WhenToBird

Molothrus ater · Icteridae

When Do Brown-headed Cowbirds Arrive in Kansas?

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

Brown-headed Cowbirds reach Kansas in early March, are common by early April, peak in the second week of May (40% of checklists), and most are gone by mid July.

When to look

First arrivalsMar 1-7early March
Common byApr 1-7early April
PeakMay 8-14the second week of May
Most gone byJul 15-21mid July

Best: the second week of May. First arrivals early March; most are gone by mid July. Peak: on about 40% of Kansas checklists.

  1. Jannot usually seen
  2. Febrare
  3. Maruncommon
  4. Aprpeak season
  5. Maypeak season
  6. Junpeak season
  7. Julpeak season
  8. Auguncommon
  9. Seprare
  10. Octrare
  11. Novrare
  12. Decnot usually seen

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

0%20%40%60%Jan 1-7: 1.3% of 8683 checklistsJan 8-14: 1.7% of 5710 checklistsJan 15-21: 1.5% of 5453 checklistsJan 22-31: 1.0% of 7868 checklistsFeb 1-7: 1.2% of 5579 checklistsFeb 8-14: 1.3% of 6307 checklistsFeb 15-21: 1.8% of 7830 checklistsFeb 22-28: 1.9% of 6124 checklistsMar 1-7: 2.9% of 6442 checklistsMar 8-14: 5.9% of 6925 checklistsMar 15-21: 7.9% of 7257 checklistsMar 22-31: 13% of 11527 checklistsApr 1-7: 19% of 8908 checklistsApr 8-14: 27% of 11070 checklistsApr 15-21: 30% of 11050 checklistsApr 22-30: 37% of 16381 checklistsMay 1-7: 40% of 15899 checklistsMay 8-14: 40% of 15349 checklistsMay 15-21: 40% of 10474 checklistsMay 22-31: 38% of 11264 checklistsJun 1-7: 39% of 6783 checklistsJun 8-14: 36% of 5654 checklistsJun 15-21: 35% of 4716 checklistsJun 22-30: 34% of 6232 checklistsJul 1-7: 31% of 5073 checklistsJul 8-14: 26% of 4528 checklistsJul 15-21: 19% of 4210 checklistsJul 22-31: 9.5% of 5986 checklistsAug 1-7: 6.3% of 4661 checklistsAug 8-14: 5.2% of 4762 checklistsAug 15-21: 4.0% of 4823 checklistsAug 22-31: 3.8% of 7214 checklistsSep 1-7: 2.2% of 5989 checklistsSep 8-14: 2.4% of 5549 checklistsSep 15-21: 2.0% of 5255 checklistsSep 22-30: 2.3% of 7370 checklistsOct 1-7: 3.7% of 5829 checklistsOct 8-14: 4.5% of 6183 checklistsOct 15-21: 4.0% of 5504 checklistsOct 22-31: 3.0% of 7289 checklistsNov 1-7: 2.2% of 5535 checklistsNov 8-14: 2.1% of 5462 checklistsNov 15-21: 1.3% of 4929 checklistsNov 22-30: 1.3% of 6627 checklistsDec 1-7: 1.0% of 4670 checklistsDec 8-14: 1.2% of 4805 checklistsDec 15-21: 1.2% of 6341 checklistsDec 22-31: 1.4% of 8186 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 Kansas 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.

Embed this map on your site

Where in Kansas

Best counties

Share of checklists at the peak
  1. Cloud CountyBest mid June · 10 checklists that week, 586 in all67%
  2. Hodgeman CountyBest mid May · 12 checklists that week, 670 in all67%
  3. Phillips CountyBest the second week of July · 16 checklists that week, 418 in all63%
  4. Grant CountyBest late May · 12 checklists that week, 344 in all63%
  5. Seward CountyBest the second week of June · 19 checklists that week, 566 in all61%
  6. Ottawa CountyBest early May · 43 checklists that week, 523 in all61%

Best spots

Share of checklists at the peak
  1. Greater Flint Hills Fee (southeast)Riley County, best late April · 22 checklists that week, 141 in all86%
  2. Cheney State Park (Mount Vernon)Kingman County, best late June · 21 checklists that week, 868 in all79%
  3. Lake OlatheJohnson County, best early June · 31 checklists that week, 3,529 in all78%
  4. Dyck Arboretum of the PlainsHarvey County, best mid June · 22 checklists that week, 983 in all75%
  5. Harvey County ParkHarvey County, best late April · 23 checklists that week, 657 in all75%

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

Best time of day

In Kansas, the Brown-headed Cowbird is most often listed on checklists started between 6 and 8 am (29% of those checklists).

0%10%20%30%40%12 am: too few checklists (150) to judge1 am: too few checklists (119) to judge2 am: too few checklists (97) to judge3 am: too few checklists (94) to judge4 am: too few checklists (124) to judge5 am: too few checklists (1459) to judge6 am: 39% of 12550 checklists7 am: 25% of 34128 checklists8 am: 21% of 45960 checklists9 am: 18% of 37806 checklists10 am: 15% of 32102 checklists11 am: 12% of 25896 checklists12 pm: 11% of 24203 checklists1 pm: 10% of 20269 checklists2 pm: 9.3% of 20772 checklists3 pm: 8.7% of 20978 checklists4 pm: 8.6% of 22094 checklists5 pm: 11% of 17739 checklists6 pm: 14% of 13963 checklists7 pm: 15% of 10110 checklists8 pm: too few checklists (4188) to judge9 pm: too few checklists (968) to judge10 pm: too few checklists (325) to judge11 pm: too few checklists (171) 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
January1.3%1.7%1.5%1.0%
February1.2%1.3%1.8%1.9%
March2.9%5.9%7.9%13%
April19%27%30%37%
May40%40%40%38%
June39%36%35%34%
July31%26%19%9.5%
August6.3%5.2%4.0%3.8%
September2.2%2.4%2.0%2.3%
October3.7%4.5%4.0%3.0%
November2.2%2.1%1.3%1.3%
December1.0%1.2%1.2%1.4%

Neighboring states

  • Nebraska: arrives mid March, 2 weeks later than Kansas
  • Oklahoma: arrives early January, 8 weeks earlier than Kansas
  • Missouri: arrives mid February, 2 weeks earlier than Kansas
  • Arkansas: arrives mid March, 2 weeks later than Kansas

Common questions

When do Brown-headed Cowbirds arrive in Kansas?
Brown-headed Cowbirds reach Kansas in early March, are common by early April, peak in the second week of May (40% of checklists), and most are gone by mid July.
When do Brown-headed Cowbirds leave Kansas?
Most Brown-headed Cowbirds have left Kansas by mid July, when reports fall below half their usual rate. Stragglers are still reported until late August.
When is the best time to see a Brown-headed Cowbird in Kansas?
The Brown-headed Cowbird is reported most often in the second week of May, on about 40% of Kansas checklists.
Where in Kansas are Brown-headed Cowbirds seen most often?
By county, Cloud County, Hodgeman County, and Phillips County have the highest peak reporting rates for the Brown-headed Cowbird (counties with at least 200 checklists).