Colorado Birding CHallenge


Birding for Conservation

The Colorado Birding Challenge is a fun, county-based birding and conservation event held during the most exciting time of the birding year. Each year in May several billion birds migrate into and through the United States and dozens of species begin to establish breeding territories in each county in Colorado.

Our inaugural Colorado Birding Challenge in May 2021 was more successful than we had expected. We anticipate that the 2022 challenge on May 7th will engage even more participants and do more to help conserve Colorado's birds.

Donate / Pledge

Support sagebrush habitat restoration in the Gunnison Basin which hosts 87% of the world population of Gunnison Sage-grouse.

Big Day: May 7, 2022

The objectives of the Big Day event in 2022 are:

    • To engage hundreds of birders in a fun day of finding and learning about Colorado's birds.


    • To raise funds for the conservation of the endangered Gunnison Sage Grouse.


    • To generate eBird data for all 64 counties on the same day.


    • To provide support for the expanding programs and work of Colorado Field Ornithologists.


It's a Team Effort

We encourage you to form a team of 2-4 members (restrictions do not apply to the non-competing category). Teams will bird during the 24 hours of May 7, 2022 within a single Colorado county of their choice. The goal is to record the highest number of species relative to a handicap value determined for the county they are birding in. All teams, other than those in the non-competing category, must abide by the ABA Big Day Rules. 

All participants are asked to solicit donations and pledge per bird species observed during the Colorado Birding Challenge to help support a specific conservation project each year. In 2022, funds will go to support the conservation of the endangered Gunnison Sage Grouse.

At the end of the day, every team submits their species list and CFO volunteers will calculate the par score for the teams and teams will be ranked by this score. All scores will be posted on this website. The winning team in each of the five competing categories will be recognized in CFO communications, honored at the CFO Annual Meeting, and will receive a certificate.

Choose a Category


The classic Big Day

Big Sit

Birding by Par

Not all Colorado counties were created equal. Some are large, some are small, some are urban, some are rural, some have diverse habitats, some not so much.

CFO has developed a handicap system based on a decade of eBird data that will establish "par" for each county. This par is essentially the total number of species that one would expect to find in that county at that time of year.

Teams will be scored according to the total species they observe divided by par for the county they birded. Teams will be ranked by the total percentage of par they score.

This is a novel approach and there are some obvious challenges, such as the disparity in data between heavily birded counties like Boulder, Denver and Larimer vs. much less birded counties like Huerfano, Moffat or Sedgwick. If anything, we hope this will motivate teams to select these under-birded counties!