WhenToBird

Mergus serrator · Anatidae

When Do Red-breasted Mergansers Arrive in Massachusetts?

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

Red-breasted Mergansers are winter birds in Massachusetts: the first arrive in the second week of October, they are common by early November, peak in late January (16% of checklists), and most are gone by late April.

When to look

First arrivalsOct 8-14the second week of October
Common byNov 1-7early November
PeakJan 22-31late January
Most gone byApr 22-30late April

Best: late January. First arrivals the second week of October; most are gone by late April. Peak: on about 16% of Massachusetts checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marpeak season
  4. Aprcommon
  5. Mayuncommon
  6. Junrare
  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%15%20%Jan 1-7: 13% of 43252 checklistsJan 8-14: 15% of 30096 checklistsJan 15-21: 16% of 28760 checklistsJan 22-31: 16% of 38135 checklistsFeb 1-7: 16% of 26442 checklistsFeb 8-14: 14% of 29034 checklistsFeb 15-21: 14% of 37383 checklistsFeb 22-28: 14% of 29977 checklistsMar 1-7: 12% of 29175 checklistsMar 8-14: 10% of 32399 checklistsMar 15-21: 11% of 34444 checklistsMar 22-31: 11% of 49126 checklistsApr 1-7: 10% of 36456 checklistsApr 8-14: 9.0% of 40908 checklistsApr 15-21: 7.8% of 42078 checklistsApr 22-30: 5.7% of 56465 checklistsMay 1-7: 3.8% of 56994 checklistsMay 8-14: 2.3% of 64079 checklistsMay 15-21: 1.4% of 52020 checklistsMay 22-31: 1.1% of 55402 checklistsJun 1-7: 0.8% of 30682 checklistsJun 8-14: 0.6% of 27557 checklistsJun 15-21: 0.6% of 26163 checklistsJun 22-30: 0.4% of 29576 checklistsJul 1-7: 0.4% of 23931 checklistsJul 8-14: 0.3% of 22389 checklistsJul 15-21: 0.3% of 22365 checklistsJul 22-31: 0.3% of 32631 checklistsAug 1-7: 0.2% of 25133 checklistsAug 8-14: 0.2% of 24610 checklistsAug 15-21: 0.2% of 25350 checklistsAug 22-31: 0.1% of 37198 checklistsSep 1-7: 0.1% of 27402 checklistsSep 8-14: 0.2% of 27700 checklistsSep 15-21: 0.2% of 28398 checklistsSep 22-30: 0.2% of 34646 checklistsOct 1-7: 0.6% of 28620 checklistsOct 8-14: 1.3% of 30144 checklistsOct 15-21: 1.8% of 28893 checklistsOct 22-31: 4.7% of 38869 checklistsNov 1-7: 6.5% of 29782 checklistsNov 8-14: 8.7% of 27582 checklistsNov 15-21: 8.7% of 26642 checklistsNov 22-30: 11% of 34390 checklistsDec 1-7: 10% of 25164 checklistsDec 8-14: 9.8% of 24892 checklistsDec 15-21: 11% of 29022 checklistsDec 22-31: 14% of 44323 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 Massachusetts 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 Massachusetts

Best counties

Share of checklists at the peak
  1. Essex CountyBest early February · 4211 checklists that week, 213,973 in all36%
  2. Barnstable CountyBest late March · 5312 checklists that week, 215,188 in all34%
  3. Dukes CountyBest mid March · 270 checklists that week, 23,670 in all31%
  4. Nantucket CountyBest mid February · 452 checklists that week, 23,895 in all29%
  5. Suffolk CountyBest late January · 2860 checklists that week, 112,443 in all25%
  6. Plymouth CountyBest early February · 1591 checklists that week, 89,282 in all20%

Best spots

Share of checklists at the peak
  1. Race RunBarnstable County, best late November · 81 checklists that week, 2,504 in all99%
  2. Herring Cove BeachBarnstable County, best mid April · 22 checklists that week, 1,292 in all99%
  3. Manomet PointPlymouth County, best early April · 30 checklists that week, 1,606 in all98%
  4. State Fish PierEssex County, best late January · 316 checklists that week, 2,575 in all98%
  5. Macmillan WharfBarnstable County, best mid January · 99 checklists that week, 2,253 in all97%
  6. Deer IslandSuffolk County, best the second week of December · 32 checklists that week, 1,473 in all96%

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

Best time of day

In Massachusetts, the Red-breasted Merganser is most often listed on checklists started between 12 and 2 pm (8.6% of those checklists).

0%5%10%12 am: too few checklists (630) to judge1 am: too few checklists (657) to judge2 am: too few checklists (645) to judge3 am: too few checklists (850) to judge4 am: too few checklists (3787) to judge5 am: too few checklists (29743) to judge6 am: 3.7% of 108601 checklists7 am: 4.9% of 186104 checklists8 am: 5.9% of 185905 checklists9 am: 7.0% of 166049 checklists10 am: 7.9% of 150508 checklists11 am: 8.4% of 131024 checklists12 pm: 8.7% of 116804 checklists1 pm: 8.5% of 112055 checklists2 pm: 8.2% of 110246 checklists3 pm: 7.1% of 104376 checklists4 pm: 4.7% of 83736 checklists5 pm: 3.0% of 63723 checklists6 pm: 2.1% of 41435 checklists7 pm: too few checklists (21041) to judge8 pm: too few checklists (5240) to judge9 pm: too few checklists (1722) to judge10 pm: too few checklists (1094) to judge11 pm: too few checklists (704) 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
January13%15%16%16%
February16%14%14%14%
March12%10%11%11%
April10%9.0%7.8%5.7%
May3.8%2.3%1.4%1.1%
June0.8%0.6%0.6%0.4%
July0.4%0.3%0.3%0.3%
August0.2%0.2%0.2%0.1%
September0.1%0.2%0.2%0.2%
October0.6%1.3%1.8%4.7%
November6.5%8.7%8.7%11%
December10%9.8%11%14%

Neighboring states

  • Rhode Island: arrives mid October, 1 week later than Massachusetts
  • New Hampshire: arrives mid October, 1 week later than Massachusetts
  • Connecticut: arrives late October, 2 weeks later than Massachusetts
  • Vermont: arrives mid October, 1 week later than Massachusetts

Common questions

When do Red-breasted Mergansers arrive in Massachusetts?
Red-breasted Mergansers are winter birds in Massachusetts: the first arrive in the second week of October, they are common by early November, peak in late January (16% of checklists), and most are gone by late April.
When do Red-breasted Mergansers leave Massachusetts?
Most Red-breasted Mergansers have left Massachusetts 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 Red-breasted Merganser in Massachusetts?
The Red-breasted Merganser is reported most often in late January, on about 16% of Massachusetts checklists.
Where in Massachusetts are Red-breasted Mergansers seen most often?
By county, Essex County, Barnstable County, and Dukes County have the highest peak reporting rates for the Red-breasted Merganser (counties with at least 200 checklists).