The researchers examined 459 natural woodlands located in or near 32 cities in southern Sweden. They counted the occurrence of different bird species, and the result is clear: in natural forests located in a city center, there are on average a quarter fewer species of forest birds compared to forests outside the city. In terms of endangered species, about half as many species were found in urban forests compared to rural forests.
Further reading
Read the article in full at lunduniversity.lu.se
Link to the article in Global Change Biology:
Urbanization causes biotic homogenization of woodland bird communities at multiple spatial scales