Use of evergreen and deciduous plants by nocturnal-roosting birds: A case study in Beijing

With continually increasing urbanization, the land cover in urban areas continues to change, resulting in the loss of biodiversity. Birds are highly sensitive to changes in habitat. Most forest birds perch on plants that provide increased safety to reduce the risk of predation, and small birds may also consider insulation when using roosting plants in winter because of cold weather. Landscaping plants thus shape the nocturnal roosting environment of urban birds, and proper planting is essential for the survival of birds at night. The use of roosting plants by urban birds should therefore be studied to provide a reference for landscaping. In the current study, we observed 1865 nocturnal roosting birds in Beijing from 2021 to 2022, with 23 species of birds from 12 families and 45 species of plants from 22 families recorded. Juniperus chinensis exhibited the highest bird rarity-weighted richness, followed by Fraxinus pennsylvanica, Phyllostachys propinqua, Pinus tabuliformis, and Ulmus pumila. The diameter at breast height, tree height, and crown width of plants used by birds was largest in summer and smallest in winter, and the perch height of birds was the highest in spring and summer and the lowest in winter. Birds used the highest proportion of deciduous plants in summer and the highest proportion of evergreen plants in winter. A significant seasonal difference in the use of evergreen and deciduous plants by small birds was noted, with a preference for deciduous plants in summer and evergreen plants in winter, while this preference was not found in large birds. These findings indicate that evergreen plants provide a vital nocturnal roosting environment for small birds in winter. To provide a better nocturnal roosting habitat for urban birds, we recommend paying attention to the combination of evergreen and deciduous plants when carrying out landscape construction.