WhenToBird

Larus marinus · Laridae

When Do Great Black-backed Gulls Arrive in Maryland?

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

Great Black-backed Gulls are winter birds in Maryland: the first arrive in late May, they are common by mid July, peak in mid November (8.1% of checklists), and most are gone by late March.

When to look

First arrivalsMay 22-31late May
Common byJul 15-21mid July
PeakNov 15-21mid November
Most gone byMar 22-31late March

Best: mid November. First arrivals late May; most are gone by late March. Peak: on about 8.1% of Maryland checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marcommon
  4. Apruncommon
  5. Mayuncommon
  6. Jununcommon
  7. Julcommon
  8. Augcommon
  9. Sepcommon
  10. Octcommon
  11. Novpeak season
  12. Decpeak season

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

0%5%10%Jan 1-7: 6.4% of 28716 checklistsJan 8-14: 6.3% of 21449 checklistsJan 15-21: 6.8% of 21267 checklistsJan 22-31: 6.5% of 29144 checklistsFeb 1-7: 7.1% of 21347 checklistsFeb 8-14: 5.4% of 22166 checklistsFeb 15-21: 5.3% of 29986 checklistsFeb 22-28: 5.4% of 22427 checklistsMar 1-7: 4.1% of 21389 checklistsMar 8-14: 4.2% of 22192 checklistsMar 15-21: 4.3% of 22823 checklistsMar 22-31: 3.4% of 33720 checklistsApr 1-7: 3.0% of 25513 checklistsApr 8-14: 2.0% of 27718 checklistsApr 15-21: 1.9% of 29328 checklistsApr 22-30: 1.5% of 42595 checklistsMay 1-7: 1.2% of 38532 checklistsMay 8-14: 1.1% of 42722 checklistsMay 15-21: 1.6% of 31936 checklistsMay 22-31: 1.9% of 36903 checklistsJun 1-7: 1.7% of 23191 checklistsJun 8-14: 1.6% of 21853 checklistsJun 15-21: 2.0% of 21000 checklistsJun 22-30: 1.9% of 25133 checklistsJul 1-7: 2.1% of 18715 checklistsJul 8-14: 2.9% of 16376 checklistsJul 15-21: 3.4% of 15793 checklistsJul 22-31: 3.6% of 21969 checklistsAug 1-7: 4.7% of 16013 checklistsAug 8-14: 4.3% of 15249 checklistsAug 15-21: 4.7% of 15674 checklistsAug 22-31: 3.9% of 24925 checklistsSep 1-7: 3.4% of 19808 checklistsSep 8-14: 3.0% of 18513 checklistsSep 15-21: 3.4% of 21901 checklistsSep 22-30: 3.8% of 22901 checklistsOct 1-7: 4.1% of 19111 checklistsOct 8-14: 4.4% of 18482 checklistsOct 15-21: 5.0% of 17380 checklistsOct 22-31: 5.3% of 23992 checklistsNov 1-7: 5.9% of 17915 checklistsNov 8-14: 9.2% of 18905 checklistsNov 15-21: 7.5% of 16259 checklistsNov 22-30: 7.6% of 22852 checklistsDec 1-7: 6.4% of 16108 checklistsDec 8-14: 5.4% of 16512 checklistsDec 15-21: 5.0% of 18952 checklistsDec 22-31: 7.3% of 29728 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 Maryland 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 Maryland

Best counties

Share of checklists at the peak
  1. Worcester CountyBest late November · 1108 checklists that week, 44,596 in all42%
  2. Cecil CountyBest late January · 386 checklists that week, 18,620 in all22%
  3. Queen Anne's CountyBest late November · 573 checklists that week, 26,875 in all22%
  4. Calvert CountyBest late November · 880 checklists that week, 43,807 in all17%
  5. St. Mary's CountyBest early November · 257 checklists that week, 20,572 in all17%
  6. Wicomico CountyBest late January · 272 checklists that week, 12,356 in all16%

Best spots

Share of checklists at the peak
  1. Sinepuxent Bay WmaWorcester County, best the second week of May · 26 checklists that week, 995 in all98%
  2. Fort Armistead ParkBaltimore County, best late December · 22 checklists that week, 587 in all91%
  3. Ocean City InletWorcester County, best early November · 110 checklists that week, 5,187 in all91%
  4. Chesapeake Beach Veterand Memorial ParkCalvert County, best early January · 21 checklists that week, 432 in all89%
  5. Congress Street ParkHarford County, best early January · 20 checklists that week, 300 in all88%

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

Best time of day

In Maryland, the Great Black-backed Gull is most often listed on checklists started between 12 and 2 pm (4.7% of those checklists).

0%2%4%6%12 am: too few checklists (486) to judge1 am: too few checklists (451) to judge2 am: too few checklists (447) to judge3 am: too few checklists (766) to judge4 am: too few checklists (2076) to judge5 am: too few checklists (11098) to judge6 am: 4.4% of 56604 checklists7 am: 3.9% of 139255 checklists8 am: 3.7% of 148626 checklists9 am: 4.3% of 126820 checklists10 am: 4.3% of 106973 checklists11 am: 4.6% of 87483 checklists12 pm: 4.7% of 74808 checklists1 pm: 4.6% of 69428 checklists2 pm: 4.4% of 67800 checklists3 pm: 4.5% of 67688 checklists4 pm: 3.5% of 60927 checklists5 pm: 2.5% of 43876 checklists6 pm: 2.1% of 32930 checklists7 pm: too few checklists (19051) to judge8 pm: too few checklists (5708) to judge9 pm: too few checklists (1977) to judge10 pm: too few checklists (1170) to judge11 pm: too few checklists (635) 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
January6.4%6.3%6.8%6.5%
February7.1%5.4%5.3%5.4%
March4.1%4.2%4.3%3.4%
April3.0%2.0%1.9%1.5%
May1.2%1.1%1.6%1.9%
June1.7%1.6%2.0%1.9%
July2.1%2.9%3.4%3.6%
August4.7%4.3%4.7%3.9%
September3.4%3.0%3.4%3.8%
October4.1%4.4%5.0%5.3%
November5.9%9.2%7.5%7.6%
December6.4%5.4%5.0%7.3%

Neighboring states

  • District of Columbia: arrives late October, 20 weeks later than Maryland
  • Delaware: arrives early November, 21 weeks later than Maryland
  • Virginia: arrives mid May, 1 week earlier than Maryland
  • Pennsylvania: arrives early October, 17 weeks later than Maryland

Common questions

When do Great Black-backed Gulls arrive in Maryland?
Great Black-backed Gulls are winter birds in Maryland: the first arrive in late May, they are common by mid July, peak in mid November (8.1% of checklists), and most are gone by late March.
When do Great Black-backed Gulls leave Maryland?
Most Great Black-backed Gulls have left Maryland by late March, when reports fall below half their usual rate. Stragglers are still reported until mid April.
When is the best time to see a Great Black-backed Gull in Maryland?
The Great Black-backed Gull is reported most often in mid November, on about 8.1% of Maryland checklists.
Where in Maryland are Great Black-backed Gulls seen most often?
By county, Worcester County, Cecil County, and Queen Anne's County have the highest peak reporting rates for the Great Black-backed Gull (counties with at least 200 checklists).