WhenToBird

Mergus merganser · Anatidae

When Do Common Mergansers Arrive in New York?

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

Common Mergansers are winter birds in New York: the first arrive in mid August, they are common by late October, peak in early March (14% of checklists), and most are gone by late April.

When to look

First arrivalsAug 15-21mid August
Common byOct 22-31late October
PeakMar 1-7early March
Most gone byApr 22-30late April

Best: early March. First arrivals mid August; most are gone by late April. Peak: on about 14% of New York checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marpeak season
  4. Aprcommon
  5. Mayuncommon
  6. Junrare
  7. Julrare
  8. Augrare
  9. Sepuncommon
  10. Octcommon
  11. Novcommon
  12. Deccommon

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

0%5%10%15%Jan 1-7: 9.8% of 66410 checklistsJan 8-14: 11% of 49310 checklistsJan 15-21: 12% of 49919 checklistsJan 22-31: 12% of 62513 checklistsFeb 1-7: 11% of 43526 checklistsFeb 8-14: 10% of 49753 checklistsFeb 15-21: 9.3% of 65147 checklistsFeb 22-28: 14% of 50173 checklistsMar 1-7: 15% of 50325 checklistsMar 8-14: 14% of 55371 checklistsMar 15-21: 14% of 56293 checklistsMar 22-31: 13% of 82677 checklistsApr 1-7: 10% of 65295 checklistsApr 8-14: 8.4% of 73080 checklistsApr 15-21: 6.9% of 73857 checklistsApr 22-30: 5.3% of 106093 checklistsMay 1-7: 3.6% of 102772 checklistsMay 8-14: 2.7% of 110051 checklistsMay 15-21: 2.2% of 94797 checklistsMay 22-31: 2.1% of 101272 checklistsJun 1-7: 1.9% of 59471 checklistsJun 8-14: 1.5% of 55497 checklistsJun 15-21: 1.4% of 51761 checklistsJun 22-30: 1.2% of 59219 checklistsJul 1-7: 1.1% of 48226 checklistsJul 8-14: 1.1% of 42315 checklistsJul 15-21: 1.2% of 40637 checklistsJul 22-31: 1.4% of 57183 checklistsAug 1-7: 1.6% of 40461 checklistsAug 8-14: 2.0% of 39880 checklistsAug 15-21: 2.0% of 41146 checklistsAug 22-31: 2.0% of 63381 checklistsSep 1-7: 2.1% of 48640 checklistsSep 8-14: 2.2% of 47882 checklistsSep 15-21: 2.3% of 49063 checklistsSep 22-30: 2.8% of 57906 checklistsOct 1-7: 3.0% of 48447 checklistsOct 8-14: 3.6% of 51901 checklistsOct 15-21: 4.5% of 46717 checklistsOct 22-31: 5.8% of 61992 checklistsNov 1-7: 7.1% of 44593 checklistsNov 8-14: 7.9% of 42566 checklistsNov 15-21: 8.3% of 39675 checklistsNov 22-30: 8.7% of 51197 checklistsDec 1-7: 9.0% of 36567 checklistsDec 8-14: 8.1% of 37254 checklistsDec 15-21: 7.7% of 43754 checklistsDec 22-31: 8.3% of 62470 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 New York 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 New York

Best counties

Share of checklists at the peak
  1. Clinton CountyBest late January · 102 checklists that week, 8,764 in all45%
  2. Schenectady CountyBest mid March · 355 checklists that week, 11,851 in all38%
  3. Chenango CountyBest mid November · 168 checklists that week, 10,785 in all38%
  4. Sullivan CountyBest the second week of March · 551 checklists that week, 28,620 in all36%
  5. Tioga CountyBest the second week of March · 626 checklists that week, 21,713 in all32%
  6. Broome CountyBest mid March · 1191 checklists that week, 52,683 in all31%

Best spots

Share of checklists at the peak
  1. Swan Lake (northwest)Sullivan County, best early April · 27 checklists that week, 562 in all99%
  2. City of Troy Land (Raymertown)Rensselaer County, best early November · 33 checklists that week, 331 in all99%
  3. Copake LakeColumbia County, best mid March · 25 checklists that week, 411 in all99%
  4. Chenango LakeChenango County, best mid November · 22 checklists that week, 298 in all97%
  5. Clinton IslandChemung County, best the second week of October · 31 checklists that week, 1,134 in all96%

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

Best time of day

In New York, the Common Merganser is most often listed on checklists started between 1 and 3 pm (7.2% of those checklists).

0%2%4%6%8%12 am: too few checklists (1146) to judge1 am: too few checklists (1055) to judge2 am: too few checklists (1121) to judge3 am: too few checklists (1353) to judge4 am: too few checklists (4785) to judge5 am: too few checklists (32052) to judge6 am: 4.1% of 124869 checklists7 am: 5.0% of 298506 checklists8 am: 5.7% of 337334 checklists9 am: 6.4% of 307787 checklists10 am: 6.9% of 270801 checklists11 am: 7.3% of 233238 checklists12 pm: 7.0% of 213830 checklists1 pm: 7.1% of 193321 checklists2 pm: 7.3% of 180741 checklists3 pm: 6.8% of 170348 checklists4 pm: 5.9% of 147224 checklists5 pm: 4.8% of 111962 checklists6 pm: 4.1% of 78261 checklists7 pm: too few checklists (44425) to judge8 pm: too few checklists (15648) to judge9 pm: too few checklists (4795) to judge10 pm: too few checklists (2454) to judge11 pm: too few checklists (1378) 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
January9.8%11%12%12%
February11%10%9.3%14%
March15%14%14%13%
April10%8.4%6.9%5.3%
May3.6%2.7%2.2%2.1%
June1.9%1.5%1.4%1.2%
July1.1%1.1%1.2%1.4%
August1.6%2.0%2.0%2.0%
September2.1%2.2%2.3%2.8%
October3.0%3.6%4.5%5.8%
November7.1%7.9%8.3%8.7%
December9.0%8.1%7.7%8.3%

Neighboring states

  • Connecticut: arrives mid October, 8 weeks later than New York
  • New Jersey: arrives early November, 10 weeks later than New York
  • Pennsylvania: arrives mid July, 4 weeks earlier than New York
  • Vermont: arrives late July, 3 weeks earlier than New York

Common questions

When do Common Mergansers arrive in New York?
Common Mergansers are winter birds in New York: the first arrive in mid August, they are common by late October, peak in early March (14% of checklists), and most are gone by late April.
When do Common Mergansers leave New York?
Most Common Mergansers have left New York by late April, 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 New York?
The Common Merganser is reported most often in early March, on about 14% of New York checklists.
Where in New York are Common Mergansers seen most often?
By county, Clinton County, Schenectady County, and Chenango County have the highest peak reporting rates for the Common Merganser (counties with at least 200 checklists).