WhenToBird

Mergus serrator · Anatidae

When Do Red-breasted Mergansers Arrive in New Hampshire?

Adult male Red-breasted Merganser
Photo: Peter Chen 2.0, CC BY 4.0 via iNaturalist

Red-breasted Mergansers are winter birds in New Hampshire: the first arrive in mid October, they are common by early November, peak in early January (7.7% of checklists), and most are gone by late March.

When to look

First arrivalsOct 15-21mid October
Common byNov 1-7early November
PeakJan 1-7early January
Most gone byMar 22-31late March

Best: early January. First arrivals mid October; most are gone by late March. Peak: on about 7.7% of New Hampshire checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marcommon
  4. Apruncommon
  5. Mayuncommon
  6. Junnot usually seen
  7. Julnot usually seen
  8. Augnot usually seen
  9. Sepnot usually seen
  10. Octuncommon
  11. Novcommon
  12. Decpeak season

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

0%5%10%Jan 1-7: 8.3% of 8253 checklistsJan 8-14: 7.1% of 5998 checklistsJan 15-21: 6.7% of 5734 checklistsJan 22-31: 7.2% of 7776 checklistsFeb 1-7: 6.1% of 5253 checklistsFeb 8-14: 5.8% of 6802 checklistsFeb 15-21: 5.2% of 8852 checklistsFeb 22-28: 5.3% of 5792 checklistsMar 1-7: 5.7% of 6187 checklistsMar 8-14: 4.8% of 6977 checklistsMar 15-21: 3.7% of 7863 checklistsMar 22-31: 3.1% of 11746 checklistsApr 1-7: 2.6% of 9329 checklistsApr 8-14: 1.9% of 10499 checklistsApr 15-21: 1.8% of 10376 checklistsApr 22-30: 1.5% of 13086 checklistsMay 1-7: 1.5% of 13198 checklistsMay 8-14: 0.9% of 14980 checklistsMay 15-21: 0.5% of 12487 checklistsMay 22-31: 0.4% of 14294 checklistsJun 1-7: 0.1% of 8974 checklistsJun 8-14: 0.2% of 8395 checklistsJun 15-21: 0.1% of 7670 checklistsJun 22-30: 0.1% of 9188 checklistsJul 1-7: 0.1% of 7707 checklistsJul 8-14: 0.1% of 6554 checklistsJul 15-21: 0.1% of 6636 checklistsJul 22-31: 0.1% of 9599 checklistsAug 1-7: 0% of 6436 checklistsAug 8-14: 0% of 6477 checklistsAug 15-21: 0.1% of 6510 checklistsAug 22-31: 0.1% of 9762 checklistsSep 1-7: 0.1% of 6700 checklistsSep 8-14: 0.1% of 6012 checklistsSep 15-21: 0.1% of 6238 checklistsSep 22-30: 0.1% of 7619 checklistsOct 1-7: 0.1% of 6702 checklistsOct 8-14: 0.4% of 6863 checklistsOct 15-21: 0.9% of 6284 checklistsOct 22-31: 2.2% of 8287 checklistsNov 1-7: 4.2% of 7584 checklistsNov 8-14: 3.6% of 6056 checklistsNov 15-21: 3.5% of 5597 checklistsNov 22-30: 4.4% of 7140 checklistsDec 1-7: 5.1% of 4623 checklistsDec 8-14: 6.0% of 4920 checklistsDec 15-21: 3.9% of 6416 checklistsDec 22-31: 7.4% of 7659 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 Hampshire 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 Hampshire

Best counties

Share of checklists at the peak
  1. Rockingham CountyBest early January · 2718 checklists that week, 84,864 in all24%
  2. Strafford CountyBest early February · 735 checklists that week, 41,888 in all8.7%
  3. Grafton CountyBest the second week of November · 583 checklists that week, 45,699 in all1.1%
  4. Cheshire CountyBest early November · 730 checklists that week, 39,834 in all0.9%
  5. Coos CountyBest early November · 541 checklists that week, 27,719 in all0.8%
  6. Belknap CountyBest late October · 286 checklists that week, 13,295 in all0.6%

Best spots

Share of checklists at the peak
  1. Hampton Harbor (Hampton Beach)Rockingham County, best early January · 21 checklists that week, 383 in all100%
  2. Odiornes PointRockingham County, best mid February · 72 checklists that week, 5,375 in all84%
  3. New Castle IslandRockingham County, best early January · 33 checklists that week, 341 in all83%
  4. Hampton Harbor (Seabrook Beach)Rockingham County, best early February · 22 checklists that week, 416 in all80%
  5. Adams Point Wildlife Management AreaStrafford County, best early February · 45 checklists that week, 1,107 in all76%
  6. Odiornes Point (High Rock)Rockingham County, best early January · 22 checklists that week, 869 in all76%

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

Best time of day

In New Hampshire, the Red-breasted Merganser is most often listed on checklists started between 12 and 2 pm (4.0% of those checklists).

0%1%2%3%4%12 am: too few checklists (219) to judge1 am: too few checklists (192) to judge2 am: too few checklists (176) to judge3 am: too few checklists (234) to judge4 am: too few checklists (1042) to judge5 am: too few checklists (6352) to judge6 am: 1.0% of 23140 checklists7 am: 1.1% of 43401 checklists8 am: 1.7% of 48039 checklists9 am: 2.3% of 43328 checklists10 am: 2.9% of 37073 checklists11 am: 3.5% of 32028 checklists12 pm: 4.0% of 27396 checklists1 pm: 4.0% of 25182 checklists2 pm: 3.7% of 24318 checklists3 pm: 3.0% of 21974 checklists4 pm: 1.4% of 17958 checklists5 pm: 0.6% of 14528 checklists6 pm: 0.5% of 9144 checklists7 pm: too few checklists (5341) to judge8 pm: too few checklists (1845) to judge9 pm: too few checklists (578) to judge10 pm: too few checklists (346) to judge11 pm: too few checklists (256) 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
January8.3%7.1%6.7%7.2%
February6.1%5.8%5.2%5.3%
March5.7%4.8%3.7%3.1%
April2.6%1.9%1.8%1.5%
May1.5%0.9%0.5%0.4%
June0.1%0.2%0.1%0.1%
July0.1%0.1%0.1%0.1%
August0%0%0.1%0.1%
September0.1%0.1%0.1%0.1%
October0.1%0.4%0.9%2.2%
November4.2%3.6%3.5%4.4%
December5.1%6.0%3.9%7.4%

Neighboring states

  • Massachusetts: arrives the second week of October, 1 week earlier than New Hampshire
  • Vermont: arrives mid October, in the same week than New Hampshire
  • Rhode Island: arrives mid October, in the same week than New Hampshire
  • Maine: arrives the second week of October, 1 week earlier than New Hampshire

Common questions

When do Red-breasted Mergansers arrive in New Hampshire?
Red-breasted Mergansers are winter birds in New Hampshire: the first arrive in mid October, they are common by early November, peak in early January (7.7% of checklists), and most are gone by late March.
When do Red-breasted Mergansers leave New Hampshire?
Most Red-breasted Mergansers have left New Hampshire by late March, when reports fall below half their usual rate. Stragglers are still reported until early May.
When is the best time to see a Red-breasted Merganser in New Hampshire?
The Red-breasted Merganser is reported most often in early January, on about 7.7% of New Hampshire checklists.
Where in New Hampshire are Red-breasted Mergansers seen most often?
By county, Rockingham County, Strafford County, and Grafton County have the highest peak reporting rates for the Red-breasted Merganser (counties with at least 200 checklists).