WhenToBird

Nycticorax nycticorax · Ardeidae

When Do Black-crowned Night Herons Arrive in Maryland?

Adult Black-crowned Night-Heron
Photo: jubileej, CC0 1.0 via iNaturalist

Black-crowned Night Herons arrive in Maryland in late March, peak in late May (1.9% of checklists), and most are gone by late September.

When to look

First arrivalsMar 22-31late March
Common byMar 22-31late March
PeakMay 22-31late May
Most gone bySep 22-30late September

Best: late May. First arrivals late March; most are gone by late September. Peak: on about 1.9% of Maryland checklists.

  1. Janrare
  2. Febrare
  3. Maruncommon
  4. Aprcommon
  5. Maypeak season
  6. Junpeak season
  7. Julpeak season
  8. Augpeak season
  9. Sepcommon
  10. Octuncommon
  11. Novuncommon
  12. Decrare

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

0%0.5%1%1.5%2%Jan 1-7: 0.2% of 28716 checklistsJan 8-14: 0.2% of 21449 checklistsJan 15-21: 0.1% of 21267 checklistsJan 22-31: 0.2% of 29144 checklistsFeb 1-7: 0.2% of 21347 checklistsFeb 8-14: 0.1% of 22166 checklistsFeb 15-21: 0.1% of 29986 checklistsFeb 22-28: 0.2% of 22427 checklistsMar 1-7: 0.1% of 21389 checklistsMar 8-14: 0.2% of 22192 checklistsMar 15-21: 0.5% of 22823 checklistsMar 22-31: 0.8% of 33720 checklistsApr 1-7: 0.9% of 25513 checklistsApr 8-14: 0.9% of 27718 checklistsApr 15-21: 1.0% of 29328 checklistsApr 22-30: 1.5% of 42595 checklistsMay 1-7: 1.4% of 38532 checklistsMay 8-14: 1.5% of 42722 checklistsMay 15-21: 1.9% of 31936 checklistsMay 22-31: 1.9% of 36903 checklistsJun 1-7: 1.9% of 23191 checklistsJun 8-14: 1.6% of 21853 checklistsJun 15-21: 1.6% of 21000 checklistsJun 22-30: 1.5% of 25133 checklistsJul 1-7: 1.5% of 18715 checklistsJul 8-14: 1.8% of 16376 checklistsJul 15-21: 1.8% of 15793 checklistsJul 22-31: 1.8% of 21969 checklistsAug 1-7: 1.6% of 16013 checklistsAug 8-14: 1.5% of 15249 checklistsAug 15-21: 1.4% of 15674 checklistsAug 22-31: 1.2% of 24925 checklistsSep 1-7: 0.9% of 19808 checklistsSep 8-14: 0.8% of 18513 checklistsSep 15-21: 0.8% of 21901 checklistsSep 22-30: 0.8% of 22901 checklistsOct 1-7: 0.6% of 19111 checklistsOct 8-14: 0.5% of 18482 checklistsOct 15-21: 0.5% of 17380 checklistsOct 22-31: 0.5% of 23992 checklistsNov 1-7: 0.4% of 17915 checklistsNov 8-14: 0.5% of 18905 checklistsNov 15-21: 0.2% of 16259 checklistsNov 22-30: 0.2% of 22852 checklistsDec 1-7: 0.2% of 16108 checklistsDec 8-14: 0.1% of 16512 checklistsDec 15-21: 0.1% of 18952 checklistsDec 22-31: 0.3% 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. Worcester CountyBest early July · 709 checklists that week, 44,596 in all5.6%
  2. Frederick CountyBest the second week of June · 1181 checklists that week, 57,576 in all5.1%
  3. Baltimore CountyBest mid May · 4103 checklists that week, 136,139 in all5.0%
  4. Somerset CountyBest late December · 465 checklists that week, 9,451 in all3.9%
  5. Montgomery CountyBest the second week of June · 3709 checklists that week, 219,548 in all3.7%
  6. Anne Arundel CountyBest early August · 1335 checklists that week, 93,516 in all2.4%

Best spots

Share of checklists at the peak
  1. Lake Whetstone ParkMontgomery County, best mid April · 28 checklists that week, 772 in all98%
  2. Baker Park (City of Frederick)Frederick County, best the second week of June · 47 checklists that week, 2,954 in all70%
  3. Sinepuxent Bay WmaWorcester County, best the second week of May · 26 checklists that week, 995 in all66%
  4. Forest Estates ParkMontgomery County, best early June · 54 checklists that week, 3,230 in all65%
  5. Patterson ParkBaltimore County, best late June · 38 checklists that week, 5,451 in all54%
  6. ParksideMontgomery County, best late June · 22 checklists that week, 862 in all50%

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

Best time of day

In Maryland, the Black-crowned Night Heron is most often listed on checklists started between 6 and 8 am (1.3% of those checklists).

0%0.5%1%1.5%2%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: 1.7% of 56604 checklists7 am: 1.2% of 139255 checklists8 am: 1.0% of 148626 checklists9 am: 0.8% of 126820 checklists10 am: 0.6% of 106973 checklists11 am: 0.6% of 87483 checklists12 pm: 0.5% of 74808 checklists1 pm: 0.5% of 69428 checklists2 pm: 0.5% of 67800 checklists3 pm: 0.5% of 67688 checklists4 pm: 0.7% of 60927 checklists5 pm: 1.1% of 43876 checklists6 pm: 1.4% 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
January0.2%0.2%0.1%0.2%
February0.2%0.1%0.1%0.2%
March0.1%0.2%0.5%0.8%
April0.9%0.9%1.0%1.5%
May1.4%1.5%1.9%1.9%
June1.9%1.6%1.6%1.5%
July1.5%1.8%1.8%1.8%
August1.6%1.5%1.4%1.2%
September0.9%0.8%0.8%0.8%
October0.6%0.5%0.5%0.5%
November0.4%0.5%0.2%0.2%
December0.2%0.1%0.1%0.3%

Neighboring states

  • District of Columbia: arrives mid November, 17 weeks earlier than Maryland
  • Delaware: arrives late March, in the same week than Maryland
  • New Jersey: arrives early April, 1 week later than Maryland
  • New York: arrives the second week of April, 2 weeks later than Maryland

Common questions

When do Black-crowned Night Herons arrive in Maryland?
Black-crowned Night Herons arrive in Maryland in late March, peak in late May (1.9% of checklists), and most are gone by late September.
When do Black-crowned Night Herons leave Maryland?
Most Black-crowned Night Herons have left Maryland by late September, when reports fall below half their usual rate.
When is the best time to see a Black-crowned Night Heron in Maryland?
The Black-crowned Night Heron is reported most often in late May, on about 1.9% of Maryland checklists.
Where in Maryland are Black-crowned Night Herons seen most often?
By county, Worcester County, Frederick County, and Baltimore County have the highest peak reporting rates for the Black-crowned Night Heron (counties with at least 200 checklists).