Explicit incentives increase citizen science recordings

From tracking land‐use change to biodiversity loss, citizen science data have become a cornerstone for conservation. However, policymakers must understand the “data‐generating process” to make good use of existing citizen science data and encourage the production of useful new data. We analyze data from the two largest German online platforms for ecological observations to explore and quantify the effect of explicit incentives on volunteer recordings, created by a large‐scale prize competition on one of the platforms. We find 10% more recordings during the prize competition. Moreover, the effects of weather and weekends are attenuated during the competition period. Finally, the diversity of recorded species decreases. Our study shows the first statistical evidence that using explicit incentives increases the quantity of citizen science data. It highlights the need to further study the effect of explicit incentives on data quality and the engagement of citizens for conservation.