WhenToBird

Larus marinus · Laridae

When Do Great Black-backed Gulls Arrive in Massachusetts?

Adult Great Black-backed Gull
Photo: Rob Wadsworth, CC0 1.0 via iNaturalist

The Great Black-backed Gull is in Massachusetts all year. It turns up on about 17% of checklists at its peak (the second week of August) and on 7.1% in its quietest week (the second week of May).

When to look

PresentAll year
Peak weekAug 8-14the second week of August
Quietest weekMay 8-14the second week of May

Best: the second week of August. Here all year. Peak: on about 17% of Massachusetts checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marcommon
  4. Aprcommon
  5. Maycommon
  6. Juncommon
  7. Julpeak season
  8. Augpeak season
  9. Seppeak season
  10. Octcommon
  11. Novpeak season
  12. Decpeak season

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

0%5%10%15%20%Jan 1-7: 15% of 43252 checklistsJan 8-14: 17% of 30096 checklistsJan 15-21: 16% of 28760 checklistsJan 22-31: 17% of 38135 checklistsFeb 1-7: 16% of 26442 checklistsFeb 8-14: 13% of 29034 checklistsFeb 15-21: 13% of 37383 checklistsFeb 22-28: 13% of 29977 checklistsMar 1-7: 11% of 29175 checklistsMar 8-14: 9.6% of 32399 checklistsMar 15-21: 10% of 34444 checklistsMar 22-31: 9.8% of 49126 checklistsApr 1-7: 9.8% of 36456 checklistsApr 8-14: 9.3% of 40908 checklistsApr 15-21: 8.8% of 42078 checklistsApr 22-30: 7.7% of 56465 checklistsMay 1-7: 7.1% of 56994 checklistsMay 8-14: 6.9% of 64079 checklistsMay 15-21: 7.4% of 52020 checklistsMay 22-31: 8.7% of 55402 checklistsJun 1-7: 8.8% of 30682 checklistsJun 8-14: 9.5% of 27557 checklistsJun 15-21: 11% of 26163 checklistsJun 22-30: 12% of 29576 checklistsJul 1-7: 12% of 23931 checklistsJul 8-14: 14% of 22389 checklistsJul 15-21: 14% of 22365 checklistsJul 22-31: 16% of 32631 checklistsAug 1-7: 16% of 25133 checklistsAug 8-14: 17% of 24610 checklistsAug 15-21: 17% of 25350 checklistsAug 22-31: 15% of 37198 checklistsSep 1-7: 15% of 27402 checklistsSep 8-14: 14% of 27700 checklistsSep 15-21: 13% of 28398 checklistsSep 22-30: 13% of 34646 checklistsOct 1-7: 12% of 28620 checklistsOct 8-14: 12% of 30144 checklistsOct 15-21: 11% of 28893 checklistsOct 22-31: 12% of 38869 checklistsNov 1-7: 12% of 29782 checklistsNov 8-14: 14% of 27582 checklistsNov 15-21: 13% of 26642 checklistsNov 22-30: 15% of 34390 checklistsDec 1-7: 14% of 25164 checklistsDec 8-14: 13% of 24892 checklistsDec 15-21: 13% of 29022 checklistsDec 22-31: 16% 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.

Embed this map on your site

Where in Massachusetts

Best counties

Share of checklists at the peak
  1. Nantucket CountyBest early July · 419 checklists that week, 23,895 in all51%
  2. Dukes CountyBest the second week of August · 517 checklists that week, 23,670 in all47%
  3. Barnstable CountyBest mid August · 4538 checklists that week, 215,188 in all39%
  4. Essex CountyBest mid January · 4996 checklists that week, 213,973 in all32%
  5. Suffolk CountyBest late January · 2860 checklists that week, 112,443 in all24%
  6. Plymouth CountyBest the second week of August · 1294 checklists that week, 89,282 in all23%

Best spots

Share of checklists at the peak
  1. Andrews PointEssex County, best the second week of July · 40 checklists that week, 3,044 in all100%
  2. Gully Point CoveEssex County, best early September · 23 checklists that week, 810 in all100%
  3. Race RunBarnstable County, best the second week of January · 42 checklists that week, 2,504 in all100%
  4. Beach PointPlymouth County, best the second week of August · 29 checklists that week, 1,022 in all99%
  5. Cape Cod National SeashoreBarnstable County, best the second week of August · 88 checklists that week, 3,402 in all98%
  6. Gloucester HarborEssex County, best mid July · 22 checklists that week, 300 in all97%

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

Best time of day

In Massachusetts, the Great Black-backed Gull is most often listed on checklists started between 11 am and 1 pm (14% of those checklists).

0%5%10%15%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: 11% of 108601 checklists7 am: 11% of 186104 checklists8 am: 12% of 185905 checklists9 am: 12% of 166049 checklists10 am: 13% of 150508 checklists11 am: 14% of 131024 checklists12 pm: 14% of 116804 checklists1 pm: 14% of 112055 checklists2 pm: 13% of 110246 checklists3 pm: 12% of 104376 checklists4 pm: 11% of 83736 checklists5 pm: 9.7% of 63723 checklists6 pm: 8.7% 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
January15%17%16%17%
February16%13%13%13%
March11%9.6%10%9.8%
April9.8%9.3%8.8%7.7%
May7.1%6.9%7.4%8.7%
June8.8%9.5%11%12%
July12%14%14%16%
August16%17%17%15%
September15%14%13%13%
October12%12%11%12%
November12%14%13%15%
December14%13%13%16%

Neighboring states

  • Rhode Island: all year, most in summer, peaks early August
  • New Hampshire: all year, most in fall, peaks early December
  • Connecticut: all year, most in summer, peaks the second week of August
  • Vermont: winter visitor, peaks the second week of January

Common questions

When do Great Black-backed Gulls arrive in Massachusetts?
The Great Black-backed Gull is in Massachusetts all year. It turns up on about 17% of checklists at its peak (the second week of August) and on 7.1% in its quietest week (the second week of May).
When do Great Black-backed Gulls leave Massachusetts?
The Great Black-backed Gull does not leave Massachusetts: it is reported all year, from 7.1% of checklists in the second week of May to 17% in the second week of August.
When is the best time to see a Great Black-backed Gull in Massachusetts?
The Great Black-backed Gull is reported most often in the second week of August, on about 17% of Massachusetts checklists.
Where in Massachusetts are Great Black-backed Gulls seen most often?
By county, Nantucket County, Dukes County, and Barnstable County have the highest peak reporting rates for the Great Black-backed Gull (counties with at least 200 checklists).