WhenToBird

Molothrus ater · Icteridae

When Do Brown-headed Cowbirds Arrive in Ohio?

Adult female Brown-headed Cowbird
Photo: Nicole, CC BY 4.0 via iNaturalist

Brown-headed Cowbirds reach Ohio in the second week of February, are common by late March, peak in late April (43% of checklists), and most are gone by the second week of July.

When to look

First arrivalsFeb 8-14the second week of February
Common byMar 22-31late March
PeakApr 22-30late April
Most gone byJul 8-14the second week of July

Best: late April. First arrivals the second week of February; most are gone by the second week of July. Peak: on about 43% of Ohio checklists.

  1. Janrare
  2. Febrare
  3. Marcommon
  4. Aprpeak season
  5. Maypeak season
  6. Junpeak season
  7. Julcommon
  8. Augrare
  9. Seprare
  10. Octrare
  11. Novrare
  12. Decrare

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

0%20%40%60%Jan 1-7: 1.9% of 46637 checklistsJan 8-14: 2.9% of 31056 checklistsJan 15-21: 3.6% of 30129 checklistsJan 22-31: 3.1% of 38665 checklistsFeb 1-7: 2.9% of 27203 checklistsFeb 8-14: 3.7% of 30626 checklistsFeb 15-21: 3.9% of 40705 checklistsFeb 22-28: 4.1% of 31391 checklistsMar 1-7: 5.4% of 32914 checklistsMar 8-14: 9.3% of 33973 checklistsMar 15-21: 12% of 33678 checklistsMar 22-31: 21% of 49889 checklistsApr 1-7: 30% of 41225 checklistsApr 8-14: 37% of 47174 checklistsApr 15-21: 43% of 47017 checklistsApr 22-30: 45% of 73055 checklistsMay 1-7: 40% of 80637 checklistsMay 8-14: 36% of 102552 checklistsMay 15-21: 37% of 64582 checklistsMay 22-31: 38% of 52766 checklistsJun 1-7: 37% of 29279 checklistsJun 8-14: 35% of 25773 checklistsJun 15-21: 34% of 23163 checklistsJun 22-30: 32% of 27794 checklistsJul 1-7: 28% of 23334 checklistsJul 8-14: 22% of 22147 checklistsJul 15-21: 14% of 20998 checklistsJul 22-31: 7.2% of 29749 checklistsAug 1-7: 5.3% of 22899 checklistsAug 8-14: 4.6% of 21972 checklistsAug 15-21: 3.8% of 22215 checklistsAug 22-31: 3.0% of 35087 checklistsSep 1-7: 2.3% of 29148 checklistsSep 8-14: 1.8% of 28042 checklistsSep 15-21: 2.0% of 26751 checklistsSep 22-30: 2.9% of 32398 checklistsOct 1-7: 4.2% of 26209 checklistsOct 8-14: 5.2% of 26809 checklistsOct 15-21: 4.3% of 23504 checklistsOct 22-31: 3.3% of 33269 checklistsNov 1-7: 2.7% of 25563 checklistsNov 8-14: 2.5% of 23810 checklistsNov 15-21: 1.7% of 22127 checklistsNov 22-30: 1.4% of 29449 checklistsDec 1-7: 2.0% of 22370 checklistsDec 8-14: 1.8% of 21581 checklistsDec 15-21: 2.5% of 24232 checklistsDec 22-31: 2.3% of 36084 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 Ohio 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 Ohio

Best counties

Share of checklists at the peak
  1. Putnam CountyBest early May · 38 checklists that week, 927 in all69%
  2. Clark CountyBest late April · 551 checklists that week, 14,637 in all67%
  3. Darke CountyBest early May · 199 checklists that week, 3,495 in all61%
  4. Paulding CountyBest the second week of May · 62 checklists that week, 1,653 in all61%
  5. Clermont CountyBest mid April · 898 checklists that week, 32,494 in all60%
  6. Champaign CountyBest early May · 83 checklists that week, 2,549 in all59%

Best spots

Share of checklists at the peak
  1. Grand River Wildlife AreaTrumbull County, best mid April · 31 checklists that week, 1,401 in all99%
  2. Buck Creek State Park (southwest)Clark County, best early May · 23 checklists that week, 313 in all96%
  3. Cranberry RunPutnam County, best late April · 26 checklists that week, 274 in all96%
  4. Buck Creek State ParkClark County, best the second week of May · 26 checklists that week, 729 in all95%
  5. Richardson Road ParklandFranklin County, best late April · 43 checklists that week, 1,927 in all94%
  6. Withrow Nature PreserveHamilton County, best early May · 34 checklists that week, 504 in all90%

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

Best time of day

In Ohio, the Brown-headed Cowbird is most often listed on checklists started between 6 and 8 am (32% of those checklists).

0%10%20%30%40%12 am: too few checklists (574) to judge1 am: too few checklists (609) to judge2 am: too few checklists (466) to judge3 am: too few checklists (478) to judge4 am: too few checklists (662) to judge5 am: too few checklists (4366) to judge6 am: 39% of 43093 checklists7 am: 29% of 142017 checklists8 am: 23% of 205296 checklists9 am: 20% of 196322 checklists10 am: 17% of 170882 checklists11 am: 15% of 144567 checklists12 pm: 14% of 126551 checklists1 pm: 13% of 117855 checklists2 pm: 11% of 112869 checklists3 pm: 11% of 109786 checklists4 pm: 12% of 103116 checklists5 pm: 14% of 78409 checklists6 pm: 16% of 56785 checklists7 pm: 15% of 37923 checklists8 pm: too few checklists (14954) to judge9 pm: too few checklists (2710) to judge10 pm: too few checklists (854) to judge11 pm: too few checklists (486) 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
January1.9%2.9%3.6%3.1%
February2.9%3.7%3.9%4.1%
March5.4%9.3%12%21%
April30%37%43%45%
May40%36%37%38%
June37%35%34%32%
July28%22%14%7.2%
August5.3%4.6%3.8%3.0%
September2.3%1.8%2.0%2.9%
October4.2%5.2%4.3%3.3%
November2.7%2.5%1.7%1.4%
December2.0%1.8%2.5%2.3%

Neighboring states

  • West Virginia: arrives late February, 2 weeks later than Ohio
  • Indiana: arrives mid February, 1 week later than Ohio
  • Michigan: arrives early March, 3 weeks later than Ohio
  • Kentucky: arrives late March, 6 weeks later than Ohio

Common questions

When do Brown-headed Cowbirds arrive in Ohio?
Brown-headed Cowbirds reach Ohio in the second week of February, are common by late March, peak in late April (43% of checklists), and most are gone by the second week of July.
When do Brown-headed Cowbirds leave Ohio?
Most Brown-headed Cowbirds have left Ohio by the second week of July, when reports fall below half their usual rate. Stragglers are still reported until mid August.
When is the best time to see a Brown-headed Cowbird in Ohio?
The Brown-headed Cowbird is reported most often in late April, on about 43% of Ohio checklists.
Where in Ohio are Brown-headed Cowbirds seen most often?
By county, Putnam County, Clark County, and Darke County have the highest peak reporting rates for the Brown-headed Cowbird (counties with at least 200 checklists).