Save the Date: Sept 6, 2025
The 2025 Colorado Birding Challenge will be held September 6, 2025.
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 migratory several billion birds move into and through the United States and dozens of species begin to establish or leave breeding territories in each county in Colorado.
The Challenge was created to provide an annual flow of funds to support specific bird conservation projects.
It's a Team Effort!
Competitive teams must consist of at least two participants and follow the ABA Big Day rules. Only birds identified within your team’s designated Colorado County will count toward your total. Please take the time to read and understand these rules, particularly the 95% rule (95 percent of each team’s final list must have been definitively seen/heard by all members of the team), and the commitment not to utilize information from other birders, including eBird reports or other electronic sources during the Challenge.
Bird Your Own Way teams are free to conduct their big day however they prefer. Do a county big day, a big sit, a feeder watch, or simply go birding.
Level Birding With Par
Not all Colorado Counties were created equal! Our great state has 64 unique counties, some are bigger than others, some have mountains, some have reservoirs. All have different habitat types and given the geographic diversity, the number and timing of migrants may be very different on any given day.
During the Challenge, we want teams to bird all the counties -- not just the "birdie" ones. In an effort to create a level playing field, CFO developed a formula that we call “par.” Using 10 years of eBird data, and taking into account how intensely each county has been birded, we’ve determined how many species might reasonably be expected to occur in each county during the Challenge. At the end of the day, teams will be ranked by the percentage of total par for their county that they observe.
Each team’s official total will be compared with the par value for the county birded, and this is how we will determine which is the winning team. For example, if one team competes in Conejos County (par 62) and reports 75 species, that represents 120% of par. A team birding in Larimer County might have a higher total, say 95 species, but since the par value for Larimer is 109, that would represent 87% of par. Thus the team birding in Conejos would finish higher.
This is a novel approach. We hope this will motivate teams to choose these under-birded counties and improve our understanding of birds across Colorado.
CATEGORIES
The Challenge - Teams in this category compete to maximize their county list using a vehicle(s) to travel throughout their selected county.
Green Challenge - Teams in this category compete using only human-powered transportation (no eBikes or other motorized vehicles.
Under 25 Challenge - All team members must be aged 25 or younger to participate in this category.
Bird Your Own Way - Individuals or teams are invited to participate in this category, whether they are traveling or simply keeping a yard list.
Competition Rules
The competition will take place on Saturday, September 6, 2025 from 12:00 AM to Midnight, rain or shine. Only birds seen or heard within your team’s designated county on this day will count toward your total.
For the three competitive categories:
Teams must consist of at least two participants and follow the ABA Big Day rules. Only birds identified within your team’s designated Colorado county will count toward your total. Please take the time to read and understand these rules, particularly the 95% rule (95 percent of each team’s total must have been definitively seen/heard by all members of the team) and the commitment not to utilize information from other birders, including eBird reports or other electronic sources during the COBC.
An eBird Trip Report must be submitted listing all birds counted as your team’s official count for the day. We encourage teams to keep individual eBird checklists for each location visited rather than keeping long traveling lists that are of limited value to researchers. Trip Reports must be emailed to cobc@cobirds.org along with your team name and county by 5 PM on Sunday, Sept. 7.
For non-competitive teams or individuals:
You are free to conduct your big day however you prefer. You can do a county big day, a big sit, a feeder watch or simply go birding. You are free to seek sponsors for your count or make a donation yourself. Register for the COBC and you’ll receive a link to set up a COBC Team Page that lets people know about your goals and allows them to support you with donations!
To add your count total to the official COBC list, keep track of your sightings by making eBird checklists, create an eBird Trip Report for September 6, 2024 and email your Trip Report along with your team name and county you birded in to cobc@cobirds.org by 5 PM on Sunday, Sept. 7.