WhenToBird

Empidonax traillii · Tyrannidae

When Do Willow Flycatchers Arrive in New Jersey?

Adult Willow Flycatcher
Photo: Steven Smethurst, CC0 1.0 via iNaturalist

Willow Flycatchers reach New Jersey in the second week of May, are common by mid May, peak in early June (13% of checklists), and most are gone by early August.

When to look

First arrivalsMay 8-14the second week of May
Common byMay 15-21mid May
PeakJun 1-7early June
Most gone byAug 1-7early August

Best: early June. First arrivals the second week of May; most are gone by early August. Peak: on about 13% of New Jersey checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprnot usually seen
  5. Maypeak season
  6. Junpeak season
  7. Julcommon
  8. Auguncommon
  9. Seprare
  10. Octnot usually seen
  11. Novnot usually seen
  12. Decnot usually seen

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

0%5%10%15%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: 0.1% of 38378 checklistsMay 8-14: 1.4% of 44071 checklistsMay 15-21: 6.8% of 34076 checklistsMay 22-31: 13% of 32558 checklistsJun 1-7: 14% of 18049 checklistsJun 8-14: 11% of 15597 checklistsJun 15-21: 9.0% of 14894 checklistsJun 22-30: 7.1% of 17187 checklistsJul 1-7: 5.8% of 13406 checklistsJul 8-14: 6.5% of 12550 checklistsJul 15-21: 7.9% of 12358 checklistsJul 22-31: 7.2% of 18382 checklistsAug 1-7: 4.3% of 13689 checklistsAug 8-14: 2.7% of 14006 checklistsAug 15-21: 1.9% of 14483 checklistsAug 22-31: 1.5% of 23182 checklistsSep 1-7: 1.2% of 17984 checklistsSep 8-14: 0.6% of 18320 checklistsSep 15-21: 0.1% of 20491 checklistsSep 22-30: 0.1% of 26176 checklistsOct 1-7: 0.1% of 24112 checklistsOct 8-14: 0% 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. Hudson CountyBest mid July · 316 checklists that week, 21,191 in all28%
  2. Somerset CountyBest early June · 1205 checklists that week, 58,057 in all24%
  3. Hunterdon CountyBest early June · 1150 checklists that week, 57,610 in all20%
  4. Mercer CountyBest early June · 1124 checklists that week, 56,614 in all19%
  5. Morris CountyBest early June · 1132 checklists that week, 59,212 in all18%
  6. Bergen CountyBest early June · 1328 checklists that week, 73,457 in all18%

Best spots

Share of checklists at the peak
  1. West Essex ParkEssex County, best early June · 31 checklists that week, 1,556 in all74%
  2. Delaware and Raritan Canal State Park (Fiddlers Creek)Mercer County, best the second week of June · 21 checklists that week, 636 in all73%
  3. Kings CreekUnion County, best mid July · 34 checklists that week, 2,390 in all72%
  4. Paulinskill River Wildlife Management AreaSussex County, best the second week of July · 20 checklists that week, 1,041 in all71%
  5. Heavenly FarmsMiddlesex County, best late May · 39 checklists that week, 471 in all69%

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

Best time of day

In New Jersey, the Willow Flycatcher is most often listed on checklists started between 6 and 8 am (3.7% of those checklists).

0%2%4%6%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: 5.0% of 50447 checklists7 am: 3.1% of 118312 checklists8 am: 2.7% of 123273 checklists9 am: 2.3% of 107783 checklists10 am: 1.7% of 97537 checklists11 am: 1.2% of 82427 checklists12 pm: 1.0% of 72581 checklists1 pm: 0.8% of 71478 checklists2 pm: 0.8% of 69994 checklists3 pm: 0.8% of 66822 checklists4 pm: 0.9% of 55950 checklists5 pm: 1.2% of 41360 checklists6 pm: 1.8% 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%
May0.1%1.4%6.8%13%
June14%11%9.0%7.1%
July5.8%6.5%7.9%7.2%
August4.3%2.7%1.9%1.5%
September1.2%0.6%0.1%0.1%
October0.1%0%0%0%
November0%0%0%0%
December0%0%0%0%

Neighboring states

  • Delaware: arrives the second week of May, in the same week than New Jersey
  • Connecticut: arrives the second week of May, in the same week than New Jersey
  • Pennsylvania: arrives the second week of May, in the same week than New Jersey
  • New York: arrives the second week of May, in the same week than New Jersey

Common questions

When do Willow Flycatchers arrive in New Jersey?
Willow Flycatchers reach New Jersey in the second week of May, are common by mid May, peak in early June (13% of checklists), and most are gone by early August.
When do Willow Flycatchers leave New Jersey?
Most Willow Flycatchers have left New Jersey by early August, when reports fall below half their usual rate. Stragglers are still reported until early September.
When is the best time to see a Willow Flycatcher in New Jersey?
The Willow Flycatcher is reported most often in early June, on about 13% of New Jersey checklists.
Where in New Jersey are Willow Flycatchers seen most often?
By county, Hudson County, Somerset County, and Hunterdon County have the highest peak reporting rates for the Willow Flycatcher (counties with at least 200 checklists).