Filling in the Gaps: Working in Un-Surveyed Areas to Create Baseline Data, Habitat Use and Abundance Estimates for Butterflies in Eastern Wyoming, USA

Butterflies are charismatic insects that are critical pollinators for plants that humans and wildlife depend on; however, butterflies have some of the largest measured declines. Two iconic butterflies in the USA, the Regal Fritillary (Argynnis idalia) and the Monarch (Danaus plexippus), are proposed for protection due to decreasing numbers from overexploitation, agricultural activities, disease and development. We surveyed 145 sites and walked 557 km from mid-June to August in 2019 and 2021 to create baseline information for butterflies and fill in knowledge gaps for these species. We observed 16,986 individuals and identified 52 species of butterflies. Generally, butterflies were more abundant at lower wind speeds and in areas with higher forb cover and less bare ground. We identified more species in locations with taller grass, higher bloom densities, higher cover of forbs, and less bare ground. We observed 11 Regal Fritillaries and 31 Monarchs extending from northeastern to southeastern Wyoming in a variety of habitats. The predicted suitable habitat of Regal Fritillaries and Monarchs was highly influenced by sagebrush cover and mean temperature of the wettest quarter according to species distribution models. Our results provide information to managers about the status, distribution, and habitat use of butterflies in a previously un-surveyed area. Historical butterfly surveys were limited to mountain ecosystems, and we provide baseline information on the habitat characteristics that support the highest abundances and most species in prairie ecosystems that can be compared to future efforts.