Abstract:

Aims Birds serve as an ideal indicator group for assessing biodiversity. The China Bird Report is currently the largest citizen science data platform for bird monitoring in China, covering 94% of the national bird species and 94.3% of the county-level administrative regions. Leveraging public science data and referring to the threatened species richness index in the Regional Biodiversity Assessment Standards (HJ 623-2011), we have developed a methodology to construct both a bird species richness index (R_{B_A}) and a threatened bird species richness index (R_{TB_A}). Through this approach, we proposed a new method for assessing regional bird diversity.

Methods We calculated the cumulative recorded bird species count in each province-level, prefecture-level, and county-level administrative regions (excluding municipal districts) in the China Bird Report from 2014 onwards, aiming to assess the coverage rate of officially released bird species checklist, and the coverage rate of threatened bird species checklist at provincial level. Furthermore, we calculated the annual R_{B_A} and R_{TB_A} for each province-level, prefecture-level, and county-level administrative regions (excluding municipal districts) from 2018. The analysis was conducted to understand the year-by-year changes in bird species richness across different regions. Besides, we also analyzed the developmental trends of dataset of the China Bird Report and tested the sensitivity of the two indices.

Results The analysis revealed a consistent increase in the bird species coverage rate from the China Bird Report across administrative regions at all levels nationwide since 2014. By 2023, the bird species coverage had surpassed 90% in 94.1% of province-level, 59.0% of prefecture-level, and 49.0% of county-level (excluding municipal districts) administrative regions. Although the coverage of threatened bird species at provincial level also exhibited an upward trend, it slightly lagged behind the coverage of all bird species. Since 2020, there had been a steady rise in the number of bird species observed at provincial level annually, but some provinces experienced a decline in the annual bird species observed in 2022. Since 2020, The R_{B_A} and R_{TB_A} values of each provincial administrative region showed an overall upward trend. R_{B_A} ranged from 0.50-0.96, R_{TB_A} ranged from 0.45-0.98, indicating that R_{TB_A} is more sensitive.

Conclusion The results of this study show that R_{B_A} and R_{TB_A} have significant application value in regions where local users submit sufficient records, and they can serve as reliable biodiversity assessment indicators. R_{TB_A} demonstrates higher sensitivity to changes in bird diversity, effectively reflecting the conservation status of local bird populations. With the development of citizen science platforms like the China Bird Report, evaluation indices based on public science, represented by R_{B_A} and R_{TB_A}, hold huge potential in species diversity assessment and species monitoring endeavors.

Key words: citizen science, birds, bird species richness index, threatened bird species richness index, biodiversity assessment