WhenToBird

Butorides virescens · Ardeidae

When Do Green Herons Arrive in Maryland?

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

Green Herons reach Maryland in the second week of April, are common by mid April, peak in early August (16% of checklists), and most are gone by late September.

When to look

First arrivalsApr 8-14the second week of April
Common byApr 15-21mid April
PeakAug 1-7early August
Most gone bySep 22-30late September

Best: early August. First arrivals the second week of April; most are gone by late September. Peak: on about 16% of Maryland checklists.

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

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

0%5%10%15%20%Jan 1-7: 0% of 28716 checklistsJan 8-14: 0.1% of 21449 checklistsJan 15-21: 0% of 21267 checklistsJan 22-31: 0% of 29144 checklistsFeb 1-7: 0% of 21347 checklistsFeb 8-14: 0% of 22166 checklistsFeb 15-21: 0% of 29986 checklistsFeb 22-28: 0% of 22427 checklistsMar 1-7: 0% of 21389 checklistsMar 8-14: 0% of 22192 checklistsMar 15-21: 0.1% of 22823 checklistsMar 22-31: 0.1% of 33720 checklistsApr 1-7: 0.4% of 25513 checklistsApr 8-14: 2.4% of 27718 checklistsApr 15-21: 5.6% of 29328 checklistsApr 22-30: 8.0% of 42595 checklistsMay 1-7: 8.7% of 38532 checklistsMay 8-14: 8.4% of 42722 checklistsMay 15-21: 9.1% of 31936 checklistsMay 22-31: 8.8% of 36903 checklistsJun 1-7: 8.6% of 23191 checklistsJun 8-14: 8.5% of 21853 checklistsJun 15-21: 8.8% of 21000 checklistsJun 22-30: 9.9% of 25133 checklistsJul 1-7: 11% of 18715 checklistsJul 8-14: 12% of 16376 checklistsJul 15-21: 14% of 15793 checklistsJul 22-31: 15% of 21969 checklistsAug 1-7: 16% of 16013 checklistsAug 8-14: 15% of 15249 checklistsAug 15-21: 15% of 15674 checklistsAug 22-31: 14% of 24925 checklistsSep 1-7: 12% of 19808 checklistsSep 8-14: 9.6% of 18513 checklistsSep 15-21: 7.4% of 21901 checklistsSep 22-30: 4.7% of 22901 checklistsOct 1-7: 2.5% of 19111 checklistsOct 8-14: 1.0% of 18482 checklistsOct 15-21: 0.5% of 17380 checklistsOct 22-31: 0.2% of 23992 checklistsNov 1-7: 0.1% of 17915 checklistsNov 8-14: 0.1% of 18905 checklistsNov 15-21: 0.1% of 16259 checklistsNov 22-30: 0.1% of 22852 checklistsDec 1-7: 0.1% of 16108 checklistsDec 8-14: 0.1% of 16512 checklistsDec 15-21: 0.1% of 18952 checklistsDec 22-31: 0.1% of 29728 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 Maryland 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 Maryland

Best counties

Share of checklists at the peak
  1. Queen Anne's CountyBest early August · 590 checklists that week, 26,875 in all34%
  2. Somerset CountyBest late July · 196 checklists that week, 9,451 in all27%
  3. Talbot CountyBest late July · 630 checklists that week, 31,140 in all22%
  4. Worcester CountyBest the second week of August · 619 checklists that week, 44,596 in all21%
  5. Howard CountyBest early August · 1570 checklists that week, 118,290 in all21%
  6. Montgomery CountyBest the second week of August · 3003 checklists that week, 219,548 in all19%

Best spots

Share of checklists at the peak
  1. ParksideMontgomery County, best late July · 24 checklists that week, 862 in all93%
  2. Mckee Beshers WmaMontgomery County, best mid June · 130 checklists that week, 9,478 in all88%
  3. ShipleyAnne Arundel County, best early July · 21 checklists that week, 148 in all83%
  4. Patuxent River ParkAnne Arundel County, best late July · 22 checklists that week, 1,189 in all78%

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

Best time of day

In Maryland, the Green Heron is most often listed on checklists started between 6 and 8 am (8.4% of those checklists).

0%5%10%15%12 am: too few checklists (486) to judge1 am: too few checklists (451) to judge2 am: too few checklists (447) to judge3 am: too few checklists (766) to judge4 am: too few checklists (2076) to judge5 am: too few checklists (11098) to judge6 am: 11% of 56604 checklists7 am: 7.2% of 139255 checklists8 am: 5.6% of 148626 checklists9 am: 4.4% of 126820 checklists10 am: 3.7% of 106973 checklists11 am: 3.3% of 87483 checklists12 pm: 3.0% of 74808 checklists1 pm: 2.9% of 69428 checklists2 pm: 2.8% of 67800 checklists3 pm: 2.8% of 67688 checklists4 pm: 3.6% of 60927 checklists5 pm: 4.9% of 43876 checklists6 pm: 6.5% of 32930 checklists7 pm: too few checklists (19051) to judge8 pm: too few checklists (5708) to judge9 pm: too few checklists (1977) to judge10 pm: too few checklists (1170) to judge11 pm: too few checklists (635) 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%0.1%0%0%
February0%0%0%0%
March0%0%0.1%0.1%
April0.4%2.4%5.6%8.0%
May8.7%8.4%9.1%8.8%
June8.6%8.5%8.8%9.9%
July11%12%14%15%
August16%15%15%14%
September12%9.6%7.4%4.7%
October2.5%1.0%0.5%0.2%
November0.1%0.1%0.1%0.1%
December0.1%0.1%0.1%0.1%

Neighboring states

  • District of Columbia: arrives early April, 1 week earlier than Maryland
  • Delaware: arrives the second week of April, in the same week than Maryland
  • Virginia: arrives early April, 1 week earlier than Maryland
  • Pennsylvania: arrives the second week of April, in the same week than Maryland

Common questions

When do Green Herons arrive in Maryland?
Green Herons reach Maryland in the second week of April, are common by mid April, peak in early August (16% of checklists), and most are gone by late September.
When do Green Herons leave Maryland?
Most Green Herons have left Maryland by late September, 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 Maryland?
The Green Heron is reported most often in early August, on about 16% of Maryland checklists.
Where in Maryland are Green Herons seen most often?
By county, Queen Anne's County, Somerset County, and Talbot County have the highest peak reporting rates for the Green Heron (counties with at least 200 checklists).