WhenToBird

Mergus merganser · Anatidae

When Do Common Mergansers Arrive in North Dakota?

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

Common Mergansers are winter birds in North Dakota: the first arrive in late October, they are common by early November, peak in mid November (9.6% of checklists), and most are gone by early May.

When to look

First arrivalsOct 22-31late October
Common byNov 1-7early November
PeakNov 15-21mid November
Most gone byMay 1-7early May

Best: mid November. First arrivals late October; most are gone by early May. Peak: on about 9.6% of North Dakota checklists.

  1. Januncommon
  2. Febuncommon
  3. Marcommon
  4. Aprpeak season
  5. Mayuncommon
  6. Junnot usually seen
  7. Julnot usually seen
  8. Augnot usually seen
  9. Sepnot usually seen
  10. Octuncommon
  11. Novpeak season
  12. Decpeak season

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

0%5%10%15%Jan 1-7: 3.6% of 1694 checklistsJan 8-14: 2.8% of 1210 checklistsJan 15-21: 3.9% of 1263 checklistsJan 22-31: 2.0% of 1984 checklistsFeb 1-7: 1.7% of 1209 checklistsFeb 8-14: 1.7% of 1307 checklistsFeb 15-21: 1.8% of 1655 checklistsFeb 22-28: 2.6% of 1619 checklistsMar 1-7: 2.5% of 1653 checklistsMar 8-14: 4.7% of 1818 checklistsMar 15-21: 6.5% of 2103 checklistsMar 22-31: 7.2% of 3714 checklistsApr 1-7: 7.7% of 2955 checklistsApr 8-14: 9.3% of 3550 checklistsApr 15-21: 7.7% of 4104 checklistsApr 22-30: 5.1% of 5712 checklistsMay 1-7: 1.9% of 5328 checklistsMay 8-14: 0.5% of 5885 checklistsMay 15-21: 0.3% of 5344 checklistsMay 22-31: 0.3% of 7512 checklistsJun 1-7: 0.3% of 4329 checklistsJun 8-14: 0.2% of 4287 checklistsJun 15-21: 0.2% of 3798 checklistsJun 22-30: 0.3% of 4361 checklistsJul 1-7: 0.2% of 2939 checklistsJul 8-14: 0.1% of 2407 checklistsJul 15-21: 0.1% of 2254 checklistsJul 22-31: 0.1% of 2852 checklistsAug 1-7: 0.1% of 2119 checklistsAug 8-14: 0% of 2044 checklistsAug 15-21: 0% of 2124 checklistsAug 22-31: 0.1% of 3168 checklistsSep 1-7: 0% of 2449 checklistsSep 8-14: 0.1% of 2310 checklistsSep 15-21: 0% of 2092 checklistsSep 22-30: 0% of 2565 checklistsOct 1-7: 0.1% of 2071 checklistsOct 8-14: 0.1% of 1918 checklistsOct 15-21: 0.2% of 1907 checklistsOct 22-31: 1.2% of 2589 checklistsNov 1-7: 4.0% of 1858 checklistsNov 8-14: 8.8% of 1753 checklistsNov 15-21: 9.5% of 1483 checklistsNov 22-30: 10% of 1928 checklistsDec 1-7: 6.5% of 1337 checklistsDec 8-14: 5.2% of 1309 checklistsDec 15-21: 2.8% of 1642 checklistsDec 22-31: 2.5% of 1830 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 North Dakota 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 North Dakota

Best counties

Share of checklists at the peak
  1. Mercer CountyBest late January · 36 checklists that week, 2,518 in all68%
  2. McLean CountyBest late November · 103 checklists that week, 1,933 in all45%
  3. Grant CountyBest mid November · 23 checklists that week, 605 in all44%
  4. Sargent CountyBest mid March · 26 checklists that week, 894 in all36%
  5. Mountrail CountyBest mid November · 53 checklists that week, 3,275 in all34%
  6. Oliver CountyBest the second week of March · 13 checklists that week, 776 in all32%

Best spots

Share of checklists at the peak
  1. Sakakawea Recreation AreaMercer County, best mid January · 20 checklists that week, 617 in all92%
  2. Sakakawea Recreation Area (Williston)Williams County, best late March · 24 checklists that week, 383 in all57%
  3. BOR LandsStark County, best early May · 23 checklists that week, 357 in all11%

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

Best time of day

In North Dakota, the Common Merganser is most often listed on checklists started between 1 and 3 pm (3.1% of those checklists).

0%1%2%3%4%12 am: too few checklists (74) to judge1 am: too few checklists (45) to judge2 am: too few checklists (42) to judge3 am: too few checklists (68) to judge4 am: too few checklists (274) to judge5 am: too few checklists (1538) to judge6 am: 0.6% of 4242 checklists7 am: 1.3% of 9520 checklists8 am: 2.0% of 13065 checklists9 am: 2.5% of 13356 checklists10 am: 2.9% of 12128 checklists11 am: 3.1% of 10772 checklists12 pm: 3.0% of 10316 checklists1 pm: 3.1% of 9169 checklists2 pm: 3.1% of 8880 checklists3 pm: 2.4% of 8688 checklists4 pm: 2.7% of 8201 checklists5 pm: 1.9% of 6687 checklists6 pm: 2.0% of 5455 checklists7 pm: 2.3% of 3926 checklists8 pm: too few checklists (2024) to judge9 pm: too few checklists (602) to judge10 pm: too few checklists (181) to judge11 pm: too few checklists (89) 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
January3.6%2.8%3.9%2.0%
February1.7%1.7%1.8%2.6%
March2.5%4.7%6.5%7.2%
April7.7%9.3%7.7%5.1%
May1.9%0.5%0.3%0.3%
June0.3%0.2%0.2%0.3%
July0.2%0.1%0.1%0.1%
August0.1%0%0%0.1%
September0%0.1%0%0%
October0.1%0.1%0.2%1.2%
November4.0%8.8%9.5%10%
December6.5%5.2%2.8%2.5%

Neighboring states

  • South Dakota: arrives the second week of October, 2 weeks earlier than North Dakota
  • Minnesota: arrives mid July, 13 weeks earlier than North Dakota
  • Nebraska: arrives early November, 1 week later than North Dakota
  • Iowa: arrives early November, 1 week later than North Dakota

Common questions

When do Common Mergansers arrive in North Dakota?
Common Mergansers are winter birds in North Dakota: the first arrive in late October, they are common by early November, peak in mid November (9.6% of checklists), and most are gone by early May.
When do Common Mergansers leave North Dakota?
Most Common Mergansers have left North Dakota by early May, when reports fall below half their usual rate.
When is the best time to see a Common Merganser in North Dakota?
The Common Merganser is reported most often in mid November, on about 9.6% of North Dakota checklists.
Where in North Dakota are Common Mergansers seen most often?
By county, Mercer County, McLean County, and Grant County have the highest peak reporting rates for the Common Merganser (counties with at least 200 checklists).