Join the 2021 City Nature Challenge: April 30th through May 9th

Join the worldwide movement to observe nature in your own neighborhood

April 20, 2021

What started as a friendly rivalry between Los Angeles and San Francisco in 2016, the City Nature Challenge has become an event that encourages documentation and understanding of biodiversity across the world.

Individuals from more than 120 major cities around the globe will be collecting data to see which communities can make the most observations about nature in their hometowns. Let's show the world what the Denver-Boulder metro area is made of!

A note from City Nature Challenge in light of the COVID-19 pandemic: "This year’s CNC will not be focused on competition; instead we want to embrace the healing power of nature and celebrate tens of thousands of people all around the world, searching for and documenting their local biodiversity, together in this event."

The two-part challenge begins April 30-May 3 with taking photographs of wild plants and animals, followed by an identification period that runs May 4 through May 9.

How to participate:

  1. Find wildlife (plants, animals, or evidence of life) in your city.
  2. Take a picture & note the location.
  3. Upload your observations using the iNaturalist app. It's free!
  4. Get feedback from actual scientists, experts, and other naturalists.

Learn more about the City Nature Challenge by visiting