WhenToBird

Mergus serrator · Anatidae

When Do Red-breasted Mergansers Arrive in Oregon?

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

Red-breasted Mergansers are winter birds in Oregon: they arrive in late October, peak in mid November (2.1% of checklists), and most are gone by early May.

When to look

First arrivalsOct 22-31late October
Common byOct 22-31late October
PeakNov 15-21mid November
Most gone byMay 1-7early May

Best: mid November. First arrivals late October; most are gone by early May. Peak: on about 2.1% of Oregon checklists.

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

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

0%1%2%3%Jan 1-7: 1.7% of 34973 checklistsJan 8-14: 1.4% of 26807 checklistsJan 15-21: 1.4% of 26567 checklistsJan 22-31: 1.9% of 36019 checklistsFeb 1-7: 1.7% of 24020 checklistsFeb 8-14: 1.6% of 25765 checklistsFeb 15-21: 1.0% of 31019 checklistsFeb 22-28: 1.3% of 24582 checklistsMar 1-7: 1.1% of 24834 checklistsMar 8-14: 1.5% of 24642 checklistsMar 15-21: 1.5% of 27420 checklistsMar 22-31: 1.3% of 39913 checklistsApr 1-7: 1.3% of 28817 checklistsApr 8-14: 1.3% of 31221 checklistsApr 15-21: 1.3% of 34402 checklistsApr 22-30: 1.3% of 47144 checklistsMay 1-7: 0.8% of 37716 checklistsMay 8-14: 0.4% of 39651 checklistsMay 15-21: 0.2% of 37496 checklistsMay 22-31: 0.1% of 56967 checklistsJun 1-7: 0.1% of 35893 checklistsJun 8-14: 0.1% of 31880 checklistsJun 15-21: 0.1% of 30942 checklistsJun 22-30: 0.1% of 38478 checklistsJul 1-7: 0.1% of 27409 checklistsJul 8-14: 0.1% of 25161 checklistsJul 15-21: 0.1% of 25473 checklistsJul 22-31: 0.1% of 33920 checklistsAug 1-7: 0.1% of 24310 checklistsAug 8-14: 0.1% of 23675 checklistsAug 15-21: 0.1% of 23623 checklistsAug 22-31: 0.1% of 33762 checklistsSep 1-7: 0.1% of 25120 checklistsSep 8-14: 0.1% of 24458 checklistsSep 15-21: 0.1% of 25528 checklistsSep 22-30: 0.1% of 31631 checklistsOct 1-7: 0.1% of 25498 checklistsOct 8-14: 0.3% of 25161 checklistsOct 15-21: 0.3% of 23701 checklistsOct 22-31: 1.1% of 30996 checklistsNov 1-7: 1.9% of 21089 checklistsNov 8-14: 2.0% of 21880 checklistsNov 15-21: 2.3% of 21501 checklistsNov 22-30: 2.0% of 28930 checklistsDec 1-7: 1.5% of 19807 checklistsDec 8-14: 1.5% of 21022 checklistsDec 15-21: 1.6% of 24817 checklistsDec 22-31: 1.5% of 37592 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 Oregon 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 Oregon

Best counties

Share of checklists at the peak
  1. Tillamook CountyBest early February · 765 checklists that week, 45,809 in all17%
  2. Lincoln CountyBest mid November · 1307 checklists that week, 66,994 in all16%
  3. Sherman CountyBest the second week of November · 238 checklists that week, 4,629 in all13%
  4. Coos CountyBest mid December · 369 checklists that week, 24,368 in all12%
  5. Curry CountyBest early February · 107 checklists that week, 12,513 in all6.4%
  6. Douglas CountyBest the second week of January · 241 checklists that week, 17,976 in all6.1%

Best spots

Share of checklists at the peak
  1. Oregon Dunes National Recreation Area (Cannery Point)Lane County, best late January · 23 checklists that week, 667 in all77%
  2. Oregon Dunes National Recreation AreaLane County, best late January · 24 checklists that week, 790 in all68%
  3. South Beach State ParkLincoln County, best the second week of March · 111 checklists that week, 3,413 in all68%
  4. Bayocean Peninsula County ParkTillamook County, best the second week of April · 33 checklists that week, 1,364 in all66%
  5. Brandon South Jetty ParkCoos County, best early December · 20 checklists that week, 937 in all65%

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

Best time of day

In Oregon, the Red-breasted Merganser is most often listed on checklists started between 1 and 3 pm (1.2% of those checklists).

0%0.5%1%1.5%12 am: too few checklists (1505) to judge1 am: too few checklists (675) to judge2 am: too few checklists (626) to judge3 am: too few checklists (1641) to judge4 am: too few checklists (3696) to judge5 am: too few checklists (14524) to judge6 am: 0.3% of 50677 checklists7 am: 0.5% of 125347 checklists8 am: 0.7% of 163668 checklists9 am: 0.9% of 160351 checklists10 am: 1.1% of 148940 checklists11 am: 1.1% of 124743 checklists12 pm: 1.1% of 112537 checklists1 pm: 1.2% of 98999 checklists2 pm: 1.1% of 94690 checklists3 pm: 1.1% of 87923 checklists4 pm: 0.7% of 75235 checklists5 pm: 0.4% of 54504 checklists6 pm: 0.3% of 40469 checklists7 pm: 0.1% of 33675 checklists8 pm: too few checklists (18715) to judge9 pm: too few checklists (5839) to judge10 pm: too few checklists (2704) to judge11 pm: too few checklists (1549) 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
January1.7%1.4%1.4%1.9%
February1.7%1.6%1.0%1.3%
March1.1%1.5%1.5%1.3%
April1.3%1.3%1.3%1.3%
May0.8%0.4%0.2%0.1%
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%0.1%
October0.1%0.3%0.3%1.1%
November1.9%2.0%2.3%2.0%
December1.5%1.5%1.6%1.5%

Neighboring states

  • Washington: arrives the second week of October, 2 weeks earlier than Oregon
  • Idaho: arrives mid October, 1 week earlier than Oregon
  • Nevada: arrives early November, 1 week later than Oregon
  • California: arrives early November, 1 week later than Oregon

Common questions

When do Red-breasted Mergansers arrive in Oregon?
Red-breasted Mergansers are winter birds in Oregon: they arrive in late October, peak in mid November (2.1% of checklists), and most are gone by early May.
When do Red-breasted Mergansers leave Oregon?
Most Red-breasted Mergansers have left Oregon by early May, when reports fall below half their usual rate.
When is the best time to see a Red-breasted Merganser in Oregon?
The Red-breasted Merganser is reported most often in mid November, on about 2.1% of Oregon checklists.
Where in Oregon are Red-breasted Mergansers seen most often?
By county, Tillamook County, Lincoln County, and Sherman County have the highest peak reporting rates for the Red-breasted Merganser (counties with at least 200 checklists).