Join us for the City Nature Challenge (CNC), an annual four-day global bioblitz at the end of April when we find and document wildlife where we live using the iNaturalist app on our phones!

Collaborating with our community, this is also a friendly citizen science competition with cities around the world to motivate more people to see how much we can contribute to the documentation of local biodiversity.

The 2025 San Diego County City Nature Challenge Portal is a one-stop-shop for San Diego County City Nature Challenge participants and anyone wanting to learn about the event.

Anyone can participate! We invite you to join one of the City Nature Challenge events around the county or participate on your own.

More About the City Nature Chalenge
The City Nature Challenge is co-organized in San Diego County by the San Diego Natural History Museum and the SDSU Biodiversity Museum. It was started by community science staff at the Natural History Museum of Los Angeles County and the California Academy of Sciences in 2016. Global participation has grown from two cities in 2016 to over 650 today.