WhenToBird

Bubo virginianus · Strigidae

When Do Great Horned Owls Arrive in Iowa?

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

Great Horned Owls are winter birds in Iowa: they arrive in mid July, peak in late December (2.3% of checklists), and most are gone by late May.

When to look

First arrivalsJul 15-21mid July
Common byJul 15-21mid July
PeakDec 22-31late December
Most gone byMay 22-31late May

Best: late December. First arrivals mid July; most are gone by late May. Peak: on about 2.3% of Iowa 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%Jan 1-7: 2.0% of 5551 checklistsJan 8-14: 1.7% of 3498 checklistsJan 15-21: 1.4% of 3803 checklistsJan 22-31: 1.6% of 4807 checklistsFeb 1-7: 1.4% of 3613 checklistsFeb 8-14: 1.1% of 4173 checklistsFeb 15-21: 1.3% of 5796 checklistsFeb 22-28: 1.4% of 4394 checklistsMar 1-7: 1.7% of 5295 checklistsMar 8-14: 1.5% of 5679 checklistsMar 15-21: 1.3% of 5418 checklistsMar 22-31: 1.3% of 8613 checklistsApr 1-7: 1.4% of 6970 checklistsApr 8-14: 1.6% of 7511 checklistsApr 15-21: 1.5% of 8321 checklistsApr 22-30: 1.3% of 11976 checklistsMay 1-7: 0.9% of 11725 checklistsMay 8-14: 0.8% of 12626 checklistsMay 15-21: 0.8% of 9372 checklistsMay 22-31: 0.6% of 10330 checklistsJun 1-7: 0.5% of 5472 checklistsJun 8-14: 0.6% of 4568 checklistsJun 15-21: 0.5% of 3870 checklistsJun 22-30: 0.4% of 4780 checklistsJul 1-7: 0.5% of 4201 checklistsJul 8-14: 0.6% of 3605 checklistsJul 15-21: 0.6% of 3621 checklistsJul 22-31: 0.6% of 5093 checklistsAug 1-7: 0.9% of 3931 checklistsAug 8-14: 0.9% of 3488 checklistsAug 15-21: 1.0% of 3802 checklistsAug 22-31: 0.7% of 6293 checklistsSep 1-7: 1.1% of 5328 checklistsSep 8-14: 1.3% of 4622 checklistsSep 15-21: 1.0% of 4367 checklistsSep 22-30: 1.1% of 6086 checklistsOct 1-7: 0.9% of 4708 checklistsOct 8-14: 1.1% of 4791 checklistsOct 15-21: 1.0% of 4429 checklistsOct 22-31: 0.9% of 5633 checklistsNov 1-7: 1.0% of 4090 checklistsNov 8-14: 1.2% of 3416 checklistsNov 15-21: 1.1% of 3398 checklistsNov 22-30: 1.3% of 4679 checklistsDec 1-7: 1.3% of 3442 checklistsDec 8-14: 1.7% of 3322 checklistsDec 15-21: 2.7% of 4619 checklistsDec 22-31: 2.2% of 5113 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 Iowa 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 Iowa

Best counties

Share of checklists at the peak
  1. Lyon CountyBest late December · 18 checklists that week, 498 in all33%
  2. Grundy CountyBest the second week of January · 10 checklists that week, 647 in all16%
  3. Sioux CountyBest mid November · 11 checklists that week, 1,159 in all13%
  4. O'Brien CountyBest the second week of January · 17 checklists that week, 342 in all13%
  5. Howard CountyBest the second week of April · 15 checklists that week, 334 in all13%
  6. Calhoun CountyBest late December · 21 checklists that week, 446 in all12%

Best spots

Share of checklists at the peak
  1. Bever ParkLinn County, best early April · 21 checklists that week, 166 in all36%
  2. Jester Park (northwest)Polk County, best early August · 20 checklists that week, 254 in all32%
  3. Martin LakeBlack Hawk County, best late March · 26 checklists that week, 523 in all29%
  4. Brookside ParkStory County, best the second week of April · 25 checklists that week, 945 in all25%
  5. Arbor Lake ParkPoweshiek County, best early May · 21 checklists that week, 302 in all19%
  6. Water Plant ParkJohnson County, best late March · 42 checklists that week, 1,004 in all16%

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

Best time of day

In Iowa, the Great Horned Owl is most often listed on checklists started between 6 and 8 pm (2.5% of those checklists).

0%1%2%3%4%12 am: too few checklists (96) to judge1 am: too few checklists (99) to judge2 am: too few checklists (67) to judge3 am: too few checklists (82) to judge4 am: too few checklists (201) to judge5 am: too few checklists (1888) to judge6 am: 2.2% of 11313 checklists7 am: 0.9% of 25717 checklists8 am: 0.7% of 29755 checklists9 am: 0.8% of 28897 checklists10 am: 0.7% of 26343 checklists11 am: 0.6% of 21210 checklists12 pm: 0.5% of 17662 checklists1 pm: 0.6% of 16595 checklists2 pm: 0.8% of 16405 checklists3 pm: 1.1% of 17030 checklists4 pm: 1.7% of 17378 checklists5 pm: 1.7% of 14251 checklists6 pm: 2.1% of 10349 checklists7 pm: 3.1% of 6233 checklists8 pm: too few checklists (2002) to judge9 pm: too few checklists (392) to judge10 pm: too few checklists (186) to judge11 pm: too few checklists (87) 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
January2.0%1.7%1.4%1.6%
February1.4%1.1%1.3%1.4%
March1.7%1.5%1.3%1.3%
April1.4%1.6%1.5%1.3%
May0.9%0.8%0.8%0.6%
June0.5%0.6%0.5%0.4%
July0.5%0.6%0.6%0.6%
August0.9%0.9%1.0%0.7%
September1.1%1.3%1.0%1.1%
October0.9%1.1%1.0%0.9%
November1.0%1.2%1.1%1.3%
December1.3%1.7%2.7%2.2%

Neighboring states

  • Missouri: arrives the second week of August, 3 weeks later than Iowa
  • Wisconsin: arrives early August, 2 weeks later than Iowa
  • Minnesota: arrives mid August, 4 weeks later than Iowa
  • Illinois: arrives the second week of August, 3 weeks later than Iowa

Common questions

When do Great Horned Owls arrive in Iowa?
Great Horned Owls are winter birds in Iowa: they arrive in mid July, peak in late December (2.3% of checklists), and most are gone by late May.
When do Great Horned Owls leave Iowa?
Most Great Horned Owls have left Iowa by late May, when reports fall below half their usual rate.
When is the best time to see a Great Horned Owl in Iowa?
The Great Horned Owl is reported most often in late December, on about 2.3% of Iowa checklists.
Where in Iowa are Great Horned Owls seen most often?
By county, Lyon County, Grundy County, and Sioux County have the highest peak reporting rates for the Great Horned Owl (counties with at least 200 checklists).