WhenToBird

Circus hudsonius · Accipitridae

When Do Northern Harriers Arrive in Washington?

Northern Harriers are winter birds in Washington: the first arrive in late July, they are common by the second week of September, peak in mid November (8.3% of checklists), and most are gone by mid April.

When to look

First arrivalsJul 22-31late July
Common bySep 8-14the second week of September
PeakNov 15-21mid November
Most gone byApr 15-21mid April

Best: mid November. First arrivals late July; most are gone by mid April. Peak: on about 8.3% of Washington 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%Jan 1-7: 6.7% of 41928 checklistsJan 8-14: 7.4% of 31152 checklistsJan 15-21: 7.4% of 31753 checklistsJan 22-31: 7.3% of 42530 checklistsFeb 1-7: 7.2% of 29739 checklistsFeb 8-14: 7.1% of 32746 checklistsFeb 15-21: 6.6% of 40328 checklistsFeb 22-28: 7.2% of 28432 checklistsMar 1-7: 7.2% of 30758 checklistsMar 8-14: 6.9% of 29368 checklistsMar 15-21: 6.8% of 32580 checklistsMar 22-31: 6.6% of 45614 checklistsApr 1-7: 6.1% of 33997 checklistsApr 8-14: 6.0% of 34729 checklistsApr 15-21: 5.0% of 38474 checklistsApr 22-30: 4.2% of 52185 checklistsMay 1-7: 3.3% of 44236 checklistsMay 8-14: 2.8% of 48708 checklistsMay 15-21: 2.5% of 41742 checklistsMay 22-31: 2.1% of 57082 checklistsJun 1-7: 2.0% of 39193 checklistsJun 8-14: 1.9% of 36042 checklistsJun 15-21: 1.8% of 34003 checklistsJun 22-30: 1.8% of 39711 checklistsJul 1-7: 1.6% of 31949 checklistsJul 8-14: 1.8% of 29086 checklistsJul 15-21: 1.8% of 28045 checklistsJul 22-31: 2.4% of 38275 checklistsAug 1-7: 2.7% of 28846 checklistsAug 8-14: 2.8% of 28036 checklistsAug 15-21: 3.4% of 27614 checklistsAug 22-31: 3.6% of 40356 checklistsSep 1-7: 3.9% of 31214 checklistsSep 8-14: 4.9% of 27795 checklistsSep 15-21: 6.1% of 29677 checklistsSep 22-30: 7.0% of 35241 checklistsOct 1-7: 7.3% of 28605 checklistsOct 8-14: 7.5% of 28655 checklistsOct 15-21: 7.5% of 24643 checklistsOct 22-31: 8.4% of 34874 checklistsNov 1-7: 7.9% of 25658 checklistsNov 8-14: 8.5% of 25700 checklistsNov 15-21: 8.1% of 24331 checklistsNov 22-30: 8.3% of 32784 checklistsDec 1-7: 7.5% of 24099 checklistsDec 8-14: 7.3% of 23339 checklistsDec 15-21: 5.8% of 27666 checklistsDec 22-31: 7.4% 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. Skagit CountyBest mid November · 1372 checklists that week, 78,154 in all33%
  2. Adams CountyBest mid December · 15 checklists that week, 4,574 in all32%
  3. Garfield CountyBest late December · 13 checklists that week, 1,130 in all30%
  4. Clark CountyBest late December · 1396 checklists that week, 53,250 in all29%
  5. Cowlitz CountyBest the second week of February · 508 checklists that week, 15,273 in all29%
  6. Lincoln CountyBest mid October · 84 checklists that week, 6,135 in all28%

Best spots

Share of checklists at the peak
  1. Port Susan BaySnohomish County, best late February · 24 checklists that week, 454 in all98%
  2. Quigley LakeClark County, best early November · 115 checklists that week, 6,702 in all93%
  3. SamishSkagit County, best late November · 43 checklists that week, 1,512 in all93%
  4. Skagit-Snoqualmie Wildlife Area Complex (Craft Island)Skagit County, best mid November · 22 checklists that week, 919 in all91%

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

Best time of day

In Washington, the Northern Harrier is most often listed on checklists started between 1 and 3 pm (6.6% of those checklists).

0%2%4%6%8%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: 3.2% of 56744 checklists7 am: 4.0% of 133294 checklists8 am: 4.8% of 184196 checklists9 am: 5.3% of 186303 checklists10 am: 5.7% of 177063 checklists11 am: 5.8% of 154936 checklists12 pm: 5.8% of 138061 checklists1 pm: 6.5% of 127449 checklists2 pm: 6.7% of 121511 checklists3 pm: 6.3% of 107793 checklists4 pm: 5.2% of 82862 checklists5 pm: 4.0% of 57183 checklists6 pm: 2.7% 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
January6.7%7.4%7.4%7.3%
February7.2%7.1%6.6%7.2%
March7.2%6.9%6.8%6.6%
April6.1%6.0%5.0%4.2%
May3.3%2.8%2.5%2.1%
June2.0%1.9%1.8%1.8%
July1.6%1.8%1.8%2.4%
August2.7%2.8%3.4%3.6%
September3.9%4.9%6.1%7.0%
October7.3%7.5%7.5%8.4%
November7.9%8.5%8.1%8.3%
December7.5%7.3%5.8%7.4%

Neighboring states

  • Oregon: arrives the second week of September, 6 weeks later than Washington
  • Idaho: arrives early March, 19 weeks earlier than Washington
  • Montana: arrives early April, 15 weeks earlier than Washington
  • Nevada: arrives the second week of October, 10 weeks later than Washington

Common questions

When do Northern Harriers arrive in Washington?
Northern Harriers are winter birds in Washington: the first arrive in late July, they are common by the second week of September, peak in mid November (8.3% of checklists), and most are gone by mid April.
When do Northern Harriers leave Washington?
Most Northern Harriers have left Washington 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 Northern Harrier in Washington?
The Northern Harrier is reported most often in mid November, on about 8.3% of Washington checklists.
Where in Washington are Northern Harriers seen most often?
By county, Skagit County, Adams County, and Garfield County have the highest peak reporting rates for the Northern Harrier (counties with at least 200 checklists).