life cycle length could be helpful in determining ideal rest period duration. Our results support the promotion of rotational grazing as a biodiversity-friendly practice on working lands. Enhancing pasture structure and floral availability through rest periods may be a practical strategy for integrating butterfly conservation into agricultural management.
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