WhenToBird

Mergus merganser · Anatidae

When Do Common Mergansers Arrive in Ohio?

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

Common Mergansers are winter birds in Ohio: the first arrive in late October, they are common by mid November, peak in early March (7.1% of checklists), and most are gone by early April.

When to look

First arrivalsOct 22-31late October
Common byNov 15-21mid November
PeakMar 1-7early March
Most gone byApr 1-7early April

Best: early March. First arrivals late October; most are gone by early April. Peak: on about 7.1% of Ohio checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marpeak season
  4. Apruncommon
  5. Mayrare
  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%Jan 1-7: 4.7% of 46637 checklistsJan 8-14: 5.3% of 31056 checklistsJan 15-21: 5.7% of 30129 checklistsJan 22-31: 5.6% of 38665 checklistsFeb 1-7: 5.9% of 27203 checklistsFeb 8-14: 5.8% of 30626 checklistsFeb 15-21: 5.3% of 40705 checklistsFeb 22-28: 8.1% of 31391 checklistsMar 1-7: 7.6% of 32914 checklistsMar 8-14: 5.8% of 33973 checklistsMar 15-21: 4.9% of 33678 checklistsMar 22-31: 3.6% of 49889 checklistsApr 1-7: 2.5% of 41225 checklistsApr 8-14: 1.5% of 47174 checklistsApr 15-21: 1.1% of 47017 checklistsApr 22-30: 0.7% of 73055 checklistsMay 1-7: 0.5% of 80637 checklistsMay 8-14: 0.3% of 102552 checklistsMay 15-21: 0.4% of 64582 checklistsMay 22-31: 0.3% of 52766 checklistsJun 1-7: 0.3% of 29279 checklistsJun 8-14: 0.3% of 25773 checklistsJun 15-21: 0.2% of 23163 checklistsJun 22-30: 0.2% of 27794 checklistsJul 1-7: 0.2% of 23334 checklistsJul 8-14: 0.3% of 22147 checklistsJul 15-21: 0.4% of 20998 checklistsJul 22-31: 0.4% of 29749 checklistsAug 1-7: 0.6% of 22899 checklistsAug 8-14: 0.6% of 21972 checklistsAug 15-21: 0.7% of 22215 checklistsAug 22-31: 0.8% of 35087 checklistsSep 1-7: 0.7% of 29148 checklistsSep 8-14: 0.6% of 28042 checklistsSep 15-21: 0.5% of 26751 checklistsSep 22-30: 0.5% of 32398 checklistsOct 1-7: 0.5% of 26209 checklistsOct 8-14: 0.6% of 26809 checklistsOct 15-21: 0.7% of 23504 checklistsOct 22-31: 1.1% of 33269 checklistsNov 1-7: 1.5% of 25563 checklistsNov 8-14: 2.2% of 23810 checklistsNov 15-21: 2.6% of 22127 checklistsNov 22-30: 2.9% of 29449 checklistsDec 1-7: 3.7% of 22370 checklistsDec 8-14: 4.0% of 21581 checklistsDec 15-21: 3.7% of 24232 checklistsDec 22-31: 3.4% of 36084 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 Ohio 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 Ohio

Best counties

Share of checklists at the peak
  1. Ashtabula CountyBest the second week of December · 99 checklists that week, 12,390 in all28%
  2. Sandusky CountyBest the second week of March · 247 checklists that week, 14,537 in all27%
  3. Pike CountyBest early December · 13 checklists that week, 595 in all23%
  4. Noble CountyBest early March · 72 checklists that week, 1,516 in all23%
  5. Washington CountyBest late January · 261 checklists that week, 7,603 in all21%
  6. Erie CountyBest early March · 532 checklists that week, 30,456 in all20%

Best spots

Share of checklists at the peak
  1. Beech ParkLorain County, best late January · 24 checklists that week, 266 in all98%
  2. Silver LakeSummit County, best early January · 31 checklists that week, 432 in all93%
  3. Bay View Fishing PierErie County, best early January · 22 checklists that week, 121 in all85%
  4. Fairport Harbor Lakefront Park (Grand River)Lake County, best mid January · 33 checklists that week, 299 in all82%
  5. Long Lake State ParkSummit County, best late February · 28 checklists that week, 144 in all82%

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

Best time of day

In Ohio, the Common Merganser is most often listed on checklists started between 1 and 3 pm (2.6% of those checklists).

0%1%2%3%12 am: too few checklists (574) to judge1 am: too few checklists (609) to judge2 am: too few checklists (466) to judge3 am: too few checklists (478) to judge4 am: too few checklists (662) to judge5 am: too few checklists (4366) to judge6 am: 1.0% of 43093 checklists7 am: 1.9% of 142017 checklists8 am: 2.1% of 205296 checklists9 am: 2.2% of 196322 checklists10 am: 2.4% of 170882 checklists11 am: 2.5% of 144567 checklists12 pm: 2.6% of 126551 checklists1 pm: 2.6% of 117855 checklists2 pm: 2.6% of 112869 checklists3 pm: 2.6% of 109786 checklists4 pm: 2.4% of 103116 checklists5 pm: 1.8% of 78409 checklists6 pm: 0.9% of 56785 checklists7 pm: 0.6% of 37923 checklists8 pm: too few checklists (14954) to judge9 pm: too few checklists (2710) to judge10 pm: too few checklists (854) to judge11 pm: too few checklists (486) 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
January4.7%5.3%5.7%5.6%
February5.9%5.8%5.3%8.1%
March7.6%5.8%4.9%3.6%
April2.5%1.5%1.1%0.7%
May0.5%0.3%0.4%0.3%
June0.3%0.3%0.2%0.2%
July0.2%0.3%0.4%0.4%
August0.6%0.6%0.7%0.8%
September0.7%0.6%0.5%0.5%
October0.5%0.6%0.7%1.1%
November1.5%2.2%2.6%2.9%
December3.7%4.0%3.7%3.4%

Neighboring states

  • West Virginia: arrives mid October, 1 week earlier than Ohio
  • Indiana: arrives late November, 4 weeks later than Ohio
  • Michigan: arrives the second week of September, 6 weeks earlier than Ohio
  • Pennsylvania: arrives mid July, 13 weeks earlier than Ohio

Common questions

When do Common Mergansers arrive in Ohio?
Common Mergansers are winter birds in Ohio: the first arrive in late October, they are common by mid November, peak in early March (7.1% of checklists), and most are gone by early April.
When do Common Mergansers leave Ohio?
Most Common Mergansers have left Ohio by early April, when reports fall below half their usual rate. Stragglers are still reported until mid April.
When is the best time to see a Common Merganser in Ohio?
The Common Merganser is reported most often in early March, on about 7.1% of Ohio checklists.
Where in Ohio are Common Mergansers seen most often?
By county, Ashtabula County, Sandusky County, and Pike County have the highest peak reporting rates for the Common Merganser (counties with at least 200 checklists).