Assessing Corvus frugilegus (Rook) habitat preferences through flock-size-specific species distribution modeling using citizen science data

Urban environments face significant challenges due to the presence of large bird flocks, such as rooks (Corvus frugilegus), which contribute to sanitation issues and property damage. Using citizen science, we gathered extensive data on rook populations in Suwon, South Korea. Over two years, citizens submitted 17,923 photographs of rooks via a smartphone application, including the locations of sightings, enabling the collection of robust datasets without extensive training. Using the MaxENT model, we analyzed rook occurrences while differentiating by flock sizes—small (≤100 individuals), medium (101–1000 individuals), and large (>1000 individuals). All models demonstrated high reliability, with AUC values exceeding 0.80. Our analysis revealed that large flocks predominantly occupied urban areas near agricultural lands, with a marked preference for close proximity, while small and medium flocks exhibited a more dispersed distribution. Furthermore, we aimed to analyze how much the Species Distribution Modeling (SDM) run with number of rook observations regardless of the flock sizes either overestimated or underestimated rook occurrence probabilities, when compared to the models run separately for each flock size. Notably, models based on the number of rook observations regardless of flock size significantly underestimated the habitat suitability for large flocks, underscoring the importance of incorporating flock size into predictive modeling. These findings emphasize the need for size-specific management strategies and highlight the utility of citizen science as a scalable tool for urban wildlife management.