WhenToBird

Molothrus ater · Icteridae

When Do Brown-headed Cowbirds Arrive in Nebraska?

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

Brown-headed Cowbirds reach Nebraska in mid March, are common by the second week of April, peak in the second week of May (41% of checklists), and most are gone by late July.

When to look

First arrivalsMar 15-21mid March
Common byApr 8-14the second week of April
PeakMay 8-14the second week of May
Most gone byJul 22-31late July

Best: the second week of May. First arrivals mid March; most are gone by late July. Peak: on about 41% of Nebraska checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  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: 0.4% of 4210 checklistsJan 8-14: 0.5% of 2891 checklistsJan 15-21: 0.4% of 2685 checklistsJan 22-31: 0.1% of 3834 checklistsFeb 1-7: 0.2% of 2803 checklistsFeb 8-14: 0.3% of 3134 checklistsFeb 15-21: 0.3% of 4508 checklistsFeb 22-28: 0.7% of 3238 checklistsMar 1-7: 1.3% of 3862 checklistsMar 8-14: 2.8% of 4894 checklistsMar 15-21: 4.6% of 5862 checklistsMar 22-31: 7.5% of 8598 checklistsApr 1-7: 14% of 5530 checklistsApr 8-14: 21% of 5528 checklistsApr 15-21: 28% of 6091 checklistsApr 22-30: 38% of 8661 checklistsMay 1-7: 43% of 9842 checklistsMay 8-14: 42% of 10044 checklistsMay 15-21: 39% of 8863 checklistsMay 22-31: 38% of 10207 checklistsJun 1-7: 39% of 4922 checklistsJun 8-14: 38% of 4054 checklistsJun 15-21: 36% of 3680 checklistsJun 22-30: 35% of 4349 checklistsJul 1-7: 36% of 3277 checklistsJul 8-14: 34% of 2803 checklistsJul 15-21: 25% of 2842 checklistsJul 22-31: 19% of 3920 checklistsAug 1-7: 11% of 2981 checklistsAug 8-14: 8.7% of 2819 checklistsAug 15-21: 6.4% of 3179 checklistsAug 22-31: 4.1% of 4599 checklistsSep 1-7: 2.6% of 3958 checklistsSep 8-14: 2.2% of 3460 checklistsSep 15-21: 1.9% of 3435 checklistsSep 22-30: 2.8% of 4975 checklistsOct 1-7: 4.1% of 3611 checklistsOct 8-14: 4.0% of 3605 checklistsOct 15-21: 3.2% of 3474 checklistsOct 22-31: 2.5% of 4352 checklistsNov 1-7: 1.6% of 3119 checklistsNov 8-14: 0.7% of 2887 checklistsNov 15-21: 0.4% of 2568 checklistsNov 22-30: 0.2% of 3506 checklistsDec 1-7: 0.2% of 2453 checklistsDec 8-14: 0.4% of 2756 checklistsDec 15-21: 0.4% of 3760 checklistsDec 22-31: 0.3% of 3746 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 Nebraska 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 Nebraska

Best counties

Share of checklists at the peak
  1. Phelps CountyBest the second week of July · 26 checklists that week, 836 in all69%
  2. Jefferson CountyBest the second week of June · 12 checklists that week, 804 in all67%
  3. Gage CountyBest the second week of June · 19 checklists that week, 1,579 in all63%
  4. Colfax CountyBest late June · 14 checklists that week, 284 in all61%
  5. Adams CountyBest the second week of June · 36 checklists that week, 936 in all61%
  6. Madison CountyBest the second week of May · 82 checklists that week, 1,920 in all60%

Best spots

Share of checklists at the peak
  1. Flanagan Lake & Recreation AreaDouglas County, best the second week of June · 23 checklists that week, 1,089 in all85%
  2. Lauritzen GardensDouglas County, best early May · 27 checklists that week, 317 in all84%
  3. Glenn Cunningham LakeDouglas County, best mid May · 23 checklists that week, 754 in all82%
  4. Mercer ParkDouglas County, best the second week of May · 47 checklists that week, 696 in all81%
  5. Homestead National Historical ParkGage County, best early May · 23 checklists that week, 163 in all81%
  6. Wilderness Park (Cardwell Branch)Lancaster County, best early May · 34 checklists that week, 189 in all80%

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

Best time of day

In Nebraska, 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 (60) to judge1 am: too few checklists (70) to judge2 am: too few checklists (74) to judge3 am: too few checklists (97) to judge4 am: too few checklists (318) to judge5 am: too few checklists (1382) to judge6 am: 38% of 6945 checklists7 am: 26% of 19066 checklists8 am: 21% of 24661 checklists9 am: 18% of 23438 checklists10 am: 16% of 20424 checklists11 am: 14% of 16727 checklists12 pm: 13% of 14774 checklists1 pm: 11% of 14443 checklists2 pm: 10% of 14830 checklists3 pm: 10% of 14445 checklists4 pm: 11% of 13353 checklists5 pm: 14% of 10506 checklists6 pm: 18% of 9208 checklists7 pm: 17% of 6334 checklists8 pm: too few checklists (2406) to judge9 pm: too few checklists (531) to judge10 pm: too few checklists (201) to judge11 pm: too few checklists (82) 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
January0.4%0.5%0.4%0.1%
February0.2%0.3%0.3%0.7%
March1.3%2.8%4.6%7.5%
April14%21%28%38%
May43%42%39%38%
June39%38%36%35%
July36%34%25%19%
August11%8.7%6.4%4.1%
September2.6%2.2%1.9%2.8%
October4.1%4.0%3.2%2.5%
November1.6%0.7%0.4%0.2%
December0.2%0.4%0.4%0.3%

Neighboring states

  • Kansas: arrives early March, 2 weeks earlier than Nebraska
  • South Dakota: arrives early April, 2 weeks later than Nebraska
  • Iowa: arrives the second week of March, 1 week earlier than Nebraska
  • Missouri: arrives mid February, 4 weeks earlier than Nebraska

Common questions

When do Brown-headed Cowbirds arrive in Nebraska?
Brown-headed Cowbirds reach Nebraska in mid March, are common by the second week of April, peak in the second week of May (41% of checklists), and most are gone by late July.
When do Brown-headed Cowbirds leave Nebraska?
Most Brown-headed Cowbirds have left Nebraska by late 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 Nebraska?
The Brown-headed Cowbird is reported most often in the second week of May, on about 41% of Nebraska checklists.
Where in Nebraska are Brown-headed Cowbirds seen most often?
By county, Phelps County, Jefferson County, and Gage County have the highest peak reporting rates for the Brown-headed Cowbird (counties with at least 200 checklists).