Abstract:

Aim: One main goal of eco-city development is to improve urban biodiversity. However, it is often difficult to determine how it may influence long-term biodiversity patterns, due to the lack of historical benchmark data. Here, we followed up on a study in urban areas of Nanchong during 2002–2004 by replicating the historical survey methods, to examine changes in the breeding bird community, accounting for nesting and habitat types. 

Methods: From late February to early July 2023, we conducted five round of repeated investigation on the numbers of breeding bird species and nests using point counts in 14 patch green spaces and line transects in 22 roadside green spaces. We compiled an annual dataset based on the recorded species and nests, and then compared it with the historical data. 

Results: We recorded a total of 28 breeding bird species and 1,599 nests (1,451 nests of 17 canopy-nesting species, 87 nests of 6 ground/shrub-nesting species, 31 nests of 4 tree-cavity-nesting species, and 30 nests of 1 artificial-building- nesting species). Compared with the historical data, the total number of breeding species increased by 1, but the average numbers of species and nests across sampling sites decreased by 1.3 (21.4%, P = 0.025) and 90.4 (67.1%, P < 0.001), respectively; the breeding bird community was affected by the interaction of nesting type and habitat type, where species number, nest number and/or Shannon-Wiener diversity index of canopy-nesting birds, ground/shrub-nesting birds and artificial-building-nesting birds showed a significant decrease (P < 0.05) in either patch green spaces or roadside green spaces. In addition, the order of species dominance changed significantly, with two ground/shrub-nesting species and one cave-nesting species that ranked in the top five in the first survey being replaced by canopy-nesting species. 

Conclusion: Over the past two decades of eco-city development in Nanchong, breeding birds have not widely obtained positive ecological benefits, resulting in significant changes in their community composition at the local scale. We recommend that the planning and development of urban green spaces take into account the needs of diverse ecological groups to more comprehensively enhance the ecological benefits of urban construction. This approach will help ensure sustainable biodiversity and the provision of ecological services.

Key words: urban biodiversity, breeding birds, nesting types, roadside green space, patch green space, ecological service functions, long-term changes