WhenToBird

Falco mexicanus · Falconidae

When Do Prairie Falcons Arrive in Colorado?

Adult Prairie Falcon
Photo: CK2AZ, CC BY 4.0 via iNaturalist

Prairie Falcons are winter birds in Colorado: the first arrive in early June, they are common by mid July, peak in early January (1.3% of checklists), and most are gone by the second week of April.

When to look

First arrivalsJun 1-7early June
Common byJul 15-21mid July
PeakJan 1-7early January
Most gone byApr 8-14the second week of April

Best: early January. First arrivals early June; most are gone by the second week of April. Peak: on about 1.3% of Colorado checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marcommon
  4. Aprcommon
  5. Mayuncommon
  6. Juncommon
  7. Julcommon
  8. Augcommon
  9. Sepcommon
  10. Octcommon
  11. Novcommon
  12. Decpeak season

Darker months: more checklists report it. Outlined: peak month.

0%0.5%1%1.5%Jan 1-7: 1.3% of 32254 checklistsJan 8-14: 1.3% of 23278 checklistsJan 15-21: 1.1% of 22933 checklistsJan 22-31: 1.2% of 30856 checklistsFeb 1-7: 1.0% of 21464 checklistsFeb 8-14: 1.0% of 22910 checklistsFeb 15-21: 0.9% of 28739 checklistsFeb 22-28: 0.8% of 21833 checklistsMar 1-7: 0.9% of 23066 checklistsMar 8-14: 1.0% of 23783 checklistsMar 15-21: 1.0% of 24797 checklistsMar 22-31: 0.8% of 38439 checklistsApr 1-7: 0.9% of 31676 checklistsApr 8-14: 0.7% of 35092 checklistsApr 15-21: 0.7% of 36778 checklistsApr 22-30: 0.5% of 50885 checklistsMay 1-7: 0.4% of 44186 checklistsMay 8-14: 0.5% of 49011 checklistsMay 15-21: 0.5% of 40784 checklistsMay 22-31: 0.5% of 53073 checklistsJun 1-7: 0.5% of 32432 checklistsJun 8-14: 0.6% of 29978 checklistsJun 15-21: 0.6% of 29457 checklistsJun 22-30: 0.6% of 36072 checklistsJul 1-7: 0.6% of 28857 checklistsJul 8-14: 0.6% of 27224 checklistsJul 15-21: 0.7% of 27629 checklistsJul 22-31: 0.7% of 37318 checklistsAug 1-7: 0.6% of 25893 checklistsAug 8-14: 0.7% of 24870 checklistsAug 15-21: 0.8% of 24035 checklistsAug 22-31: 0.8% of 35691 checklistsSep 1-7: 0.8% of 27068 checklistsSep 8-14: 0.8% of 26709 checklistsSep 15-21: 0.8% of 26098 checklistsSep 22-30: 0.9% of 31550 checklistsOct 1-7: 0.9% of 24110 checklistsOct 8-14: 0.8% of 23352 checklistsOct 15-21: 0.8% of 21895 checklistsOct 22-31: 0.9% of 28319 checklistsNov 1-7: 0.7% of 21698 checklistsNov 8-14: 0.8% of 21061 checklistsNov 15-21: 0.8% of 19855 checklistsNov 22-30: 0.9% of 25798 checklistsDec 1-7: 0.9% of 18626 checklistsDec 8-14: 1.0% of 19004 checklistsDec 15-21: 1.1% of 23103 checklistsDec 22-31: 1.3% of 30802 checklistsJanFebMarAprMayJunJulAugSepOctNovDec
Share of complete checklists reporting it, by week (4 per month). Grey bars: fewer than 10 checklists, not counted.

Frequency is the share of complete checklists in Colorado that listed the bird, 2016–2025. It is not a head count, and it follows where and when people go birding. How to read it.

JanFebMarAprMayJunJulAugSepOctNovDec
today
Second week of November

Each county is shaded by the share of complete checklists there that listed the bird, blended with the weeks either side. Darker is more often. It follows where people watch birds, not how many birds there are. How to read it.

