WhenToBird

Phalacrocorax carbo · Phalacrocoracidae

When Do Great Cormorants Arrive in Connecticut?

Adult Great Cormorant
Photo: bemma, CC BY 4.0 via iNaturalist

Great Cormorants are winter birds in Connecticut: they arrive in mid November, peak in mid January (2.7% of checklists), and most are gone by late March.

When to look

First arrivalsNov 15-21mid November
Common byNov 15-21mid November
PeakJan 15-21mid January
Most gone byMar 22-31late March

Best: mid January. First arrivals mid November; most are gone by late March. Peak: on about 2.7% of Connecticut checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marcommon
  4. Apruncommon
  5. Maynot usually seen
  6. Junnot usually seen
  7. Julnot usually seen
  8. Augnot usually seen
  9. Seprare
  10. Octuncommon
  11. Novcommon
  12. Deccommon

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

0%1%2%3%Jan 1-7: 2.2% of 18950 checklistsJan 8-14: 2.5% of 13676 checklistsJan 15-21: 2.8% of 13377 checklistsJan 22-31: 2.8% of 17004 checklistsFeb 1-7: 2.1% of 10218 checklistsFeb 8-14: 1.7% of 11568 checklistsFeb 15-21: 1.3% of 15916 checklistsFeb 22-28: 1.5% of 11413 checklistsMar 1-7: 1.7% of 10754 checklistsMar 8-14: 1.5% of 12051 checklistsMar 15-21: 1.4% of 12616 checklistsMar 22-31: 1.0% of 17801 checklistsApr 1-7: 0.4% of 13186 checklistsApr 8-14: 0.2% of 14428 checklistsApr 15-21: 0.2% of 14738 checklistsApr 22-30: 0.1% of 21753 checklistsMay 1-7: 0.1% of 22494 checklistsMay 8-14: 0.1% of 23363 checklistsMay 15-21: 0.1% of 20219 checklistsMay 22-31: 0.1% of 20778 checklistsJun 1-7: 0.1% of 12234 checklistsJun 8-14: 0.1% of 12491 checklistsJun 15-21: 0% of 10856 checklistsJun 22-30: 0.1% of 11964 checklistsJul 1-7: 0.1% of 9437 checklistsJul 8-14: 0.1% of 8599 checklistsJul 15-21: 0.1% of 8252 checklistsJul 22-31: 0.1% of 11329 checklistsAug 1-7: 0.1% of 8116 checklistsAug 8-14: 0.1% of 8051 checklistsAug 15-21: 0% of 8502 checklistsAug 22-31: 0.1% of 13673 checklistsSep 1-7: 0.1% of 9873 checklistsSep 8-14: 0.1% of 9735 checklistsSep 15-21: 0.2% of 10120 checklistsSep 22-30: 0.2% of 12543 checklistsOct 1-7: 0.5% of 10735 checklistsOct 8-14: 0.3% of 10869 checklistsOct 15-21: 0.4% of 10436 checklistsOct 22-31: 0.7% of 13808 checklistsNov 1-7: 0.6% of 10507 checklistsNov 8-14: 0.7% of 9827 checklistsNov 15-21: 0.9% of 9904 checklistsNov 22-30: 1.4% of 13396 checklistsDec 1-7: 1.7% of 8974 checklistsDec 8-14: 1.2% of 9468 checklistsDec 15-21: 1.4% of 11614 checklistsDec 22-31: 2.1% 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.

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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 all10%
  2. Fairfield CountyBest mid January · 3646 checklists that week, 139,848 in all4.1%
  3. New Haven CountyBest mid January · 2609 checklists that week, 139,721 in all1.7%
  4. Middlesex CountyBest the second week of February · 786 checklists that week, 39,919 in all1.0%
  5. Tolland CountyBest the second week of November · 715 checklists that week, 39,004 in all0.4%
  6. Hartford CountyBest early March · 1741 checklists that week, 105,735 in all0.4%

Best spots

Share of checklists at the peak
  1. Elizabeth Creamer PreserveNew Haven County, best early February · 33 checklists that week, 487 in all76%
  2. Ocean Beach ParkNew London County, best late January · 64 checklists that week, 569 in all69%
  3. Enders IslandNew London County, best late January · 22 checklists that week, 303 in all59%
  4. Osprey BeachNew London County, best late January · 24 checklists that week, 157 in all54%
  5. Harkness Memorial State ParkNew London County, best late January · 76 checklists that week, 2,880 in all52%
  6. Greenwich Point ParkFairfield County, best the second week of February · 54 checklists that week, 2,871 in all48%

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

Best time of day

In Connecticut, the Great Cormorant is most often listed on checklists started between 11 am and 1 pm (1.1% of those checklists).

0%0.5%1%1.5%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: 0.3% of 33657 checklists7 am: 0.7% of 62964 checklists8 am: 0.7% of 70645 checklists9 am: 1.0% of 64870 checklists10 am: 1.0% of 58827 checklists11 am: 1.1% of 51689 checklists12 pm: 1.0% of 45288 checklists1 pm: 0.9% of 44765 checklists2 pm: 1.0% of 44173 checklists3 pm: 0.9% of 41979 checklists4 pm: 0.4% of 33219 checklists5 pm: 0.2% of 24828 checklists6 pm: 0.1% 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
January2.2%2.5%2.8%2.8%
February2.1%1.7%1.3%1.5%
March1.7%1.5%1.4%1.0%
April0.4%0.2%0.2%0.1%
May0.1%0.1%0.1%0.1%
June0.1%0.1%0%0.1%
July0.1%0.1%0.1%0.1%
August0.1%0.1%0%0.1%
September0.1%0.1%0.2%0.2%
October0.5%0.3%0.4%0.7%
November0.6%0.7%0.9%1.4%
December1.7%1.2%1.4%2.1%

Neighboring states

  • Rhode Island: arrives the second week of September, 9 weeks earlier than Connecticut
  • Massachusetts: arrives early October, 6 weeks earlier than Connecticut
  • New Jersey: arrives mid October, 4 weeks earlier than Connecticut
  • New York: arrives late October, 3 weeks earlier than Connecticut

Common questions

When do Great Cormorants arrive in Connecticut?
Great Cormorants are winter birds in Connecticut: they arrive in mid November, peak in mid January (2.7% of checklists), and most are gone by late March.
When do Great Cormorants leave Connecticut?
Most Great Cormorants have left Connecticut by late March, when reports fall below half their usual rate.
When is the best time to see a Great Cormorant in Connecticut?
The Great Cormorant is reported most often in mid January, on about 2.7% of Connecticut checklists.
Where in Connecticut are Great Cormorants seen most often?
By county, New London County, Fairfield County, and New Haven County have the highest peak reporting rates for the Great Cormorant (counties with at least 200 checklists).