WhenToBird

Somateria mollissima · Anatidae

When Do Common Eiders Arrive in Connecticut?

Adult male Common Eider
Photo: Christoph Moning, CC BY 4.0 via iNaturalist

Common Eiders are winter birds in Connecticut: they arrive in the second week of November, peak in early January (3.8% of checklists), and most are gone by the second week of March.

When to look

First arrivalsNov 8-14the second week of November
Common byNov 8-14the second week of November
PeakJan 1-7early January
Most gone byMar 8-14the second week of March

Best: early January. First arrivals the second week of November; most are gone by the second week of March. Peak: on about 3.8% of Connecticut checklists.

  1. Janpeak season
  2. Febpeak season
  3. Maruncommon
  4. Apruncommon
  5. Mayrare
  6. Junrare
  7. Julrare
  8. Augrare
  9. Seprare
  10. Octuncommon
  11. Novcommon
  12. Decpeak season

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

0%2%4%6%Jan 1-7: 3.5% of 18950 checklistsJan 8-14: 3.6% of 13676 checklistsJan 15-21: 3.5% of 13377 checklistsJan 22-31: 3.2% of 17004 checklistsFeb 1-7: 3.1% of 10218 checklistsFeb 8-14: 2.4% of 11568 checklistsFeb 15-21: 1.1% of 15916 checklistsFeb 22-28: 1.6% of 11413 checklistsMar 1-7: 1.4% of 10754 checklistsMar 8-14: 1.3% of 12051 checklistsMar 15-21: 1.0% of 12616 checklistsMar 22-31: 0.9% of 17801 checklistsApr 1-7: 0.6% of 13186 checklistsApr 8-14: 0.3% of 14428 checklistsApr 15-21: 0.3% of 14738 checklistsApr 22-30: 0.2% of 21753 checklistsMay 1-7: 0.3% of 22494 checklistsMay 8-14: 0.3% of 23363 checklistsMay 15-21: 0.3% of 20219 checklistsMay 22-31: 0.3% of 20778 checklistsJun 1-7: 0.4% of 12234 checklistsJun 8-14: 0.4% of 12491 checklistsJun 15-21: 0.4% of 10856 checklistsJun 22-30: 0.4% of 11964 checklistsJul 1-7: 0.4% of 9437 checklistsJul 8-14: 0.4% of 8599 checklistsJul 15-21: 0.5% of 8252 checklistsJul 22-31: 0.4% of 11329 checklistsAug 1-7: 0.2% of 8116 checklistsAug 8-14: 0.5% of 8051 checklistsAug 15-21: 0.6% of 8502 checklistsAug 22-31: 0.5% of 13673 checklistsSep 1-7: 0.6% of 9873 checklistsSep 8-14: 0.5% of 9735 checklistsSep 15-21: 0.4% of 10120 checklistsSep 22-30: 0.6% of 12543 checklistsOct 1-7: 0.6% of 10735 checklistsOct 8-14: 0.4% of 10869 checklistsOct 15-21: 0.2% of 10436 checklistsOct 22-31: 0.7% of 13808 checklistsNov 1-7: 0.9% of 10507 checklistsNov 8-14: 1.4% of 9827 checklistsNov 15-21: 1.8% of 9904 checklistsNov 22-30: 2.4% of 13396 checklistsDec 1-7: 2.7% of 8974 checklistsDec 8-14: 2.8% of 9468 checklistsDec 15-21: 2.2% of 11614 checklistsDec 22-31: 4.2% 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 London CountyBest mid January · 1490 checklists that week, 65,205 in all20%
  2. New Haven CountyBest early December · 1921 checklists that week, 139,721 in all4.3%
  3. Middlesex CountyBest early January · 1226 checklists that week, 39,919 in all1.3%
  4. Fairfield CountyBest early January · 5158 checklists that week, 139,848 in all0.9%

Best spots

Share of checklists at the peak
  1. Town BeachNew London County, best late September · 21 checklists that week, 222 in all95%
  2. Stonington PointNew London County, best early January · 95 checklists that week, 1,092 in all93%
  3. Enders IslandNew London County, best mid January · 23 checklists that week, 303 in all89%
  4. Ocean Beach ParkNew London County, best mid March · 22 checklists that week, 569 in all88%
  5. MistackNew London County, best early January · 33 checklists that week, 294 in all74%
  6. Harkness Memorial State ParkNew London County, best late January · 76 checklists that week, 2,880 in all73%

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

Best time of day

In Connecticut, the Common Eider is most often listed on checklists started between 11 am and 1 pm (1.7% 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: 0.4% of 33657 checklists7 am: 0.8% of 62964 checklists8 am: 1.4% of 70645 checklists9 am: 1.4% of 64870 checklists10 am: 1.6% of 58827 checklists11 am: 1.7% of 51689 checklists12 pm: 1.6% of 45288 checklists1 pm: 1.6% of 44765 checklists2 pm: 1.6% of 44173 checklists3 pm: 1.2% of 41979 checklists4 pm: 0.6% of 33219 checklists5 pm: 0.3% of 24828 checklists6 pm: 0.3% 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
January3.5%3.6%3.5%3.2%
February3.1%2.4%1.1%1.6%
March1.4%1.3%1.0%0.9%
April0.6%0.3%0.3%0.2%
May0.3%0.3%0.3%0.3%
June0.4%0.4%0.4%0.4%
July0.4%0.4%0.5%0.4%
August0.2%0.5%0.6%0.5%
September0.6%0.5%0.4%0.6%
October0.6%0.4%0.2%0.7%
November0.9%1.4%1.8%2.4%
December2.7%2.8%2.2%4.2%

Neighboring states

  • Rhode Island: arrives the second week of November, in the same week than Connecticut
  • Massachusetts: arrives the second week of November, in the same week than Connecticut
  • New Jersey: arrives the second week of November, in the same week than Connecticut
  • New York: arrives mid November, 1 week later than Connecticut

Common questions

When do Common Eiders arrive in Connecticut?
Common Eiders are winter birds in Connecticut: they arrive in the second week of November, peak in early January (3.8% of checklists), and most are gone by the second week of March.
When do Common Eiders leave Connecticut?
Most Common Eiders have left Connecticut by the second week of March, when reports fall below half their usual rate. Stragglers are still reported until mid March.
When is the best time to see a Common Eider in Connecticut?
The Common Eider is reported most often in early January, on about 3.8% of Connecticut checklists.
Where in Connecticut are Common Eiders seen most often?
By county, New London County, New Haven County, and Middlesex County have the highest peak reporting rates for the Common Eider (counties with at least 200 checklists).