WhenToBird

Bubo virginianus · Strigidae

When Do Great Horned Owls Arrive in Illinois?

Adult Great Horned Owl
Photo: Michael Warner, CC BY 4.0 via iNaturalist

Great Horned Owls are winter birds in Illinois: they arrive in the second week of August, peak in late December (2.7% of checklists), and most are gone by mid May.

When to look

First arrivalsAug 8-14the second week of August
Common byAug 8-14the second week of August
PeakDec 22-31late December
Most gone byMay 15-21mid May

Best: late December. First arrivals the second week of August; most are gone by mid May. Peak: on about 2.7% of Illinois checklists.

  1. Janpeak season
  2. Febcommon
  3. Marcommon
  4. Aprcommon
  5. Maycommon
  6. Jununcommon
  7. Juluncommon
  8. Augcommon
  9. Sepcommon
  10. Octcommon
  11. Novcommon
  12. Decpeak season

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

0%1%2%3%4%Jan 1-7: 2.5% of 29700 checklistsJan 8-14: 2.1% of 20189 checklistsJan 15-21: 1.8% of 19784 checklistsJan 22-31: 2.1% of 26641 checklistsFeb 1-7: 1.9% of 20478 checklistsFeb 8-14: 1.7% of 21967 checklistsFeb 15-21: 1.6% of 28735 checklistsFeb 22-28: 1.9% of 24223 checklistsMar 1-7: 1.9% of 26775 checklistsMar 8-14: 2.1% of 27579 checklistsMar 15-21: 2.1% of 27193 checklistsMar 22-31: 1.7% of 42278 checklistsApr 1-7: 1.9% of 34579 checklistsApr 8-14: 2.1% of 38290 checklistsApr 15-21: 2.0% of 39261 checklistsApr 22-30: 1.8% of 59584 checklistsMay 1-7: 1.7% of 60485 checklistsMay 8-14: 1.5% of 59647 checklistsMay 15-21: 1.1% of 43173 checklistsMay 22-31: 0.8% of 47913 checklistsJun 1-7: 0.7% of 31151 checklistsJun 8-14: 0.6% of 27692 checklistsJun 15-21: 0.6% of 23983 checklistsJun 22-30: 0.7% of 28448 checklistsJul 1-7: 0.6% of 21273 checklistsJul 8-14: 0.6% of 19284 checklistsJul 15-21: 0.7% of 17712 checklistsJul 22-31: 0.7% of 24500 checklistsAug 1-7: 0.9% of 18498 checklistsAug 8-14: 0.9% of 19331 checklistsAug 15-21: 1.1% of 19983 checklistsAug 22-31: 1.2% of 31892 checklistsSep 1-7: 1.5% of 26396 checklistsSep 8-14: 1.7% of 25011 checklistsSep 15-21: 1.5% of 23597 checklistsSep 22-30: 1.5% of 30638 checklistsOct 1-7: 1.5% of 23949 checklistsOct 8-14: 1.5% of 24412 checklistsOct 15-21: 1.5% of 22359 checklistsOct 22-31: 1.5% of 29794 checklistsNov 1-7: 1.5% of 21877 checklistsNov 8-14: 1.4% of 19742 checklistsNov 15-21: 1.8% of 18989 checklistsNov 22-30: 2.0% of 23905 checklistsDec 1-7: 2.2% of 16935 checklistsDec 8-14: 2.3% of 16687 checklistsDec 15-21: 3.1% of 20931 checklistsDec 22-31: 2.6% 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. Douglas CountyBest the second week of March · 24 checklists that week, 992 in all24%
  2. Stark CountyBest the second week of September · 13 checklists that week, 574 in all12%
  3. Warren CountyBest late February · 11 checklists that week, 658 in all12%
  4. Monroe CountyBest mid March · 38 checklists that week, 2,547 in all11%
  5. Ford CountyBest mid September · 14 checklists that week, 762 in all11%
  6. Bureau CountyBest late January · 216 checklists that week, 10,244 in all11%

Best spots

Share of checklists at the peak
  1. Lincoln Marsh Natural AreaDuPage County, best early March · 42 checklists that week, 1,512 in all57%
  2. MayslakeDuPage County, best the second week of April · 27 checklists that week, 556 in all56%
  3. Maple Grove 1DuPage County, best mid April · 54 checklists that week, 1,460 in all39%
  4. Openlands Open SpaceLake County, best late November · 20 checklists that week, 352 in all36%
  5. Waterfall Glen (northwest)DuPage County, best mid December · 23 checklists that week, 402 in all35%

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

Best time of day

In Illinois, the Great Horned Owl is most often listed on checklists started between 5 and 7 pm (2.4% of those checklists).

0%1%2%3%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: 2.6% of 95511 checklists7 am: 1.2% of 164584 checklists8 am: 1.1% of 163654 checklists9 am: 1.0% of 141804 checklists10 am: 0.9% of 122882 checklists11 am: 0.8% of 100640 checklists12 pm: 0.8% of 89894 checklists1 pm: 1.0% of 82729 checklists2 pm: 1.1% of 79801 checklists3 pm: 1.6% of 82169 checklists4 pm: 2.3% of 75124 checklists5 pm: 2.3% of 57708 checklists6 pm: 2.7% 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
January2.5%2.1%1.8%2.1%
February1.9%1.7%1.6%1.9%
March1.9%2.1%2.1%1.7%
April1.9%2.1%2.0%1.8%
May1.7%1.5%1.1%0.8%
June0.7%0.6%0.6%0.7%
July0.6%0.6%0.7%0.7%
August0.9%0.9%1.1%1.2%
September1.5%1.7%1.5%1.5%
October1.5%1.5%1.5%1.5%
November1.5%1.4%1.8%2.0%
December2.2%2.3%3.1%2.6%

Neighboring states

  • Indiana: arrives the second week of August, in the same week than Illinois
  • Wisconsin: arrives early August, 1 week earlier than Illinois
  • Michigan: arrives mid August, 1 week later than Illinois
  • Iowa: arrives mid July, 3 weeks earlier than Illinois

Common questions

When do Great Horned Owls arrive in Illinois?
Great Horned Owls are winter birds in Illinois: they arrive in the second week of August, peak in late December (2.7% of checklists), and most are gone by mid May.
When do Great Horned Owls leave Illinois?
Most Great Horned Owls have left Illinois by mid May, when reports fall below half their usual rate.
When is the best time to see a Great Horned Owl in Illinois?
The Great Horned Owl is reported most often in late December, on about 2.7% of Illinois checklists.
Where in Illinois are Great Horned Owls seen most often?
By county, Douglas County, Stark County, and Warren County have the highest peak reporting rates for the Great Horned Owl (counties with at least 200 checklists).