Despite rapid and ongoing conversion of natural lands to concrete-dominated urban centers, hundreds of bird species and thousands of plant species are thriving in cities, scientists report in a journal of the Royal Society of Biological Sciences.
The mix of species in any particular city reflects the unique biotic heritage of their geographic location, they wrote.
"While urbanization has caused cities to lose large numbers of plants and animals, the good news is that cities still retain endemic native species, which opens the door for new policies on regional and global biodiversity conservation," study lead author Myla F.J. Aronson of Rutgers University said.
The findings highlight the value of green space in cities, which have become important refuges for native species and migrating wildlife, the researchers said.
Still, cities support far fewer species (about 92 percent less for birds and 75 percent less for native plants) than expected for similar areas of undeveloped land, they said.
"We do pay a steep price in biodiversity as urbanization expands," coauthor Frank La Sorte at the Cornell Lab of Ornithology said.
"But even though areas that have been urbanized have far fewer species, we found that those areas retain a unique regional flavor," he said. "That uniqueness is something that people can take pride in retaining and rebuilding."
The study was conducted by a working group at the University of California, Santa Barbara's National Center for Ecological Analysis and Synthesis.