WhenToBird

2 loon species in Connecticut

When Do Loons Arrive in Connecticut?

Adult Common Loon
Photo: Hungry-Sarracenia Photo, CC BY 4.0 via iNaturalist

Common Loons and Red-throated Loons are the loons you are most likely to see in Connecticut. Common Loons are winter birds in Connecticut: the first arrive in mid October, they are common by early November, peak in late January (11% of checklists), and most are gone by mid April.

When to look

First arrivalsOct 15-21mid October
Common byNov 1-7early November
PeakJan 22-31late January
Most gone byApr 15-21mid April

Best: late January. First arrivals mid October; most are gone by mid April. Peak: on about 11% of Connecticut checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marpeak season
  4. Aprcommon
  5. Mayuncommon
  6. Jununcommon
  7. Julrare
  8. Augrare
  9. Seprare
  10. Octuncommon
  11. Novpeak season
  12. Decpeak season

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

Loons in Connecticut, species by species

SpeciesFirst arrivalsCommon byPeakMost gone byPeak %
Common LoonOct 15-21Nov 1-7Jan 22-31Apr 15-2111%
Red-throated LoonOct 15-21Nov 1-7Dec 1-7Apr 8-145.3%
0%5%10%15%Common LoonRed-throated LoonJanFebMarAprMayJunJulAugSepOctNovDec
  • Common Loon
  • Red-throated Loon
Share of complete checklists reporting each species, by week (4 per month). Gaps: fewer than 10 checklists that week.

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.

Where in Connecticut

Best counties for Common Loon

Share of checklists at the peak
  1. New London CountyBest late January · 2072 checklists that week, 65,205 in all31%
  2. Fairfield CountyBest late January · 4195 checklists that week, 139,848 in all18%
  3. New Haven CountyBest late March · 4100 checklists that week, 139,721 in all14%
  4. Middlesex CountyBest early January · 1226 checklists that week, 39,919 in all11%
  5. Litchfield CountyBest the second week of April · 1705 checklists that week, 69,766 in all6.4%
  6. Tolland CountyBest early December · 628 checklists that week, 39,004 in all1.3%

Common questions

When do loons arrive in Connecticut?
Common Loons are winter birds in Connecticut: the first arrive in mid October, they are common by early November, peak in late January (11% of checklists), and most are gone by mid April.
When do loons leave Connecticut?
Most Common Loons have left Connecticut by mid April, when reports fall below half their usual rate. Stragglers are still reported until early June.
When is the best time to see loons in Connecticut?
The Common Loon is reported most often in late January, on about 11% of Connecticut checklists.
Which loons are in Connecticut?
Common Loon and Red-throated Loon are reported regularly; the Common Loon is the most common.