WhenToBird

Molothrus ater · Icteridae

When Do Brown-headed Cowbirds Arrive in South Carolina?

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

Brown-headed Cowbirds are in South Carolina all year, but most are here in spring: numbers build from mid March, peak in late April (26% of checklists), and fall back by early July. In the quietest week (the second week of September) they are still on about 4.8% of checklists.

When to look

Numbers buildMar 15-21mid March
PeakApr 22-30late April
Fall back byJul 1-7early July
FewestSep 8-14the second week of September

Best: late April. Here all year; numbers build from mid March and fall back by early July. Peak: on about 26% of South Carolina checklists.

  1. Januncommon
  2. Febuncommon
  3. Marpeak season
  4. Aprpeak season
  5. Maypeak season
  6. Junpeak season
  7. Julcommon
  8. Auguncommon
  9. Sepuncommon
  10. Octuncommon
  11. Novuncommon
  12. Decuncommon

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

0%10%20%30%Jan 1-7: 5.7% of 15487 checklistsJan 8-14: 6.4% of 11691 checklistsJan 15-21: 6.5% of 11994 checklistsJan 22-31: 6.5% of 16225 checklistsFeb 1-7: 7.0% of 12192 checklistsFeb 8-14: 7.3% of 14044 checklistsFeb 15-21: 8.9% of 18483 checklistsFeb 22-28: 9.6% of 12045 checklistsMar 1-7: 12% of 11511 checklistsMar 8-14: 13% of 11704 checklistsMar 15-21: 17% of 11526 checklistsMar 22-31: 20% of 17386 checklistsApr 1-7: 24% of 13148 checklistsApr 8-14: 25% of 13193 checklistsApr 15-21: 26% of 13936 checklistsApr 22-30: 27% of 19002 checklistsMay 1-7: 26% of 14133 checklistsMay 8-14: 24% of 13668 checklistsMay 15-21: 23% of 11064 checklistsMay 22-31: 23% of 14461 checklistsJun 1-7: 21% of 10231 checklistsJun 8-14: 20% of 9417 checklistsJun 15-21: 21% of 8012 checklistsJun 22-30: 20% of 9720 checklistsJul 1-7: 17% of 7907 checklistsJul 8-14: 14% of 7338 checklistsJul 15-21: 9.0% of 7312 checklistsJul 22-31: 6.3% of 10877 checklistsAug 1-7: 6.0% of 7816 checklistsAug 8-14: 6.4% of 7655 checklistsAug 15-21: 4.7% of 7797 checklistsAug 22-31: 5.1% of 11246 checklistsSep 1-7: 5.0% of 8956 checklistsSep 8-14: 4.5% of 8929 checklistsSep 15-21: 4.9% of 9389 checklistsSep 22-30: 5.1% of 13028 checklistsOct 1-7: 6.5% of 11063 checklistsOct 8-14: 6.7% of 10968 checklistsOct 15-21: 6.7% of 10264 checklistsOct 22-31: 6.8% of 12917 checklistsNov 1-7: 6.3% of 8802 checklistsNov 8-14: 5.9% of 8339 checklistsNov 15-21: 5.1% of 8798 checklistsNov 22-30: 5.1% of 12925 checklistsDec 1-7: 4.9% of 8541 checklistsDec 8-14: 5.1% of 8609 checklistsDec 15-21: 5.7% of 9961 checklistsDec 22-31: 5.5% of 17541 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 South Carolina 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 South Carolina

Best counties

Share of checklists at the peak
  1. Clarendon CountyBest early July · 116 checklists that week, 9,189 in all55%
  2. Allendale CountyBest late May · 28 checklists that week, 1,172 in all43%
  3. Cherokee CountyBest the second week of April · 88 checklists that week, 2,823 in all43%
  4. Orangeburg CountyBest mid April · 194 checklists that week, 8,992 in all43%
  5. Lexington CountyBest late April · 996 checklists that week, 27,992 in all40%
  6. Williamsburg CountyBest early May · 36 checklists that week, 1,512 in all39%

Best spots

Share of checklists at the peak
  1. SnowdenCharleston County, best mid February · 23 checklists that week, 738 in all83%
  2. History ParkLexington County, best late April · 28 checklists that week, 512 in all70%
  3. Cedar Falls ParkGreenville County, best early May · 66 checklists that week, 651 in all67%
  4. Cowpens National BattlefieldCherokee County, best mid May · 30 checklists that week, 925 in all65%
  5. Bunched Arrowhead Heritage PreserveGreenville County, best mid April · 43 checklists that week, 1,544 in all63%

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

Best time of day

In South Carolina, 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 (222) to judge1 am: too few checklists (160) to judge2 am: too few checklists (132) to judge3 am: too few checklists (212) to judge4 am: too few checklists (267) to judge5 am: too few checklists (1898) to judge6 am: 22% of 19280 checklists7 am: 19% of 66492 checklists8 am: 15% of 73941 checklists9 am: 13% of 63039 checklists10 am: 10% of 52652 checklists11 am: 8.7% of 41908 checklists12 pm: 7.8% of 36782 checklists1 pm: 7.6% of 33300 checklists2 pm: 7.7% of 32248 checklists3 pm: 9.4% of 35451 checklists4 pm: 11% of 34410 checklists5 pm: 11% of 27073 checklists6 pm: 14% of 17375 checklists7 pm: too few checklists (10313) to judge8 pm: too few checklists (2756) to judge9 pm: too few checklists (672) to judge10 pm: too few checklists (412) to judge11 pm: too few checklists (256) 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
January5.7%6.4%6.5%6.5%
February7.0%7.3%8.9%9.6%
March12%13%17%20%
April24%25%26%27%
May26%24%23%23%
June21%20%21%20%
July17%14%9.0%6.3%
August6.0%6.4%4.7%5.1%
September5.0%4.5%4.9%5.1%
October6.5%6.7%6.7%6.8%
November6.3%5.9%5.1%5.1%
December4.9%5.1%5.7%5.5%

Neighboring states

  • North Carolina: arrives mid March, in the same week than South Carolina
  • Georgia: arrives mid March, in the same week than South Carolina
  • Tennessee: arrives mid March, in the same week than South Carolina
  • Virginia: arrives late March, 1 week later than South Carolina

Common questions

When do Brown-headed Cowbirds arrive in South Carolina?
Brown-headed Cowbirds are in South Carolina all year, but most are here in spring: numbers build from mid March, peak in late April (26% of checklists), and fall back by early July. In the quietest week (the second week of September) they are still on about 4.8% of checklists.
When do Brown-headed Cowbirds leave South Carolina?
Brown-headed Cowbirds never fully leave South Carolina: numbers fall back below half their usual rate by early July, but some are still reported in every week, about 4.8% of checklists at the low.
When is the best time to see a Brown-headed Cowbird in South Carolina?
The Brown-headed Cowbird is reported most often in late April, on about 26% of South Carolina checklists.
Where in South Carolina are Brown-headed Cowbirds seen most often?
By county, Clarendon County, Allendale County, and Cherokee County have the highest peak reporting rates for the Brown-headed Cowbird (counties with at least 200 checklists).