WhenToBird

Mergus serrator · Anatidae

When Do Red-breasted Mergansers Arrive in Washington?

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

Red-breasted Mergansers are winter birds in Washington: the first arrive in the second week of October, they are common by late October, peak in mid January (11% of checklists), and most are gone by late April.

When to look

First arrivalsOct 8-14the second week of October
Common byOct 22-31late October
PeakJan 15-21mid January
Most gone byApr 22-30late April

Best: mid January. First arrivals the second week of October; most are gone by late April. Peak: on about 11% of Washington 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%Jan 1-7: 11% of 41928 checklistsJan 8-14: 11% of 31152 checklistsJan 15-21: 11% of 31753 checklistsJan 22-31: 11% of 42530 checklistsFeb 1-7: 10% of 29739 checklistsFeb 8-14: 8.8% of 32746 checklistsFeb 15-21: 8.4% of 40328 checklistsFeb 22-28: 9.0% of 28432 checklistsMar 1-7: 8.5% of 30758 checklistsMar 8-14: 7.7% of 29368 checklistsMar 15-21: 7.2% of 32580 checklistsMar 22-31: 6.6% of 45614 checklistsApr 1-7: 6.5% of 33997 checklistsApr 8-14: 6.5% of 34729 checklistsApr 15-21: 6.0% of 38474 checklistsApr 22-30: 4.7% of 52185 checklistsMay 1-7: 3.0% of 44236 checklistsMay 8-14: 1.4% of 48708 checklistsMay 15-21: 0.5% of 41742 checklistsMay 22-31: 0.2% of 57082 checklistsJun 1-7: 0.1% of 39193 checklistsJun 8-14: 0.1% of 36042 checklistsJun 15-21: 0.1% of 34003 checklistsJun 22-30: 0.1% of 39711 checklistsJul 1-7: 0.1% of 31949 checklistsJul 8-14: 0.1% of 29086 checklistsJul 15-21: 0.1% of 28045 checklistsJul 22-31: 0.1% of 38275 checklistsAug 1-7: 0.1% of 28846 checklistsAug 8-14: 0.1% of 28036 checklistsAug 15-21: 0.1% of 27614 checklistsAug 22-31: 0.1% of 40356 checklistsSep 1-7: 0.1% of 31214 checklistsSep 8-14: 0.1% of 27795 checklistsSep 15-21: 0.1% of 29677 checklistsSep 22-30: 0.4% of 35241 checklistsOct 1-7: 0.8% of 28605 checklistsOct 8-14: 1.7% of 28655 checklistsOct 15-21: 3.2% of 24643 checklistsOct 22-31: 6.1% of 34874 checklistsNov 1-7: 7.7% of 25658 checklistsNov 8-14: 8.8% of 25700 checklistsNov 15-21: 9.2% of 24331 checklistsNov 22-30: 9.3% of 32784 checklistsDec 1-7: 9.7% of 24099 checklistsDec 8-14: 9.4% of 23339 checklistsDec 15-21: 8.9% of 27666 checklistsDec 22-31: 9.9% of 42130 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 Washington 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 Washington

Best counties

Share of checklists at the peak
  1. Jefferson CountyBest mid January · 1021 checklists that week, 59,663 in all48%
  2. Clallam CountyBest early January · 1697 checklists that week, 85,362 in all26%
  3. San Juan CountyBest late January · 570 checklists that week, 35,337 in all26%
  4. Island CountyBest mid January · 802 checklists that week, 46,092 in all22%
  5. Kitsap CountyBest early January · 2357 checklists that week, 74,545 in all20%
  6. Whatcom CountyBest late November · 1528 checklists that week, 64,687 in all20%

Best spots

Share of checklists at the peak
  1. Port WilliamsClallam County, best the second week of January · 21 checklists that week, 612 in all95%
  2. Washington State Department of Natural Resources (WADNR) State Resource Management AreaSkagit County, best early February · 49 checklists that week, 1,277 in all93%
  3. Port GambleKitsap County, best the second week of February · 29 checklists that week, 681 in all93%
  4. Lighthouse Marine ParkWhatcom County, best late April · 37 checklists that week, 1,449 in all92%
  5. Marrowstone PointJefferson County, best late April · 24 checklists that week, 677 in all91%

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

Best time of day

In Washington, the Red-breasted Merganser is most often listed on checklists started between 1 and 3 pm (5.9% of those checklists).

0%2%4%6%12 am: too few checklists (796) to judge1 am: too few checklists (776) to judge2 am: too few checklists (709) to judge3 am: too few checklists (901) to judge4 am: too few checklists (3221) to judge5 am: too few checklists (16576) to judge6 am: 1.7% of 56744 checklists7 am: 3.5% of 133294 checklists8 am: 4.4% of 184196 checklists9 am: 4.9% of 186303 checklists10 am: 5.4% of 177063 checklists11 am: 5.6% of 154936 checklists12 pm: 5.7% of 138061 checklists1 pm: 5.9% of 127449 checklists2 pm: 5.9% of 121511 checklists3 pm: 5.4% of 107793 checklists4 pm: 3.5% of 82862 checklists5 pm: 1.9% of 57183 checklists6 pm: 1.3% of 39886 checklists7 pm: too few checklists (26969) to judge8 pm: too few checklists (12427) to judge9 pm: too few checklists (3658) to judge10 pm: too few checklists (1500) to judge11 pm: too few checklists (834) 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
January11%11%11%11%
February10%8.8%8.4%9.0%
March8.5%7.7%7.2%6.6%
April6.5%6.5%6.0%4.7%
May3.0%1.4%0.5%0.2%
June0.1%0.1%0.1%0.1%
July0.1%0.1%0.1%0.1%
August0.1%0.1%0.1%0.1%
September0.1%0.1%0.1%0.4%
October0.8%1.7%3.2%6.1%
November7.7%8.8%9.2%9.3%
December9.7%9.4%8.9%9.9%

Neighboring states

  • Oregon: arrives late October, 2 weeks later than Washington
  • Idaho: arrives mid October, 1 week later than Washington
  • Montana: arrives late February, 18 weeks later than Washington
  • Nevada: arrives early November, 3 weeks later than Washington

Common questions

When do Red-breasted Mergansers arrive in Washington?
Red-breasted Mergansers are winter birds in Washington: the first arrive in the second week of October, they are common by late October, peak in mid January (11% of checklists), and most are gone by late April.
When do Red-breasted Mergansers leave Washington?
Most Red-breasted Mergansers have left Washington by late April, when reports fall below half their usual rate. Stragglers are still reported until the second week of May.
When is the best time to see a Red-breasted Merganser in Washington?
The Red-breasted Merganser is reported most often in mid January, on about 11% of Washington checklists.
Where in Washington are Red-breasted Mergansers seen most often?
By county, Jefferson County, Clallam County, and San Juan County have the highest peak reporting rates for the Red-breasted Merganser (counties with at least 200 checklists).