D3296: Using community science to track monarchs in the West

In the Western United States, migratory monarch butterflies experienced precipitous declines, with an estimated 95% reduction of individuals recorded at overwintering sites since the 1980's and just 2,000 adults reported in Thanksgiving of 2020. Spring is a critical time for monarchs, as it is when the population numbers are the lowest and the adults that successfully survive the winter are old and physiologically stressed. This is also when adults start leaving the overwintering sites to reproduce and begin the journey inland from the Pacific Coast. In this study, we use a community-science approach, the Western Monarch Mystery Challenge, to collect wide-scale data on monarch occurrence throughout the Western United States between Valentine's Day and Earth Day from 2020-2022. Participants submitted images of adult monarchs that were then processed by our team to determine the geolocation of the observation, the sex of the butterfly, and its approximate age based on wing wear. Our results suggest that urban landscapes, especially in Northern California, are apparent hotspots of monarch abundance in early spring. We also collected a number of submissions from historically under surveyed regions – areas which might be critical to restoration strategies to bolster breeding habitat in the early spring. The results of this study lend important insight into monarch declines in the West and reveal regions of conservation priority to support this vulnerable population.