WhenToBird

Butorides virescens · Ardeidae

When Do Green Herons Arrive in Oregon?

Adult male Green Heron
Photo: Jonathan Eisen, CC BY 4.0 via iNaturalist

Green Herons reach Oregon in late April, are common by early May, peak in late August (5.2% of checklists), and most are gone by early October.

When to look

First arrivalsApr 22-30late April
Common byMay 1-7early May
PeakAug 22-31late August
Most gone byOct 1-7early October

Best: late August. First arrivals late April; most are gone by early October. Peak: on about 5.2% of Oregon checklists.

  1. Janrare
  2. Febrare
  3. Marrare
  4. Apruncommon
  5. Mayuncommon
  6. Juncommon
  7. Julpeak season
  8. Augpeak season
  9. Seppeak season
  10. Octuncommon
  11. Novrare
  12. Decrare

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

0%2%4%6%Jan 1-7: 0.4% of 34973 checklistsJan 8-14: 0.3% of 26807 checklistsJan 15-21: 0.3% of 26567 checklistsJan 22-31: 0.3% of 36019 checklistsFeb 1-7: 0.4% of 24020 checklistsFeb 8-14: 0.2% of 25765 checklistsFeb 15-21: 0.2% of 31019 checklistsFeb 22-28: 0.3% of 24582 checklistsMar 1-7: 0.2% of 24834 checklistsMar 8-14: 0.3% of 24642 checklistsMar 15-21: 0.2% of 27420 checklistsMar 22-31: 0.3% of 39913 checklistsApr 1-7: 0.3% of 28817 checklistsApr 8-14: 0.5% of 31221 checklistsApr 15-21: 0.7% of 34402 checklistsApr 22-30: 1.2% of 47144 checklistsMay 1-7: 1.4% of 37716 checklistsMay 8-14: 1.5% of 39651 checklistsMay 15-21: 1.7% of 37496 checklistsMay 22-31: 1.6% of 56967 checklistsJun 1-7: 1.7% of 35893 checklistsJun 8-14: 1.9% of 31880 checklistsJun 15-21: 2.1% of 30942 checklistsJun 22-30: 2.0% of 38478 checklistsJul 1-7: 2.7% of 27409 checklistsJul 8-14: 3.1% of 25161 checklistsJul 15-21: 3.6% of 25473 checklistsJul 22-31: 4.1% of 33920 checklistsAug 1-7: 4.4% of 24310 checklistsAug 8-14: 4.6% of 23675 checklistsAug 15-21: 5.5% of 23623 checklistsAug 22-31: 5.2% of 33762 checklistsSep 1-7: 4.9% of 25120 checklistsSep 8-14: 4.1% of 24458 checklistsSep 15-21: 3.2% of 25528 checklistsSep 22-30: 2.3% of 31631 checklistsOct 1-7: 1.4% of 25498 checklistsOct 8-14: 1.1% of 25161 checklistsOct 15-21: 0.5% of 23701 checklistsOct 22-31: 0.4% of 30996 checklistsNov 1-7: 0.4% of 21089 checklistsNov 8-14: 0.3% of 21880 checklistsNov 15-21: 0.3% of 21501 checklistsNov 22-30: 0.4% of 28930 checklistsDec 1-7: 0.4% of 19807 checklistsDec 8-14: 0.3% of 21022 checklistsDec 15-21: 0.3% of 24817 checklistsDec 22-31: 0.3% 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. Washington CountyBest mid August · 1548 checklists that week, 110,376 in all22%
  2. Marion CountyBest late August · 1226 checklists that week, 52,870 in all12%
  3. Jackson CountyBest mid August · 871 checklists that week, 60,428 in all9.2%
  4. Multnomah CountyBest late August · 4230 checklists that week, 182,088 in all8.7%
  5. Josephine CountyBest mid August · 294 checklists that week, 20,837 in all8.0%
  6. Yamhill CountyBest mid September · 151 checklists that week, 11,537 in all7.6%

Best spots

Share of checklists at the peak
  1. Commonwealth Lake ParkWashington County, best the second week of August · 44 checklists that week, 4,071 in all85%
  2. Wapato Lake National Wildlife RefugeWashington County, best late August · 22 checklists that week, 605 in all81%
  3. Fernhill WetlandsWashington County, best the second week of August · 118 checklists that week, 6,516 in all79%
  4. Koll Center WetlandsWashington County, best the second week of August · 80 checklists that week, 6,234 in all78%
  5. Delta PondsLane County, best mid July · 32 checklists that week, 2,465 in all77%
  6. Fernhill Wetlands (Carnation)Washington County, best early August · 23 checklists that week, 1,458 in all75%

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

Best time of day

In Oregon, the Green Heron is most often listed on checklists started between 6 and 8 am (2.5% of those checklists).

0%1%2%3%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: 2.7% of 50677 checklists7 am: 2.5% of 125347 checklists8 am: 2.0% of 163668 checklists9 am: 1.8% of 160351 checklists10 am: 1.6% of 148940 checklists11 am: 1.4% of 124743 checklists12 pm: 1.2% of 112537 checklists1 pm: 1.0% of 98999 checklists2 pm: 1.0% of 94690 checklists3 pm: 0.9% of 87923 checklists4 pm: 1.0% of 75235 checklists5 pm: 1.3% of 54504 checklists6 pm: 1.6% of 40469 checklists7 pm: 1.3% 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
January0.4%0.3%0.3%0.3%
February0.4%0.2%0.2%0.3%
March0.2%0.3%0.2%0.3%
April0.3%0.5%0.7%1.2%
May1.4%1.5%1.7%1.6%
June1.7%1.9%2.1%2.0%
July2.7%3.1%3.6%4.1%
August4.4%4.6%5.5%5.2%
September4.9%4.1%3.2%2.3%
October1.4%1.1%0.5%0.4%
November0.4%0.3%0.3%0.4%
December0.4%0.3%0.3%0.3%

Neighboring states

  • Washington: arrives the second week of June, 6 weeks later than Oregon
  • Nevada: arrives late March, 4 weeks earlier than Oregon
  • California: arrives early March, 7 weeks earlier than Oregon
  • Arizona: year-round, peaks late September

Common questions

When do Green Herons arrive in Oregon?
Green Herons reach Oregon in late April, are common by early May, peak in late August (5.2% of checklists), and most are gone by early October.
When do Green Herons leave Oregon?
Most Green Herons have left Oregon by early October, when reports fall below half their usual rate. Stragglers are still reported until the second week of October.
When is the best time to see a Green Heron in Oregon?
The Green Heron is reported most often in late August, on about 5.2% of Oregon checklists.
Where in Oregon are Green Herons seen most often?
By county, Washington County, Marion County, and Jackson County have the highest peak reporting rates for the Green Heron (counties with at least 200 checklists).