WhenToBird

Molothrus ater · Icteridae

When Do Brown-headed Cowbirds Arrive in Virginia?

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

Brown-headed Cowbirds are in Virginia all year, but most are here in spring: numbers build from late March, peak in late April (30% of checklists), and fall back by early July. In the quietest week (mid September) they are still on about 2.3% of checklists.

When to look

Numbers buildMar 22-31late March
PeakApr 22-30late April
Fall back byJul 1-7early July
FewestSep 15-21mid September

Best: late April. Here all year; numbers build from late March and fall back by early July. Peak: on about 30% of Virginia checklists.

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

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

0%10%20%30%40%Jan 1-7: 2.8% of 32817 checklistsJan 8-14: 3.2% of 25111 checklistsJan 15-21: 3.4% of 25510 checklistsJan 22-31: 3.4% of 34492 checklistsFeb 1-7: 3.3% of 24950 checklistsFeb 8-14: 4.1% of 28224 checklistsFeb 15-21: 5.0% of 43578 checklistsFeb 22-28: 5.2% of 26467 checklistsMar 1-7: 7.0% of 25851 checklistsMar 8-14: 9.5% of 25901 checklistsMar 15-21: 13% of 26747 checklistsMar 22-31: 20% of 40819 checklistsApr 1-7: 26% of 31351 checklistsApr 8-14: 29% of 33239 checklistsApr 15-21: 31% of 37284 checklistsApr 22-30: 31% of 54364 checklistsMay 1-7: 29% of 47698 checklistsMay 8-14: 27% of 46174 checklistsMay 15-21: 26% of 36444 checklistsMay 22-31: 25% of 43203 checklistsJun 1-7: 23% of 28503 checklistsJun 8-14: 22% of 25485 checklistsJun 15-21: 21% of 23728 checklistsJun 22-30: 19% of 28785 checklistsJul 1-7: 17% of 22294 checklistsJul 8-14: 12% of 20481 checklistsJul 15-21: 8.3% of 18914 checklistsJul 22-31: 5.7% of 26976 checklistsAug 1-7: 4.8% of 19555 checklistsAug 8-14: 4.7% of 18744 checklistsAug 15-21: 3.7% of 18721 checklistsAug 22-31: 3.5% of 28763 checklistsSep 1-7: 2.8% of 23594 checklistsSep 8-14: 2.3% of 22581 checklistsSep 15-21: 2.2% of 23036 checklistsSep 22-30: 2.4% of 29687 checklistsOct 1-7: 3.2% of 24321 checklistsOct 8-14: 3.2% of 23946 checklistsOct 15-21: 3.4% of 22191 checklistsOct 22-31: 3.1% of 30161 checklistsNov 1-7: 3.1% of 21431 checklistsNov 8-14: 3.6% of 22758 checklistsNov 15-21: 2.8% of 19988 checklistsNov 22-30: 2.4% of 27665 checklistsDec 1-7: 2.3% of 19324 checklistsDec 8-14: 2.5% of 20316 checklistsDec 15-21: 2.5% of 25675 checklistsDec 22-31: 2.3% of 38677 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 Virginia 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 Virginia

Best counties

Share of checklists at the peak
  1. Manassas Park CountyBest late April · 10 checklists that week, 343 in all58%
  2. Louisa CountyBest the second week of April · 137 checklists that week, 5,590 in all54%
  3. Shenandoah CountyBest the second week of April · 186 checklists that week, 9,361 in all51%
  4. Buchanan CountyBest mid April · 37 checklists that week, 1,612 in all51%
  5. Powhatan CountyBest late April · 300 checklists that week, 5,825 in all50%
  6. Richmond CountyBest mid August · 59 checklists that week, 3,905 in all49%

Best spots

Share of checklists at the peak
  1. Warrenton ReservoirFauquier County, best early May · 42 checklists that week, 545 in all91%
  2. New QuarterYork County, best mid June · 21 checklists that week, 1,099 in all84%
  3. Oak Marr City ParkFairfax County, best early May · 41 checklists that week, 847 in all83%
  4. Neighborhood ParkCharlottesville County, best late April · 21 checklists that week, 250 in all80%
  5. Algonkian Regional ParkLoudoun County, best early May · 214 checklists that week, 4,531 in all77%
  6. Cape Charles State Natural Area PreserveNorthampton County, best late April · 47 checklists that week, 725 in all76%

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

Best time of day

In Virginia, the Brown-headed Cowbird is most often listed on checklists started between 6 and 8 am (20% of those checklists).

0%10%20%30%12 am: too few checklists (485) to judge1 am: too few checklists (488) to judge2 am: too few checklists (423) to judge3 am: too few checklists (565) to judge4 am: too few checklists (1410) to judge5 am: too few checklists (10265) to judge6 am: 25% of 64788 checklists7 am: 18% of 169128 checklists8 am: 15% of 180748 checklists9 am: 13% of 153462 checklists10 am: 10% of 128966 checklists11 am: 8.9% of 104204 checklists12 pm: 8.3% of 91604 checklists1 pm: 7.8% of 85547 checklists2 pm: 7.1% of 82355 checklists3 pm: 7.4% of 82265 checklists4 pm: 8.4% of 76714 checklists5 pm: 10% of 56782 checklists6 pm: 11% of 40131 checklists7 pm: too few checklists (24290) to judge8 pm: too few checklists (7744) to judge9 pm: too few checklists (2383) to judge10 pm: too few checklists (1122) to judge11 pm: too few checklists (651) 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
January2.8%3.2%3.4%3.4%
February3.3%4.1%5.0%5.2%
March7.0%9.5%13%20%
April26%29%31%31%
May29%27%26%25%
June23%22%21%19%
July17%12%8.3%5.7%
August4.8%4.7%3.7%3.5%
September2.8%2.3%2.2%2.4%
October3.2%3.2%3.4%3.1%
November3.1%3.6%2.8%2.4%
December2.3%2.5%2.5%2.3%

Neighboring states

  • District of Columbia: arrives late February, 4 weeks earlier than Virginia
  • Maryland: arrives late March, in the same week than Virginia
  • West Virginia: arrives late February, 4 weeks earlier than Virginia
  • Delaware: arrives late March, in the same week than Virginia

Common questions

When do Brown-headed Cowbirds arrive in Virginia?
Brown-headed Cowbirds are in Virginia all year, but most are here in spring: numbers build from late March, peak in late April (30% of checklists), and fall back by early July. In the quietest week (mid September) they are still on about 2.3% of checklists.
When do Brown-headed Cowbirds leave Virginia?
Brown-headed Cowbirds never fully leave Virginia: numbers fall back below half their usual rate by early July, but some are still reported in every week, about 2.3% of checklists at the low.
When is the best time to see a Brown-headed Cowbird in Virginia?
The Brown-headed Cowbird is reported most often in late April, on about 30% of Virginia checklists.
Where in Virginia are Brown-headed Cowbirds seen most often?
By county, Manassas Park County, Louisa County, and Shenandoah County have the highest peak reporting rates for the Brown-headed Cowbird (counties with at least 200 checklists).