The Global Urban Bird Survey: A novel approach to quantifying urban bird diversity through community science

Abstract

Birds are a vital component of urban biodiversity worldwide, yet accurately measuring their abundance and diversity is challenging because most bird survey methods are not designed for highly urbanized environments. Surveys are often limited to parks and other green spaces and are biased toward wealthier neighborhoods and high-income countries, hindering our understanding of how birds use all urban habitats. Our aim was to develop and evaluate an inclusive, global method for surveying urban birds across diverse city environments. We developed the Global Urban Bird Survey, a community-based method using acoustic recorders to inventory birds. Local experts trained and coordinated community members, who conducted repeated surveys in five cities between 2022 and 2024: Dakar (Senegal), Nairobi (Kenya), Rio de Janeiro (Brazil), Paris (France), and Toronto (Canada). Survey locations were selected via a stratified block-randomized design within city cores, ensuring unbiased coverage across urban habitats. We compared the performance of the Global Urban Bird Survey with eBird, a widely used source of community-science data, to assess species richness, occurrence, and spatial coverage. Acoustic surveys effectively captured urban bird diversity. eBird detected significantly higher mean species richness than the Global Urban Bird Survey in Dakar, Nairobi, Paris, and Rio de Janeiro, while no significant difference was observed in Toronto. However, eBird’s spatial coverage was substantially lower than that of the Global Urban Bird Survey, particularly in low-income cities, highlighting gaps in community-science datasets. The Global Urban Bird Survey provides a robust, scalable approach to monitoring urban avian biodiversity across a range of habitats and socioeconomic contexts. Broader, more representative sampling of urban environments is critical for understanding global patterns of biodiversity. Community-based acoustic monitoring complements existing community-science efforts, offering a valuable tool for inclusive conservation planning and informed urban biodiversity management worldwide.