WhenToBird

Mergus serrator · Anatidae

When Do Red-breasted Mergansers Arrive in Maine?

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

Red-breasted Mergansers are winter birds in Maine: the first arrive in the second week of October, they are common by late October, peak in mid January (18% of checklists), and most are gone by mid April.

When to look

First arrivalsOct 8-14the second week of October
Common byOct 22-31late October
PeakJan 15-21mid January
Most gone byApr 15-21mid April

Best: mid January. First arrivals the second week of October; most are gone by mid April. Peak: on about 18% of Maine checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marpeak season
  4. Aprcommon
  5. Mayuncommon
  6. Junnot usually seen
  7. Julnot usually seen
  8. Augnot usually seen
  9. Sepnot usually seen
  10. Octcommon
  11. Novpeak season
  12. Decpeak season

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

0%5%10%15%20%Jan 1-7: 17% of 15499 checklistsJan 8-14: 18% of 11141 checklistsJan 15-21: 18% of 10729 checklistsJan 22-31: 18% of 15084 checklistsFeb 1-7: 15% of 9403 checklistsFeb 8-14: 16% of 11268 checklistsFeb 15-21: 14% of 14061 checklistsFeb 22-28: 15% of 9977 checklistsMar 1-7: 14% of 9649 checklistsMar 8-14: 12% of 11781 checklistsMar 15-21: 11% of 11613 checklistsMar 22-31: 9.8% of 17798 checklistsApr 1-7: 9.2% of 14638 checklistsApr 8-14: 8.7% of 16511 checklistsApr 15-21: 8.0% of 17164 checklistsApr 22-30: 6.6% of 22602 checklistsMay 1-7: 5.3% of 22556 checklistsMay 8-14: 3.2% of 27842 checklistsMay 15-21: 1.9% of 27748 checklistsMay 22-31: 0.9% of 38715 checklistsJun 1-7: 0.6% of 26916 checklistsJun 8-14: 0.3% of 23737 checklistsJun 15-21: 0.2% of 22733 checklistsJun 22-30: 0.3% of 28248 checklistsJul 1-7: 0.2% of 20290 checklistsJul 8-14: 0.3% of 18534 checklistsJul 15-21: 0.3% of 17319 checklistsJul 22-31: 0.2% of 22815 checklistsAug 1-7: 0.2% of 15004 checklistsAug 8-14: 0.3% of 14603 checklistsAug 15-21: 0.2% of 14972 checklistsAug 22-31: 0.2% of 19813 checklistsSep 1-7: 0.4% of 14567 checklistsSep 8-14: 0.3% of 14520 checklistsSep 15-21: 0.5% of 14339 checklistsSep 22-30: 0.5% of 16879 checklistsOct 1-7: 0.9% of 12959 checklistsOct 8-14: 2.1% of 13168 checklistsOct 15-21: 4.1% of 11184 checklistsOct 22-31: 7.8% of 13717 checklistsNov 1-7: 11% of 9823 checklistsNov 8-14: 12% of 9007 checklistsNov 15-21: 13% of 8528 checklistsNov 22-30: 14% of 10228 checklistsDec 1-7: 14% of 7505 checklistsDec 8-14: 15% of 7982 checklistsDec 15-21: 16% of 10455 checklistsDec 22-31: 17% of 14285 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 Maine 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 Maine

Best counties

Share of checklists at the peak
  1. Sagadahoc CountyBest late December · 477 checklists that week, 21,736 in all29%
  2. York CountyBest early December · 1296 checklists that week, 101,844 in all28%
  3. Lincoln CountyBest mid January · 1148 checklists that week, 59,429 in all27%
  4. Cumberland CountyBest mid January · 2625 checklists that week, 169,501 in all24%
  5. Knox CountyBest mid December · 401 checklists that week, 34,453 in all24%
  6. Hancock CountyBest late December · 2144 checklists that week, 118,358 in all22%

Best spots

Share of checklists at the peak
  1. Back CreekYork County, best late November · 20 checklists that week, 620 in all96%
  2. Eastern PromenadeCumberland County, best late November · 32 checklists that week, 1,074 in all92%
  3. Reid State ParkSagadahoc County, best late January · 32 checklists that week, 663 in all90%
  4. Simonton CoveCumberland County, best the second week of April · 27 checklists that week, 776 in all90%
  5. Parsons BeachYork County, best late November · 23 checklists that week, 1,272 in all90%

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

Best time of day

In Maine, the Red-breasted Merganser is most often listed on checklists started between 1 and 3 pm (8.8% of those checklists).

0%5%10%12 am: too few checklists (510) to judge1 am: too few checklists (517) to judge2 am: too few checklists (581) to judge3 am: too few checklists (3242) to judge4 am: too few checklists (7221) to judge5 am: 2.1% of 19895 checklists6 am: 3.9% of 54578 checklists7 am: 4.2% of 92775 checklists8 am: 5.3% of 86962 checklists9 am: 6.2% of 78989 checklists10 am: 7.1% of 70954 checklists11 am: 7.8% of 59331 checklists12 pm: 8.1% of 50943 checklists1 pm: 8.9% of 49775 checklists2 pm: 8.7% of 49001 checklists3 pm: 7.1% of 43252 checklists4 pm: 4.9% of 33413 checklists5 pm: 2.9% of 25547 checklists6 pm: 1.7% of 18309 checklists7 pm: too few checklists (14287) to judge8 pm: too few checklists (5336) to judge9 pm: too few checklists (2253) to judge10 pm: too few checklists (1518) to judge11 pm: too few checklists (720) 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
January17%18%18%18%
February15%16%14%15%
March14%12%11%9.8%
April9.2%8.7%8.0%6.6%
May5.3%3.2%1.9%0.9%
June0.6%0.3%0.2%0.3%
July0.2%0.3%0.3%0.2%
August0.2%0.3%0.2%0.2%
September0.4%0.3%0.5%0.5%
October0.9%2.1%4.1%7.8%
November11%12%13%14%
December14%15%16%17%

Neighboring states

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

Common questions

When do Red-breasted Mergansers arrive in Maine?
Red-breasted Mergansers are winter birds in Maine: the first arrive in the second week of October, they are common by late October, peak in mid January (18% of checklists), and most are gone by mid April.
When do Red-breasted Mergansers leave Maine?
Most Red-breasted Mergansers have left Maine by mid April, when reports fall below half their usual rate. Stragglers are still reported until mid May.
When is the best time to see a Red-breasted Merganser in Maine?
The Red-breasted Merganser is reported most often in mid January, on about 18% of Maine checklists.
Where in Maine are Red-breasted Mergansers seen most often?
By county, Sagadahoc County, York County, and Lincoln County have the highest peak reporting rates for the Red-breasted Merganser (counties with at least 200 checklists).