WhenToBird

Sterna hirundo · Laridae

When Do Common Terns Arrive in Connecticut?

Adult Common Tern
Photo: Сергей Неклюдов, CC BY 4.0 via iNaturalist

Common Terns reach Connecticut in early May, are common by mid May, peak in early August (13% of checklists), and most are gone by early September.

When to look

First arrivalsMay 1-7early May
Common byMay 15-21mid May
PeakAug 1-7early August
Most gone bySep 1-7early September

Best: early August. First arrivals early May; most are gone by early September. Peak: on about 13% of Connecticut checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprrare
  5. Mayuncommon
  6. Juncommon
  7. Julpeak season
  8. Augpeak season
  9. Sepuncommon
  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% of 12616 checklistsMar 22-31: 0% of 17801 checklistsApr 1-7: 0% of 13186 checklistsApr 8-14: 0.1% of 14428 checklistsApr 15-21: 0.1% of 14738 checklistsApr 22-30: 0.2% of 21753 checklistsMay 1-7: 1.3% of 22494 checklistsMay 8-14: 3.1% of 23363 checklistsMay 15-21: 4.6% of 20219 checklistsMay 22-31: 5.4% of 20778 checklistsJun 1-7: 5.1% of 12234 checklistsJun 8-14: 4.6% of 12491 checklistsJun 15-21: 4.8% of 10856 checklistsJun 22-30: 7.1% of 11964 checklistsJul 1-7: 7.9% of 9437 checklistsJul 8-14: 9.7% of 8599 checklistsJul 15-21: 11% of 8252 checklistsJul 22-31: 13% of 11329 checklistsAug 1-7: 14% of 8116 checklistsAug 8-14: 13% of 8051 checklistsAug 15-21: 10% of 8502 checklistsAug 22-31: 6.3% of 13673 checklistsSep 1-7: 3.5% of 9873 checklistsSep 8-14: 1.8% of 9735 checklistsSep 15-21: 1.1% of 10120 checklistsSep 22-30: 0.4% of 12543 checklistsOct 1-7: 0.2% of 10735 checklistsOct 8-14: 0.1% 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% 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% 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 August · 1925 checklists that week, 139,721 in all32%
  2. New London CountyBest late July · 1243 checklists that week, 65,205 in all21%
  3. Fairfield CountyBest early August · 1666 checklists that week, 139,848 in all16%
  4. Middlesex CountyBest the second week of August · 513 checklists that week, 39,919 in all9.8%

Best spots

Share of checklists at the peak
  1. Stewart B. Mckinney National Wildlife Refuge (Falkner Island)New Haven County, best late July · 25 checklists that week, 100 in all100%
  2. Cedar PointFairfield County, best mid June · 34 checklists that week, 1,206 in all92%
  3. Stratford PointFairfield County, best the second week of August · 72 checklists that week, 3,352 in all88%
  4. Harkness Memorial State ParkNew London County, best late July · 92 checklists that week, 2,880 in all88%
  5. Morse ParkNew Haven County, best early August · 105 checklists that week, 3,681 in all86%
  6. Shoal PointFairfield County, best late June · 31 checklists that week, 312 in all86%

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

Best time of day

In Connecticut, the Common Tern is most often listed on checklists started between 5 and 7 pm (2.7% of those checklists).

0%1%2%3%4%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: 2.8% of 33657 checklists7 am: 2.1% of 62964 checklists8 am: 2.6% of 70645 checklists9 am: 2.6% of 64870 checklists10 am: 2.4% of 58827 checklists11 am: 2.2% of 51689 checklists12 pm: 2.1% of 45288 checklists1 pm: 2.1% of 44765 checklists2 pm: 2.1% of 44173 checklists3 pm: 1.9% of 41979 checklists4 pm: 2.3% of 33219 checklists5 pm: 2.6% of 24828 checklists6 pm: 3.0% 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%0%
April0%0.1%0.1%0.2%
May1.3%3.1%4.6%5.4%
June5.1%4.6%4.8%7.1%
July7.9%9.7%11%13%
August14%13%10%6.3%
September3.5%1.8%1.1%0.4%
October0.2%0.1%0.1%0.1%
November0.1%0%0%0.1%
December0%0%0%0%

Neighboring states

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

Common questions

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