WhenToBird

Chroicocephalus philadelphia · Laridae

When Do Bonaparte's Gulls Arrive in New Jersey?

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

Bonaparte's Gulls arrive in New Jersey in late February, peak in early April (2.9% of checklists), and most are gone by late May.

When to look

First arrivalsFeb 22-28late February
Common byFeb 22-28late February
PeakApr 1-7early April
Most gone byMay 22-31late May

Best: early April. First arrivals late February; most are gone by late May. Peak: on about 2.9% of New Jersey checklists.

  1. Janpeak season
  2. Febcommon
  3. Marpeak season
  4. Aprpeak season
  5. Maycommon
  6. Jununcommon
  7. Julrare
  8. Augrare
  9. Seprare
  10. Octcommon
  11. Novpeak season
  12. Decpeak season

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

0%1%2%3%4%Jan 1-7: 3.0% of 28167 checklistsJan 8-14: 2.5% of 20583 checklistsJan 15-21: 2.0% of 19739 checklistsJan 22-31: 1.9% of 24586 checklistsFeb 1-7: 1.3% of 17226 checklistsFeb 8-14: 0.8% of 19567 checklistsFeb 15-21: 0.7% of 26553 checklistsFeb 22-28: 1.0% of 19046 checklistsMar 1-7: 1.3% of 17969 checklistsMar 8-14: 1.4% of 18976 checklistsMar 15-21: 1.5% of 18581 checklistsMar 22-31: 2.4% of 27590 checklistsApr 1-7: 3.8% of 21202 checklistsApr 8-14: 2.7% of 23609 checklistsApr 15-21: 1.9% of 25056 checklistsApr 22-30: 1.4% of 36679 checklistsMay 1-7: 1.4% of 38378 checklistsMay 8-14: 1.5% of 44071 checklistsMay 15-21: 1.1% of 34076 checklistsMay 22-31: 0.9% of 32558 checklistsJun 1-7: 0.2% of 18049 checklistsJun 8-14: 0.1% of 15597 checklistsJun 15-21: 0.1% of 14894 checklistsJun 22-30: 0.1% of 17187 checklistsJul 1-7: 0.1% of 13406 checklistsJul 8-14: 0.1% of 12550 checklistsJul 15-21: 0.1% of 12358 checklistsJul 22-31: 0.2% of 18382 checklistsAug 1-7: 0.2% of 13689 checklistsAug 8-14: 0.2% of 14006 checklistsAug 15-21: 0.2% of 14483 checklistsAug 22-31: 0.2% of 23182 checklistsSep 1-7: 0.2% of 17984 checklistsSep 8-14: 0.1% of 18320 checklistsSep 15-21: 0.1% of 20491 checklistsSep 22-30: 0.2% of 26176 checklistsOct 1-7: 0.2% of 24112 checklistsOct 8-14: 0.3% of 24603 checklistsOct 15-21: 0.6% of 24549 checklistsOct 22-31: 1.3% of 26206 checklistsNov 1-7: 2.3% of 17469 checklistsNov 8-14: 2.6% of 15102 checklistsNov 15-21: 2.1% of 14958 checklistsNov 22-30: 1.5% of 19447 checklistsDec 1-7: 1.5% of 14017 checklistsDec 8-14: 1.8% of 14625 checklistsDec 15-21: 1.7% of 16937 checklistsDec 22-31: 2.3% of 26651 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 Jersey 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 Jersey

Best counties

Share of checklists at the peak
  1. Cumberland CountyBest early April · 268 checklists that week, 13,927 in all11%
  2. Hunterdon CountyBest the second week of April · 1392 checklists that week, 57,610 in all10%
  3. Middlesex CountyBest early April · 1215 checklists that week, 46,761 in all10%
  4. Cape May CountyBest the second week of March · 2231 checklists that week, 189,832 in all10%
  5. Ocean CountyBest late December · 2958 checklists that week, 87,340 in all7.7%
  6. Monmouth CountyBest early January · 2737 checklists that week, 79,748 in all6.4%

Best spots

Share of checklists at the peak
  1. Fishing CreekCape May County, best mid March · 44 checklists that week, 999 in all85%
  2. Allie Clark Field ComplexMiddlesex County, best the second week of April · 137 checklists that week, 2,340 in all77%
  3. DelancoBurlington County, best the second week of April · 29 checklists that week, 295 in all76%
  4. Cape May Point State Park (Sunset Beach)Cape May County, best mid January · 38 checklists that week, 2,113 in all60%
  5. Norburys LandingCape May County, best late February · 29 checklists that week, 667 in all58%
  6. Public BeachMonmouth County, best late December · 26 checklists that week, 622 in all58%

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

Best time of day

In New Jersey, the Bonaparte's Gull is most often listed on checklists started between 6 and 8 am (1.5% of those checklists).

0%0.5%1%1.5%2%12 am: too few checklists (746) to judge1 am: too few checklists (640) to judge2 am: too few checklists (606) to judge3 am: too few checklists (755) to judge4 am: too few checklists (1681) to judge5 am: too few checklists (11258) to judge6 am: 1.8% of 50447 checklists7 am: 1.4% of 118312 checklists8 am: 1.1% of 123273 checklists9 am: 1.2% of 107783 checklists10 am: 1.2% of 97537 checklists11 am: 1.3% of 82427 checklists12 pm: 1.4% of 72581 checklists1 pm: 1.5% of 71478 checklists2 pm: 1.4% of 69994 checklists3 pm: 1.3% of 66822 checklists4 pm: 1.0% of 55950 checklists5 pm: 0.8% of 41360 checklists6 pm: 0.7% of 28122 checklists7 pm: too few checklists (14727) to judge8 pm: too few checklists (4257) to judge9 pm: too few checklists (1273) to judge10 pm: too few checklists (920) to judge11 pm: too few checklists (693) 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
January3.0%2.5%2.0%1.9%
February1.3%0.8%0.7%1.0%
March1.3%1.4%1.5%2.4%
April3.8%2.7%1.9%1.4%
May1.4%1.5%1.1%0.9%
June0.2%0.1%0.1%0.1%
July0.1%0.1%0.1%0.2%
August0.2%0.2%0.2%0.2%
September0.2%0.1%0.1%0.2%
October0.2%0.3%0.6%1.3%
November2.3%2.6%2.1%1.5%
December1.5%1.8%1.7%2.3%

Neighboring states

  • Delaware: arrives early November, 15 weeks earlier than New Jersey
  • Connecticut: arrives late July, 20 weeks later than New Jersey
  • Pennsylvania: arrives the second week of March, 2 weeks later than New Jersey
  • New York: arrives late July, 20 weeks later than New Jersey

Common questions

When do Bonaparte's Gulls arrive in New Jersey?
Bonaparte's Gulls arrive in New Jersey in late February, peak in early April (2.9% of checklists), and most are gone by late May.
When do Bonaparte's Gulls leave New Jersey?
Most Bonaparte's Gulls have left New Jersey by late May, when reports fall below half their usual rate.
When is the best time to see a Bonaparte's Gull in New Jersey?
The Bonaparte's Gull is reported most often in early April, on about 2.9% of New Jersey checklists.
Where in New Jersey are Bonaparte's Gulls seen most often?
By county, Cumberland County, Hunterdon County, and Middlesex County have the highest peak reporting rates for the Bonaparte's Gull (counties with at least 200 checklists).