Abstract: Birds are important indicator species that reflect urban ecological health status and effectiveness of ecological restoration. The current ecological planning and restoration for Pearl River Delta in China lacks supports from bird ecology related data, leading to the quantitative knowledge gap on birds’ habitat selection and movement mechanisms, thus posing challenges for the construction of bird-friendly cities. Taking Hong Kong as the study area, by analyzing eBird data before and during the COVID-19 pandemic, we revealed four major responding mechanisms of local birds when the dramatic pandemic-triggered decrease in human mobility occurred using Shannon index and maximum entropy model: (1) the standard deviation (25.68) of overall bird diversity during breeding season was apparently higher than performances throughout the whole year (15.25) and during overwintering season (12.43), which indicated a higher level of sensitivity to changes in human mobility; (2) the overall bird diversity was high and stable in northern districts, and medium and fluctuated seasonally in central and southern districts, low and fluctuated markedly in core urban districts; (3) the increases no less than 24% in distribution probabilities of the dominant land bird and waterbird species, compared with pre-pandemic situations, mainly occurred in land cover types including grassland, agricultural land, woodland, shrubland, and rural settlement; (4) agricultural land was the only land cover type whose area proportions within  500 m×500 m quadrats were positively correlated with averaged increases in distribution probabilities of the dominant land bird (r=0.25) and waterbird species (r=0.049). Based on the above results, we suggest cities within the Pearl River Delta to generate pertinent schemes for ecological planning and restoration by considering the characteristics of local bird ecology, including seasonal fluctuations, species compositions, and covers.

Key words: birds, spatiotemporal pattern, ecological planning, ecological restoration, eBird.