Scientists are analyzing a rare snapshot in time of urban plants and animals. To better understand whether rapidly growing cities are hosting the same species, a concept known as urban homogenization, a team from the California Academy of Sciences analyzed an immense volume of data gathered by citizen scientists during the four-day global City Nature Challenge. The 14 U.S. cities included in the study amassed more than 65,000 wildlife observations identified to species level through the mobile app iNaturalist. Study findings suggest that despite similarities across cities, urban biodiversity still strongly reflects the species that are native to a region. However, observations of shared “cosmopolitan” species like pigeons, white-tailed deer, and dandelions were more numerous than locally occurring species. The study, published today in the journal PeerJ: Life & Environment, highlights the value of citizen science data in addressing complex questions about rapid changes in urban ecology.
“We found that the best predictor for the composition of a city’s plant and animal community is the surrounding region,” says Dr. Misha Leong, lead author and postdoctoral researcher. “This is reassuring in many ways because it tells us that urban biodiversity is not converging at the pace some predicted.”
Previously, multi-city studies examining urban homogenization were limited to simple species lists, but data gathered from the 2016 – 2018 City Nature Challenges allowed researchers to compare relative species abundance as well. Over 5,000 species were documented in the 14 U.S. cities involved in the study. Of those documented, only 100 species occurred in half of the participating cities. Even though the proportion of cosmopolitan species to native species is small, cosmopolitan species are more abundant—leaving researchers to investigate why.
Read more at California Academy of Sciences
Image: The Mission blue butterfly is a rare species only found in the San Francisco Bay Area. (Credit: Scott Loarie © California Academy of Sciences)