WhenToBird

Nycticorax nycticorax · Ardeidae

When Do Black-crowned Night Herons Arrive in Maine?

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

Black-crowned Night Herons arrive in Maine in mid April, peak in the second week of May (1.3% of checklists), and most are gone by mid September.

When to look

First arrivalsApr 15-21mid April
Common byApr 15-21mid April
PeakMay 8-14the second week of May
Most gone bySep 15-21mid September

Best: the second week of May. First arrivals mid April; most are gone by mid September. Peak: on about 1.3% of Maine checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marrare
  4. Aprcommon
  5. Maypeak season
  6. Juncommon
  7. Julpeak season
  8. Augpeak season
  9. Seppeak season
  10. Octuncommon
  11. Novrare
  12. Decrare

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

0%0.5%1%1.5%2%Jan 1-7: 0% of 15499 checklistsJan 8-14: 0% of 11141 checklistsJan 15-21: 0% of 10729 checklistsJan 22-31: 0% of 15084 checklistsFeb 1-7: 0.1% of 9403 checklistsFeb 8-14: 0.1% of 11268 checklistsFeb 15-21: 0% of 14061 checklistsFeb 22-28: 0% of 9977 checklistsMar 1-7: 0% of 9649 checklistsMar 8-14: 0% of 11781 checklistsMar 15-21: 0% of 11613 checklistsMar 22-31: 0.1% of 17798 checklistsApr 1-7: 0.3% of 14638 checklistsApr 8-14: 0.5% of 16511 checklistsApr 15-21: 0.3% of 17164 checklistsApr 22-30: 1.0% of 22602 checklistsMay 1-7: 1.1% of 22556 checklistsMay 8-14: 1.5% of 27842 checklistsMay 15-21: 1.2% of 27748 checklistsMay 22-31: 0.6% of 38715 checklistsJun 1-7: 0.4% of 26916 checklistsJun 8-14: 0.5% of 23737 checklistsJun 15-21: 0.6% of 22733 checklistsJun 22-30: 0.6% of 28248 checklistsJul 1-7: 0.7% of 20290 checklistsJul 8-14: 0.7% of 18534 checklistsJul 15-21: 0.8% of 17319 checklistsJul 22-31: 1.1% of 22815 checklistsAug 1-7: 1.4% of 15004 checklistsAug 8-14: 1.2% of 14603 checklistsAug 15-21: 1.2% of 14972 checklistsAug 22-31: 1.2% of 19813 checklistsSep 1-7: 0.9% of 14567 checklistsSep 8-14: 0.8% of 14520 checklistsSep 15-21: 0.6% of 14339 checklistsSep 22-30: 0.3% of 16879 checklistsOct 1-7: 0.2% of 12959 checklistsOct 8-14: 0.1% of 13168 checklistsOct 15-21: 0.1% of 11184 checklistsOct 22-31: 0.1% of 13717 checklistsNov 1-7: 0.1% of 9823 checklistsNov 8-14: 0.1% of 9007 checklistsNov 15-21: 0.1% of 8528 checklistsNov 22-30: 0.1% of 10228 checklistsDec 1-7: 0.1% of 7505 checklistsDec 8-14: 0% of 7982 checklistsDec 15-21: 0% of 10455 checklistsDec 22-31: 0% of 14285 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 Maine 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 Maine

Best counties

Share of checklists at the peak
  1. York CountyBest the second week of August · 1826 checklists that week, 101,844 in all5.4%
  2. Cumberland CountyBest the second week of May · 8112 checklists that week, 169,501 in all3.5%
  3. Knox CountyBest mid September · 626 checklists that week, 34,453 in all1.3%
  4. Lincoln CountyBest late June · 1892 checklists that week, 59,429 in all1.0%
  5. Penobscot CountyBest the second week of August · 826 checklists that week, 56,895 in all0.7%
  6. Aroostook CountyBest mid August · 162 checklists that week, 16,817 in all0.5%

Best spots

Share of checklists at the peak
  1. Great Pond (Biddeford Pool)York County, best mid April · 33 checklists that week, 1,098 in all72%
  2. Salt BayLincoln County, best late June · 20 checklists that week, 865 in all53%
  3. Back Cove (Fall Brook)Cumberland County, best late August · 21 checklists that week, 272 in all42%
  4. Weskeag River (South Thomaston)Knox County, best late August · 24 checklists that week, 163 in all38%
  5. Simonton CoveCumberland County, best late June · 20 checklists that week, 776 in all37%

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

Best time of day

In Maine, the Black-crowned Night Heron is most often listed on checklists started between 5 and 7 am (1.0% of those checklists).

0%0.5%1%1.5%12 am: too few checklists (510) to judge1 am: too few checklists (517) to judge2 am: too few checklists (581) to judge3 am: too few checklists (3242) to judge4 am: too few checklists (7221) to judge5 am: 0.9% of 19895 checklists6 am: 1.0% of 54578 checklists7 am: 0.6% of 92775 checklists8 am: 0.5% of 86962 checklists9 am: 0.5% of 78989 checklists10 am: 0.4% of 70954 checklists11 am: 0.3% of 59331 checklists12 pm: 0.4% of 50943 checklists1 pm: 0.4% of 49775 checklists2 pm: 0.3% of 49001 checklists3 pm: 0.4% of 43252 checklists4 pm: 0.5% of 33413 checklists5 pm: 0.7% of 25547 checklists6 pm: 1.3% of 18309 checklists7 pm: too few checklists (14287) to judge8 pm: too few checklists (5336) to judge9 pm: too few checklists (2253) to judge10 pm: too few checklists (1518) to judge11 pm: too few checklists (720) 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%
February0.1%0.1%0%0%
March0%0%0%0.1%
April0.3%0.5%0.3%1.0%
May1.1%1.5%1.2%0.6%
June0.4%0.5%0.6%0.6%
July0.7%0.7%0.8%1.1%
August1.4%1.2%1.2%1.2%
September0.9%0.8%0.6%0.3%
October0.2%0.1%0.1%0.1%
November0.1%0.1%0.1%0.1%
December0.1%0%0%0%

Neighboring states

  • Massachusetts: arrives early April, 2 weeks earlier than Maine
  • Vermont: arrives the second week of May, 3 weeks later than Maine
  • Rhode Island: arrives late March, 3 weeks earlier than Maine
  • Connecticut: arrives the second week of April, 1 week earlier than Maine

Common questions

When do Black-crowned Night Herons arrive in Maine?
Black-crowned Night Herons arrive in Maine in mid April, peak in the second week of May (1.3% of checklists), and most are gone by mid September.
When do Black-crowned Night Herons leave Maine?
Most Black-crowned Night Herons have left Maine by mid September, when reports fall below half their usual rate.
When is the best time to see a Black-crowned Night Heron in Maine?
The Black-crowned Night Heron is reported most often in the second week of May, on about 1.3% of Maine checklists.
Where in Maine are Black-crowned Night Herons seen most often?
By county, York County, Cumberland County, and Knox County have the highest peak reporting rates for the Black-crowned Night Heron (counties with at least 200 checklists).