Assessing urban environmental quality and citizen science data quality: Identifying indicator bird species in cities of China

Bioindicators are frequently employed for rapid, large-scale assessments of biodiversity and environmental quality. An ideal indicator species should be easy to recognize and have a wide distribution, making them suitable for long-term monitoring of urban ecosystem changes through citizen science projects. To date, bird species or groups of birds proposed as bioindicators in urban areas across China is still missing, and reliability of the data from China’s citizen science bird projects (China Bird Report, CBR) have not been accessed. In this study, we conducted standardized bird surveys in the provincial capitals of 34 administrative regions in China. By considering bird species diversity, phylogenetic diversity, functional diversity, environmental heterogeneity, and urban built-up area, areas with high environmental quality (HEQ) and their indicator bird species were identified by the indicator value (IndVal). Our results showed that the Spotted Dove (Spilopelia chinensis), Chinese Blackbird (Turdus mandarinus), Light-vented Bulbul (Pycnonotus sinensis), Azure-winged Magpie (Cyanopica cyanus), and Barn Swallow (Hirundo rustica) were identified as important indicator species for urban ecosystems in China. The present study also highlights that the quality of the data generated from CBR should be improved. Specifically, there is a need for improved data quality control in the early stages of reporting and enhanced data filtering and analysis methods in the later stages to mitigate sampling biases.