WhenToBird

Astur cooperii · Accipitridae

When Do Cooper's Hawks Arrive in Colorado?

Adult male Cooper's Hawk
Photo: Shirley Zundell, CC BY 4.0 via iNaturalist

Cooper's Hawks are in Colorado all year, but most are here in spring: numbers build from late March, peak in late April (6.8% of checklists), and fall back by mid May. In the quietest week (mid February) they are still on about 2.3% of checklists.

When to look

Numbers buildMar 22-31late March
PeakApr 22-30late April
Fall back byMay 15-21mid May
FewestFeb 15-21mid February

Best: late April. Here all year; numbers build from late March and fall back by mid May. Peak: on about 6.8% of Colorado checklists.

  1. Jancommon
  2. Febuncommon
  3. Marcommon
  4. Aprpeak season
  5. Maypeak season
  6. Juncommon
  7. Julcommon
  8. Augpeak season
  9. Seppeak season
  10. Octcommon
  11. Novcommon
  12. Deccommon

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

0%2%4%6%8%Jan 1-7: 3.3% of 32254 checklistsJan 8-14: 3.0% of 23278 checklistsJan 15-21: 2.9% of 22933 checklistsJan 22-31: 2.7% of 30856 checklistsFeb 1-7: 2.6% of 21464 checklistsFeb 8-14: 2.4% of 22910 checklistsFeb 15-21: 2.1% of 28739 checklistsFeb 22-28: 2.4% of 21833 checklistsMar 1-7: 2.6% of 23066 checklistsMar 8-14: 2.9% of 23783 checklistsMar 15-21: 3.5% of 24797 checklistsMar 22-31: 4.6% of 38439 checklistsApr 1-7: 5.9% of 31676 checklistsApr 8-14: 6.0% of 35092 checklistsApr 15-21: 6.8% of 36778 checklistsApr 22-30: 6.7% of 50885 checklistsMay 1-7: 6.8% of 44186 checklistsMay 8-14: 6.3% of 49011 checklistsMay 15-21: 5.5% of 40784 checklistsMay 22-31: 4.2% of 53073 checklistsJun 1-7: 3.4% of 32432 checklistsJun 8-14: 3.2% of 29978 checklistsJun 15-21: 2.8% of 29457 checklistsJun 22-30: 3.0% of 36072 checklistsJul 1-7: 3.4% of 28857 checklistsJul 8-14: 3.1% of 27224 checklistsJul 15-21: 3.3% of 27629 checklistsJul 22-31: 3.5% of 37318 checklistsAug 1-7: 4.5% of 25893 checklistsAug 8-14: 5.0% of 24870 checklistsAug 15-21: 5.2% of 24035 checklistsAug 22-31: 5.6% of 35691 checklistsSep 1-7: 5.9% of 27068 checklistsSep 8-14: 6.9% of 26709 checklistsSep 15-21: 6.4% of 26098 checklistsSep 22-30: 5.6% of 31550 checklistsOct 1-7: 5.0% of 24110 checklistsOct 8-14: 4.4% of 23352 checklistsOct 15-21: 3.7% of 21895 checklistsOct 22-31: 3.5% of 28319 checklistsNov 1-7: 3.1% of 21698 checklistsNov 8-14: 2.9% of 21061 checklistsNov 15-21: 3.1% of 19855 checklistsNov 22-30: 3.0% of 25798 checklistsDec 1-7: 3.2% of 18626 checklistsDec 8-14: 3.2% of 19004 checklistsDec 15-21: 3.5% of 23103 checklistsDec 22-31: 2.8% 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.

Embed this map on your site

Where in Colorado

Best counties

Share of checklists at the peak
  1. Broomfield CountyBest the second week of September · 332 checklists that week, 16,139 in all15%
  2. Phillips CountyBest late November · 24 checklists that week, 1,052 in all12%
  3. Jefferson CountyBest early May · 5703 checklists that week, 183,749 in all12%
  4. Baca CountyBest the second week of October · 33 checklists that week, 3,209 in all12%
  5. Kit Carson CountyBest late September · 74 checklists that week, 2,633 in all12%
  6. Pueblo CountyBest late September · 556 checklists that week, 26,547 in all11%

Best spots

Share of checklists at the peak
  1. Matthews/Winters ParkJefferson County, best late April · 56 checklists that week, 502 in all61%
  2. Mesa Meadows ParkJefferson County, best mid April · 42 checklists that week, 2,624 in all55%
  3. Chatfield Lake (Fairview Reservoir Number 2)Jefferson County, best late April · 35 checklists that week, 1,041 in all51%
  4. Environmental Learning CenterLarimer County, best the second week of April · 67 checklists that week, 3,919 in all44%
  5. Bear Creek ParkDenver County, best late August · 27 checklists that week, 806 in all43%

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

Best time of day

In Colorado, the Cooper's Hawk is most often listed on checklists started between 6 and 8 am (5.9% of those checklists).

0%2%4%6%8%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: 6.4% of 71991 checklists7 am: 5.6% of 159189 checklists8 am: 5.4% of 177206 checklists9 am: 4.8% of 165269 checklists10 am: 4.0% of 141029 checklists11 am: 3.4% of 115283 checklists12 pm: 3.0% of 96068 checklists1 pm: 3.1% of 89512 checklists2 pm: 3.3% of 86319 checklists3 pm: 3.4% of 82496 checklists4 pm: 3.6% of 71648 checklists5 pm: 4.1% of 52445 checklists6 pm: 4.0% 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
January3.3%3.0%2.9%2.7%
February2.6%2.4%2.1%2.4%
March2.6%2.9%3.5%4.6%
April5.9%6.0%6.8%6.7%
May6.8%6.3%5.5%4.2%
June3.4%3.2%2.8%3.0%
July3.4%3.1%3.3%3.5%
August4.5%5.0%5.2%5.6%
September5.9%6.9%6.4%5.6%
October5.0%4.4%3.7%3.5%
November3.1%2.9%3.1%3.0%
December3.2%3.2%3.5%2.8%

Neighboring states

  • Wyoming: arrives the second week of July, 14 weeks later than Colorado
  • New Mexico: year-round, peaks the second week of April
  • Utah: year-round, peaks mid September
  • Nebraska: arrives mid June, 11 weeks later than Colorado

Common questions

When do Cooper's Hawks arrive in Colorado?
Cooper's Hawks are in Colorado all year, but most are here in spring: numbers build from late March, peak in late April (6.8% of checklists), and fall back by mid May. In the quietest week (mid February) they are still on about 2.3% of checklists.
When do Cooper's Hawks leave Colorado?
Cooper's Hawks never fully leave Colorado: numbers fall back below half their usual rate by mid May, but some are still reported in every week, about 2.3% of checklists at the low.
When is the best time to see a Cooper's Hawk in Colorado?
The Cooper's Hawk is reported most often in late April, on about 6.8% of Colorado checklists.
Where in Colorado are Cooper's Hawks seen most often?
By county, Broomfield County, Phillips County, and Jefferson County have the highest peak reporting rates for the Cooper's Hawk (counties with at least 200 checklists).