WhenToBird

Stelgidopteryx serripennis · Hirundinidae

When Do Northern Rough-winged Swallows Arrive in New Jersey?

Adult Northern Rough-winged Swallow
Photo: Peter Chen 2.0, CC BY 4.0 via iNaturalist

Northern Rough-winged Swallows reach New Jersey in late March, are common by early April, peak in late April (13% of checklists), and most are gone by early August.

When to look

First arrivalsMar 22-31late March
Common byApr 1-7early April
PeakApr 22-30late April
Most gone byAug 1-7early August

Best: late April. First arrivals late March; most are gone by early August. Peak: on about 13% of New Jersey checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Maruncommon
  4. Aprpeak season
  5. Maypeak season
  6. Junpeak season
  7. Julcommon
  8. Augcommon
  9. Seprare
  10. Octrare
  11. Novnot usually seen
  12. Decnot usually seen

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

0%5%10%15%Jan 1-7: 0.1% of 28167 checklistsJan 8-14: 0.1% of 20583 checklistsJan 15-21: 0.1% of 19739 checklistsJan 22-31: 0.2% of 24586 checklistsFeb 1-7: 0.1% of 17226 checklistsFeb 8-14: 0.1% of 19567 checklistsFeb 15-21: 0.1% of 26553 checklistsFeb 22-28: 0% of 19046 checklistsMar 1-7: 0% of 17969 checklistsMar 8-14: 0.1% of 18976 checklistsMar 15-21: 0.1% of 18581 checklistsMar 22-31: 2.1% of 27590 checklistsApr 1-7: 6.2% of 21202 checklistsApr 8-14: 9.4% of 23609 checklistsApr 15-21: 12% of 25056 checklistsApr 22-30: 13% of 36679 checklistsMay 1-7: 13% of 38378 checklistsMay 8-14: 11% of 44071 checklistsMay 15-21: 9.5% of 34076 checklistsMay 22-31: 9.9% of 32558 checklistsJun 1-7: 8.7% of 18049 checklistsJun 8-14: 9.6% of 15597 checklistsJun 15-21: 9.3% of 14894 checklistsJun 22-30: 10% of 17187 checklistsJul 1-7: 8.6% of 13406 checklistsJul 8-14: 8.3% of 12550 checklistsJul 15-21: 7.0% of 12358 checklistsJul 22-31: 6.2% of 18382 checklistsAug 1-7: 5.4% of 13689 checklistsAug 8-14: 3.8% of 14006 checklistsAug 15-21: 3.1% of 14483 checklistsAug 22-31: 2.7% of 23182 checklistsSep 1-7: 1.6% of 17984 checklistsSep 8-14: 1.1% of 18320 checklistsSep 15-21: 0.8% of 20491 checklistsSep 22-30: 0.9% of 26176 checklistsOct 1-7: 1.0% of 24112 checklistsOct 8-14: 1.1% of 24603 checklistsOct 15-21: 0.9% of 24549 checklistsOct 22-31: 0.6% of 26206 checklistsNov 1-7: 0.2% of 17469 checklistsNov 8-14: 0.1% of 15102 checklistsNov 15-21: 0.1% of 14958 checklistsNov 22-30: 0.1% of 19447 checklistsDec 1-7: 0.1% of 14017 checklistsDec 8-14: 0.1% of 14625 checklistsDec 15-21: 0.1% of 16937 checklistsDec 22-31: 0.1% 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 mid June · 355 checklists that week, 20,077 in all28%
  2. Hunterdon CountyBest mid April · 1392 checklists that week, 57,610 in all25%
  3. Bergen CountyBest early May · 2580 checklists that week, 73,457 in all25%
  4. Passaic CountyBest late April · 1220 checklists that week, 24,933 in all25%
  5. Gloucester CountyBest early August · 542 checklists that week, 36,378 in all18%
  6. Somerset CountyBest late April · 2345 checklists that week, 58,057 in all17%

Best spots

Share of checklists at the peak
  1. Municipal LakeWarren County, best early June · 30 checklists that week, 1,477 in all84%
  2. Musconetcong River GreenwayWarren County, best the second week of May · 22 checklists that week, 757 in all84%
  3. Hainesville Wildlife Management AreaSussex County, best late April · 22 checklists that week, 516 in all83%
  4. Point View ReservoirPassaic County, best late April · 23 checklists that week, 487 in all82%
  5. South Branch River ReserveHunterdon County, best mid May · 53 checklists that week, 3,829 in all80%
  6. Cramers CreekHunterdon County, best late April · 31 checklists that week, 1,218 in all78%

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

Best time of day

In New Jersey, the Northern Rough-winged Swallow is most often listed on checklists started between 6 and 8 am (5.6% of those checklists).

0%2%4%6%8%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: 7.7% of 50447 checklists7 am: 4.8% of 118312 checklists8 am: 4.5% of 123273 checklists9 am: 4.3% of 107783 checklists10 am: 3.7% of 97537 checklists11 am: 3.3% of 82427 checklists12 pm: 3.1% of 72581 checklists1 pm: 3.1% of 71478 checklists2 pm: 3.1% of 69994 checklists3 pm: 3.0% of 66822 checklists4 pm: 3.6% of 55950 checklists5 pm: 4.8% of 41360 checklists6 pm: 6.2% 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
January0.1%0.1%0.1%0.2%
February0.1%0.1%0.1%0%
March0%0.1%0.1%2.1%
April6.2%9.4%12%13%
May13%11%9.5%9.9%
June8.7%9.6%9.3%10%
July8.6%8.3%7.0%6.2%
August5.4%3.8%3.1%2.7%
September1.6%1.1%0.8%0.9%
October1.0%1.1%0.9%0.6%
November0.2%0.1%0.1%0.1%
December0.1%0.1%0.1%0.1%

Neighboring states

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

Common questions

When do Northern Rough-winged Swallows arrive in New Jersey?
Northern Rough-winged Swallows reach New Jersey in late March, are common by early April, peak in late April (13% of checklists), and most are gone by early August.
When do Northern Rough-winged Swallows leave New Jersey?
Most Northern Rough-winged Swallows have left New Jersey by early August, when reports fall below half their usual rate. Stragglers are still reported until the second week of September.
When is the best time to see a Northern Rough-winged Swallow in New Jersey?
The Northern Rough-winged Swallow is reported most often in late April, on about 13% of New Jersey checklists.
Where in New Jersey are Northern Rough-winged Swallows seen most often?
By county, Warren County, Hunterdon County, and Bergen County have the highest peak reporting rates for the Northern Rough-winged Swallow (counties with at least 200 checklists).