WhenToBird

Mergus merganser · Anatidae

When Do Common Mergansers Arrive in Minnesota?

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

Common Mergansers are winter birds in Minnesota: the first arrive in mid July, they are common by early November, peak in late March (14% of checklists), and most are gone by early May.

When to look

First arrivalsJul 15-21mid July
Common byNov 1-7early November
PeakMar 22-31late March
Most gone byMay 1-7early May

Best: late March. First arrivals mid July; most are gone by early May. Peak: on about 14% of Minnesota checklists.

  1. Januncommon
  2. Febcommon
  3. Marpeak season
  4. Aprpeak season
  5. Mayuncommon
  6. Junrare
  7. Julrare
  8. Augrare
  9. Seprare
  10. Octuncommon
  11. Novcommon
  12. Deccommon

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

0%5%10%15%Jan 1-7: 4.9% of 20628 checklistsJan 8-14: 4.7% of 14594 checklistsJan 15-21: 4.1% of 14238 checklistsJan 22-31: 3.3% of 20725 checklistsFeb 1-7: 3.7% of 14484 checklistsFeb 8-14: 3.2% of 15988 checklistsFeb 15-21: 2.9% of 20718 checklistsFeb 22-28: 5.7% of 15754 checklistsMar 1-7: 8.7% of 16125 checklistsMar 8-14: 12% of 19035 checklistsMar 15-21: 14% of 19586 checklistsMar 22-31: 14% of 30192 checklistsApr 1-7: 13% of 24262 checklistsApr 8-14: 11% of 30223 checklistsApr 15-21: 8.4% of 29085 checklistsApr 22-30: 5.4% of 43574 checklistsMay 1-7: 2.4% of 39300 checklistsMay 8-14: 1.1% of 45927 checklistsMay 15-21: 1.1% of 36632 checklistsMay 22-31: 1.1% of 43809 checklistsJun 1-7: 0.9% of 23418 checklistsJun 8-14: 0.8% of 20450 checklistsJun 15-21: 1.1% of 19470 checklistsJun 22-30: 0.9% of 23418 checklistsJul 1-7: 0.9% of 19104 checklistsJul 8-14: 0.9% of 16927 checklistsJul 15-21: 1.1% of 15635 checklistsJul 22-31: 1.1% of 22073 checklistsAug 1-7: 1.0% of 16255 checklistsAug 8-14: 1.0% of 16840 checklistsAug 15-21: 1.0% of 17475 checklistsAug 22-31: 1.2% of 26545 checklistsSep 1-7: 1.2% of 20750 checklistsSep 8-14: 1.4% of 18494 checklistsSep 15-21: 1.6% of 18215 checklistsSep 22-30: 1.5% of 24463 checklistsOct 1-7: 1.2% of 18252 checklistsOct 8-14: 1.1% of 19527 checklistsOct 15-21: 2.0% of 17098 checklistsOct 22-31: 2.7% of 24570 checklistsNov 1-7: 3.3% of 16744 checklistsNov 8-14: 5.3% of 13483 checklistsNov 15-21: 7.4% of 12525 checklistsNov 22-30: 9.5% of 17023 checklistsDec 1-7: 10% of 11645 checklistsDec 8-14: 7.5% of 11567 checklistsDec 15-21: 4.8% of 13343 checklistsDec 22-31: 4.8% of 19759 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 Minnesota 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 Minnesota

Best counties

Share of checklists at the peak
  1. Beltrami CountyBest mid November · 115 checklists that week, 6,476 in all56%
  2. Nobles CountyBest early March · 31 checklists that week, 1,250 in all42%
  3. Goodhue CountyBest early March · 264 checklists that week, 16,294 in all37%
  4. Lincoln CountyBest late March · 17 checklists that week, 1,063 in all35%
  5. Freeborn CountyBest late March · 86 checklists that week, 2,409 in all34%
  6. Mille Lacs CountyBest mid April · 60 checklists that week, 1,955 in all32%

Best spots

Share of checklists at the peak
  1. Pickerel SloughGoodhue County, best the second week of February · 20 checklists that week, 682 in all97%
  2. Steamboat ParkWashington County, best the second week of February · 22 checklists that week, 698 in all96%
  3. Lake ByllesbyGoodhue County, best early March · 38 checklists that week, 1,274 in all94%
  4. Colvill ParkGoodhue County, best the second week of January · 65 checklists that week, 579 in all94%
  5. Hazen P. Mooers ParkWashington County, best mid March · 108 checklists that week, 893 in all91%

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

Best time of day

In Minnesota, the Common Merganser is most often listed on checklists started between 2 and 4 pm (5.1% of those checklists).

0%2%4%6%12 am: too few checklists (349) to judge1 am: too few checklists (331) to judge2 am: too few checklists (286) to judge3 am: too few checklists (364) to judge4 am: too few checklists (863) to judge5 am: too few checklists (7598) to judge6 am: 3.1% of 35775 checklists7 am: 3.5% of 90565 checklists8 am: 3.4% of 110612 checklists9 am: 4.1% of 106128 checklists10 am: 4.3% of 96131 checklists11 am: 4.3% of 83750 checklists12 pm: 4.5% of 76254 checklists1 pm: 5.0% of 73480 checklists2 pm: 5.2% of 73703 checklists3 pm: 5.1% of 75249 checklists4 pm: 4.6% of 68810 checklists5 pm: 3.9% of 51899 checklists6 pm: 3.7% of 38524 checklists7 pm: 2.2% of 25120 checklists8 pm: too few checklists (10568) to judge9 pm: too few checklists (2420) to judge10 pm: too few checklists (748) to judge11 pm: too few checklists (420) 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
January4.9%4.7%4.1%3.3%
February3.7%3.2%2.9%5.7%
March8.7%12%14%14%
April13%11%8.4%5.4%
May2.4%1.1%1.1%1.1%
June0.9%0.8%1.1%0.9%
July0.9%0.9%1.1%1.1%
August1.0%1.0%1.0%1.2%
September1.2%1.4%1.6%1.5%
October1.2%1.1%2.0%2.7%
November3.3%5.3%7.4%9.5%
December10%7.5%4.8%4.8%

Neighboring states

  • Iowa: arrives early November, 14 weeks later than Minnesota
  • Wisconsin: arrives mid September, 8 weeks later than Minnesota
  • South Dakota: arrives the second week of October, 11 weeks later than Minnesota
  • North Dakota: arrives late October, 13 weeks later than Minnesota

Common questions

When do Common Mergansers arrive in Minnesota?
Common Mergansers are winter birds in Minnesota: the first arrive in mid July, they are common by early November, peak in late March (14% of checklists), and most are gone by early May.
When do Common Mergansers leave Minnesota?
Most Common Mergansers have left Minnesota by early May, when reports fall below half their usual rate. Stragglers are still reported until late May.
When is the best time to see a Common Merganser in Minnesota?
The Common Merganser is reported most often in late March, on about 14% of Minnesota checklists.
Where in Minnesota are Common Mergansers seen most often?
By county, Beltrami County, Nobles County, and Goodhue County have the highest peak reporting rates for the Common Merganser (counties with at least 200 checklists).