WhenToBird

Molothrus ater · Icteridae

When Do Brown-headed Cowbirds Arrive in Indiana?

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

Brown-headed Cowbirds reach Indiana in mid February, are common by late March, peak in late April (46% of checklists), and most are gone by the second week of July.

When to look

First arrivalsFeb 15-21mid February
Common byMar 22-31late March
PeakApr 22-30late April
Most gone byJul 8-14the second week of July

Best: late April. First arrivals mid February; most are gone by the second week of July. Peak: on about 46% of Indiana 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: 2.4% of 18123 checklistsJan 8-14: 3.4% of 12006 checklistsJan 15-21: 3.2% of 12403 checklistsJan 22-31: 3.3% of 16181 checklistsFeb 1-7: 2.9% of 12546 checklistsFeb 8-14: 3.8% of 14250 checklistsFeb 15-21: 4.1% of 18077 checklistsFeb 22-28: 4.6% of 13590 checklistsMar 1-7: 6.5% of 14545 checklistsMar 8-14: 9.8% of 14594 checklistsMar 15-21: 14% of 13894 checklistsMar 22-31: 23% of 22400 checklistsApr 1-7: 32% of 18069 checklistsApr 8-14: 40% of 19579 checklistsApr 15-21: 44% of 19518 checklistsApr 22-30: 48% of 30544 checklistsMay 1-7: 46% of 28430 checklistsMay 8-14: 44% of 30624 checklistsMay 15-21: 42% of 22920 checklistsMay 22-31: 41% of 21234 checklistsJun 1-7: 37% of 12279 checklistsJun 8-14: 37% of 10904 checklistsJun 15-21: 38% of 9488 checklistsJun 22-30: 34% of 11362 checklistsJul 1-7: 32% of 9947 checklistsJul 8-14: 24% of 9585 checklistsJul 15-21: 16% of 8929 checklistsJul 22-31: 8.2% of 12639 checklistsAug 1-7: 5.4% of 9528 checklistsAug 8-14: 4.6% of 9451 checklistsAug 15-21: 3.8% of 9442 checklistsAug 22-31: 3.1% of 14969 checklistsSep 1-7: 2.4% of 12628 checklistsSep 8-14: 1.8% of 11793 checklistsSep 15-21: 2.0% of 11396 checklistsSep 22-30: 2.4% of 14203 checklistsOct 1-7: 3.9% of 11365 checklistsOct 8-14: 5.1% of 12092 checklistsOct 15-21: 4.6% of 10440 checklistsOct 22-31: 3.4% of 13883 checklistsNov 1-7: 2.6% of 10476 checklistsNov 8-14: 2.3% of 9776 checklistsNov 15-21: 1.7% of 9035 checklistsNov 22-30: 1.3% of 12547 checklistsDec 1-7: 1.8% of 9078 checklistsDec 8-14: 1.8% of 8732 checklistsDec 15-21: 1.8% of 11024 checklistsDec 22-31: 2.2% of 15432 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 Indiana 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 Indiana

Best counties

Share of checklists at the peak
  1. Clinton CountyBest the second week of June · 15 checklists that week, 900 in all76%
  2. Delaware CountyBest the second week of July · 64 checklists that week, 6,085 in all71%
  3. Starke CountyBest the second week of June · 24 checklists that week, 2,111 in all69%
  4. Blackford CountyBest late June · 11 checklists that week, 962 in all68%
  5. Benton CountyBest early July · 17 checklists that week, 993 in all65%
  6. Washington CountyBest late April · 91 checklists that week, 1,463 in all65%

Best spots

Share of checklists at the peak
  1. Vaughn HollowBrown County, best late March · 44 checklists that week, 919 in all96%
  2. Fort Benjamin Harrison State ParkMarion County, best mid April · 99 checklists that week, 1,724 in all90%
  3. Scales Lake State BeachWarrick County, best mid April · 31 checklists that week, 645 in all89%
  4. Butler Athletic FieldsMarion County, best late April · 25 checklists that week, 296 in all86%
  5. Prairie Creek ReservoirDelaware County, best late April · 22 checklists that week, 618 in all85%

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

Best time of day

In Indiana, 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 (240) to judge1 am: too few checklists (231) to judge2 am: too few checklists (222) to judge3 am: too few checklists (202) to judge4 am: too few checklists (674) to judge5 am: too few checklists (4329) to judge6 am: 39% of 20589 checklists7 am: 29% of 58470 checklists8 am: 23% of 86931 checklists9 am: 21% of 78239 checklists10 am: 18% of 66080 checklists11 am: 16% of 54904 checklists12 pm: 14% of 47610 checklists1 pm: 13% of 44814 checklists2 pm: 12% of 43790 checklists3 pm: 12% of 42983 checklists4 pm: 12% of 45349 checklists5 pm: 14% of 35993 checklists6 pm: 16% of 26447 checklists7 pm: 15% of 17740 checklists8 pm: too few checklists (7603) to judge9 pm: too few checklists (1721) to judge10 pm: too few checklists (517) to judge11 pm: too few checklists (272) 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
January2.4%3.4%3.2%3.3%
February2.9%3.8%4.1%4.6%
March6.5%9.8%14%23%
April32%40%44%48%
May46%44%42%41%
June37%37%38%34%
July32%24%16%8.2%
August5.4%4.6%3.8%3.1%
September2.4%1.8%2.0%2.4%
October3.9%5.1%4.6%3.4%
November2.6%2.3%1.7%1.3%
December1.8%1.8%1.8%2.2%

Neighboring states

  • Illinois: arrives mid February, in the same week than Indiana
  • Kentucky: arrives late March, 5 weeks later than Indiana
  • Ohio: arrives the second week of February, 1 week earlier than Indiana
  • Michigan: arrives early March, 2 weeks later than Indiana

Common questions

When do Brown-headed Cowbirds arrive in Indiana?
Brown-headed Cowbirds reach Indiana in mid February, are common by late March, peak in late April (46% of checklists), and most are gone by the second week of July.
When do Brown-headed Cowbirds leave Indiana?
Most Brown-headed Cowbirds have left Indiana by the second week of July, when reports fall below half their usual rate. Stragglers are still reported until the second week of August.
When is the best time to see a Brown-headed Cowbird in Indiana?
The Brown-headed Cowbird is reported most often in late April, on about 46% of Indiana checklists.
Where in Indiana are Brown-headed Cowbirds seen most often?
By county, Clinton County, Delaware County, and Starke County have the highest peak reporting rates for the Brown-headed Cowbird (counties with at least 200 checklists).