WhenToBird

Vireo philadelphicus · Vireonidae

When Do Philadelphia Vireos Arrive in New Jersey?

Adult Philadelphia Vireo
Photo: Sue Carnahan, CC BY 4.0 via iNaturalist

Philadelphia Vireos mostly pass through New Jersey: they arrive in early September, peak in mid September (1.7% of checklists), and most are gone by early October.

When to look

First arrivalsSep 1-7early September
Common bySep 1-7early September
PeakSep 15-21mid September
Most gone byOct 1-7early October

Best: mid September. First arrivals early September; most are gone by early October. Peak: on about 1.7% of New Jersey checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprnot usually seen
  5. Maynot usually seen
  6. Junnot usually seen
  7. Julnot usually seen
  8. Auguncommon
  9. Seppeak season
  10. Octcommon
  11. Novnot usually seen
  12. Decnot usually seen

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

0%0.5%1%1.5%2%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% of 36679 checklistsMay 1-7: 0.1% of 38378 checklistsMay 8-14: 0.1% of 44071 checklistsMay 15-21: 0.1% of 34076 checklistsMay 22-31: 0.1% 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% of 14006 checklistsAug 15-21: 0.1% of 14483 checklistsAug 22-31: 0.2% of 23182 checklistsSep 1-7: 0.7% of 17984 checklistsSep 8-14: 1.9% of 18320 checklistsSep 15-21: 1.9% of 20491 checklistsSep 22-30: 1.5% of 26176 checklistsOct 1-7: 1.0% of 24112 checklistsOct 8-14: 0.2% of 24603 checklistsOct 15-21: 0.1% of 24549 checklistsOct 22-31: 0.1% of 26206 checklistsNov 1-7: 0.1% 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. Warren CountyBest the second week of September · 322 checklists that week, 20,077 in all3.2%
  2. Burlington CountyBest mid September · 1000 checklists that week, 52,358 in all3.0%
  3. Monmouth CountyBest mid September · 1565 checklists that week, 79,748 in all2.6%
  4. Passaic CountyBest mid September · 445 checklists that week, 24,933 in all2.5%
  5. Sussex CountyBest mid September · 493 checklists that week, 30,305 in all2.3%
  6. Cape May CountyBest mid September · 5541 checklists that week, 189,832 in all2.2%

Best spots

Share of checklists at the peak
  1. Island Beach State Park (north)Ocean County, best the second week of September · 69 checklists that week, 1,171 in all11%
  2. Higbee Beach Wildlife Management AreaCape May County, best the second week of September · 400 checklists that week, 9,268 in all11%
  3. Gateway National Recreation Area (northwest 4)Monmouth County, best the second week of September · 28 checklists that week, 272 in all11%
  4. Memorial Park (Pine Grove)Burlington County, best mid September · 23 checklists that week, 487 in all11%
  5. Heavenly FarmsMiddlesex County, best late September · 20 checklists that week, 471 in all11%
  6. Gateway National Recreation Area (Sandy Hook Point)Monmouth County, best late September · 43 checklists that week, 791 in all10%

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

Best time of day

In New Jersey, the Philadelphia Vireo is most often listed on checklists started between 6 and 8 am (0.4% of those checklists).

0%0.5%1%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: 0.5% of 50447 checklists7 am: 0.4% of 118312 checklists8 am: 0.2% of 123273 checklists9 am: 0.2% of 107783 checklists10 am: 0.1% of 97537 checklists11 am: 0.1% of 82427 checklists12 pm: 0.1% of 72581 checklists1 pm: 0.1% of 71478 checklists2 pm: 0.1% of 69994 checklists3 pm: 0.1% of 66822 checklists4 pm: 0.1% of 55950 checklists5 pm: 0.1% of 41360 checklists6 pm: 0.1% 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%
May0.1%0.1%0.1%0.1%
June0.1%0%0%0%
July0%0%0%0%
August0%0%0.1%0.2%
September0.7%1.9%1.9%1.5%
October1.0%0.2%0.1%0.1%
November0.1%0%0%0%
December0%0%0%0%

Neighboring states

  • Delaware: arrives the second week of September, 1 week later than New Jersey
  • Connecticut: arrives early September, in the same week than New Jersey
  • Pennsylvania: arrives early September, in the same week than New Jersey
  • New York: arrives early September, in the same week than New Jersey

Common questions

When do Philadelphia Vireos arrive in New Jersey?
Philadelphia Vireos mostly pass through New Jersey: they arrive in early September, peak in mid September (1.7% of checklists), and most are gone by early October.
When do Philadelphia Vireos leave New Jersey?
Most Philadelphia Vireos have left New Jersey by early October, when reports fall below half their usual rate.
When is the best time to see a Philadelphia Vireo in New Jersey?
The Philadelphia Vireo is reported most often in mid September, on about 1.7% of New Jersey checklists.
Where in New Jersey are Philadelphia Vireos seen most often?
By county, Warren County, Burlington County, and Monmouth County have the highest peak reporting rates for the Philadelphia Vireo (counties with at least 200 checklists).