WhenToBird

Stelgidopteryx serripennis · Hirundinidae

When Do Northern Rough-winged Swallows Arrive in Connecticut?

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

Northern Rough-winged Swallows reach Connecticut in late March, are common by the second week of April, peak in early May (12% of checklists), and most are gone by mid July.

When to look

First arrivalsMar 22-31late March
Common byApr 8-14the second week of April
PeakMay 1-7early May
Most gone byJul 15-21mid July

Best: early May. First arrivals late March; most are gone by mid July. Peak: on about 12% of Connecticut checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marrare
  4. Aprpeak season
  5. Maypeak season
  6. Juncommon
  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 18950 checklistsJan 8-14: 0% of 13676 checklistsJan 15-21: 0% of 13377 checklistsJan 22-31: 0% of 17004 checklistsFeb 1-7: 0% of 10218 checklistsFeb 8-14: 0% of 11568 checklistsFeb 15-21: 0% of 15916 checklistsFeb 22-28: 0% of 11413 checklistsMar 1-7: 0% of 10754 checklistsMar 8-14: 0% of 12051 checklistsMar 15-21: 0.1% of 12616 checklistsMar 22-31: 0.7% of 17801 checklistsApr 1-7: 2.8% of 13186 checklistsApr 8-14: 5.4% of 14428 checklistsApr 15-21: 9.7% of 14738 checklistsApr 22-30: 13% of 21753 checklistsMay 1-7: 13% of 22494 checklistsMay 8-14: 12% of 23363 checklistsMay 15-21: 10% of 20219 checklistsMay 22-31: 8.5% of 20778 checklistsJun 1-7: 7.8% of 12234 checklistsJun 8-14: 9.3% of 12491 checklistsJun 15-21: 8.5% of 10856 checklistsJun 22-30: 9.2% of 11964 checklistsJul 1-7: 9.3% of 9437 checklistsJul 8-14: 7.7% of 8599 checklistsJul 15-21: 5.3% of 8252 checklistsJul 22-31: 3.5% of 11329 checklistsAug 1-7: 2.9% of 8116 checklistsAug 8-14: 1.8% of 8051 checklistsAug 15-21: 1.2% of 8502 checklistsAug 22-31: 1.0% of 13673 checklistsSep 1-7: 0.5% of 9873 checklistsSep 8-14: 0.2% of 9735 checklistsSep 15-21: 0.2% of 10120 checklistsSep 22-30: 0.3% of 12543 checklistsOct 1-7: 0.1% of 10735 checklistsOct 8-14: 0.2% of 10869 checklistsOct 15-21: 0.1% of 10436 checklistsOct 22-31: 0.1% of 13808 checklistsNov 1-7: 0.1% of 10507 checklistsNov 8-14: 0.1% of 9827 checklistsNov 15-21: 0% of 9904 checklistsNov 22-30: 0.1% of 13396 checklistsDec 1-7: 0% of 8974 checklistsDec 8-14: 0% of 9468 checklistsDec 15-21: 0.1% of 11614 checklistsDec 22-31: 0% of 16616 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 Connecticut 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 Connecticut

Best counties

Share of checklists at the peak
  1. New Haven CountyBest early May · 5748 checklists that week, 139,721 in all19%
  2. Fairfield CountyBest the second week of May · 4844 checklists that week, 139,848 in all13%
  3. Windham CountyBest the second week of July · 353 checklists that week, 19,034 in all13%
  4. Litchfield CountyBest early May · 2259 checklists that week, 69,766 in all10%
  5. Tolland CountyBest early May · 1600 checklists that week, 39,004 in all10%
  6. Hartford CountyBest late April · 3603 checklists that week, 105,735 in all9.5%

Best spots

Share of checklists at the peak
  1. Aspetuck ReservoirFairfield County, best late April · 47 checklists that week, 714 in all88%
  2. Samp Mortar ReservoirFairfield County, best late April · 20 checklists that week, 336 in all85%
  3. Quinebaug Fish HatcheryWindham County, best early May · 33 checklists that week, 1,048 in all85%
  4. Dismal SwampNew Haven County, best late April · 239 checklists that week, 2,003 in all80%
  5. Maltby Lakes WestNew Haven County, best the second week of May · 24 checklists that week, 513 in all78%
  6. Liberty PointFairfield County, best late April · 25 checklists that week, 750 in all69%

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

Best time of day

In Connecticut, the Northern Rough-winged Swallow is most often listed on checklists started between 5 and 7 pm (5.5% of those checklists).

0%2%4%6%12 am: too few checklists (325) to judge1 am: too few checklists (367) to judge2 am: too few checklists (488) to judge3 am: too few checklists (792) to judge4 am: too few checklists (2722) to judge5 am: too few checklists (9489) to judge6 am: 5.0% of 33657 checklists7 am: 4.2% of 62964 checklists8 am: 4.2% of 70645 checklists9 am: 3.5% of 64870 checklists10 am: 3.3% of 58827 checklists11 am: 2.9% of 51689 checklists12 pm: 2.6% of 45288 checklists1 pm: 2.6% of 44765 checklists2 pm: 2.7% of 44173 checklists3 pm: 3.0% of 41979 checklists4 pm: 4.1% of 33219 checklists5 pm: 5.2% of 24828 checklists6 pm: 5.8% of 15856 checklists7 pm: too few checklists (8126) to judge8 pm: too few checklists (1994) to judge9 pm: too few checklists (533) to judge10 pm: too few checklists (349) to judge11 pm: too few checklists (286) 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%0.1%0.7%
April2.8%5.4%9.7%13%
May13%12%10%8.5%
June7.8%9.3%8.5%9.2%
July9.3%7.7%5.3%3.5%
August2.9%1.8%1.2%1.0%
September0.5%0.2%0.2%0.3%
October0.1%0.2%0.1%0.1%
November0.1%0.1%0%0.1%
December0%0%0.1%0%

Neighboring states

  • Rhode Island: arrives early April, 1 week later than Connecticut
  • Massachusetts: arrives early April, 1 week later than Connecticut
  • New Jersey: arrives late March, in the same week than Connecticut
  • New York: arrives early April, 1 week later than Connecticut

Common questions

When do Northern Rough-winged Swallows arrive in Connecticut?
Northern Rough-winged Swallows reach Connecticut in late March, are common by the second week of April, peak in early May (12% of checklists), and most are gone by mid July.
When do Northern Rough-winged Swallows leave Connecticut?
Most Northern Rough-winged Swallows have left Connecticut by mid July, when reports fall below half their usual rate. Stragglers are still reported until mid August.
When is the best time to see a Northern Rough-winged Swallow in Connecticut?
The Northern Rough-winged Swallow is reported most often in early May, on about 12% of Connecticut checklists.
Where in Connecticut are Northern Rough-winged Swallows seen most often?
By county, New Haven County, Fairfield County, and Windham County have the highest peak reporting rates for the Northern Rough-winged Swallow (counties with at least 200 checklists).