WhenToBird

Setophaga castanea · Parulidae

When Do Bay-breasted Warblers Arrive in New Jersey?

Adult Bay-breasted Warbler
Photo: Roger A. Morales-Flores, CC BY 4.0 via iNaturalist

Bay-breasted Warblers mostly pass through New Jersey: they arrive in early May, peak in mid May (3.3% of checklists), and most are gone by early June.

When to look

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

Best: mid May. First arrivals early May; most are gone by early June. Peak: on about 3.3% of New Jersey checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprrare
  5. Maypeak season
  6. Jununcommon
  7. Julnot usually seen
  8. Auguncommon
  9. Sepcommon
  10. Octcommon
  11. Novnot usually seen
  12. Decnot usually seen

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

0%2%4%6%Jan 1-7: 0% of 28167 checklistsJan 8-14: 0% of 20583 checklistsJan 15-21: 0% of 19739 checklistsJan 22-31: 0% of 24586 checklistsFeb 1-7: 0% of 17226 checklistsFeb 8-14: 0% of 19567 checklistsFeb 15-21: 0% of 26553 checklistsFeb 22-28: 0% of 19046 checklistsMar 1-7: 0% of 17969 checklistsMar 8-14: 0% of 18976 checklistsMar 15-21: 0% of 18581 checklistsMar 22-31: 0% of 27590 checklistsApr 1-7: 0% of 21202 checklistsApr 8-14: 0% of 23609 checklistsApr 15-21: 0% of 25056 checklistsApr 22-30: 0.1% of 36679 checklistsMay 1-7: 0.6% of 38378 checklistsMay 8-14: 2.8% of 44071 checklistsMay 15-21: 5.9% of 34076 checklistsMay 22-31: 1.4% of 32558 checklistsJun 1-7: 0.1% of 18049 checklistsJun 8-14: 0% of 15597 checklistsJun 15-21: 0% of 14894 checklistsJun 22-30: 0% of 17187 checklistsJul 1-7: 0% of 13406 checklistsJul 8-14: 0% of 12550 checklistsJul 15-21: 0% of 12358 checklistsJul 22-31: 0% of 18382 checklistsAug 1-7: 0% of 13689 checklistsAug 8-14: 0.1% of 14006 checklistsAug 15-21: 0.1% of 14483 checklistsAug 22-31: 0.4% of 23182 checklistsSep 1-7: 1.2% of 17984 checklistsSep 8-14: 2.5% of 18320 checklistsSep 15-21: 2.7% of 20491 checklistsSep 22-30: 2.4% of 26176 checklistsOct 1-7: 1.2% of 24112 checklistsOct 8-14: 0.6% of 24603 checklistsOct 15-21: 0.1% of 24549 checklistsOct 22-31: 0.1% of 26206 checklistsNov 1-7: 0% of 17469 checklistsNov 8-14: 0% of 15102 checklistsNov 15-21: 0% of 14958 checklistsNov 22-30: 0% of 19447 checklistsDec 1-7: 0% of 14017 checklistsDec 8-14: 0% of 14625 checklistsDec 15-21: 0% of 16937 checklistsDec 22-31: 0% 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. Passaic CountyBest mid May · 1018 checklists that week, 24,933 in all14%
  2. Somerset CountyBest the second week of September · 1095 checklists that week, 58,057 in all6.2%
  3. Essex CountyBest mid May · 827 checklists that week, 28,396 in all6.1%
  4. Union CountyBest mid May · 729 checklists that week, 23,647 in all6.0%
  5. Burlington CountyBest mid September · 1000 checklists that week, 52,358 in all6.0%
  6. Middlesex CountyBest mid May · 1278 checklists that week, 46,761 in all5.1%

Best spots

Share of checklists at the peak
  1. Island Beach State Park (north)Ocean County, best late May · 35 checklists that week, 1,171 in all34%
  2. William Warren ParkMiddlesex County, best late May · 36 checklists that week, 325 in all33%
  3. Garret Mountain ReservationPassaic County, best late May · 268 checklists that week, 5,614 in all33%
  4. South Mountain Reservation (Maplewood)Essex County, best mid May · 40 checklists that week, 306 in all31%
  5. Island Beach State ParkOcean County, best mid May · 51 checklists that week, 1,190 in all26%
  6. Washington Valley ParkSomerset County, best the second week of September · 165 checklists that week, 1,255 in all23%

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

Best time of day

In New Jersey, the Bay-breasted Warbler is most often listed on checklists started between 6 and 8 am (1.6% of those checklists).

0%1%2%3%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: 2.6% of 50447 checklists7 am: 1.2% of 118312 checklists8 am: 0.8% of 123273 checklists9 am: 0.6% of 107783 checklists10 am: 0.4% of 97537 checklists11 am: 0.3% of 82427 checklists12 pm: 0.3% of 72581 checklists1 pm: 0.3% of 71478 checklists2 pm: 0.2% of 69994 checklists3 pm: 0.3% of 66822 checklists4 pm: 0.2% of 55950 checklists5 pm: 0.3% of 41360 checklists6 pm: 0.2% 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
January0%0%0%0%
February0%0%0%0%
March0%0%0%0%
April0%0%0%0.1%
May0.6%2.8%5.9%1.4%
June0.1%0%0%0%
July0%0%0%0%
August0%0.1%0.1%0.4%
September1.2%2.5%2.7%2.4%
October1.2%0.6%0.1%0.1%
November0%0%0%0%
December0%0%0%0%

Neighboring states

  • Delaware: arrives late August, 15 weeks later than New Jersey
  • Connecticut: arrives early May, in the same week than New Jersey
  • Pennsylvania: arrives late August, 15 weeks later than New Jersey
  • New York: arrives early May, in the same week than New Jersey

Common questions

When do Bay-breasted Warblers arrive in New Jersey?
Bay-breasted Warblers mostly pass through New Jersey: they arrive in early May, peak in mid May (3.3% of checklists), and most are gone by early June.
When do Bay-breasted Warblers leave New Jersey?
Most Bay-breasted Warblers have left New Jersey by early June, when reports fall below half their usual rate.
When is the best time to see a Bay-breasted Warbler in New Jersey?
The Bay-breasted Warbler is reported most often in mid May, on about 3.3% of New Jersey checklists.
Where in New Jersey are Bay-breasted Warblers seen most often?
By county, Passaic County, Somerset County, and Essex County have the highest peak reporting rates for the Bay-breasted Warbler (counties with at least 200 checklists).