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Poster Short Abstract

The City Nature Challenge Berlin engages citizens in biodiversity monitoring. Analysis of 2023–2024 data highlights the role of highly active participants and species experts in generating quality observations across diverse taxonomic groups

Poster Abstract

Human-induced biodiversity loss calls for innovative, resource-efficient monitoring approaches, such as Citizen Science, to complement traditional methods. BioBlitz events are an established Citizen Science format that generates as many species observations as possible in a short period within a defined area, through collaboration among scientists, citizens, and nature enthusiasts. The City Nature Challenge is the most prominent large-scale urban BioBlitz worldwide. Participation in the City Nature Challenge Berlin increased from 184 contributors in 2023 to 361 in 2024, reflecting growing public engagement. Analysis of observations revealed that while a few highly active participants contributed disproportionately to total observations, their involvement strongly influenced data quality and coverage. Comparison with the Global Biodiversity Information Facility reference dataset showed that taxonomic groups such as birds, reptiles, fish, and mammals were more likely to reach “Research Grade” on iNaturalist, while fungi, lichens, insects, arachnids, protozoans, and chromista were more dependent on expert contributions. Of 2,440 reference species, 1,027 (42%) were detected during the 2023–2024 events. These findings highlight that BioBlitz events provide valuable, high-quality data that complement long-term biodiversity monitoring and help address research gaps, particularly for endangered, invasive, and conservation-relevant species. We encourage researchers to explore large BioBlitz datasets in other regions or at larger geographic scales to maximize the potential of citizen-generated biodiversity data.