City Nature Challenge

Boulder-Denver Bioblitz: April 26-29, 2019

Which city has the most nature? 

The 2019 City Nature Challenge will help us find out! Last year Boulder County and the Denver Metro Area competed against 60+ cities throughout the globe and came up with some impressive numbers: 

  • 8,321 total observations
  • 1,634 plant and wildlife species identified
  • 418 observers
  • 531 identifiers

This year Boulder County and the Denver Metro Area are joining forces. Help us show the world how biodiverse our region is by making as many observations of as many species as possible from April 26-29, 2019! Document nature in your backyard, by your school, in your favorite park or open space area, 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.

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 17,329 participants from 68 cities documented nearly 442,000 observations of plants and wildlife, and identified over 18,000 species!

The 2019 City Nature Challenge will take place from April 26 – May 5. The first four days, April 26 – 29, are the days that observations will be collected (aka the Bioblitz), and the last six days, April 30 – May 5, 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 26 – April 29. 

The Boulder-Denver Metropolitan Area City Nature Challenge encompasses Adams, Arapahoe, Boulder, Broomfield, Clear Creek, Denver, Douglas, Elbert, Gilpin, Jefferson, and Park Counties. 

The Boulder-Denver City Nature Challenge is organized by

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! 

Thanks to our sponsors for making prizes available to CNC participants:

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 Kent Schnacke at Colorado Parks & Wildlife:
  • For opportunities and events in Boulder County, contact Melanie Hill at the WILD Foundation:

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 2019 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 Boulder-Denver CNC.

Host an event

A mini bioblitz, big bioblitz, guided nature hike, lunch break scavenger hunt, friendly competitions, CNC presentations or events… the possibilities are endless!

Make it a class project

If you’re an educator, you could create a weekend 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 26-29, 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 Boulder-Denver 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 midnight on May 5. 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 an ID party.

Event & Outreach Partners

Bird Conservancy of the Rockies

Bluff Lake Nature Center

Boulder County Parks & Open Space

Butterfly Pavilion

City of Boulder Open Space & Mountain Parks

Denver Audubon Society

Rocky Mountain Wild

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.*

City Nature Challenge Events

Saturday April 27, 7:00am-2:00pm: Barr Lake State Park Festivities

Location: Barr Lake State Park

Led by: Bird Conservancy of the Rockies

Join the Bird Conservancy of the Rockies at Barr Lake State Park for a day full of festivities. Activities include: Bird banding, Guided bird, mammal, invertebrate, and tree/plant hikes, and a Kite Festival.

Saturday April 27, 7:00am-3:00pm: Regis University Bioblitz

Location: Regis University / Lowell Ponds State Wildlife Area

Led by: Regis University Sustainability Club

Regis University will be hosting a BioBlitz on Saturday April 27th From 7:00-3:00. Meet at the Regis Quad where we will hold a brief training on how to use iNaturalist and then match participants with those more familiar with the taxonomy for a semi-guided identification hike. We will collect data on Regis’ campus and the adjacent Lowell Ponds riparian area along Clear Creek. This event is in collaboration with Regis Sustainability and the Regis University Student Government Association (RUSGA). Please come celebrate biodiversity with us.

Saturday April 27, 8:00am-11:00am: Family Day at Bluff Lake Nature Center

Location: Bluff Lake Nature Center

FREE monthly family day with several activities, including crafts, a volunteer project with Volunteers for Outdoor Colorado, and a table about City Nature Challenge with a challenge to identify 500 species. Geared towards families with kids aged 4-12.

Saturday April 27, 10:00am-12:00pm: Nature on Your Cell Phone

Location: Ron Stewart Preserve at Rabbit Mountain

Led by: Boulder County Parks and Open Space

There are many apps available to help you learn about nature–much more convenient than a printed field guide. We will learn about a number of these, go for a short hike to learn to use iNaturalist to identify any organism your camera can capture, and discover how to contribute photos to the iNaturalist City Nature Challenge. For more information, contact Deborah Price,

Saturday April 27, 10:00am-4:00pm: Butterfly Pavilion Hike

Location: Butterfly Pavilion

All are welcome to join the Butterfly Pavilion for the City Nature Challenge. Hike along the Butterfly Pavilion Nature Trails and search for all the wildlife you can find!

Saturday April 27, 9:00am-11:00am: Audubon Nature Center Bioblitz

Location: Audubon Center at Chatfield

Led by: Denver Audubon

Join the Denver Audubon in a bioblitz at the Chatfield Center led by Audubon Master Naturalist Graduates. Great learning opportunity for the public!

Sunday April 28, 9:00am-1:00pm: Wildflower Bonanza Hike with Boulder OSMP & WILD Foundation

Location: Goshawk Ridge Trail (exact location provided with registration email)

Led by: City of Boulder Open Space & Mountain Parks and the WILD Foundation

Join the City Nature Challenge fun with OSMP naturalists Dave Sutherland and Melanie Hill on a special nature hike with OSMP and the WILD Foundation to find and report plants and animals on OSMP. We’ll take a hike on the Goshawk Ridge trail, which winds through one of the most beautiful and pristine parts of OSMP. Its pine forests and lush, wet meadows are thick with wildflowers and a haven for wildlife. At this time of year, we may see more Pasque flowers than you ever imagined in one place! Bring your camera or smartphone with the iNaturalist app loaded and ready to go. 4 miles, 700’ elevation gain. Meeting location provided with your reservation confirmation email.

Registration is required for this activity and is limited to 19 people. Register here!


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