WhenToBird

Setophaga caerulescens · Parulidae

When Do Black-throated Blue Warblers Arrive in Massachusetts?

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

Black-throated Blue Warblers mostly pass through Massachusetts: the first show up in late April, they are common by early May, peak in the second week of May (9.8% of checklists), and most are gone by late May.

When to look

First arrivalsApr 22-30late April
Common byMay 1-7early May
PeakMay 8-14the second week of May
Most gone byMay 22-31late May

Best: the second week of May. First arrivals late April; most are gone by late May. Peak: on about 9.8% of Massachusetts checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Apruncommon
  5. Maypeak season
  6. Jununcommon
  7. Julrare
  8. Augrare
  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 43252 checklistsJan 8-14: 0.1% of 30096 checklistsJan 15-21: 0.1% of 28760 checklistsJan 22-31: 0% of 38135 checklistsFeb 1-7: 0% of 26442 checklistsFeb 8-14: 0% of 29034 checklistsFeb 15-21: 0% of 37383 checklistsFeb 22-28: 0% of 29977 checklistsMar 1-7: 0% of 29175 checklistsMar 8-14: 0% of 32399 checklistsMar 15-21: 0% of 34444 checklistsMar 22-31: 0.1% of 49126 checklistsApr 1-7: 0% of 36456 checklistsApr 8-14: 0.1% of 40908 checklistsApr 15-21: 0.1% of 42078 checklistsApr 22-30: 0.6% of 56465 checklistsMay 1-7: 6.0% of 56994 checklistsMay 8-14: 11% of 64079 checklistsMay 15-21: 12% of 52020 checklistsMay 22-31: 3.6% of 55402 checklistsJun 1-7: 2.1% of 30682 checklistsJun 8-14: 2.0% of 27557 checklistsJun 15-21: 2.0% of 26163 checklistsJun 22-30: 1.5% of 29576 checklistsJul 1-7: 1.7% of 23931 checklistsJul 8-14: 1.1% of 22389 checklistsJul 15-21: 1.0% of 22365 checklistsJul 22-31: 0.6% of 32631 checklistsAug 1-7: 0.4% of 25133 checklistsAug 8-14: 0.4% of 24610 checklistsAug 15-21: 0.4% of 25350 checklistsAug 22-31: 0.6% of 37198 checklistsSep 1-7: 0.8% of 27402 checklistsSep 8-14: 1.0% of 27700 checklistsSep 15-21: 1.5% of 28398 checklistsSep 22-30: 1.7% of 34646 checklistsOct 1-7: 1.8% of 28620 checklistsOct 8-14: 1.3% of 30144 checklistsOct 15-21: 0.8% of 28893 checklistsOct 22-31: 0.3% of 38869 checklistsNov 1-7: 0.1% of 29782 checklistsNov 8-14: 0.1% of 27582 checklistsNov 15-21: 0.1% of 26642 checklistsNov 22-30: 0.1% of 34390 checklistsDec 1-7: 0% of 25164 checklistsDec 8-14: 0.1% of 24892 checklistsDec 15-21: 0.1% of 29022 checklistsDec 22-31: 0.1% 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.

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Where in Massachusetts

Best counties

Share of checklists at the peak
  1. Essex CountyBest the second week of May · 8595 checklists that week, 213,973 in all15%
  2. Berkshire CountyBest late May · 3139 checklists that week, 92,890 in all14%
  3. Hampden CountyBest the second week of May · 1320 checklists that week, 35,410 in all13%
  4. Middlesex CountyBest the second week of May · 14184 checklists that week, 307,511 in all12%
  5. Franklin CountyBest mid May · 1382 checklists that week, 41,382 in all12%
  6. Suffolk CountyBest the second week of May · 4553 checklists that week, 112,443 in all12%

Best spots

Share of checklists at the peak
  1. October Mountain State Forest (east)Berkshire County, best early June · 22 checklists that week, 312 in all65%
  2. October Mountain State ForestBerkshire County, best late May · 22 checklists that week, 473 in all64%
  3. High Ledges Wildlife SanctuaryFranklin County, best late May · 20 checklists that week, 274 in all60%
  4. Flag PondEssex County, best the second week of May · 23 checklists that week, 147 in all55%
  5. Marblehead Neck Wildlife SanctuaryEssex County, best the second week of May · 336 checklists that week, 4,966 in all54%

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

Best time of day

In Massachusetts, the Black-throated Blue Warbler is most often listed on checklists started between 6 and 8 am (3.1% of those checklists).

0%2%4%6%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: 4.1% of 108601 checklists7 am: 2.5% of 186104 checklists8 am: 1.9% of 185905 checklists9 am: 1.6% of 166049 checklists10 am: 1.3% of 150508 checklists11 am: 1.1% of 131024 checklists12 pm: 0.9% of 116804 checklists1 pm: 0.9% of 112055 checklists2 pm: 0.8% of 110246 checklists3 pm: 0.7% of 104376 checklists4 pm: 0.8% of 83736 checklists5 pm: 0.8% of 63723 checklists6 pm: 0.7% 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
January0.1%0.1%0.1%0%
February0%0%0%0%
March0%0%0%0.1%
April0%0.1%0.1%0.6%
May6.0%11%12%3.6%
June2.1%2.0%2.0%1.5%
July1.7%1.1%1.0%0.6%
August0.4%0.4%0.4%0.6%
September0.8%1.0%1.5%1.7%
October1.8%1.3%0.8%0.3%
November0.1%0.1%0.1%0.1%
December0%0.1%0.1%0.1%

Neighboring states

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

Common questions

When do Black-throated Blue Warblers arrive in Massachusetts?
Black-throated Blue Warblers mostly pass through Massachusetts: the first show up in late April, they are common by early May, peak in the second week of May (9.8% of checklists), and most are gone by late May.
When do Black-throated Blue Warblers leave Massachusetts?
Most Black-throated Blue Warblers have left Massachusetts by late May, when reports fall below half their usual rate. Stragglers are still reported until the second week of July.
When is the best time to see a Black-throated Blue Warbler in Massachusetts?
The Black-throated Blue Warbler is reported most often in the second week of May, on about 9.8% of Massachusetts checklists.
Where in Massachusetts are Black-throated Blue Warblers seen most often?
By county, Essex County, Berkshire County, and Hampden County have the highest peak reporting rates for the Black-throated Blue Warbler (counties with at least 200 checklists).