A citizen army for science: Quantifying the contributions of citizen scientists to our understanding of monarch butterfly biology

The first monarch citizen science program was launched in the 1950s, and since then, thousands of volunteers have made fundamental contributions to our accumulating knowledge of monarch biology. We quantified these efforts and the degree to which citizen science has contributed to monarch scholarship. We estimate that in 2011 volunteers spent over 72,000 hours collecting data useful for monarch research. Of 503 monarch-focused research publications in which new results were presented from 1940 to 2014, 17% used citizen science data. We address persistent gaps in the use and coverage of these data and show that, despite a typical view of volunteers as mere data collectors for scientists, many citizens are deeply engaged in all aspects of monarch research and data use. Finally, we argue that monarchs provide a model system for understanding the impacts of citizen science on scholarship, public engagement, and conservation.