City Nature Challenge

Ready for some friendly competition? City Nature Challenge is a global effort to document urban biodiversity—and to see which city can make the most observations, record the most species, and rally the most participants! To take part, use the iNaturalist app to photograph and share the wild plants and animals you find in your community.

Our record-breaking 2025 Challenge just wrapped—click below for photos and observations from around the world!

Started in 2016 as a competition between San Francisco and Los Angeles, the City Nature Challenge has grown into an international event, motivating people around the world to find and document wildlife in and around their cities, using biodiversity recording apps and platforms like iNaturalist.

Run by the Community Science teams at the California Academy of Sciences and the Natural History Museum of Los Angeles County, the City Nature Challenge is an annual four-day global urban bioblitz at the end of April, where cities are in a collaboration-meets-friendly-competition to see not only what can be accomplished when we all work toward a common goal, but also which city can gather the most observations of nature, find the most species, and engage the most people in the event.

From getting the word out to hosting events, the Academy's Bay Area partners make City Nature Challenge the inspiring, empowering, and fun 4-day nature bioblitz that it is—and we are incredibly grateful. Click the links below to learn more about each group.

Bay Nature Magazine | BioBlitz Club | California Native Plant Society | California Native Plant Society Yerba Buena Chapter | California Lichen Society | California State Parks: Candlestick Point SRA | California State Parks: Sugarloaf Ridge SP | East Bay Regional Park District | El Cerrito Trail Trekkers | Enterprise for Youth | Friends of the Urban Forest | Foodwise | Golden Gate Bird Alliance | Golden Gate National Parks Conservancy | Grassroots Ecology | John Muir Land Trust | Keep Coyote Creek Beautiful | Latino Outdoors SF Bay Area | Marin County Parks | Nature in the City | Pepperwood | Presidio Trust | Rotary Nature Center Friends | San Francisco Botanical Garden | San Francisco Environment Department | San Francisco Public Library | San Francisco Unified School District | San Mateo County Parks | Sisterhood Gardens | Solano County Office of Education | Solano Land Trust | Sonoma Ecology Center | Treasure Island Development Authority | Wild Oyster Project