WhenToBird

Molothrus ater · Icteridae

Brown-headed Cowbird: When and Where to See It

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

The Brown-headed Cowbird reaches Connecticut first, around mid January, and Montana last, around late April.

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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0%10%20%30%Jan 1-7: 2.0% of 1114036 checklistsJan 8-14: 2.3% of 824708 checklistsJan 15-21: 2.5% of 825978 checklistsJan 22-31: 2.4% of 1105853 checklistsFeb 1-7: 2.7% of 779772 checklistsFeb 8-14: 3.0% of 864504 checklistsFeb 15-21: 3.4% of 1127933 checklistsFeb 22-28: 3.8% of 840124 checklistsMar 1-7: 4.8% of 839610 checklistsMar 8-14: 6.3% of 870138 checklistsMar 15-21: 8.2% of 898456 checklistsMar 22-31: 12% of 1335637 checklistsApr 1-7: 16% of 1030617 checklistsApr 8-14: 20% of 1124024 checklistsApr 15-21: 23% of 1194575 checklistsApr 22-30: 26% of 1675723 checklistsMay 1-7: 29% of 1449080 checklistsMay 8-14: 28% of 1538353 checklistsMay 15-21: 27% of 1219898 checklistsMay 22-31: 25% of 1452282 checklistsJun 1-7: 23% of 900636 checklistsJun 8-14: 21% of 829907 checklistsJun 15-21: 20% of 773255 checklistsJun 22-30: 19% of 916255 checklistsJul 1-7: 18% of 717733 checklistsJul 8-14: 15% of 658223 checklistsJul 15-21: 11% of 638752 checklistsJul 22-31: 6.6% of 895727 checklistsAug 1-7: 5.0% of 655651 checklistsAug 8-14: 4.5% of 650038 checklistsAug 15-21: 3.8% of 654639 checklistsAug 22-31: 3.2% of 974928 checklistsSep 1-7: 2.5% of 765914 checklistsSep 8-14: 2.0% of 738674 checklistsSep 15-21: 2.0% of 750433 checklistsSep 22-30: 2.3% of 944196 checklistsOct 1-7: 2.9% of 760106 checklistsOct 8-14: 3.1% of 793131 checklistsOct 15-21: 3.1% of 728727 checklistsOct 22-31: 2.8% of 959954 checklistsNov 1-7: 2.6% of 709464 checklistsNov 8-14: 2.3% of 693424 checklistsNov 15-21: 2.1% of 653952 checklistsNov 22-30: 1.9% of 871137 checklistsDec 1-7: 2.0% of 627591 checklistsDec 8-14: 1.9% of 642427 checklistsDec 15-21: 2.0% of 775638 checklistsDec 22-31: 1.9% of 1132751 checklistsJanFebMarAprMayJunJulAugSepOctNovDec
Share of complete checklists reporting it, by week (4 per month). Grey bars: fewer than 10 checklists, not counted.

Pooled across every state in the data, so it leans toward states with the most birders.

States, in order of first arrivals

StatePatternFirst arrivalsPeakMost gone byPeak %
OklahomaSummer visitorJan 1-7May 8-14Jul 8-1434%
ConnecticutSummer visitorJan 15-21Apr 22-30Jul 8-1430%
OhioSummer visitorFeb 8-14Apr 22-30Jul 8-1443%
PennsylvaniaSummer visitorFeb 8-14Apr 22-30Jul 8-1435%
IllinoisSummer visitorFeb 15-21May 1-7Jul 15-2145%
IndianaSummer visitorFeb 15-21Apr 22-30Jul 8-1446%
MissouriSummer visitorFeb 15-21May 1-7Jul 8-1447%
New YorkSummer visitorFeb 15-21Apr 22-30Jul 8-1426%
CaliforniaSummer visitorFeb 15-21May 22-31Jul 15-2117%
District of ColumbiaSummer visitorFeb 22-28Apr 22-30Jul 8-1443%
Rhode IslandSummer visitorFeb 22-28Apr 22-30Jul 8-1435%
West VirginiaSummer visitorFeb 22-28Apr 15-21Jul 1-730%
KansasSummer visitorMar 1-7May 8-14Jul 15-2140%
MichiganSummer visitorMar 1-7May 1-7Jul 8-1436%
MassachusettsSummer visitorMar 1-7May 1-7Jul 8-1428%
AlabamaAll year, most in springMar 1-7May 1-7Jul 1-726%
LouisianaAll year, most in springMar 1-7Apr 15-21Jul 1-726%
New HampshireSummer visitorMar 1-7May 1-7Jul 8-1417%
VermontSummer visitorMar 1-7May 1-7Jul 1-714%
IowaSummer visitorMar 8-14May 8-14Jul 15-2146%
WisconsinSummer visitorMar 8-14May 8-14Jul 8-1440%
MississippiAll year, most in springMar 8-14Apr 15-21Jul 1-728%
ArizonaSummer visitorMar 8-14May 22-31Aug 1-725%
TexasAll year, most in springMar 8-14May 8-14Jul 8-1420%
MaineSummer visitorMar 8-14May 1-7Jun 22-3012%
NebraskaSummer visitorMar 15-21May 8-14Jul 22-3141%
ArkansasAll year, most in springMar 15-21Apr 22-30Jul 1-739%
TennesseeAll year, most in springMar 15-21Apr 15-21Jul 1-736%
GeorgiaAll year, most in springMar 15-21Apr 15-21Jun 22-3028%
North CarolinaAll year, most in springMar 15-21Apr 15-21Jul 1-729%
South CarolinaAll year, most in springMar 15-21Apr 22-30Jul 1-726%
KentuckyAll year, most in springMar 22-31Apr 22-30Jul 1-745%
MarylandAll year, most in springMar 22-31Apr 22-30Jul 1-736%
DelawareAll year, most in springMar 22-31Apr 22-30Jul 1-735%
New JerseyAll year, most in springMar 22-31Apr 22-30Jul 1-735%
VirginiaAll year, most in springMar 22-31Apr 22-30Jul 1-730%
NevadaSummer visitorMar 22-31May 8-14Aug 1-721%
MinnesotaSummer visitorApr 1-7May 8-14Jul 8-1437%
South DakotaSummer visitorApr 1-7May 15-21Jul 15-2136%
OregonSummer visitorApr 1-7May 15-21Jul 15-2124%
ColoradoSummer visitorApr 8-14May 15-21Jul 8-1425%
WashingtonSummer visitorApr 8-14May 15-21Jul 15-2125%
New MexicoSummer visitorApr 8-14May 15-21Jul 22-3117%
North DakotaSummer visitorApr 15-21May 22-31Jul 8-1445%
IdahoSummer visitorApr 15-21May 22-31Jul 15-2128%
WyomingSummer visitorApr 15-21May 22-31Jul 15-2121%
UtahSummer visitorApr 15-21May 22-31Jul 15-2119%
MontanaSummer visitorApr 22-30May 22-31Jul 15-2134%
FloridaSummer visitorSep 22-30Apr 1-7Jul 8-146.3%

Summer visitor in: Oklahoma, Florida