WhenToBird

Molothrus ater · Icteridae

When Do Brown-headed Cowbirds Arrive in Tennessee?

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

Brown-headed Cowbirds are in Tennessee all year, but most are here in spring: numbers build from mid March, peak in mid April (36% of checklists), and fall back by early July. In the quietest week (the second week of September) they are still on about 2.8% of checklists.

When to look

Numbers buildMar 15-21mid 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 mid March and fall back by early July. Peak: on about 36% of Tennessee checklists.

  1. Januncommon
  2. Febuncommon
  3. Marcommon
  4. Aprpeak season
  5. Maypeak season
  6. Junpeak season
  7. Julcommon
  8. Auguncommon
  9. Seprare
  10. Octuncommon
  11. Novuncommon
  12. Decrare

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

0%10%20%30%40%Jan 1-7: 4.8% of 16696 checklistsJan 8-14: 5.9% of 13056 checklistsJan 15-21: 7.7% of 13646 checklistsJan 22-31: 5.7% of 18071 checklistsFeb 1-7: 6.2% of 13342 checklistsFeb 8-14: 7.5% of 14316 checklistsFeb 15-21: 9.2% of 20395 checklistsFeb 22-28: 8.8% of 13129 checklistsMar 1-7: 11% of 12701 checklistsMar 8-14: 14% of 12789 checklistsMar 15-21: 18% of 13599 checklistsMar 22-31: 26% of 20293 checklistsApr 1-7: 32% of 15779 checklistsApr 8-14: 35% of 16646 checklistsApr 15-21: 37% of 18625 checklistsApr 22-30: 36% of 26689 checklistsMay 1-7: 34% of 21054 checklistsMay 8-14: 33% of 19954 checklistsMay 15-21: 33% of 14494 checklistsMay 22-31: 31% of 17790 checklistsJun 1-7: 29% of 11344 checklistsJun 8-14: 27% of 11049 checklistsJun 15-21: 27% of 9625 checklistsJun 22-30: 26% of 11522 checklistsJul 1-7: 23% of 9208 checklistsJul 8-14: 16% of 8814 checklistsJul 15-21: 11% of 8887 checklistsJul 22-31: 7.2% of 12739 checklistsAug 1-7: 6.0% of 9632 checklistsAug 8-14: 5.7% of 9514 checklistsAug 15-21: 4.6% of 9619 checklistsAug 22-31: 3.7% of 14227 checklistsSep 1-7: 3.0% of 11988 checklistsSep 8-14: 2.7% of 11660 checklistsSep 15-21: 2.6% of 11774 checklistsSep 22-30: 3.6% of 15658 checklistsOct 1-7: 5.3% of 12641 checklistsOct 8-14: 7.0% of 12389 checklistsOct 15-21: 6.9% of 10249 checklistsOct 22-31: 6.7% of 14085 checklistsNov 1-7: 6.7% of 10700 checklistsNov 8-14: 6.3% of 10709 checklistsNov 15-21: 5.9% of 9955 checklistsNov 22-30: 4.9% of 13423 checklistsDec 1-7: 5.0% of 10106 checklistsDec 8-14: 4.3% of 10478 checklistsDec 15-21: 5.1% of 12177 checklistsDec 22-31: 5.1% of 17397 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 Tennessee 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 Tennessee

Best counties

Share of checklists at the peak
  1. Weakley CountyBest late June · 35 checklists that week, 2,092 in all90%
  2. Houston CountyBest late June · 21 checklists that week, 1,234 in all83%
  3. Benton CountyBest late April · 80 checklists that week, 2,202 in all75%
  4. Lauderdale CountyBest late April · 54 checklists that week, 888 in all66%
  5. Giles CountyBest mid May · 27 checklists that week, 803 in all63%
  6. Haywood CountyBest the second week of April · 48 checklists that week, 1,498 in all62%

Best spots

Share of checklists at the peak
  1. Penal Farm Lake Number Three (Penal Farm Lake Number Two)Shelby County, best late May · 22 checklists that week, 851 in all90%
  2. LichtermanShelby County, best the second week of May · 23 checklists that week, 932 in all88%
  3. Natchez Trace ParkwayWilliamson County, best the second week of May · 22 checklists that week, 445 in all87%
  4. Shelby FarmsShelby County, best late April · 35 checklists that week, 879 in all84%
  5. Piersol LakeShelby County, best late April · 31 checklists that week, 291 in all84%
  6. To FullerShelby County, best mid May · 20 checklists that week, 508 in all83%

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

Best time of day

In Tennessee, the Brown-headed Cowbird is most often listed on checklists started between 6 and 8 am (24% of those checklists).

0%10%20%30%12 am: too few checklists (224) to judge1 am: too few checklists (253) to judge2 am: too few checklists (245) to judge3 am: too few checklists (267) to judge4 am: too few checklists (582) to judge5 am: too few checklists (5688) to judge6 am: 29% of 36828 checklists7 am: 22% of 72816 checklists8 am: 19% of 76910 checklists9 am: 16% of 69071 checklists10 am: 14% of 60943 checklists11 am: 12% of 52311 checklists12 pm: 11% of 46524 checklists1 pm: 11% of 41133 checklists2 pm: 10% of 40305 checklists3 pm: 10% of 41013 checklists4 pm: 12% of 40029 checklists5 pm: 13% of 29775 checklists6 pm: 14% of 20977 checklists7 pm: too few checklists (12529) to judge8 pm: too few checklists (4456) to judge9 pm: too few checklists (1056) to judge10 pm: too few checklists (445) to judge11 pm: too few checklists (252) 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
January4.8%5.9%7.7%5.7%
February6.2%7.5%9.2%8.8%
March11%14%18%26%
April32%35%37%36%
May34%33%33%31%
June29%27%27%26%
July23%16%11%7.2%
August6.0%5.7%4.6%3.7%
September3.0%2.7%2.6%3.6%
October5.3%7.0%6.9%6.7%
November6.7%6.3%5.9%4.9%
December5.0%4.3%5.1%5.1%

Neighboring states

  • Kentucky: arrives late March, 1 week later than Tennessee
  • Georgia: arrives mid March, in the same week than Tennessee
  • Alabama: arrives early March, 2 weeks earlier than Tennessee
  • Indiana: arrives mid February, 4 weeks earlier than Tennessee

Common questions

When do Brown-headed Cowbirds arrive in Tennessee?
Brown-headed Cowbirds are in Tennessee all year, but most are here in spring: numbers build from mid March, peak in mid April (36% of checklists), and fall back by early July. In the quietest week (the second week of September) they are still on about 2.8% of checklists.
When do Brown-headed Cowbirds leave Tennessee?
Brown-headed Cowbirds never fully leave Tennessee: numbers fall back below half their usual rate by early July, but some are still reported in every week, about 2.8% of checklists at the low.
When is the best time to see a Brown-headed Cowbird in Tennessee?
The Brown-headed Cowbird is reported most often in mid April, on about 36% of Tennessee checklists.
Where in Tennessee are Brown-headed Cowbirds seen most often?
By county, Weakley County, Houston County, and Benton County have the highest peak reporting rates for the Brown-headed Cowbird (counties with at least 200 checklists).