Detecting the response of bird communities and biodiversity to habitat loss and fragmentation due to urbanization.

Birds are considered a good model for indicators of biodiversity response to habitat variations, as they are very sensitive to environmental change. However, continuous observations of habitat alterations from undisturbed landscapes to human-dominated ones, as well as the associated effects on bird biodiversity, are lacking. In this study, New Jiangwan Town in Shanghai, China was selected to illustrate the response of bird species, and thus biodiversity, to habitat loss and fragmentation. Land use/land cover (LULC) data and bird records from 2002 to 2013 were collected and analyzed. The results suggested that, due to urban sprawl, the area of wetland and shrub land had dropped by 82.4% and 87.3% by the end of 2013. Four different urbanization stages were identified in terms of the spatio-temporal variations in the landscape. To measure bird biodiversity, species richness and relative abundance were calculated, and they could account for the overall trend in biodiversity but might mask the process of species replacement. As an indicator of biodiversity accounting, the mean species abundance (MSA) of the original species would not include exotic or invasive species in its calculation, and its value decreased from 100% to 76.8% to 52.2% to 24.5% in the four corresponding stages. Finally, suggested by redundant analysis, the effects of habitat loss and fragmentation on bird biodiversity differed in various bird communities, and the area and connectivity of wetlands were the most significant variables. Our findings could provide important information to inform bird biodiversity protection and habitat restoration.