WhenToBird

Buteo lagopus · Accipitridae

When Do Rough-legged Hawks Arrive in Illinois?

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

Rough-legged Hawks are winter birds in Illinois: they arrive in early November, peak in late January (2.0% of checklists), and most are gone by early March.

When to look

First arrivalsNov 1-7early November
Common byNov 1-7early November
PeakJan 22-31late January
Most gone byMar 1-7early March

Best: late January. First arrivals early November; most are gone by early March. Peak: on about 2.0% of Illinois checklists.

  1. Janpeak season
  2. Febpeak season
  3. Maruncommon
  4. Aprrare
  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%1%2%3%Jan 1-7: 1.2% of 29700 checklistsJan 8-14: 1.6% of 20189 checklistsJan 15-21: 2.3% of 19784 checklistsJan 22-31: 2.0% of 26641 checklistsFeb 1-7: 1.7% of 20478 checklistsFeb 8-14: 1.1% of 21967 checklistsFeb 15-21: 1.6% of 28735 checklistsFeb 22-28: 1.5% of 24223 checklistsMar 1-7: 0.6% of 26775 checklistsMar 8-14: 0.3% of 27579 checklistsMar 15-21: 0.2% of 27193 checklistsMar 22-31: 0.2% of 42278 checklistsApr 1-7: 0.1% of 34579 checklistsApr 8-14: 0.1% of 38290 checklistsApr 15-21: 0.1% of 39261 checklistsApr 22-30: 0.1% of 59584 checklistsMay 1-7: 0.1% of 60485 checklistsMay 8-14: 0.1% of 59647 checklistsMay 15-21: 0% of 43173 checklistsMay 22-31: 0.1% of 47913 checklistsJun 1-7: 0% of 31151 checklistsJun 8-14: 0% of 27692 checklistsJun 15-21: 0% of 23983 checklistsJun 22-30: 0% of 28448 checklistsJul 1-7: 0% of 21273 checklistsJul 8-14: 0% of 19284 checklistsJul 15-21: 0% of 17712 checklistsJul 22-31: 0% of 24500 checklistsAug 1-7: 0% of 18498 checklistsAug 8-14: 0% of 19331 checklistsAug 15-21: 0% of 19983 checklistsAug 22-31: 0% of 31892 checklistsSep 1-7: 0% of 26396 checklistsSep 8-14: 0% of 25011 checklistsSep 15-21: 0% of 23597 checklistsSep 22-30: 0% of 30638 checklistsOct 1-7: 0% of 23949 checklistsOct 8-14: 0% of 24412 checklistsOct 15-21: 0.1% of 22359 checklistsOct 22-31: 0.4% of 29794 checklistsNov 1-7: 0.7% of 21877 checklistsNov 8-14: 1.2% of 19742 checklistsNov 15-21: 1.0% of 18989 checklistsNov 22-30: 1.0% of 23905 checklistsDec 1-7: 0.7% of 16935 checklistsDec 8-14: 0.8% of 16687 checklistsDec 15-21: 1.1% of 20931 checklistsDec 22-31: 1.2% of 29011 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 Illinois 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 Illinois

Best counties

Share of checklists at the peak
  1. Grundy CountyBest mid January · 67 checklists that week, 5,050 in all25%
  2. Jasper CountyBest the second week of February · 11 checklists that week, 1,292 in all23%
  3. Putnam CountyBest early February · 19 checklists that week, 3,333 in all22%
  4. Iroquois CountyBest mid January · 52 checklists that week, 2,566 in all17%
  5. Cumberland CountyBest mid February · 18 checklists that week, 798 in all16%
  6. Woodford CountyBest mid January · 117 checklists that week, 8,431 in all15%

Best spots

Share of checklists at the peak
  1. Goose Lake Prairie State Natural AreaGrundy County, best late January · 45 checklists that week, 1,288 in all56%
  2. Dead Stick Pond (Gun Club Ponds)Cook County, best early January · 41 checklists that week, 316 in all38%
  3. Park No. 564Cook County, best late January · 49 checklists that week, 2,758 in all32%
  4. Bartel Grassland Land and Water ReserveCook County, best mid February · 35 checklists that week, 1,224 in all32%

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

Best time of day

In Illinois, the Rough-legged Hawk is most often listed on checklists started between 1 and 3 pm (0.7% of those checklists).

0%0.5%1%12 am: too few checklists (484) to judge1 am: too few checklists (631) to judge2 am: too few checklists (485) to judge3 am: too few checklists (610) to judge4 am: too few checklists (2321) to judge5 am: too few checklists (23536) to judge6 am: 0.1% of 95511 checklists7 am: 0.2% of 164584 checklists8 am: 0.3% of 163654 checklists9 am: 0.5% of 141804 checklists10 am: 0.5% of 122882 checklists11 am: 0.6% of 100640 checklists12 pm: 0.6% of 89894 checklists1 pm: 0.7% of 82729 checklists2 pm: 0.7% of 79801 checklists3 pm: 0.6% of 82169 checklists4 pm: 0.4% of 75124 checklists5 pm: 0.1% of 57708 checklists6 pm: 0.1% of 41843 checklists7 pm: too few checklists (20943) to judge8 pm: too few checklists (6131) to judge9 pm: too few checklists (1677) to judge10 pm: too few checklists (843) to judge11 pm: too few checklists (448) 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%2.3%2.0%
February1.7%1.1%1.6%1.5%
March0.6%0.3%0.2%0.2%
April0.1%0.1%0.1%0.1%
May0.1%0.1%0%0.1%
June0%0%0%0%
July0%0%0%0%
August0%0%0%0%
September0%0%0%0%
October0%0%0.1%0.4%
November0.7%1.2%1.0%1.0%
December0.7%0.8%1.1%1.2%

Neighboring states

  • Indiana: arrives the second week of November, 1 week later than Illinois
  • Wisconsin: arrives early November, in the same week than Illinois
  • Michigan: arrives late October, 1 week earlier than Illinois
  • Iowa: arrives the second week of November, 1 week later than Illinois

Common questions

When do Rough-legged Hawks arrive in Illinois?
Rough-legged Hawks are winter birds in Illinois: they arrive in early November, peak in late January (2.0% of checklists), and most are gone by early March.
When do Rough-legged Hawks leave Illinois?
Most Rough-legged Hawks have left Illinois by early March, when reports fall below half their usual rate.
When is the best time to see a Rough-legged Hawk in Illinois?
The Rough-legged Hawk is reported most often in late January, on about 2.0% of Illinois checklists.
Where in Illinois are Rough-legged Hawks seen most often?
By county, Grundy County, Jasper County, and Putnam County have the highest peak reporting rates for the Rough-legged Hawk (counties with at least 200 checklists).