WhenToBird

Circus hudsonius · Accipitridae

When Do Northern Harriers Arrive in Oregon?

Northern Harriers are in Oregon all year, but most are here in winter: numbers build from the second week of September, peak in mid November (10% of checklists), and fall back by the second week of April. In the quietest week (early July) they are still on about 2.3% of checklists.

When to look

Numbers buildSep 8-14the second week of September
PeakNov 15-21mid November
Fall back byApr 8-14the second week of April
FewestJul 1-7early July

Best: mid November. Here all year; numbers build from the second week of September and fall back by the second week of April. Peak: on about 10% of Oregon checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marpeak season
  4. Aprpeak season
  5. Maycommon
  6. Jununcommon
  7. Juluncommon
  8. Augcommon
  9. Seppeak season
  10. Octpeak season
  11. Novpeak season
  12. Decpeak season

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

0%5%10%15%Jan 1-7: 9.0% of 34973 checklistsJan 8-14: 8.9% of 26807 checklistsJan 15-21: 9.8% of 26567 checklistsJan 22-31: 9.3% of 36019 checklistsFeb 1-7: 9.1% of 24020 checklistsFeb 8-14: 7.6% of 25765 checklistsFeb 15-21: 7.4% of 31019 checklistsFeb 22-28: 7.8% of 24582 checklistsMar 1-7: 7.9% of 24834 checklistsMar 8-14: 7.9% of 24642 checklistsMar 15-21: 7.6% of 27420 checklistsMar 22-31: 7.6% of 39913 checklistsApr 1-7: 8.0% of 28817 checklistsApr 8-14: 7.3% of 31221 checklistsApr 15-21: 6.0% of 34402 checklistsApr 22-30: 5.0% of 47144 checklistsMay 1-7: 4.3% of 37716 checklistsMay 8-14: 4.0% of 39651 checklistsMay 15-21: 4.4% of 37496 checklistsMay 22-31: 4.1% of 56967 checklistsJun 1-7: 3.1% of 35893 checklistsJun 8-14: 3.0% of 31880 checklistsJun 15-21: 2.4% of 30942 checklistsJun 22-30: 2.2% of 38478 checklistsJul 1-7: 2.4% of 27409 checklistsJul 8-14: 2.4% of 25161 checklistsJul 15-21: 2.5% of 25473 checklistsJul 22-31: 2.6% of 33920 checklistsAug 1-7: 3.4% of 24310 checklistsAug 8-14: 3.7% of 23675 checklistsAug 15-21: 4.3% of 23623 checklistsAug 22-31: 4.9% of 33762 checklistsSep 1-7: 5.7% of 25120 checklistsSep 8-14: 6.0% of 24458 checklistsSep 15-21: 7.7% of 25528 checklistsSep 22-30: 8.2% of 31631 checklistsOct 1-7: 7.3% of 25498 checklistsOct 8-14: 7.5% of 25161 checklistsOct 15-21: 8.9% of 23701 checklistsOct 22-31: 9.1% of 30996 checklistsNov 1-7: 9.3% of 21089 checklistsNov 8-14: 10% of 21880 checklistsNov 15-21: 9.7% of 21501 checklistsNov 22-30: 9.9% of 28930 checklistsDec 1-7: 9.6% of 19807 checklistsDec 8-14: 8.6% of 21022 checklistsDec 15-21: 9.1% of 24817 checklistsDec 22-31: 8.6% 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. Columbia CountyBest the second week of December · 443 checklists that week, 27,750 in all34%
  2. Lake CountyBest the second week of January · 20 checklists that week, 13,301 in all33%
  3. Polk CountyBest mid November · 511 checklists that week, 29,096 in all33%
  4. Crook CountyBest late January · 142 checklists that week, 9,466 in all31%
  5. Morrow CountyBest the second week of February · 35 checklists that week, 3,484 in all29%
  6. Harney CountyBest late October · 347 checklists that week, 40,943 in all29%

Best spots

Share of checklists at the peak
  1. Fern Ridge Wildlife AreaLane County, best mid December · 34 checklists that week, 4,157 in all95%
  2. William L. Finley National Wildlife Refuge Research Natural AreaBenton County, best late January · 137 checklists that week, 2,178 in all91%
  3. Fern Ridge Wildlife Area (Coyote Creek)Lane County, best the second week of May · 36 checklists that week, 981 in all85%

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

Best time of day

In Oregon, the Northern Harrier is most often listed on checklists started between 10 am and 12 pm (7.6% 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: 3.7% of 50677 checklists7 am: 5.2% of 125347 checklists8 am: 6.5% of 163668 checklists9 am: 7.4% of 160351 checklists10 am: 7.6% of 148940 checklists11 am: 7.6% of 124743 checklists12 pm: 7.0% of 112537 checklists1 pm: 7.4% of 98999 checklists2 pm: 7.4% of 94690 checklists3 pm: 7.3% of 87923 checklists4 pm: 6.1% of 75235 checklists5 pm: 4.7% of 54504 checklists6 pm: 3.8% of 40469 checklists7 pm: 2.0% 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
January9.0%8.9%9.8%9.3%
February9.1%7.6%7.4%7.8%
March7.9%7.9%7.6%7.6%
April8.0%7.3%6.0%5.0%
May4.3%4.0%4.4%4.1%
June3.1%3.0%2.4%2.2%
July2.4%2.4%2.5%2.6%
August3.4%3.7%4.3%4.9%
September5.7%6.0%7.7%8.2%
October7.3%7.5%8.9%9.1%
November9.3%10%9.7%9.9%
December9.6%8.6%9.1%8.6%

Neighboring states

  • Washington: arrives late July, 6 weeks earlier than Oregon
  • Idaho: arrives early March, 23 weeks later than Oregon
  • Nevada: arrives the second week of October, 4 weeks later than Oregon
  • California: arrives the second week of October, 4 weeks later than Oregon

Common questions

When do Northern Harriers arrive in Oregon?
Northern Harriers are in Oregon all year, but most are here in winter: numbers build from the second week of September, peak in mid November (10% of checklists), and fall back by the second week of April. In the quietest week (early July) they are still on about 2.3% of checklists.
When do Northern Harriers leave Oregon?
Northern Harriers never fully leave Oregon: numbers fall back below half their usual rate by the second week of April, but some are still reported in every week, about 2.3% of checklists at the low.
When is the best time to see a Northern Harrier in Oregon?
The Northern Harrier is reported most often in mid November, on about 10% of Oregon checklists.
Where in Oregon are Northern Harriers seen most often?
By county, Columbia County, Lake County, and Polk County have the highest peak reporting rates for the Northern Harrier (counties with at least 200 checklists).