WhenToBird

Tachycineta bicolor · Hirundinidae

When Do Tree Swallows Arrive in Connecticut?

Adult Tree Swallow
Photo: Carter Dorscht, CC0 1.0 via iNaturalist

Tree Swallows reach Connecticut in mid March, are common by early April, peak in late May (33% of checklists), and most are gone by early September.

When to look

First arrivalsMar 15-21mid March
Common byApr 1-7early April
PeakMay 22-31late May
Most gone bySep 1-7early September

Best: late May. First arrivals mid March; most are gone by early September. Peak: on about 33% of Connecticut 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. Sepcommon
  10. Octuncommon
  11. Novrare
  12. Decnot usually seen

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

0%10%20%30%40%Jan 1-7: 0.1% of 18950 checklistsJan 8-14: 0.1% of 13676 checklistsJan 15-21: 0.1% of 13377 checklistsJan 22-31: 0% of 17004 checklistsFeb 1-7: 0% of 10218 checklistsFeb 8-14: 0.1% of 11568 checklistsFeb 15-21: 0.1% of 15916 checklistsFeb 22-28: 0.1% of 11413 checklistsMar 1-7: 0.4% of 10754 checklistsMar 8-14: 1.7% of 12051 checklistsMar 15-21: 3.7% of 12616 checklistsMar 22-31: 10% of 17801 checklistsApr 1-7: 16% of 13186 checklistsApr 8-14: 22% of 14428 checklistsApr 15-21: 26% of 14738 checklistsApr 22-30: 29% of 21753 checklistsMay 1-7: 30% of 22494 checklistsMay 8-14: 31% of 23363 checklistsMay 15-21: 34% of 20219 checklistsMay 22-31: 33% of 20778 checklistsJun 1-7: 32% of 12234 checklistsJun 8-14: 30% of 12491 checklistsJun 15-21: 30% of 10856 checklistsJun 22-30: 27% of 11964 checklistsJul 1-7: 24% of 9437 checklistsJul 8-14: 21% of 8599 checklistsJul 15-21: 19% of 8252 checklistsJul 22-31: 18% of 11329 checklistsAug 1-7: 19% of 8116 checklistsAug 8-14: 18% of 8051 checklistsAug 15-21: 19% of 8502 checklistsAug 22-31: 17% of 13673 checklistsSep 1-7: 14% of 9873 checklistsSep 8-14: 8.4% of 9735 checklistsSep 15-21: 8.4% of 10120 checklistsSep 22-30: 9.3% of 12543 checklistsOct 1-7: 7.8% of 10735 checklistsOct 8-14: 6.8% of 10869 checklistsOct 15-21: 5.5% of 10436 checklistsOct 22-31: 3.4% of 13808 checklistsNov 1-7: 1.4% of 10507 checklistsNov 8-14: 0.7% of 9827 checklistsNov 15-21: 0.4% of 9904 checklistsNov 22-30: 0.1% of 13396 checklistsDec 1-7: 0.1% of 8974 checklistsDec 8-14: 0.1% of 9468 checklistsDec 15-21: 0.1% of 11614 checklistsDec 22-31: 0.1% 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.

Embed this map on your site

Where in Connecticut

Best counties

Share of checklists at the peak
  1. Litchfield CountyBest mid May · 2417 checklists that week, 69,766 in all42%
  2. New Haven CountyBest late May · 4805 checklists that week, 139,721 in all39%
  3. Windham CountyBest early June · 391 checklists that week, 19,034 in all38%
  4. Tolland CountyBest the second week of May · 1577 checklists that week, 39,004 in all32%
  5. Middlesex CountyBest the second week of May · 1592 checklists that week, 39,919 in all32%
  6. New London CountyBest mid May · 1754 checklists that week, 65,205 in all30%

Best spots

Share of checklists at the peak
  1. Game Farm PondNew Haven County, best early June · 21 checklists that week, 1,312 in all100%
  2. Lake ChamberlainNew Haven County, best mid April · 22 checklists that week, 463 in all99%
  3. Westmoor ParkHartford County, best late May · 50 checklists that week, 1,091 in all94%
  4. Stewart B. Mckinney National Wildlife Refuge (Lewis Gut)Fairfield County, best mid June · 21 checklists that week, 1,029 in all92%

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

Best time of day

In Connecticut, the Tree Swallow is most often listed on checklists started between 6 and 8 am (16% of those checklists).

0%5%10%15%20%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: 18% of 33657 checklists7 am: 15% of 62964 checklists8 am: 17% of 70645 checklists9 am: 15% of 64870 checklists10 am: 13% of 58827 checklists11 am: 12% of 51689 checklists12 pm: 10% of 45288 checklists1 pm: 10% of 44765 checklists2 pm: 9.8% of 44173 checklists3 pm: 9.2% of 41979 checklists4 pm: 11% of 33219 checklists5 pm: 15% of 24828 checklists6 pm: 17% 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
January0.1%0.1%0.1%0%
February0%0.1%0.1%0.1%
March0.4%1.7%3.7%10%
April16%22%26%29%
May30%31%34%33%
June32%30%30%27%
July24%21%19%18%
August19%18%19%17%
September14%8.4%8.4%9.3%
October7.8%6.8%5.5%3.4%
November1.4%0.7%0.4%0.1%
December0.1%0.1%0.1%0.1%

Neighboring states

  • Rhode Island: arrives mid March, in the same week than Connecticut
  • Massachusetts: arrives mid March, in the same week than Connecticut
  • New Jersey: arrives early March, 2 weeks earlier than Connecticut
  • New York: arrives mid March, in the same week than Connecticut

Common questions

When do Tree Swallows arrive in Connecticut?
Tree Swallows reach Connecticut in mid March, are common by early April, peak in late May (33% of checklists), and most are gone by early September.
When do Tree Swallows leave Connecticut?
Most Tree Swallows have left Connecticut by early September, when reports fall below half their usual rate. Stragglers are still reported until late October.
When is the best time to see a Tree Swallow in Connecticut?
The Tree Swallow is reported most often in late May, on about 33% of Connecticut checklists.
Where in Connecticut are Tree Swallows seen most often?
By county, Litchfield County, New Haven County, and Windham County have the highest peak reporting rates for the Tree Swallow (counties with at least 200 checklists).