City Nature Challenge Marks 10 Years of Bringing the World Together to Study Biodiversity

SAN FRANCISCO, CA (March 18, 2025) — City Nature Challenge, one of the world’s largest community science events, returns for its 10th year of connecting people through local nature and their communities. Kicking off Friday, April 25 at 12:01 a.m., the Challenge runs through 11:59 p.m. on Monday, April 28. From participating in organized biodiversity surveys to recording the wildlife in their own neighborhood, City Nature Challenge encourages community scientists of all levels to explore their local environment—all while contributing to biodiversity science and conservation and using free mobile apps like iNaturalist. Identification of photographed species will be crowdsourced through the online community April 29 – May 4, and results will be announced on May 5.

"We're thrilled to celebrate 10 years of City Nature Challenge, one of the most impactful community science events in the world. Over the past decade, its reach has expanded across hundreds of cities on all seven continents and has engaged tens of thousands of participants who contribute millions of observations each year," says Rebecca Johnson, PhD, Director of Community Science at the California Academy of Sciences and Challenge Co-Founder. "Not only does the City Nature Challenge provide an amazing opportunity for people all over the world to celebrate nature near them, but the data we collect together is critical to informing conservation decision-making at all scales, from the local to the global. Every year, participants document rare and endangered species, new invasive species, and make other important contributions to our understanding of biodiversity."

Launched by the California Academy of Sciences and the Natural History Museums of Los Angeles County (NHMLAC) in 2016, the Challenge started with just 1,000 observers in San Francisco and Los Angeles. In 2024, the Challenge broke numerous records, with more than 83,500 community scientists around the world amassing over 2.4 million observations from 690 cities in 51 countries. Since its inception, City Nature Challenge has collected over 7.13 million urban biodiversity observations of 94,000+ species, and engaged over 364,000 people.

In previous years, observations made during the Challenge have helped scientists detect patterns of biodiversity change on a global and local scale. These wildlife observations provide invaluable insights that support scientists, conservationists, and policymakers to make informed resource management and conservation decisions that can help curb biodiversity loss. City Nature Challenge is aligned with conservation strategies both locally and globally, particularly the 30x30 effort as outlined in the Kunming-Montreal Global Biodiversity Framework targets. California is a world leader in 30x30, which aims to protect 30% of the world’s lands and coastal waters by 2030.

“Last year, we were able to share the success of the City Nature Challenge in front of hundreds of world leaders at the United Nations’ Convention on Biological Diversity,” said Lila Higgins, NHMLAC’s Senior Manager of Community Science and Challenge Co-Founder. “It really shows that events like City Nature Challenge — which started off as just a fun way to engage Californians with their local nature — can grow into large-scale efforts helping to tackle really big global problems.”

How to Participate
For both budding and veteran community scientists, participation is easy. Photos taken during the Challenge can be uploaded to iNaturalist, where an online community of naturalists confirms species identifications.

Wildlife can be found in the participants’ homes, neighborhoods, backyards or anywhere else, and can be any wild plant, animal, fungi, slime mold or other evidence of life (scat, fur, tracks, shells, etc.). Whether participating in an organized habitat survey or making observations in their own neighborhood, participants can upload photos or sound recordings of their findings to iNaturalist or their city’s chosen platform via app or website where they can learn more about the plants and animals they find as their observations are identified.

Those not able to take photos or record their observations can still participate by helping identify species documented in their area during and after the Challenge. Many organizers in cities around the world will be hosting wildlife identification events Tuesday, April 29 – Sunday, May 4.

See participating cities and learn more about the City Nature Challenge.

Social Media
#CityNatureChallenge
Twitter handle: @citnatchallenge
Instagram: @citnatchallenge

Assets
Photos can be found here.
Credit: Gayle Laird © California Academy of Sciences

Media Contacts
Megan Ely, mely@calacademy.org
Josh Chesler, jchesler@nhm.org (NHMLAC)