WhenToBird

Molothrus ater · Icteridae

When Do Brown-headed Cowbirds Arrive in Mississippi?

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

Brown-headed Cowbirds are in Mississippi all year, but most are here in spring: numbers build from the second week of March, peak in mid April (28% of checklists), and fall back by early July. In the quietest week (the second week of September) they are still on about 2.5% of checklists.

When to look

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

Best: mid April. Here all year; numbers build from the second week of March and fall back by early July. Peak: on about 28% of Mississippi checklists.

  1. Januncommon
  2. Febcommon
  3. Marpeak season
  4. Aprpeak season
  5. Maypeak season
  6. Junpeak season
  7. Julcommon
  8. Augrare
  9. Seprare
  10. Octuncommon
  11. Novuncommon
  12. Decuncommon

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

0%10%20%30%Jan 1-7: 5.6% of 4836 checklistsJan 8-14: 5.8% of 3323 checklistsJan 15-21: 6.9% of 3400 checklistsJan 22-31: 6.2% of 4705 checklistsFeb 1-7: 7.6% of 3387 checklistsFeb 8-14: 8.2% of 3911 checklistsFeb 15-21: 11% of 4691 checklistsFeb 22-28: 11% of 3409 checklistsMar 1-7: 14% of 3276 checklistsMar 8-14: 15% of 3273 checklistsMar 15-21: 18% of 3552 checklistsMar 22-31: 23% of 5618 checklistsApr 1-7: 25% of 4432 checklistsApr 8-14: 27% of 4907 checklistsApr 15-21: 29% of 5239 checklistsApr 22-30: 28% of 7043 checklistsMay 1-7: 27% of 4597 checklistsMay 8-14: 27% of 4383 checklistsMay 15-21: 25% of 3088 checklistsMay 22-31: 25% of 3805 checklistsJun 1-7: 21% of 2658 checklistsJun 8-14: 20% of 2469 checklistsJun 15-21: 21% of 2112 checklistsJun 22-30: 20% of 2534 checklistsJul 1-7: 17% of 2099 checklistsJul 8-14: 12% of 1885 checklistsJul 15-21: 6.2% of 1811 checklistsJul 22-31: 4.1% of 2793 checklistsAug 1-7: 4.0% of 2045 checklistsAug 8-14: 3.3% of 2210 checklistsAug 15-21: 3.8% of 2437 checklistsAug 22-31: 2.9% of 3415 checklistsSep 1-7: 2.1% of 2837 checklistsSep 8-14: 2.6% of 2585 checklistsSep 15-21: 2.8% of 2870 checklistsSep 22-30: 3.3% of 3610 checklistsOct 1-7: 3.8% of 2938 checklistsOct 8-14: 5.6% of 3457 checklistsOct 15-21: 4.8% of 3168 checklistsOct 22-31: 5.0% of 3752 checklistsNov 1-7: 4.9% of 2847 checklistsNov 8-14: 4.5% of 2648 checklistsNov 15-21: 3.6% of 2599 checklistsNov 22-30: 5.1% of 3389 checklistsDec 1-7: 4.8% of 2419 checklistsDec 8-14: 4.2% of 2526 checklistsDec 15-21: 4.6% of 2966 checklistsDec 22-31: 5.5% of 4466 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 Mississippi 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 Mississippi

Best counties

Share of checklists at the peak
  1. Jefferson Davis CountyBest late March · 11 checklists that week, 370 in all88%
  2. Yalobusha CountyBest late June · 10 checklists that week, 368 in all72%
  3. Humphreys CountyBest late May · 17 checklists that week, 560 in all67%
  4. Yazoo CountyBest late March · 16 checklists that week, 440 in all67%
  5. Bolivar CountyBest the second week of May · 13 checklists that week, 384 in all64%
  6. Warren CountyBest mid April · 83 checklists that week, 1,855 in all61%

Best spots

Share of checklists at the peak
  1. Plymouth BluffLowndes County, best the second week of April · 27 checklists that week, 333 in all95%
  2. Vicksburg National Military ParkWarren County, best early April · 25 checklists that week, 383 in all92%
  3. Lake Yazoo (East Pascagoula)Jackson County, best late January · 24 checklists that week, 585 in all67%
  4. The DellLafayette County, best the second week of April · 29 checklists that week, 431 in all66%

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

Best time of day

In Mississippi, 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 (54) to judge1 am: too few checklists (48) to judge2 am: too few checklists (28) to judge3 am: too few checklists (60) to judge4 am: too few checklists (114) to judge5 am: too few checklists (1139) to judge6 am: 20% of 9054 checklists7 am: 20% of 18481 checklists8 am: 16% of 17525 checklists9 am: 13% of 15482 checklists10 am: 10% of 14380 checklists11 am: 9.8% of 12728 checklists12 pm: 9.4% of 11009 checklists1 pm: 8.8% of 10651 checklists2 pm: 9.0% of 10787 checklists3 pm: 9.2% of 11221 checklists4 pm: 12% of 11861 checklists5 pm: 13% of 8854 checklists6 pm: 10% of 6018 checklists7 pm: too few checklists (2387) to judge8 pm: too few checklists (314) to judge9 pm: too few checklists (114) to judge10 pm: too few checklists (63) to judge11 pm: too few checklists (48) 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
January5.6%5.8%6.9%6.2%
February7.6%8.2%11%11%
March14%15%18%23%
April25%27%29%28%
May27%27%25%25%
June21%20%21%20%
July17%12%6.2%4.1%
August4.0%3.3%3.8%2.9%
September2.1%2.6%2.8%3.3%
October3.8%5.6%4.8%5.0%
November4.9%4.5%3.6%5.1%
December4.8%4.2%4.6%5.5%

Neighboring states

  • Alabama: arrives early March, 1 week earlier than Mississippi
  • Louisiana: arrives early March, 1 week earlier than Mississippi
  • Arkansas: arrives mid March, 1 week later than Mississippi
  • Georgia: arrives mid March, 1 week later than Mississippi

Common questions

When do Brown-headed Cowbirds arrive in Mississippi?
Brown-headed Cowbirds are in Mississippi all year, but most are here in spring: numbers build from the second week of March, peak in mid April (28% of checklists), and fall back by early July. In the quietest week (the second week of September) they are still on about 2.5% of checklists.
When do Brown-headed Cowbirds leave Mississippi?
Brown-headed Cowbirds never fully leave Mississippi: numbers fall back below half their usual rate by early July, but some are still reported in every week, about 2.5% of checklists at the low.
When is the best time to see a Brown-headed Cowbird in Mississippi?
The Brown-headed Cowbird is reported most often in mid April, on about 28% of Mississippi checklists.
Where in Mississippi are Brown-headed Cowbirds seen most often?
By county, Jefferson Davis County, Yalobusha County, and Humphreys County have the highest peak reporting rates for the Brown-headed Cowbird (counties with at least 200 checklists).