WhenToBird

Chroicocephalus philadelphia · Laridae

When Do Bonaparte's Gulls Arrive in New York?

Adult Bonaparte's Gull
Photo: Kevin Krebs, CC BY 4.0 via iNaturalist

Bonaparte's Gulls are winter birds in New York: they arrive in late July, peak in the second week of November (3.7% of checklists), and most are gone by early February.

When to look

First arrivalsJul 22-31late July
Common byJul 22-31late July
PeakNov 8-14the second week of November
Most gone byFeb 1-7early February

Best: the second week of November. First arrivals late July; most are gone by early February. Peak: on about 3.7% of New York checklists.

  1. Jancommon
  2. Febuncommon
  3. Maruncommon
  4. Aprcommon
  5. Mayuncommon
  6. Junrare
  7. Juluncommon
  8. Auguncommon
  9. Sepuncommon
  10. Octpeak season
  11. Novpeak season
  12. Deccommon

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

0%2%4%6%Jan 1-7: 1.8% of 66410 checklistsJan 8-14: 1.7% of 49310 checklistsJan 15-21: 1.4% of 49919 checklistsJan 22-31: 1.2% of 62513 checklistsFeb 1-7: 0.7% of 43526 checklistsFeb 8-14: 0.5% of 49753 checklistsFeb 15-21: 0.4% of 65147 checklistsFeb 22-28: 0.3% of 50173 checklistsMar 1-7: 0.2% of 50325 checklistsMar 8-14: 0.1% of 55371 checklistsMar 15-21: 0.4% of 56293 checklistsMar 22-31: 1.1% of 82677 checklistsApr 1-7: 2.4% of 65295 checklistsApr 8-14: 2.9% of 73080 checklistsApr 15-21: 2.6% of 73857 checklistsApr 22-30: 1.7% of 106093 checklistsMay 1-7: 1.1% of 102772 checklistsMay 8-14: 0.7% of 110051 checklistsMay 15-21: 0.6% of 94797 checklistsMay 22-31: 0.6% of 101272 checklistsJun 1-7: 0.4% of 59471 checklistsJun 8-14: 0.3% of 55497 checklistsJun 15-21: 0.1% of 51761 checklistsJun 22-30: 0.2% of 59219 checklistsJul 1-7: 0.2% of 48226 checklistsJul 8-14: 0.2% of 42315 checklistsJul 15-21: 0.4% of 40637 checklistsJul 22-31: 0.8% of 57183 checklistsAug 1-7: 1.0% of 40461 checklistsAug 8-14: 1.3% of 39880 checklistsAug 15-21: 1.3% of 41146 checklistsAug 22-31: 1.2% of 63381 checklistsSep 1-7: 1.0% of 48640 checklistsSep 8-14: 1.1% of 47882 checklistsSep 15-21: 0.8% of 49063 checklistsSep 22-30: 0.8% of 57906 checklistsOct 1-7: 0.8% of 48447 checklistsOct 8-14: 1.1% of 51901 checklistsOct 15-21: 1.9% of 46717 checklistsOct 22-31: 2.7% of 61992 checklistsNov 1-7: 4.0% of 44593 checklistsNov 8-14: 3.9% of 42566 checklistsNov 15-21: 3.2% of 39675 checklistsNov 22-30: 2.9% of 51197 checklistsDec 1-7: 2.6% of 36567 checklistsDec 8-14: 1.9% of 37254 checklistsDec 15-21: 1.8% of 43754 checklistsDec 22-31: 2.3% of 62470 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 New York 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 New York

Best counties

Share of checklists at the peak
  1. Niagara CountyBest late November · 704 checklists that week, 28,936 in all36%
  2. Chautauqua CountyBest the second week of November · 561 checklists that week, 35,772 in all24%
  3. Cayuga CountyBest the second week of November · 273 checklists that week, 20,184 in all18%
  4. Erie CountyBest the second week of November · 1554 checklists that week, 110,645 in all16%
  5. Monroe CountyBest the second week of November · 2426 checklists that week, 166,009 in all15%
  6. Oswego CountyBest the second week of November · 530 checklists that week, 39,208 in all13%

Best spots

Share of checklists at the peak
  1. Whirlpool State ParkNiagara County, best early December · 24 checklists that week, 286 in all98%
  2. Union SpringsCayuga County, best early June · 31 checklists that week, 158 in all97%
  3. BarcelonaChautauqua County, best the second week of November · 27 checklists that week, 1,044 in all95%
  4. Town of Penfield LandMonroe County, best the second week of November · 63 checklists that week, 2,665 in all95%

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

Best time of day

In New York, the Bonaparte's Gull is most often listed on checklists started between 10 am and 12 pm (1.5% of those checklists).

0%0.5%1%1.5%12 am: too few checklists (1146) to judge1 am: too few checklists (1055) to judge2 am: too few checklists (1121) to judge3 am: too few checklists (1353) to judge4 am: too few checklists (4785) to judge5 am: too few checklists (32052) to judge6 am: 1.1% of 124869 checklists7 am: 1.3% of 298506 checklists8 am: 1.3% of 337334 checklists9 am: 1.4% of 307787 checklists10 am: 1.5% of 270801 checklists11 am: 1.5% of 233238 checklists12 pm: 1.4% of 213830 checklists1 pm: 1.4% of 193321 checklists2 pm: 1.4% of 180741 checklists3 pm: 1.1% of 170348 checklists4 pm: 0.9% of 147224 checklists5 pm: 0.9% of 111962 checklists6 pm: 0.7% of 78261 checklists7 pm: too few checklists (44425) to judge8 pm: too few checklists (15648) to judge9 pm: too few checklists (4795) to judge10 pm: too few checklists (2454) to judge11 pm: too few checklists (1378) 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
January1.8%1.7%1.4%1.2%
February0.7%0.5%0.4%0.3%
March0.2%0.1%0.4%1.1%
April2.4%2.9%2.6%1.7%
May1.1%0.7%0.6%0.6%
June0.4%0.3%0.1%0.2%
July0.2%0.2%0.4%0.8%
August1.0%1.3%1.3%1.2%
September1.0%1.1%0.8%0.8%
October0.8%1.1%1.9%2.7%
November4.0%3.9%3.2%2.9%
December2.6%1.9%1.8%2.3%

Neighboring states

  • Connecticut: arrives late July, in the same week than New York
  • New Jersey: arrives late February, 20 weeks earlier than New York
  • Pennsylvania: arrives the second week of March, 18 weeks earlier than New York
  • Vermont: arrives mid July, 1 week earlier than New York

Common questions

When do Bonaparte's Gulls arrive in New York?
Bonaparte's Gulls are winter birds in New York: they arrive in late July, peak in the second week of November (3.7% of checklists), and most are gone by early February.
When do Bonaparte's Gulls leave New York?
Most Bonaparte's Gulls have left New York by early February, when reports fall below half their usual rate.
When is the best time to see a Bonaparte's Gull in New York?
The Bonaparte's Gull is reported most often in the second week of November, on about 3.7% of New York checklists.
Where in New York are Bonaparte's Gulls seen most often?
By county, Niagara County, Chautauqua County, and Cayuga County have the highest peak reporting rates for the Bonaparte's Gull (counties with at least 200 checklists).