WhenToBird

Ardea herodias · Ardeidae

When Do Great Blue Herons Arrive in Massachusetts?

Adult Great Blue Heron
Photo: mostbittern, CC BY 4.0 via iNaturalist

Great Blue Herons are in Massachusetts all year, but most are here in summer: numbers build from the second week of April, peak in late August (25% of checklists), and fall back by early November. In the quietest week (late February) they are still on about 3.7% of checklists.

When to look

Numbers buildApr 8-14the second week of April
PeakAug 22-31late August
Fall back byNov 1-7early November
FewestFeb 22-28late February

Best: late August. Here all year; numbers build from the second week of April and fall back by early November. Peak: on about 25% of Massachusetts checklists.

  1. Januncommon
  2. Febuncommon
  3. Marcommon
  4. Aprcommon
  5. Maycommon
  6. Juncommon
  7. Julpeak season
  8. Augpeak season
  9. Seppeak season
  10. Octpeak season
  11. Novcommon
  12. Decuncommon

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

0%10%20%30%Jan 1-7: 6.2% of 43252 checklistsJan 8-14: 5.6% of 30096 checklistsJan 15-21: 4.8% of 28760 checklistsJan 22-31: 4.8% of 38135 checklistsFeb 1-7: 4.7% of 26442 checklistsFeb 8-14: 4.2% of 29034 checklistsFeb 15-21: 3.3% of 37383 checklistsFeb 22-28: 4.0% of 29977 checklistsMar 1-7: 4.0% of 29175 checklistsMar 8-14: 4.6% of 32399 checklistsMar 15-21: 7.0% of 34444 checklistsMar 22-31: 11% of 49126 checklistsApr 1-7: 14% of 36456 checklistsApr 8-14: 15% of 40908 checklistsApr 15-21: 15% of 42078 checklistsApr 22-30: 17% of 56465 checklistsMay 1-7: 16% of 56994 checklistsMay 8-14: 16% of 64079 checklistsMay 15-21: 16% of 52020 checklistsMay 22-31: 16% of 55402 checklistsJun 1-7: 17% of 30682 checklistsJun 8-14: 18% of 27557 checklistsJun 15-21: 17% of 26163 checklistsJun 22-30: 18% of 29576 checklistsJul 1-7: 19% of 23931 checklistsJul 8-14: 20% of 22389 checklistsJul 15-21: 22% of 22365 checklistsJul 22-31: 24% of 32631 checklistsAug 1-7: 25% of 25133 checklistsAug 8-14: 25% of 24610 checklistsAug 15-21: 25% of 25350 checklistsAug 22-31: 25% of 37198 checklistsSep 1-7: 25% of 27402 checklistsSep 8-14: 25% of 27700 checklistsSep 15-21: 24% of 28398 checklistsSep 22-30: 22% of 34646 checklistsOct 1-7: 22% of 28620 checklistsOct 8-14: 20% of 30144 checklistsOct 15-21: 18% of 28893 checklistsOct 22-31: 16% of 38869 checklistsNov 1-7: 15% of 29782 checklistsNov 8-14: 13% of 27582 checklistsNov 15-21: 12% of 26642 checklistsNov 22-30: 11% of 34390 checklistsDec 1-7: 9.4% of 25164 checklistsDec 8-14: 7.7% of 24892 checklistsDec 15-21: 7.7% of 29022 checklistsDec 22-31: 6.9% 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.

Embed this map on your site

Where in Massachusetts

Best counties

Share of checklists at the peak
  1. Hampden CountyBest late August · 929 checklists that week, 35,410 in all37%
  2. Plymouth CountyBest early September · 1317 checklists that week, 89,282 in all33%
  3. Bristol CountyBest mid August · 908 checklists that week, 65,262 in all31%
  4. Middlesex CountyBest late August · 6420 checklists that week, 307,511 in all31%
  5. Barnstable CountyBest the second week of September · 4133 checklists that week, 215,188 in all29%
  6. Nantucket CountyBest the second week of December · 355 checklists that week, 23,895 in all27%

Best spots

Share of checklists at the peak
  1. Frank G Feeley ParkMiddlesex County, best the second week of July · 25 checklists that week, 372 in all100%
  2. Connecticut River ReservoirHampshire County, best the second week of June · 20 checklists that week, 1,745 in all98%
  3. Sears LandMiddlesex County, best late May · 39 checklists that week, 1,084 in all98%
  4. Burrage Pond Wildlife Management AreaPlymouth County, best the second week of June · 61 checklists that week, 2,866 in all98%

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

Best time of day

In Massachusetts, the Great Blue Heron is most often listed on checklists started between 6 and 8 am (18% of those checklists).

0%10%20%30%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: 21% of 108601 checklists7 am: 17% of 186104 checklists8 am: 15% of 185905 checklists9 am: 14% of 166049 checklists10 am: 12% of 150508 checklists11 am: 12% of 131024 checklists12 pm: 11% of 116804 checklists1 pm: 12% of 112055 checklists2 pm: 12% of 110246 checklists3 pm: 12% of 104376 checklists4 pm: 14% of 83736 checklists5 pm: 16% of 63723 checklists6 pm: 17% 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
January6.2%5.6%4.8%4.8%
February4.7%4.2%3.3%4.0%
March4.0%4.6%7.0%11%
April14%15%15%17%
May16%16%16%16%
June17%18%17%18%
July19%20%22%24%
August25%25%25%25%
September25%25%24%22%
October22%20%18%16%
November15%13%12%11%
December9.4%7.7%7.7%6.9%

Neighboring states

  • Rhode Island: arrives early July, 11 weeks later than Massachusetts
  • New Hampshire: arrives the second week of March, 4 weeks earlier than Massachusetts
  • Connecticut: arrives early May, 3 weeks later than Massachusetts
  • Vermont: arrives mid March, 3 weeks earlier than Massachusetts

Common questions

When do Great Blue Herons arrive in Massachusetts?
Great Blue Herons are in Massachusetts all year, but most are here in summer: numbers build from the second week of April, peak in late August (25% of checklists), and fall back by early November. In the quietest week (late February) they are still on about 3.7% of checklists.
When do Great Blue Herons leave Massachusetts?
Great Blue Herons never fully leave Massachusetts: numbers fall back below half their usual rate by early November, but some are still reported in every week, about 3.7% of checklists at the low.
When is the best time to see a Great Blue Heron in Massachusetts?
The Great Blue Heron is reported most often in late August, on about 25% of Massachusetts checklists.
Where in Massachusetts are Great Blue Herons seen most often?
By county, Hampden County, Plymouth County, and Bristol County have the highest peak reporting rates for the Great Blue Heron (counties with at least 200 checklists).