Nest composition adjustments by Chinese bulbuls pycnonotus sinensis in an Urbanized landscape of Hangzhou (E China)

Urbanization changes the abundance and type of resources upon which birds depend, including the type and availability of nesting materials. Although more and more bird species worldwide are colonizing and adapting to urban environments, the ecological processes underlying the responses to urbanization and the relevant resource changes remain unclear. Here we examined the responses of the Chinese Bulbul Pycnonotus sinensis to urbanization by assessing nest composition and available nesting materials at five land-use categories (mountains, farmlands, riparians, urban parks, strips of street trees) of intensifying development in Hangzhou, China. In each land-use category, we classified used and available nesting materials as anthropogenic (e.g. plastics, paper pieces, cloth pieces, nylon particles, threads) or natural materials (e.g. plant culms, roots, leaves). We found that the proportion of anthropogenic nesting materials used by Chinese Bulbuls differed significantly across land-use categories, and it increased significantly with urbanization. Additionally, the increasing amount of anthropogenic nesting materials with urbanization can be attributed to an increase in the availability of anthropogenic nesting materials toward the urban core. Our results indicate that Chinese Bulbuls can adjust the composition of their nests in response to urbanization.