WhenToBird

Butorides virescens · Ardeidae

When Do Green Herons Arrive in Massachusetts?

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

Green Herons reach Massachusetts in late April, are common by the second week of May, peak in the second week of August (9.4% of checklists), and most are gone by mid September.

When to look

First arrivalsApr 22-30late April
Common byMay 8-14the second week of May
PeakAug 8-14the second week of August
Most gone bySep 15-21mid September

Best: the second week of August. First arrivals late April; most are gone by mid September. Peak: on about 9.4% of Massachusetts checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Apruncommon
  5. Maycommon
  6. Juncommon
  7. Julpeak season
  8. Augpeak season
  9. Seppeak season
  10. Octrare
  11. Novnot usually seen
  12. Decnot usually seen

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

0%5%10%Jan 1-7: 0% of 43252 checklistsJan 8-14: 0% of 30096 checklistsJan 15-21: 0% of 28760 checklistsJan 22-31: 0% of 38135 checklistsFeb 1-7: 0% of 26442 checklistsFeb 8-14: 0% of 29034 checklistsFeb 15-21: 0% of 37383 checklistsFeb 22-28: 0% of 29977 checklistsMar 1-7: 0% of 29175 checklistsMar 8-14: 0% of 32399 checklistsMar 15-21: 0% of 34444 checklistsMar 22-31: 0% of 49126 checklistsApr 1-7: 0% of 36456 checklistsApr 8-14: 0.1% of 40908 checklistsApr 15-21: 0.4% of 42078 checklistsApr 22-30: 1.4% of 56465 checklistsMay 1-7: 2.7% of 56994 checklistsMay 8-14: 3.1% of 64079 checklistsMay 15-21: 4.2% of 52020 checklistsMay 22-31: 4.0% of 55402 checklistsJun 1-7: 4.1% of 30682 checklistsJun 8-14: 4.5% of 27557 checklistsJun 15-21: 5.4% of 26163 checklistsJun 22-30: 5.7% of 29576 checklistsJul 1-7: 6.3% of 23931 checklistsJul 8-14: 6.4% of 22389 checklistsJul 15-21: 7.3% of 22365 checklistsJul 22-31: 8.8% of 32631 checklistsAug 1-7: 9.7% of 25133 checklistsAug 8-14: 9.4% of 24610 checklistsAug 15-21: 9.2% of 25350 checklistsAug 22-31: 8.7% of 37198 checklistsSep 1-7: 7.5% of 27402 checklistsSep 8-14: 5.8% of 27700 checklistsSep 15-21: 3.7% of 28398 checklistsSep 22-30: 2.2% of 34646 checklistsOct 1-7: 0.8% of 28620 checklistsOct 8-14: 0.4% of 30144 checklistsOct 15-21: 0.2% of 28893 checklistsOct 22-31: 0.1% of 38869 checklistsNov 1-7: 0.1% of 29782 checklistsNov 8-14: 0.1% of 27582 checklistsNov 15-21: 0.1% of 26642 checklistsNov 22-30: 0% of 34390 checklistsDec 1-7: 0% of 25164 checklistsDec 8-14: 0% of 24892 checklistsDec 15-21: 0% of 29022 checklistsDec 22-31: 0% of 44323 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 Massachusetts 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 Massachusetts

Best counties

Share of checklists at the peak
  1. Hampden CountyBest the second week of August · 527 checklists that week, 35,410 in all18%
  2. Dukes CountyBest the second week of August · 517 checklists that week, 23,670 in all15%
  3. Hampshire CountyBest the second week of August · 2299 checklists that week, 162,423 in all14%
  4. Middlesex CountyBest late August · 6420 checklists that week, 307,511 in all12%
  5. Barnstable CountyBest early August · 4569 checklists that week, 215,188 in all12%
  6. Bristol CountyBest the second week of August · 852 checklists that week, 65,262 in all12%

Best spots

Share of checklists at the peak
  1. Foley FieldHampshire County, best late July · 126 checklists that week, 2,425 in all97%
  2. West Roxbury High School Recreational FieldsSuffolk County, best late August · 27 checklists that week, 619 in all88%
  3. Larence SwampHampshire County, best late July · 29 checklists that week, 843 in all88%
  4. Broad Brook - Fitzgerald Lake Greenway (southeast)Hampshire County, best late August · 20 checklists that week, 981 in all83%

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

Best time of day

In Massachusetts, the Green Heron is most often listed on checklists started between 6 and 8 am (3.9% of those checklists).

0%2%4%6%12 am: too few checklists (630) to judge1 am: too few checklists (657) to judge2 am: too few checklists (645) to judge3 am: too few checklists (850) to judge4 am: too few checklists (3787) to judge5 am: too few checklists (29743) to judge6 am: 5.0% of 108601 checklists7 am: 3.2% of 186104 checklists8 am: 2.6% of 185905 checklists9 am: 2.1% of 166049 checklists10 am: 1.7% of 150508 checklists11 am: 1.5% of 131024 checklists12 pm: 1.3% of 116804 checklists1 pm: 1.2% of 112055 checklists2 pm: 1.3% of 110246 checklists3 pm: 1.4% of 104376 checklists4 pm: 2.1% of 83736 checklists5 pm: 2.8% of 63723 checklists6 pm: 3.6% of 41435 checklists7 pm: too few checklists (21041) to judge8 pm: too few checklists (5240) to judge9 pm: too few checklists (1722) to judge10 pm: too few checklists (1094) to judge11 pm: too few checklists (704) 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%0%0%0%
February0%0%0%0%
March0%0%0%0%
April0%0.1%0.4%1.4%
May2.7%3.1%4.2%4.0%
June4.1%4.5%5.4%5.7%
July6.3%6.4%7.3%8.8%
August9.7%9.4%9.2%8.7%
September7.5%5.8%3.7%2.2%
October0.8%0.4%0.2%0.1%
November0.1%0.1%0.1%0%
December0%0%0%0%

Neighboring states

  • Rhode Island: arrives late April, in the same week than Massachusetts
  • New Hampshire: arrives early May, 1 week later than Massachusetts
  • Connecticut: arrives late April, in the same week than Massachusetts
  • Vermont: arrives late April, in the same week than Massachusetts

Common questions

When do Green Herons arrive in Massachusetts?
Green Herons reach Massachusetts in late April, are common by the second week of May, peak in the second week of August (9.4% of checklists), and most are gone by mid September.
When do Green Herons leave Massachusetts?
Most Green Herons have left Massachusetts by mid September, when reports fall below half their usual rate. Stragglers are still reported until early October.
When is the best time to see a Green Heron in Massachusetts?
The Green Heron is reported most often in the second week of August, on about 9.4% of Massachusetts checklists.
Where in Massachusetts are Green Herons seen most often?
By county, Hampden County, Dukes County, and Hampshire County have the highest peak reporting rates for the Green Heron (counties with at least 200 checklists).