See how the WILD Foundation is responding to COVID-19

City Nature Challenge

Denver-Boulder Bioblitz: April 24-27, 2020

COVID-19 Update

In light of the COVID-19 pandemic, City Nature Challenge (CNC) organizers have made some modifications to the 2020 City Nature Challenge to help keep organizers & participants safe.

Firstly, this year’s CNC is no longer a competition. Instead, we want to embrace the healing power of nature and encourage the collaborative aspect of the CNC. This will allow people to safely document biodiversity in whatever way they can, even from the safety of their own homes if necessary. We urge all participants to carefully follow public health guidelines provided by your local governments, as they are changing in real-time.

We strongly encourage all participants to explore nature from their homes, backyards, neighborhoods, and nearby parks and trails that tend to be less populated. Let’s keep the environment and our community members safe. #StayHomeColorado!

Which city has the most nature? 

The 2020 City Nature Challenge will help us find out! Last year Denver Metro Area and Boulder County competed against 159 cities throughout the globe and came up with some impressive numbers: 

  • 6,211 total observations
  • 970 plant and wildlife species identified
  • 406 observers
  • 259 identifiers

Of the 159 cities that competed in the 2019 CNC, Denver-Boulder placed 43rd for Total Number of Observations, 47th for Total Number of Species Observed, 33rd for Total Number of Participants, and 2nd for Most People in an Arid Climate. Let’s see what we can do in 2020!

Help us show the world how biodiverse our region is by documenting observations of wild plants and animals from April 24-27, 2020! Document nature in your home, backyard, neighborhood, or nearby parks or trails during off hours, and upload your observations to iNaturalist, an online platform for citizen scientists. Any observations of plants, animals, and fungus found throughout our boundary will count. 

The Denver-Boulder City Nature Challenge is organized by

About the City Nature Challenge

The City Nature Challenge (CNC) is an ongoing project to document urban biodiversity and engage city residents in the nature around them. The project is framed as a competition between cities to see which can make the most observations, identify the most species, or have the most participants. The program was started in 2016 by the Natural History Museum of Los Angeles and the California Academy of Sciences as a competition between Los Angeles and San Francisco. This past year in 2019, more than 35,000 participants from 159 cities documented over 963,000 observations of plants and wildlife, and identified over 31,000 species – 1,100+ of those species were threatened/rare/endangered!

The 2020 City Nature Challenge will take place from April 24 – May 3. The first four days, April 24 – 27, are the days that observations will be collected (aka the Bioblitz), and the last six days, April 28 – May 3, are when those observations will be identified and verified. Participants can also continue to upload observations during this six-day period as long as the sightings took place during April 24 – April 27. 



Where can you go to make observations in Denver-Boulder?

The Denver-Boulder Metropolitan Area City Nature Challenge encompasses Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, and Jefferson Counties.

In short: anywhere wild nature exists!

However, in light of the COVID-19 pandemic, we urge all participants to carefully follow public health guidelines & stay at home orders provided by local governments. We encourage all participants to explore nature close to their homes*. If you have trails and open space nearby, that’s great! Please be respectful of all people and wildlife around you, follow all social distancing requirements, and abide by local land and facility closures. If you must venture out beyond your neighborhood, please avoid overcrowded areas and visit during off days/times. Local officials are struggling to disperse large gatherings of people both in private residences and throughout our trail systems. Let’s do our part to keep our environment and community members safe by avoiding these busy areas. As Governor Polis has stated,

“Our mountains, our trails, our beautiful rivers, they’re going to be there. Let’s take a few weeks and not visit some of these areas and just recreate in our neighborhoods.”

Remember that your own backyard is teeming with wild nature! Your home is a complex ecosystem and contributor to the larger landscape. Be sure to spend lots of time in your yard and/or neighborhood exploring the diversity of plants, birds, insects, mammals, and other wildlife coming through at all hours. You might meet some neighbors you never knew you had!

*If you are concerned about revealing the location of a sensitive organism (or where your house is), you can hide the exact location from the public by changing the “geoprivacy” of the observation to “obscured.”

Why should you participate?

There is nature all around us, even in our cities! Knowing what species are here and where they are helps us study and protect them, but the ONLY way to effectively do that is by working together (scientists, land managers, community members, you name it) to find and document nature in our area. By participating in the CNC, not only do you learn more about local nature, but you can also make our urban areas a better place – for you and other species!

Get involved!

There are many ways that you can get involved with various levels of commitment. Some suggestions are listed below. If you are interested in contributing in any way, do not hesitate to contact us!


  • For opportunities and events in the Denver Metro Area, contact Sarah Burton at Colorado Parks & Wildlife: [email protected]
  • For opportunities and events in Boulder County, contact Melanie Hill at the WILD Foundation: [email protected]

Spread the word

Whether it’s informing your email lists, posting on your Facebook or Twitter accounts, distributing some of our posters and flyers, or just telling your friends, it all helps. The more promotion CNC has the more successful it will be!

Offer extra credit to students

We realize the 2020 CNC takes place right before finals week for many universities in the area. Offer extra credit to your students by encouraging them to take a study break to get out into nature and contribute to the Denver-Boulder CNC.

Host a virtual event

Teach others how to use iNaturalist, challenge others to a friendly competition, host a City Nature Challenge presentation or webinar…the possibilities are endless!

Make it a class project

If you’re an educator, you could create an assignment to get your students outside and teach them the value of citizen science. They don’t even have to put their phones down!

Make observations

Whenever you’re outside between April 24-27, whether you’re on a hike, walking the dog, or taking the trash out, pause a moment to observe the nature around you. You might discover something you’ve never noticed before!

Sponsor the Denver-Boulder CNC

Make a donation or sponsor a prize for iNaturalist participants. We’re looking for items like binoculars, a variety of outdoor gear, nature guide books, outdoor attire, gift cards, and more.

Make species identifications

We can only count observations toward our project if they are identified down to the species level by 11:59pm on May 3. We will need lots of help assigning those IDs as the observations roll in! You could do this in your PJs from your couch, or you could make it a social event by planning a virtual ID party. 

If you’re interested in joining or hosting a virtual ID party, fill out this form and we’ll contact you with more info.

Event & Outreach Partners

Americas for Conservation

Bird Conservancy of the Rockies

Bluff Lake Nature Center

Boulder County Parks & Open Space

Butterfly Pavilion

City of Aurora Open Space & Natural Resources

City of Boulder Open Space & Mountain Parks

High Line Canal Conservancy

Majestic View Nature Center

Regis University

University of Colorado Boulder

How to contribute observations


*While any observation will count, we encourage you to only upload wild and non-captive observations.  Please, no photos of people, pets, or potted-plants.*

*If you are concerned about revealing the location of a sensitive organism (or where your house is), you can hide the exact location from the public by changing the “geoprivacy” of the observation to “obscured.*


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