WhenToBird

Sternula antillarum · Laridae

When Do Least Terns Arrive in Connecticut?

Adult Least Tern
Photo: datadan, CC BY 4.0 via iNaturalist

Least Terns reach Connecticut in early May, are common by the second week of May, peak in late July (8.5% of checklists), and most are gone by mid August.

When to look

First arrivalsMay 1-7early May
Common byMay 8-14the second week of May
PeakJul 22-31late July
Most gone byAug 15-21mid August

Best: late July. First arrivals early May; most are gone by mid August. Peak: on about 8.5% of Connecticut checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprnot usually seen
  5. Maycommon
  6. Juncommon
  7. Julpeak season
  8. Augpeak season
  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%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% of 14428 checklistsApr 15-21: 0% of 14738 checklistsApr 22-30: 0.1% of 21753 checklistsMay 1-7: 0.8% of 22494 checklistsMay 8-14: 2.7% of 23363 checklistsMay 15-21: 4.7% of 20219 checklistsMay 22-31: 5.6% of 20778 checklistsJun 1-7: 5.0% of 12234 checklistsJun 8-14: 4.1% of 12491 checklistsJun 15-21: 3.7% of 10856 checklistsJun 22-30: 4.6% of 11964 checklistsJul 1-7: 5.3% of 9437 checklistsJul 8-14: 7.5% of 8599 checklistsJul 15-21: 7.9% of 8252 checklistsJul 22-31: 9.3% of 11329 checklistsAug 1-7: 8.1% of 8116 checklistsAug 8-14: 5.9% of 8051 checklistsAug 15-21: 3.4% of 8502 checklistsAug 22-31: 1.8% of 13673 checklistsSep 1-7: 0.5% of 9873 checklistsSep 8-14: 0.1% of 9735 checklistsSep 15-21: 0.1% of 10120 checklistsSep 22-30: 0% of 12543 checklistsOct 1-7: 0% of 10735 checklistsOct 8-14: 0% of 10869 checklistsOct 15-21: 0% of 10436 checklistsOct 22-31: 0% of 13808 checklistsNov 1-7: 0% of 10507 checklistsNov 8-14: 0% of 9827 checklistsNov 15-21: 0% of 9904 checklistsNov 22-30: 0% 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.

Embed this map on your site

Where in Connecticut

Best counties

Share of checklists at the peak
  1. New Haven CountyBest mid July · 1766 checklists that week, 139,721 in all26%
  2. New London CountyBest late July · 1243 checklists that week, 65,205 in all12%
  3. Fairfield CountyBest late July · 2415 checklists that week, 139,848 in all5.5%
  4. Middlesex CountyBest mid July · 474 checklists that week, 39,919 in all4.2%

Best spots

Share of checklists at the peak
  1. Beard Cove (historical) (Cedar Beach)New Haven County, best the second week of July · 22 checklists that week, 1,177 in all93%
  2. Morse ParkNew Haven County, best late June · 97 checklists that week, 3,681 in all90%
  3. Beard Cove (historical)New Haven County, best the second week of July · 193 checklists that week, 8,925 in all85%
  4. Harkness Memorial State ParkNew London County, best the second week of July · 40 checklists that week, 2,880 in all85%
  5. Great Island MarshesNew London County, best mid May · 20 checklists that week, 439 in all81%
  6. Great MeadowsFairfield County, best mid May · 62 checklists that week, 3,190 in all76%

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

Best time of day

In Connecticut, the Least Tern is most often listed on checklists started between 9 and 11 am (1.8% of those checklists).

0%0.5%1%1.5%2%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: 1.4% of 33657 checklists7 am: 1.1% of 62964 checklists8 am: 1.6% of 70645 checklists9 am: 1.8% of 64870 checklists10 am: 1.7% of 58827 checklists11 am: 1.7% of 51689 checklists12 pm: 1.6% of 45288 checklists1 pm: 1.6% of 44765 checklists2 pm: 1.5% of 44173 checklists3 pm: 1.4% of 41979 checklists4 pm: 1.6% of 33219 checklists5 pm: 1.7% of 24828 checklists6 pm: 1.8% 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%0%
April0%0%0%0.1%
May0.8%2.7%4.7%5.6%
June5.0%4.1%3.7%4.6%
July5.3%7.5%7.9%9.3%
August8.1%5.9%3.4%1.8%
September0.5%0.1%0.1%0%
October0%0%0%0%
November0%0%0%0%
December0%0%0%0%

Neighboring states

  • Rhode Island: arrives early May, in the same week than Connecticut
  • Massachusetts: arrives early May, in the same week than Connecticut
  • New Jersey: arrives late April, 1 week earlier than Connecticut
  • New York: arrives mid May, 2 weeks later than Connecticut

Common questions

When do Least Terns arrive in Connecticut?
Least Terns reach Connecticut in early May, are common by the second week of May, peak in late July (8.5% of checklists), and most are gone by mid August.
When do Least Terns leave Connecticut?
Most Least Terns have left Connecticut by mid August, when reports fall below half their usual rate. Stragglers are still reported until late August.
When is the best time to see a Least Tern in Connecticut?
The Least Tern is reported most often in late July, on about 8.5% of Connecticut checklists.
Where in Connecticut are Least Terns seen most often?
By county, New Haven County, New London County, and Fairfield County have the highest peak reporting rates for the Least Tern (counties with at least 200 checklists).