WhenToBird

Geothlypis philadelphia · Parulidae

When Do Mourning Warblers Arrive in Massachusetts?

Adult Mourning Warbler
Photo: John Rosford, CC BY 4.0 via iNaturalist

Mourning Warblers mostly pass through Massachusetts: they arrive in mid May, peak in late May (1.0% of checklists), and most are gone by early June.

When to look

First arrivalsMay 15-21mid May
Common byMay 15-21mid May
PeakMay 22-31late May
Most gone byJun 1-7early June

Best: late May. First arrivals mid May; most are gone by early June. Peak: on about 1.0% of Massachusetts checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprnot usually seen
  5. Maypeak season
  6. Junpeak season
  7. Julrare
  8. Augrare
  9. Sepuncommon
  10. Octrare
  11. Novnot usually seen
  12. Decnot usually seen

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

0%0.5%1%1.5%Jan 1-7: 0% of 43252 checklistsJan 8-14: 0% of 30096 checklistsJan 15-21: 0% 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% of 49126 checklistsApr 1-7: 0% of 36456 checklistsApr 8-14: 0% of 40908 checklistsApr 15-21: 0% of 42078 checklistsApr 22-30: 0% of 56465 checklistsMay 1-7: 0% of 56994 checklistsMay 8-14: 0.1% of 64079 checklistsMay 15-21: 0.8% of 52020 checklistsMay 22-31: 1.3% of 55402 checklistsJun 1-7: 0.9% of 30682 checklistsJun 8-14: 0.2% of 27557 checklistsJun 15-21: 0.1% of 26163 checklistsJun 22-30: 0.1% of 29576 checklistsJul 1-7: 0.1% of 23931 checklistsJul 8-14: 0.1% of 22389 checklistsJul 15-21: 0.1% of 22365 checklistsJul 22-31: 0.1% of 32631 checklistsAug 1-7: 0.1% of 25133 checklistsAug 8-14: 0.1% of 24610 checklistsAug 15-21: 0.1% of 25350 checklistsAug 22-31: 0.1% of 37198 checklistsSep 1-7: 0.1% of 27402 checklistsSep 8-14: 0.2% of 27700 checklistsSep 15-21: 0.2% of 28398 checklistsSep 22-30: 0.1% of 34646 checklistsOct 1-7: 0.1% of 28620 checklistsOct 8-14: 0.1% of 30144 checklistsOct 15-21: 0.1% of 28893 checklistsOct 22-31: 0% of 38869 checklistsNov 1-7: 0% of 29782 checklistsNov 8-14: 0% of 27582 checklistsNov 15-21: 0% of 26642 checklistsNov 22-30: 0% of 34390 checklistsDec 1-7: 0% of 25164 checklistsDec 8-14: 0% of 24892 checklistsDec 15-21: 0% of 29022 checklistsDec 22-31: 0% 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 early June · 3662 checklists that week, 213,973 in all2.4%
  2. Hampshire CountyBest late May · 5510 checklists that week, 162,423 in all1.9%
  3. Suffolk CountyBest late May · 3650 checklists that week, 112,443 in all1.3%
  4. Berkshire CountyBest early June · 1650 checklists that week, 92,890 in all1.3%
  5. Middlesex CountyBest late May · 10402 checklists that week, 307,511 in all1.2%
  6. Plymouth CountyBest early June · 1638 checklists that week, 89,282 in all0.9%

Best spots

Share of checklists at the peak
  1. Connecticut River Greenway State ParkHampshire County, best early June · 40 checklists that week, 1,783 in all38%
  2. Leverett PondSuffolk County, best the second week of June · 32 checklists that week, 2,911 in all20%
  3. Nahant Thicket Wildlife SanctuaryEssex County, best the second week of June · 21 checklists that week, 1,248 in all19%
  4. Marblehead Neck Wildlife SanctuaryEssex County, best early June · 191 checklists that week, 4,966 in all18%
  5. October Mountain State Forest (east)Berkshire County, best early June · 22 checklists that week, 312 in all13%
  6. Quabbin Reservoir WatershedHampshire County, best early June · 75 checklists that week, 1,878 in all13%

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

Best time of day

In Massachusetts, the Mourning Warbler is most often listed on checklists started between 6 and 8 am (0.3% of those checklists).

0%0.5%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: 0.4% of 108601 checklists7 am: 0.2% of 186104 checklists8 am: 0.1% of 185905 checklists9 am: 0.1% of 166049 checklists10 am: 0.1% of 150508 checklists11 am: 0.1% of 131024 checklists12 pm: 0.1% of 116804 checklists1 pm: 0.1% of 112055 checklists2 pm: 0.1% of 110246 checklists3 pm: 0.1% of 104376 checklists4 pm: 0.1% of 83736 checklists5 pm: 0.1% of 63723 checklists6 pm: 0.1% 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%0%0%0%
February0%0%0%0%
March0%0%0%0%
April0%0%0%0%
May0%0.1%0.8%1.3%
June0.9%0.2%0.1%0.1%
July0.1%0.1%0.1%0.1%
August0.1%0.1%0.1%0.1%
September0.1%0.2%0.2%0.1%
October0.1%0.1%0.1%0%
November0%0%0%0%
December0%0%0%0%

Neighboring states

  • New Hampshire: arrives mid May, in the same week than Massachusetts
  • Vermont: arrives mid May, in the same week than Massachusetts
  • New York: arrives the second week of May, 1 week earlier than Massachusetts
  • District of Columbia: arrives the second week of September, 15 weeks later than Massachusetts

Common questions

When do Mourning Warblers arrive in Massachusetts?
Mourning Warblers mostly pass through Massachusetts: they arrive in mid May, peak in late May (1.0% of checklists), and most are gone by early June.
When do Mourning Warblers leave Massachusetts?
Most Mourning Warblers have left Massachusetts by early June, when reports fall below half their usual rate.
When is the best time to see a Mourning Warbler in Massachusetts?
The Mourning Warbler is reported most often in late May, on about 1.0% of Massachusetts checklists.
Where in Massachusetts are Mourning Warblers seen most often?
By county, Essex County, Hampshire County, and Suffolk County have the highest peak reporting rates for the Mourning Warbler (counties with at least 200 checklists).