WhenToBird

Helmitheros vermivorum · Parulidae

When Do Worm-eating Warblers Arrive in New Jersey?

Adult Worm-eating Warbler
Photo: kirk gardner, CC BY 4.0 via iNaturalist

Worm-eating Warblers arrive in New Jersey in mid April, peak in the second week of May (3.5% of checklists), and most are gone by early July.

When to look

First arrivalsApr 15-21mid April
Common byApr 15-21mid April
PeakMay 8-14the second week of May
Most gone byJul 1-7early July

Best: the second week of May. First arrivals mid April; most are gone by early July. Peak: on about 3.5% of New Jersey checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprcommon
  5. Maypeak season
  6. Juncommon
  7. Juluncommon
  8. Auguncommon
  9. Sepuncommon
  10. Octnot usually seen
  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: 0.1% of 23609 checklistsApr 15-21: 0.4% of 25056 checklistsApr 22-30: 2.3% of 36679 checklistsMay 1-7: 4.2% of 38378 checklistsMay 8-14: 3.5% of 44071 checklistsMay 15-21: 2.9% of 34076 checklistsMay 22-31: 2.7% of 32558 checklistsJun 1-7: 2.4% of 18049 checklistsJun 8-14: 2.3% of 15597 checklistsJun 15-21: 2.0% of 14894 checklistsJun 22-30: 1.2% of 17187 checklistsJul 1-7: 1.0% of 13406 checklistsJul 8-14: 0.7% of 12550 checklistsJul 15-21: 0.4% of 12358 checklistsJul 22-31: 0.3% of 18382 checklistsAug 1-7: 0.5% of 13689 checklistsAug 8-14: 0.8% of 14006 checklistsAug 15-21: 1.1% of 14483 checklistsAug 22-31: 1.1% of 23182 checklistsSep 1-7: 0.6% of 17984 checklistsSep 8-14: 0.5% of 18320 checklistsSep 15-21: 0.2% of 20491 checklistsSep 22-30: 0.1% of 26176 checklistsOct 1-7: 0.1% of 24112 checklistsOct 8-14: 0.1% of 24603 checklistsOct 15-21: 0% of 24549 checklistsOct 22-31: 0% 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 the second week of June · 446 checklists that week, 24,933 in all13%
  2. Warren CountyBest the second week of June · 312 checklists that week, 20,077 in all12%
  3. Atlantic CountyBest early May · 995 checklists that week, 28,208 in all8.3%
  4. Sussex CountyBest late May · 1355 checklists that week, 30,305 in all7.8%
  5. Cumberland CountyBest early May · 791 checklists that week, 13,927 in all6.9%
  6. Cape May CountyBest early May · 7177 checklists that week, 189,832 in all5.8%

Best spots

Share of checklists at the peak
  1. East Creek PondCape May County, best early May · 23 checklists that week, 162 in all71%
  2. Belleplain State Forest (southeast)Cape May County, best late May · 36 checklists that week, 383 in all70%
  3. Evert PreserveBurlington County, best late May · 20 checklists that week, 332 in all64%
  4. Glassboro Wildlife Management AreaGloucester County, best the second week of May · 56 checklists that week, 651 in all62%
  5. Belleplain State ForestCape May County, best late May · 79 checklists that week, 953 in all61%
  6. Peaslee Wildlife Management AreaAtlantic County, best early May · 33 checklists that week, 367 in all61%

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

Best time of day

In New Jersey, the Worm-eating Warbler is most often listed on checklists started between 6 and 8 am (1.7% 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: 1.3% of 118312 checklists8 am: 1.1% of 123273 checklists9 am: 0.9% of 107783 checklists10 am: 0.8% of 97537 checklists11 am: 0.6% of 82427 checklists12 pm: 0.4% of 72581 checklists1 pm: 0.3% of 71478 checklists2 pm: 0.3% of 69994 checklists3 pm: 0.3% of 66822 checklists4 pm: 0.3% of 55950 checklists5 pm: 0.4% of 41360 checklists6 pm: 0.3% 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%0.1%0.4%2.3%
May4.2%3.5%2.9%2.7%
June2.4%2.3%2.0%1.2%
July1.0%0.7%0.4%0.3%
August0.5%0.8%1.1%1.1%
September0.6%0.5%0.2%0.1%
October0.1%0.1%0%0%
November0%0%0%0%
December0%0%0%0%

Neighboring states

  • Delaware: arrives mid April, in the same week than New Jersey
  • Connecticut: arrives late April, 1 week later than New Jersey
  • Pennsylvania: arrives late April, 1 week later than New Jersey
  • New York: arrives late April, 1 week later than New Jersey

Common questions

When do Worm-eating Warblers arrive in New Jersey?
Worm-eating Warblers arrive in New Jersey in mid April, peak in the second week of May (3.5% of checklists), and most are gone by early July.
When do Worm-eating Warblers leave New Jersey?
Most Worm-eating Warblers have left New Jersey by early July, when reports fall below half their usual rate.
When is the best time to see a Worm-eating Warbler in New Jersey?
The Worm-eating Warbler is reported most often in the second week of May, on about 3.5% of New Jersey checklists.
Where in New Jersey are Worm-eating Warblers seen most often?
By county, Passaic County, Warren County, and Atlantic County have the highest peak reporting rates for the Worm-eating Warbler (counties with at least 200 checklists).