CCS City Nature Challenge

City Nature Challenge


The City Nature Challenge began as a nature-observation competition between the San Francisco Bay Area and Los Angeles County in 2016. Since then, the competition has expanded worldwide, with over 160 cities participating in 2019. Participants use the iNaturalist app to photograph, catalogue and identify observations of wildlife in the area, thus learning from each other and contributing to a global database that scientists all over the world can access and use to help better understand and protect nature.

In 2019, Sacramento took part in the City Nature Challenge for the first time, and we were amazed by its success! Over 500 people participated, logging 9,798 local observations of 1,279 species. Many different collaborators contributed to the success of the CNC Sacramento. In Woodland, CA, educators taught elementary students how to bioblitz, and the California Naturalist Program, along with several research and nature centers, hosted their own bioblitzes.

Based on the amazing turnout last year, we’re aiming for 10,000 observations in 2023. Click here to read more about the City Nature Challenge and find out how you can get involved.

Blog entry Diego Serrano

Bradshaw Scholar Reflections on the 2023 City Nature Challenge

Congratulations to our UC Davis Center for Regional Change Bradshaw Scholar, Diego Serrano! The past 2 quarters, Diego helped us with a variety of projects, including the Sacramento Region City Nature Challenge. We’re so proud of how much he learned and accomplished. Read Diego’s reflections on his experience.

Blog entry Sarah Angulo

Kicking off the 2023 City Nature Challenge Sacramento

Eighth annual challenge grows to over 450 participating cities on six continents; results announced on May 8

The Center for Community and Citizen Science is excited to once again host the City Nature Challenge for the Sacramento Region. As community and citizen science initiatives build momentum around the world, this year’s eighth annual City Nature Challenge includes more than 450 cities across six continents. Kicking off April 28 at 12:01 am in each time zone, the Challenge runs through May 1, 11:59 pm.

Blog entry Sarah Angulo

Warming up for the City Nature Challenge 2023 with UC Davis Wildlife Society Bioblitz

Just shy of 20 intrepid UC Davis students braved the cold for a morning Bioblitz at the UC Davis Arboretum in February. The purpose of this event was to introduce iNaturalist, practice making observations, and explore the nature in the Arboretum together. It was organized for The Wildlife Society club at UC Davis, with Laci Gerhart and Sarah Angulo facilitating. 

Blog entry

City Nature Challenge 2022 Recap

Infographic showing highlights of the City Nature Challenge 2022: Greater Sacramento Region

Every spring, cities from around the world compete in the City Nature Challenge, a four-day nature observation competition, in an effort to help document urban biodiversity. Held April 29 - May 2, the City Nature Challenge 2022 marked the 7th annual international bioblitz with the most impressive global results yet.

Blog entry

An Overview of the City Nature Challenge

Alexandria Tillett Miller

What is the City Nature Challenge?

The City Nature Challenge is a collaborative international bioblitz that started in 2016 as a competition between Los Angeles and San Francisco. The objective for the challenge is to motivate people in their surrounding area to get outside and document wildlife and general biodiversity. In 2017, the City Nature Challenge went national, and one year later, became a world-wide event.


Did Covid-19 make the “City Nature Challenge” less green?

For his capstone project in the Wild Davis course, taught by CCS Faculty Fellow Laci Gerhart, Nicholas Monty explored spatial shifts in City Nature Challenge observation patterns between 2019 and 2020, using remote sensing measurements of relative “greenness.” We’re happy to share his fascinating approach here. Thank you Nicholas!


This Friday: 2020 City Nature Challenge!

     “This year we want to celebrate life where life is challenged.” 
                                                                                                - Jaime González


City Nature Challenge & COVID-19

The global challenge… fought locally

2020’s City Nature Challenge has been modified to keep organizers and participants safe during the COVID-19 pandemic. Rather than the typical competition, this year’s CNC is focusing on collaboration and spending restorative time in nature. You can still document biodiversity safely, although it may require some extra creativity or staying in your home.

The 2020 City Nature Challenge takes place in two parts —

  • April 24 – 27: Taking pictures of wild plants and animals.
  • April 28 – May 3: Identifying what was found.

Engaging Educators in the City Nature Challenge

The Center collaborated with the California Naturalist Program, educators in the Woodland Joint Unified School District, and a variety of local nature centers and reserves to encourage participation in the Sacramento City Nature Challenge. Despite being its first year participating in this global competition (as one of more than 160 cities worldwide), over 500 people in the Sacramento region logged 9,798 observations of over 1,200 unique species using iNaturalist.


City Nature Challenge Comes to Sacramento Region

For the first time ever, the Sacramento Region will be participating in the City Nature Challenge. We will be competing with more than 160 cities all over the world to see who can catalogue the most nature in just 4 days! We think that joining this global effort to discover local biodiversity through citizen science is a great opportunity for the Center, and for the region.  



April 26th 2019- April 29th 2019

The City Nature Challenge began as a nature-observation competition between the San Francisco Bay Area and Los Angeles County in 2016, organized around simple charge: “which city can find the most nature?” Since then, the competition has expanded rapidly, and this year more than 120 cities will participate worldwide!

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