WhenToBird

Mergus merganser · Anatidae

Common Merganser: When and Where to See It

Adult female Common Merganser
Photo: Christoph Moning, CC BY 4.0 via iNaturalist

The Common Merganser reaches Colorado first, around early September, and Virginia last, around early December.

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%2%4%6%8%Jan 1-7: 6.0% of 1114036 checklistsJan 8-14: 6.0% of 824708 checklistsJan 15-21: 6.0% of 825978 checklistsJan 22-31: 6.2% of 1105853 checklistsFeb 1-7: 6.1% of 779772 checklistsFeb 8-14: 5.6% of 864504 checklistsFeb 15-21: 5.1% of 1127933 checklistsFeb 22-28: 7.1% of 840124 checklistsMar 1-7: 7.5% of 839610 checklistsMar 8-14: 7.4% of 870138 checklistsMar 15-21: 7.0% of 898456 checklistsMar 22-31: 6.6% of 1335637 checklistsApr 1-7: 5.6% of 1030617 checklistsApr 8-14: 4.6% of 1124024 checklistsApr 15-21: 3.5% of 1194575 checklistsApr 22-30: 2.7% of 1675723 checklistsMay 1-7: 2.0% of 1449080 checklistsMay 8-14: 1.6% of 1538353 checklistsMay 15-21: 1.6% of 1219898 checklistsMay 22-31: 1.5% of 1452282 checklistsJun 1-7: 1.3% of 900636 checklistsJun 8-14: 1.2% of 829907 checklistsJun 15-21: 1.1% of 773255 checklistsJun 22-30: 1.1% of 916255 checklistsJul 1-7: 1.0% of 717733 checklistsJul 8-14: 1.0% of 658223 checklistsJul 15-21: 1.0% of 638752 checklistsJul 22-31: 1.0% of 895727 checklistsAug 1-7: 1.0% of 655651 checklistsAug 8-14: 1.1% of 650038 checklistsAug 15-21: 1.1% of 654639 checklistsAug 22-31: 1.2% of 974928 checklistsSep 1-7: 1.3% of 765914 checklistsSep 8-14: 1.4% of 738674 checklistsSep 15-21: 1.4% of 750433 checklistsSep 22-30: 1.4% of 944196 checklistsOct 1-7: 1.5% of 760106 checklistsOct 8-14: 1.5% of 793131 checklistsOct 15-21: 1.8% of 728727 checklistsOct 22-31: 2.4% of 959954 checklistsNov 1-7: 2.9% of 709464 checklistsNov 8-14: 3.6% of 693424 checklistsNov 15-21: 3.9% of 653952 checklistsNov 22-30: 4.3% of 871137 checklistsDec 1-7: 4.7% of 627591 checklistsDec 8-14: 4.7% of 642427 checklistsDec 15-21: 4.6% of 775638 checklistsDec 22-31: 4.9% 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 %
MontanaAll year, most in springMar 8-14Apr 1-7Apr 22-3014%
WyomingAll year, most in springMar 15-21Apr 8-14May 22-3115%
VermontSummer visitorJul 22-31Apr 1-7May 8-1420%
New HampshireSummer visitorSep 22-30Apr 1-7May 8-1414%
AlaskaAll year, most in winterOct 8-14Apr 1-7May 1-719%
South DakotaWinter visitorOct 8-14Dec 1-7Apr 8-1414%
MassachusettsWinter visitorOct 15-21Mar 8-14Apr 15-2113%
ConnecticutWinter visitorOct 15-21Mar 8-14Apr 15-2110%
IdahoAll year, most in winterOct 15-21Mar 15-21Apr 22-3012%
West VirginiaWinter visitorOct 15-21Feb 1-7Apr 8-1411%
CaliforniaWinter visitorOct 15-21Jan 22-31May 22-314.3%
North DakotaWinter visitorOct 22-31Nov 15-21May 1-79.6%
OhioWinter visitorOct 22-31Mar 1-7Apr 1-77.1%
New JerseyWinter visitorNov 1-7Mar 1-7Apr 8-1414%
WashingtonAll year, most in winterNov 1-7Jan 8-14Apr 15-2114%
IowaWinter visitorNov 1-7Mar 8-14Apr 1-712%
NebraskaWinter visitorNov 1-7Mar 8-14Apr 1-79.4%
New MexicoWinter visitorNov 1-7Jan 15-21Mar 22-318.0%
IllinoisWinter visitorNov 8-14Mar 1-7Mar 22-3114%
KansasWinter visitorNov 8-14Feb 1-7Mar 8-148.3%
Rhode IslandWinter visitorNov 8-14Mar 1-7Apr 1-78.8%
District of ColumbiaWinter visitorNov 15-21Feb 1-7Mar 15-2111%
MarylandWinter visitorNov 15-21Jan 22-31Apr 1-79.2%
MissouriWinter visitorNov 15-21Feb 1-7Mar 8-143.9%
ArizonaWinter visitorNov 22-30Jan 15-21Mar 22-315.5%
IndianaWinter visitorNov 22-30Feb 1-7Mar 15-214.0%
DelawareWinter visitorDec 1-7Feb 15-21Apr 1-77.1%
OklahomaWinter visitorDec 1-7Jan 15-21Mar 1-73.5%
VirginiaWinter visitorDec 1-7Feb 1-7Apr 1-74.0%
PennsylvaniaWinter visitorJul 15-21Mar 1-7Apr 15-2117%
MinnesotaWinter visitorJul 15-21Mar 22-31May 1-714%
New YorkWinter visitorAug 15-21Mar 1-7Apr 22-3014%
OregonWinter visitorAug 15-21Jan 15-21Apr 8-1411%
ColoradoWinter visitorSep 1-7Jan 15-21Apr 22-3014%
NevadaWinter visitorSep 1-7Jan 15-21May 1-714%
MichiganWinter visitorSep 8-14Mar 8-14Apr 22-3015%
MaineWinter visitorSep 8-14Mar 22-31May 1-79.2%
WisconsinWinter visitorSep 15-21Mar 8-14Apr 15-2114%
UtahWinter visitorSep 15-21Mar 8-14Apr 15-217.6%

Winter visitor in: South Dakota, North Dakota, Pennsylvania, Minnesota, New York, Oregon

Passes through: Montana, Wyoming

Summer visitor in: Vermont