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Where in Colorado

Best counties

Share of checklists at the peak
  1. Kit Carson CountyBest early February · 21 checklists that week, 2,633 in all19%
  2. Lincoln CountyBest the second week of January · 10 checklists that week, 2,707 in all15%
  3. Washington CountyBest late January · 12 checklists that week, 2,511 in all11%
  4. Cheyenne CountyBest the second week of February · 17 checklists that week, 1,388 in all9.5%
  5. Sedgwick CountyBest the second week of January · 11 checklists that week, 1,168 in all9.5%
  6. Yuma CountyBest late January · 21 checklists that week, 3,844 in all9.2%

Best spots

Share of checklists at the peak
  1. Valley Reservoir Number OneEl Paso County, best the second week of March · 90 checklists that week, 3,638 in all57%
  2. Rueter-Hess ReservoirDouglas County, best late October · 20 checklists that week, 742 in all36%
  3. Antero ReservoirPark County, best late August · 33 checklists that week, 250 in all35%
  4. South Valley ParkJefferson County, best late June · 20 checklists that week, 702 in all32%
  5. Red Rocks ParkJefferson County, best the second week of March · 33 checklists that week, 1,764 in all30%
  6. Rocky Mountain Arsenal National Wildlife Refuge (east)Adams County, best early October · 20 checklists that week, 560 in all28%

Busy spots report more of everything; compare the checklist counts before you drive anywhere.

Best time of day

In Colorado, the Prairie Falcon is most often listed on checklists started between 10 am and 12 pm (0.9% of those checklists).

0%0.5%1%12 am: too few checklists (512) to judge1 am: too few checklists (468) to judge2 am: too few checklists (513) to judge3 am: too few checklists (656) to judge4 am: too few checklists (1918) to judge5 am: too few checklists (16045) to judge6 am: 0.6% of 71991 checklists7 am: 0.7% of 159189 checklists8 am: 0.8% of 177206 checklists9 am: 0.9% of 165269 checklists10 am: 0.9% of 141029 checklists11 am: 0.9% of 115283 checklists12 pm: 0.8% of 96068 checklists1 pm: 0.8% of 89512 checklists2 pm: 0.9% of 86319 checklists3 pm: 0.7% of 82496 checklists4 pm: 0.7% of 71648 checklists5 pm: 0.5% of 52445 checklists6 pm: 0.4% of 40199 checklists7 pm: too few checklists (24246) to judge8 pm: too few checklists (7986) to judge9 pm: too few checklists (2004) to judge10 pm: too few checklists (888) to judge11 pm: too few checklists (450) to judge12a3a6a9a12p3p6p9p
Share of checklists started in each local hour that reported it. It reflects when people go birding as well as when birds are active. Grey hours have too few checklists (under 2% of the state’s, or under 200) to judge.
Week-by-week table
MonthDays 1-78-1415-2122-end
January1.3%1.3%1.1%1.2%
February1.0%1.0%0.9%0.8%
March0.9%1.0%1.0%0.8%
April0.9%0.7%0.7%0.5%
May0.4%0.5%0.5%0.5%
June0.5%0.6%0.6%0.6%
July0.6%0.6%0.7%0.7%
August0.6%0.7%0.8%0.8%
September0.8%0.8%0.8%0.9%
October0.9%0.8%0.8%0.9%
November0.7%0.8%0.8%0.9%
December0.9%1.0%1.1%1.3%

Neighboring states

  • Wyoming: year-round, peaks late July
  • Utah: arrives late August, 11 weeks later than Colorado
  • South Dakota: arrives late May, 1 week earlier than Colorado
  • Arizona: arrives the second week of September, 13 weeks later than Colorado

Common questions

When do Prairie Falcons arrive in Colorado?
Prairie Falcons are winter birds in Colorado: the first arrive in early June, they are common by mid July, peak in early January (1.3% of checklists), and most are gone by the second week of April.
When do Prairie Falcons leave Colorado?
Most Prairie Falcons have left Colorado by the second week of April, when reports fall below half their usual rate. Stragglers are still reported until late April.
When is the best time to see a Prairie Falcon in Colorado?
The Prairie Falcon is reported most often in early January, on about 1.3% of Colorado checklists.
Where in Colorado are Prairie Falcons seen most often?
By county, Kit Carson County, Lincoln County, and Washington County have the highest peak reporting rates for the Prairie Falcon (counties with at least 200 checklists).