WhenToBird

Mergus merganser · Anatidae

When Do Common Mergansers Arrive in Oklahoma?

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

Common Mergansers are winter birds in Oklahoma: they arrive in early December, peak in mid January (3.5% of checklists), and most are gone by early March.

When to look

First arrivalsDec 1-7early December
Common byDec 1-7early December
PeakJan 15-21mid January
Most gone byMar 1-7early March

Best: mid January. First arrivals early December; most are gone by early March. Peak: on about 3.5% of Oklahoma checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marcommon
  4. Aprrare
  5. Maynot usually seen
  6. Junnot usually seen
  7. Julnot usually seen
  8. Augnot usually seen
  9. Sepnot usually seen
  10. Octnot usually seen
  11. Novuncommon
  12. Deccommon

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

0%2%4%6%Jan 1-7: 3.0% of 6087 checklistsJan 8-14: 2.9% of 4350 checklistsJan 15-21: 4.1% of 4381 checklistsJan 22-31: 3.4% of 6165 checklistsFeb 1-7: 2.7% of 4259 checklistsFeb 8-14: 2.1% of 4589 checklistsFeb 15-21: 1.7% of 7001 checklistsFeb 22-28: 2.4% of 4482 checklistsMar 1-7: 1.4% of 4724 checklistsMar 8-14: 0.7% of 4571 checklistsMar 15-21: 0.6% of 4393 checklistsMar 22-31: 0.3% of 7544 checklistsApr 1-7: 0.1% of 5967 checklistsApr 8-14: 0.1% of 6543 checklistsApr 15-21: 0.1% of 7366 checklistsApr 22-30: 0.1% of 10618 checklistsMay 1-7: 0.1% of 8835 checklistsMay 8-14: 0.1% of 8247 checklistsMay 15-21: 0.2% of 6081 checklistsMay 22-31: 0.1% of 7283 checklistsJun 1-7: 0.1% of 4256 checklistsJun 8-14: 0% of 3774 checklistsJun 15-21: 0.1% of 3541 checklistsJun 22-30: 0.2% of 4159 checklistsJul 1-7: 0.1% of 3209 checklistsJul 8-14: 0% of 2916 checklistsJul 15-21: 0.2% of 2861 checklistsJul 22-31: 0% of 4146 checklistsAug 1-7: 0.1% of 3043 checklistsAug 8-14: 0.1% of 2839 checklistsAug 15-21: 0.1% of 3014 checklistsAug 22-31: 0.1% of 4759 checklistsSep 1-7: 0.1% of 3861 checklistsSep 8-14: 0.1% of 3748 checklistsSep 15-21: 0.1% of 3569 checklistsSep 22-30: 0% of 4830 checklistsOct 1-7: 0.1% of 3809 checklistsOct 8-14: 0.1% of 4142 checklistsOct 15-21: 0.1% of 3705 checklistsOct 22-31: 0.1% of 4738 checklistsNov 1-7: 0.1% of 3823 checklistsNov 8-14: 0.4% of 3849 checklistsNov 15-21: 0.4% of 3722 checklistsNov 22-30: 0.7% of 4795 checklistsDec 1-7: 1.0% of 3324 checklistsDec 8-14: 1.6% of 3574 checklistsDec 15-21: 1.2% of 3884 checklistsDec 22-31: 2.3% of 5774 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 Oklahoma 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 Oklahoma

Best counties

Share of checklists at the peak
  1. Alfalfa CountyBest early February · 48 checklists that week, 3,843 in all22%
  2. Noble CountyBest mid January · 54 checklists that week, 1,320 in all21%
  3. Kay CountyBest mid January · 25 checklists that week, 897 in all18%
  4. Blaine CountyBest the second week of February · 13 checklists that week, 732 in all18%
  5. Cimarron CountyBest mid February · 79 checklists that week, 5,146 in all14%
  6. Pawnee CountyBest mid January · 29 checklists that week, 948 in all13%

Best spots

Share of checklists at the peak
  1. Lake Yahola (north)Tulsa County, best late January · 23 checklists that week, 612 in all36%
  2. Lake Hefner (northeast)Oklahoma County, best late January · 34 checklists that week, 807 in all32%
  3. Lake HefnerOklahoma County, best mid February · 48 checklists that week, 2,749 in all31%
  4. Lake Hefner (Ski Island Lake)Oklahoma County, best late January · 26 checklists that week, 428 in all31%
  5. Lynn Lane ReservoirTulsa County, best early January · 51 checklists that week, 372 in all30%
  6. Lake Hefner (north)Oklahoma County, best late January · 23 checklists that week, 276 in all26%

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

Best time of day

In Oklahoma, the Common Merganser is most often listed on checklists started between 3 and 5 pm (1.2% of those checklists).

0%0.5%1%1.5%12 am: too few checklists (91) to judge1 am: too few checklists (65) to judge2 am: too few checklists (73) to judge3 am: too few checklists (73) to judge4 am: too few checklists (100) to judge5 am: too few checklists (647) to judge6 am: 0.3% of 8353 checklists7 am: 0.6% of 24509 checklists8 am: 0.7% of 27848 checklists9 am: 0.8% of 25316 checklists10 am: 0.8% of 21161 checklists11 am: 0.9% of 18730 checklists12 pm: 0.8% of 16097 checklists1 pm: 0.9% of 14028 checklists2 pm: 1.0% of 13599 checklists3 pm: 1.3% of 14228 checklists4 pm: 1.2% of 14597 checklists5 pm: 0.7% of 12125 checklists6 pm: 0.2% of 9337 checklists7 pm: 0.1% of 6944 checklists8 pm: too few checklists (2403) to judge9 pm: too few checklists (459) to judge10 pm: too few checklists (226) to judge11 pm: too few checklists (141) 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
January3.0%2.9%4.1%3.4%
February2.7%2.1%1.7%2.4%
March1.4%0.7%0.6%0.3%
April0.1%0.1%0.1%0.1%
May0.1%0.1%0.2%0.1%
June0.1%0%0.1%0.2%
July0.1%0%0.2%0%
August0.1%0.1%0.1%0.1%
September0.1%0.1%0.1%0%
October0.1%0.1%0.1%0.1%
November0.1%0.4%0.4%0.7%
December1.0%1.6%1.2%2.3%

Neighboring states

  • Kansas: arrives the second week of November, 3 weeks earlier than Oklahoma
  • Missouri: arrives mid November, 2 weeks earlier than Oklahoma
  • Nebraska: arrives early November, 4 weeks earlier than Oklahoma
  • Iowa: arrives early November, 4 weeks earlier than Oklahoma

Common questions

When do Common Mergansers arrive in Oklahoma?
Common Mergansers are winter birds in Oklahoma: they arrive in early December, peak in mid January (3.5% of checklists), and most are gone by early March.
When do Common Mergansers leave Oklahoma?
Most Common Mergansers have left Oklahoma by early March, when reports fall below half their usual rate.
When is the best time to see a Common Merganser in Oklahoma?
The Common Merganser is reported most often in mid January, on about 3.5% of Oklahoma checklists.
Where in Oklahoma are Common Mergansers seen most often?
By county, Alfalfa County, Noble County, and Kay County have the highest peak reporting rates for the Common Merganser (counties with at least 200 checklists).