WhenToBird

Setophaga caerulescens · Parulidae

When Do Black-throated Blue Warblers Arrive in Maine?

Adult male Black-throated Blue Warbler
Photo: Dan Vickers, CC BY 4.0 via iNaturalist

Black-throated Blue Warblers reach Maine in late April, are common by early May, peak in mid May (11% of checklists), and most are gone by mid July.

When to look

First arrivalsApr 22-30late April
Common byMay 1-7early May
PeakMay 15-21mid May
Most gone byJul 15-21mid July

Best: mid May. First arrivals late April; most are gone by mid July. Peak: on about 11% of Maine checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Apruncommon
  5. Maypeak season
  6. Juncommon
  7. Julcommon
  8. Auguncommon
  9. Sepuncommon
  10. Octuncommon
  11. Novnot usually seen
  12. Decnot usually seen

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

0%5%10%15%Jan 1-7: 0.1% of 15499 checklistsJan 8-14: 0.1% of 11141 checklistsJan 15-21: 0.1% of 10729 checklistsJan 22-31: 0% of 15084 checklistsFeb 1-7: 0% of 9403 checklistsFeb 8-14: 0% 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% of 17798 checklistsApr 1-7: 0% of 14638 checklistsApr 8-14: 0% of 16511 checklistsApr 15-21: 0% of 17164 checklistsApr 22-30: 0.2% of 22602 checklistsMay 1-7: 4.3% of 22556 checklistsMay 8-14: 11% of 27842 checklistsMay 15-21: 13% of 27748 checklistsMay 22-31: 8.1% of 38715 checklistsJun 1-7: 7.4% of 26916 checklistsJun 8-14: 7.4% of 23737 checklistsJun 15-21: 7.1% of 22733 checklistsJun 22-30: 7.9% of 28248 checklistsJul 1-7: 6.9% of 20290 checklistsJul 8-14: 5.8% of 18534 checklistsJul 15-21: 4.9% of 17319 checklistsJul 22-31: 3.3% of 22815 checklistsAug 1-7: 1.7% of 15004 checklistsAug 8-14: 1.2% of 14603 checklistsAug 15-21: 1.5% of 14972 checklistsAug 22-31: 1.5% of 19813 checklistsSep 1-7: 1.7% of 14567 checklistsSep 8-14: 2.2% of 14520 checklistsSep 15-21: 2.2% of 14339 checklistsSep 22-30: 1.8% of 16879 checklistsOct 1-7: 2.1% of 12959 checklistsOct 8-14: 1.0% of 13168 checklistsOct 15-21: 0.5% of 11184 checklistsOct 22-31: 0.2% of 13717 checklistsNov 1-7: 0.1% of 9823 checklistsNov 8-14: 0.1% of 9007 checklistsNov 15-21: 0% of 8528 checklistsNov 22-30: 0.1% of 10228 checklistsDec 1-7: 0.1% of 7505 checklistsDec 8-14: 0.1% of 7982 checklistsDec 15-21: 0.1% 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. Piscataquis CountyBest late May · 862 checklists that week, 14,837 in all27%
  2. Waldo CountyBest mid May · 1075 checklists that week, 33,433 in all20%
  3. Franklin CountyBest early July · 571 checklists that week, 14,182 in all20%
  4. Oxford CountyBest late May · 838 checklists that week, 15,115 in all19%
  5. Somerset CountyBest late June · 1036 checklists that week, 12,202 in all18%
  6. Aroostook CountyBest mid June · 949 checklists that week, 16,817 in all16%

Best spots

Share of checklists at the peak
  1. Three BrooksLincoln County, best late May · 26 checklists that week, 161 in all78%
  2. Erickson FieldsKnox County, best late May · 32 checklists that week, 229 in all68%
  3. Long CoveWaldo County, best mid May · 167 checklists that week, 2,744 in all59%
  4. Sandy Stream PondPiscataquis County, best the second week of June · 21 checklists that week, 116 in all55%
  5. Pettingill Farm MuseumCumberland County, best late May · 31 checklists that week, 102 in all54%

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

Best time of day

In Maine, the Black-throated Blue Warbler is most often listed on checklists started between 5 and 7 am (8.2% of those checklists).

0%5%10%15%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: 10% of 19895 checklists6 am: 7.4% of 54578 checklists7 am: 4.8% of 92775 checklists8 am: 3.9% of 86962 checklists9 am: 3.4% of 78989 checklists10 am: 2.7% of 70954 checklists11 am: 2.2% of 59331 checklists12 pm: 2.0% of 50943 checklists1 pm: 1.8% of 49775 checklists2 pm: 1.6% of 49001 checklists3 pm: 1.6% of 43252 checklists4 pm: 1.8% of 33413 checklists5 pm: 1.8% of 25547 checklists6 pm: 1.6% 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
January0.1%0.1%0.1%0%
February0%0%0%0%
March0%0%0%0%
April0%0%0%0.2%
May4.3%11%13%8.1%
June7.4%7.4%7.1%7.9%
July6.9%5.8%4.9%3.3%
August1.7%1.2%1.5%1.5%
September1.7%2.2%2.2%1.8%
October2.1%1.0%0.5%0.2%
November0.1%0.1%0%0.1%
December0.1%0.1%0.1%0%

Neighboring states

  • New Hampshire: arrives late April, in the same week than Maine
  • Massachusetts: arrives late April, in the same week than Maine
  • Vermont: arrives late April, in the same week than Maine
  • Rhode Island: arrives late April, in the same week than Maine

Common questions

When do Black-throated Blue Warblers arrive in Maine?
Black-throated Blue Warblers reach Maine in late April, are common by early May, peak in mid May (11% of checklists), and most are gone by mid July.
When do Black-throated Blue Warblers leave Maine?
Most Black-throated Blue Warblers have left Maine by mid July, 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 Black-throated Blue Warbler in Maine?
The Black-throated Blue Warbler is reported most often in mid May, on about 11% of Maine checklists.
Where in Maine are Black-throated Blue Warblers seen most often?
By county, Piscataquis County, Waldo County, and Franklin County have the highest peak reporting rates for the Black-throated Blue Warbler (counties with at least 200 checklists).