Urban Forestry & Urban Greening | 2021
Raptor breeding sites indicate high taxonomic and functional diversities of wintering birds in urban ecosystems
Abstract
Abstract With ongoing rapid urbanization, urban biodiversity conservation is becoming a primary issue for the maintenance of urban ecosystem functions, and given that birds play valuable ecosystem roles, their preservation is a matter of both ecological and social importance. Although it is generally considered that urban areas have low biodiversity and ecosystem value, these areas can serve as important wintering grounds for both resident and migratory birds. However, as comprehensive surveys of such biota are time- and resource-consuming, it would be useful to establish efficient conservation surrogates that could be used to identify areas of conservation importance. In this study, I evaluated the efficacy of raptor habitats as a conservation surrogate for high avian taxonomic and functional diversities in urban ecosystems in the wintering season. From December 2019 to February 2020 (wintering season), avian species that appeared within 500 m of 30 Northern Goshawk (Accipiter gentilis) breeding sites in eastern Kanagawa Prefecture, Japan, were investigated using point counts. I subsequently measured species richness and dendrogram-based functional diversity (FD) as indicators of avian taxonomic diversity and the ecosystem functions provided by birds, respectively, and performed the same procedures at 30 randomly selected points in areas similar to goshawk breeding habitats. Thereafter, using generalized linear models, I compared species richness and FD at sites with and without goshawk nests. I accordingly found that the presence of goshawk breeding sites is significantly positively associated with avian species richness and FD, explaining most of the variability in these data (species richness: 66.4 %, FD: 66.0 %). In conclusion, these findings indicate that goshawk breeding sites could be used as a conservation surrogate to identify and preserve habitat hotspots for wintering birds in urban ecosystems. These results can provide a basis for implementing appropriate conservation measures to maintain avian diversity in urban ecosystems.