Big cities with small green areas hold a lower species richness and proportion of migrant birds: a global analysis

LEVEAU, LUCAS MATIAS

URBAN FORESTRY & URBAN GREENING

ELSEVIER GMBH

Año: 2021

1618-8667

Several studies around the world have shown that species richness and proportion of migrant species in birdcommunities increase toward the poles as a result of increased climatic seasonality and a considerable annualvariation of resources. Since migrant species can use urban green areas (UGAs), they may be negatively affected bythe loss of green areas and human disturbances. The aim of this study was to analyze the global pattern of migrantspecies richness and proportion in UGAs, considering the effects of both climatic seasonality and urbanization. Data ofbird communities in UGAs were gathered through a search of scientific articles, book chapters, thesis works andunpublished data. Datasets that included a list of observed species, the numbers of parks surveyed and othermethodological characteristics were considered for the analysis. Then, generalized linear models were used to relatetotal bird species richness and migratory species richness and proportion in each dataset to environmental andmethodological variables that controlled for different sampling efforts among studies. A total of 37 cities from fourcontinents were analyzed. Total bird richness increased with the size of UGAs and in the northern hemisphere. Asexpected, richness and proportion of migrants increased with increasing annual range of temperature andprecipitation, and was higher in the Northern Hemisphere. Richness and proportion of migrants decreased withincreasing population size of cities but increased with size of UGAs surveyed. The results suggest that big cities havea negative impact on richness and proportion of migrant species. However, increasing the size and number of UGAsmay benefit migrant species presence in cities.