WhenToBird

Lophodytes cucullatus · Anatidae

When Do Hooded Mergansers Arrive in Oregon?

Adult male Hooded Merganser
Photo: Justin Flint, CC BY 4.0 via iNaturalist

Hooded Mergansers are winter birds in Oregon: the first arrive in the second week of July, they are common by late October, peak in mid November (10% of checklists), and most are gone by early April.

When to look

First arrivalsJul 8-14the second week of July
Common byOct 22-31late October
PeakNov 15-21mid November
Most gone byApr 1-7early April

Best: mid November. First arrivals the second week of July; most are gone by early April. Peak: on about 10% of Oregon checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marpeak season
  4. Aprcommon
  5. Mayuncommon
  6. Junrare
  7. Juluncommon
  8. Auguncommon
  9. Sepuncommon
  10. Octcommon
  11. Novpeak season
  12. Decpeak season

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

0%5%10%15%Jan 1-7: 10% of 34973 checklistsJan 8-14: 9.6% of 26807 checklistsJan 15-21: 9.3% of 26567 checklistsJan 22-31: 9.6% of 36019 checklistsFeb 1-7: 9.4% of 24020 checklistsFeb 8-14: 8.1% of 25765 checklistsFeb 15-21: 7.7% of 31019 checklistsFeb 22-28: 7.9% of 24582 checklistsMar 1-7: 8.1% of 24834 checklistsMar 8-14: 7.8% of 24642 checklistsMar 15-21: 6.8% of 27420 checklistsMar 22-31: 6.0% of 39913 checklistsApr 1-7: 5.3% of 28817 checklistsApr 8-14: 4.3% of 31221 checklistsApr 15-21: 3.2% of 34402 checklistsApr 22-30: 2.5% of 47144 checklistsMay 1-7: 1.9% of 37716 checklistsMay 8-14: 1.7% of 39651 checklistsMay 15-21: 1.5% of 37496 checklistsMay 22-31: 1.2% of 56967 checklistsJun 1-7: 1.1% of 35893 checklistsJun 8-14: 1.2% of 31880 checklistsJun 15-21: 1.4% of 30942 checklistsJun 22-30: 1.3% of 38478 checklistsJul 1-7: 1.7% of 27409 checklistsJul 8-14: 1.9% of 25161 checklistsJul 15-21: 2.1% of 25473 checklistsJul 22-31: 2.2% of 33920 checklistsAug 1-7: 2.6% of 24310 checklistsAug 8-14: 2.6% of 23675 checklistsAug 15-21: 2.7% of 23623 checklistsAug 22-31: 2.6% of 33762 checklistsSep 1-7: 2.7% of 25120 checklistsSep 8-14: 2.7% of 24458 checklistsSep 15-21: 2.6% of 25528 checklistsSep 22-30: 2.8% of 31631 checklistsOct 1-7: 2.6% of 25498 checklistsOct 8-14: 2.7% of 25161 checklistsOct 15-21: 3.2% of 23701 checklistsOct 22-31: 6.4% of 30996 checklistsNov 1-7: 8.9% of 21089 checklistsNov 8-14: 10% of 21880 checklistsNov 15-21: 9.9% of 21501 checklistsNov 22-30: 11% of 28930 checklistsDec 1-7: 9.9% of 19807 checklistsDec 8-14: 9.9% of 21022 checklistsDec 15-21: 9.5% of 24817 checklistsDec 22-31: 9.4% 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. Gilliam CountyBest late December · 59 checklists that week, 2,323 in all36%
  2. Sherman CountyBest early February · 73 checklists that week, 4,629 in all26%
  3. Hood River CountyBest late November · 152 checklists that week, 9,695 in all24%
  4. Douglas CountyBest early December · 261 checklists that week, 17,976 in all22%
  5. Klamath CountyBest late November · 302 checklists that week, 26,875 in all21%
  6. Clatsop CountyBest early December · 512 checklists that week, 44,300 in all21%

Best spots

Share of checklists at the peak
  1. Errol Heights PropertyMultnomah County, best mid November · 45 checklists that week, 1,547 in all97%
  2. River Island Natural AreaClackamas County, best mid February · 22 checklists that week, 770 in all96%
  3. Sandy River Greenway TrailMultnomah County, best late November · 22 checklists that week, 1,433 in all94%
  4. Whitaker Ponds Nature ParkMultnomah County, best early December · 136 checklists that week, 6,890 in all94%
  5. Klamath FallsKlamath County, best late December · 24 checklists that week, 720 in all87%

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

Best time of day

In Oregon, the Hooded Merganser is most often listed on checklists started between 1 and 3 pm (6.1% of those checklists).

0%2%4%6%8%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: 2.8% of 50677 checklists7 am: 4.1% of 125347 checklists8 am: 5.2% of 163668 checklists9 am: 5.9% of 160351 checklists10 am: 5.9% of 148940 checklists11 am: 5.8% of 124743 checklists12 pm: 5.6% of 112537 checklists1 pm: 6.1% of 98999 checklists2 pm: 6.1% of 94690 checklists3 pm: 5.9% of 87923 checklists4 pm: 4.0% of 75235 checklists5 pm: 2.5% of 54504 checklists6 pm: 1.6% of 40469 checklists7 pm: 0.9% 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
January10%9.6%9.3%9.6%
February9.4%8.1%7.7%7.9%
March8.1%7.8%6.8%6.0%
April5.3%4.3%3.2%2.5%
May1.9%1.7%1.5%1.2%
June1.1%1.2%1.4%1.3%
July1.7%1.9%2.1%2.2%
August2.6%2.6%2.7%2.6%
September2.7%2.7%2.6%2.8%
October2.6%2.7%3.2%6.4%
November8.9%10%9.9%11%
December9.9%9.9%9.5%9.4%

Neighboring states

  • Washington: arrives early August, 3 weeks later than Oregon
  • Idaho: arrives the second week of October, 12 weeks later than Oregon
  • Nevada: arrives late October, 14 weeks later than Oregon
  • California: arrives early November, 15 weeks later than Oregon

Common questions

When do Hooded Mergansers arrive in Oregon?
Hooded Mergansers are winter birds in Oregon: the first arrive in the second week of July, they are common by late October, peak in mid November (10% of checklists), and most are gone by early April.
When do Hooded Mergansers leave Oregon?
Most Hooded Mergansers have left Oregon by early April, when reports fall below half their usual rate. Stragglers are still reported until early May.
When is the best time to see a Hooded Merganser in Oregon?
The Hooded Merganser is reported most often in mid November, on about 10% of Oregon checklists.
Where in Oregon are Hooded Mergansers seen most often?
By county, Gilliam County, Sherman County, and Hood River County have the highest peak reporting rates for the Hooded Merganser (counties with at least 200 checklists).