WhenToBird

Buteo lagopus · Accipitridae

When Do Rough-legged Hawks Arrive in Colorado?

Adult Rough-legged Hawk
Photo: Rev. Lee A. Payne, Jr., CC BY 4.0 via iNaturalist

Rough-legged Hawks are winter birds in Colorado: they arrive in the second week of November, peak in mid January (1.5% of checklists), and most are gone by late March.

When to look

First arrivalsNov 8-14the second week of November
Common byNov 8-14the second week of November
PeakJan 15-21mid January
Most gone byMar 22-31late March

Best: mid January. First arrivals the second week of November; most are gone by late March. Peak: on about 1.5% of Colorado checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marcommon
  4. Apruncommon
  5. Maynot usually seen
  6. Junnot usually seen
  7. Julnot usually seen
  8. Augnot usually seen
  9. Sepnot usually seen
  10. Octuncommon
  11. Novcommon
  12. Deccommon

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

0%0.5%1%1.5%2%Jan 1-7: 1.2% of 32254 checklistsJan 8-14: 1.6% of 23278 checklistsJan 15-21: 1.5% of 22933 checklistsJan 22-31: 1.5% of 30856 checklistsFeb 1-7: 1.2% of 21464 checklistsFeb 8-14: 1.1% of 22910 checklistsFeb 15-21: 1.0% of 28739 checklistsFeb 22-28: 0.9% of 21833 checklistsMar 1-7: 0.8% of 23066 checklistsMar 8-14: 0.7% of 23783 checklistsMar 15-21: 0.8% of 24797 checklistsMar 22-31: 0.4% of 38439 checklistsApr 1-7: 0.4% of 31676 checklistsApr 8-14: 0.4% of 35092 checklistsApr 15-21: 0.1% of 36778 checklistsApr 22-30: 0.1% of 50885 checklistsMay 1-7: 0% of 44186 checklistsMay 8-14: 0% of 49011 checklistsMay 15-21: 0% of 40784 checklistsMay 22-31: 0% of 53073 checklistsJun 1-7: 0% of 32432 checklistsJun 8-14: 0% of 29978 checklistsJun 15-21: 0% of 29457 checklistsJun 22-30: 0% of 36072 checklistsJul 1-7: 0% of 28857 checklistsJul 8-14: 0% of 27224 checklistsJul 15-21: 0% of 27629 checklistsJul 22-31: 0% of 37318 checklistsAug 1-7: 0% of 25893 checklistsAug 8-14: 0.1% of 24870 checklistsAug 15-21: 0% of 24035 checklistsAug 22-31: 0% of 35691 checklistsSep 1-7: 0% of 27068 checklistsSep 8-14: 0% of 26709 checklistsSep 15-21: 0% of 26098 checklistsSep 22-30: 0% of 31550 checklistsOct 1-7: 0.1% of 24110 checklistsOct 8-14: 0.1% of 23352 checklistsOct 15-21: 0.2% of 21895 checklistsOct 22-31: 0.2% of 28319 checklistsNov 1-7: 0.5% of 21698 checklistsNov 8-14: 0.4% of 21061 checklistsNov 15-21: 0.6% of 19855 checklistsNov 22-30: 0.6% of 25798 checklistsDec 1-7: 0.8% of 18626 checklistsDec 8-14: 0.7% of 19004 checklistsDec 15-21: 1.0% of 23103 checklistsDec 22-31: 1.1% 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. Phillips CountyBest the second week of January · 23 checklists that week, 1,052 in all46%
  2. Logan CountyBest mid January · 53 checklists that week, 4,117 in all24%
  3. Kit Carson CountyBest the second week of February · 16 checklists that week, 2,633 in all24%
  4. Washington CountyBest early January · 12 checklists that week, 2,511 in all21%
  5. Cheyenne CountyBest late January · 29 checklists that week, 1,388 in all21%
  6. Conejos CountyBest the second week of February · 13 checklists that week, 1,636 in all21%

Best spots

Share of checklists at the peak
  1. Carbondale Nature ParkGarfield County, best late January · 23 checklists that week, 342 in all19%
  2. Barr Lake (northwest)Adams County, best mid December · 42 checklists that week, 2,694 in all16%
  3. Flagler Reservoir State Wildlife AreaKit Carson County, best late December · 22 checklists that week, 602 in all16%
  4. Barr LakeAdams County, best late January · 70 checklists that week, 2,800 in all16%

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

Best time of day

In Colorado, the Rough-legged Hawk is most often listed on checklists started between 11 am and 1 pm (0.6% 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: 0.2% of 71991 checklists7 am: 0.2% of 159189 checklists8 am: 0.3% of 177206 checklists9 am: 0.4% of 165269 checklists10 am: 0.5% of 141029 checklists11 am: 0.6% of 115283 checklists12 pm: 0.5% of 96068 checklists1 pm: 0.5% of 89512 checklists2 pm: 0.5% of 86319 checklists3 pm: 0.4% of 82496 checklists4 pm: 0.3% of 71648 checklists5 pm: 0.1% of 52445 checklists6 pm: 0.1% 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
January1.2%1.6%1.5%1.5%
February1.2%1.1%1.0%0.9%
March0.8%0.7%0.8%0.4%
April0.4%0.4%0.1%0.1%
May0%0%0%0%
June0%0%0%0%
July0%0%0%0%
August0%0.1%0%0%
September0%0%0%0%
October0.1%0.1%0.2%0.2%
November0.5%0.4%0.6%0.6%
December0.8%0.7%1.0%1.1%

Neighboring states

  • Wyoming: arrives mid October, 3 weeks earlier than Colorado
  • Utah: arrives the second week of November, in the same week than Colorado
  • Nebraska: arrives mid November, 1 week later than Colorado
  • South Dakota: arrives late October, 2 weeks earlier than Colorado

Common questions

When do Rough-legged Hawks arrive in Colorado?
Rough-legged Hawks are winter birds in Colorado: they arrive in the second week of November, peak in mid January (1.5% of checklists), and most are gone by late March.
When do Rough-legged Hawks leave Colorado?
Most Rough-legged Hawks have left Colorado by late March, when reports fall below half their usual rate.
When is the best time to see a Rough-legged Hawk in Colorado?
The Rough-legged Hawk is reported most often in mid January, on about 1.5% of Colorado checklists.
Where in Colorado are Rough-legged Hawks seen most often?
By county, Phillips County, Logan County, and Kit Carson County have the highest peak reporting rates for the Rough-legged Hawk (counties with at least 200 checklists).