WhenToBird

Butorides virescens · Ardeidae

When Do Green Herons Arrive in California?

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

Green Herons reach California in early March, are common by the second week of April, peak in early September (5.8% of checklists), and most are gone by late November.

When to look

First arrivalsMar 1-7early March
Common byApr 8-14the second week of April
PeakSep 1-7early September
Most gone byNov 22-30late November

Best: early September. First arrivals early March; most are gone by late November. Peak: on about 5.8% of California checklists.

  1. Januncommon
  2. Febuncommon
  3. Maruncommon
  4. Aprcommon
  5. Maypeak season
  6. Junpeak season
  7. Julpeak season
  8. Augpeak season
  9. Seppeak season
  10. Octcommon
  11. Novcommon
  12. Deccommon

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

0%2%4%6%Jan 1-7: 2.3% of 112336 checklistsJan 8-14: 2.3% of 85518 checklistsJan 15-21: 2.1% of 86488 checklistsJan 22-31: 2.1% of 116174 checklistsFeb 1-7: 2.0% of 75171 checklistsFeb 8-14: 1.9% of 84467 checklistsFeb 15-21: 1.6% of 105683 checklistsFeb 22-28: 1.9% of 83396 checklistsMar 1-7: 2.1% of 77470 checklistsMar 8-14: 2.1% of 75180 checklistsMar 15-21: 2.1% of 80770 checklistsMar 22-31: 2.2% of 114116 checklistsApr 1-7: 2.5% of 84057 checklistsApr 8-14: 2.8% of 83692 checklistsApr 15-21: 3.0% of 89242 checklistsApr 22-30: 3.8% of 114289 checklistsMay 1-7: 4.2% of 85728 checklistsMay 8-14: 4.1% of 91984 checklistsMay 15-21: 4.4% of 75478 checklistsMay 22-31: 4.7% of 106250 checklistsJun 1-7: 4.5% of 70051 checklistsJun 8-14: 4.6% of 67485 checklistsJun 15-21: 4.4% of 66269 checklistsJun 22-30: 4.7% of 79172 checklistsJul 1-7: 5.1% of 62877 checklistsJul 8-14: 4.9% of 60328 checklistsJul 15-21: 5.0% of 59705 checklistsJul 22-31: 5.5% of 83796 checklistsAug 1-7: 5.8% of 60215 checklistsAug 8-14: 5.7% of 60172 checklistsAug 15-21: 5.4% of 59877 checklistsAug 22-31: 5.9% of 89107 checklistsSep 1-7: 6.0% of 72000 checklistsSep 8-14: 5.5% of 71228 checklistsSep 15-21: 4.7% of 76808 checklistsSep 22-30: 4.2% of 100204 checklistsOct 1-7: 3.7% of 76571 checklistsOct 8-14: 3.3% of 80874 checklistsOct 15-21: 3.1% of 74581 checklistsOct 22-31: 3.1% of 97498 checklistsNov 1-7: 3.0% of 70851 checklistsNov 8-14: 2.7% of 72431 checklistsNov 15-21: 2.6% of 66767 checklistsNov 22-30: 2.6% of 94737 checklistsDec 1-7: 2.7% of 65393 checklistsDec 8-14: 2.2% of 67449 checklistsDec 15-21: 2.2% of 83421 checklistsDec 22-31: 2.1% of 124993 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 California 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 California

Best counties

Share of checklists at the peak
  1. Lake CountyBest the second week of August · 223 checklists that week, 12,989 in all25%
  2. Yolo CountyBest the second week of August · 941 checklists that week, 67,424 in all21%
  3. Imperial CountyBest the second week of June · 183 checklists that week, 24,551 in all18%
  4. Sacramento CountyBest mid June · 1632 checklists that week, 121,767 in all13%
  5. Solano CountyBest early September · 421 checklists that week, 25,325 in all12%
  6. San Joaquin CountyBest early August · 490 checklists that week, 33,237 in all12%

Best spots

Share of checklists at the peak
  1. Ellis Lake ParkContra Costa County, best late May · 28 checklists that week, 852 in all89%
  2. Upper Otay LakeSan Diego County, best late July · 26 checklists that week, 234 in all81%
  3. Reflection LakeSan Mateo County, best late November · 20 checklists that week, 418 in all79%
  4. Mather Regional ParkSacramento County, best the second week of June · 35 checklists that week, 1,173 in all79%
  5. Atascadero LakeSan Luis Obispo County, best mid August · 37 checklists that week, 1,657 in all78%
  6. Vasona Lake County ParkSanta Clara County, best early July · 22 checklists that week, 2,703 in all77%

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

Best time of day

In California, the Green Heron is most often listed on checklists started between 6 and 8 am (5.5% of those checklists).

0%2%4%6%12 am: too few checklists (1688) to judge1 am: too few checklists (1451) to judge2 am: too few checklists (1402) to judge3 am: too few checklists (1743) to judge4 am: too few checklists (4647) to judge5 am: too few checklists (32158) to judge6 am: 5.6% of 186053 checklists7 am: 5.5% of 444086 checklists8 am: 4.8% of 535846 checklists9 am: 3.6% of 486061 checklists10 am: 2.9% of 411130 checklists11 am: 2.5% of 325798 checklists12 pm: 2.3% of 269132 checklists1 pm: 2.2% of 244762 checklists2 pm: 2.3% of 235420 checklists3 pm: 2.3% of 232365 checklists4 pm: 2.3% of 208688 checklists5 pm: 2.6% of 146104 checklists6 pm: 2.8% of 96867 checklists7 pm: too few checklists (50942) to judge8 pm: too few checklists (14803) to judge9 pm: too few checklists (5561) to judge10 pm: too few checklists (3546) to judge11 pm: too few checklists (2092) 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
January2.3%2.3%2.1%2.1%
February2.0%1.9%1.6%1.9%
March2.1%2.1%2.1%2.2%
April2.5%2.8%3.0%3.8%
May4.2%4.1%4.4%4.7%
June4.5%4.6%4.4%4.7%
July5.1%4.9%5.0%5.5%
August5.8%5.7%5.4%5.9%
September6.0%5.5%4.7%4.2%
October3.7%3.3%3.1%3.1%
November3.0%2.7%2.6%2.6%
December2.7%2.2%2.2%2.1%

Neighboring states

  • Nevada: arrives late March, 3 weeks later than California
  • Arizona: year-round, peaks late September
  • Oregon: arrives late April, 7 weeks later than California
  • New Mexico: arrives mid April, 6 weeks later than California

Common questions

When do Green Herons arrive in California?
Green Herons reach California in early March, are common by the second week of April, peak in early September (5.8% of checklists), and most are gone by late November.
When do Green Herons leave California?
Most Green Herons have left California by late November, when reports fall below half their usual rate. Stragglers are still reported until early February.
When is the best time to see a Green Heron in California?
The Green Heron is reported most often in early September, on about 5.8% of California checklists.
Where in California are Green Herons seen most often?
By county, Lake County, Yolo County, and Imperial County have the highest peak reporting rates for the Green Heron (counties with at least 200 checklists).