WhenToBird

Nannopterum auritum · Phalacrocoracidae

When Do Double-crested Cormorants Arrive in Connecticut?

Adult Double-crested Cormorant
Photo: jubileej, CC0 1.0 via iNaturalist

Double-crested Cormorants reach Connecticut in mid March, are common by early April, peak in late August (25% of checklists), and most are gone by mid November.

When to look

First arrivalsMar 15-21mid March
Common byApr 1-7early April
PeakAug 22-31late August
Most gone byNov 15-21mid November

Best: late August. First arrivals mid March; most are gone by mid November. Peak: on about 25% of Connecticut checklists.

  1. Janrare
  2. Febnot usually seen
  3. Maruncommon
  4. Aprcommon
  5. Maycommon
  6. Juncommon
  7. Julpeak season
  8. Augpeak season
  9. Seppeak season
  10. Octpeak season
  11. Novcommon
  12. Decuncommon

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

0%10%20%30%Jan 1-7: 1.9% of 18950 checklistsJan 8-14: 0.8% of 13676 checklistsJan 15-21: 0.6% of 13377 checklistsJan 22-31: 0.7% of 17004 checklistsFeb 1-7: 0.4% of 10218 checklistsFeb 8-14: 0.3% of 11568 checklistsFeb 15-21: 0.3% of 15916 checklistsFeb 22-28: 0.3% of 11413 checklistsMar 1-7: 0.5% of 10754 checklistsMar 8-14: 0.8% of 12051 checklistsMar 15-21: 2.4% of 12616 checklistsMar 22-31: 6.7% of 17801 checklistsApr 1-7: 12% of 13186 checklistsApr 8-14: 16% of 14428 checklistsApr 15-21: 18% of 14738 checklistsApr 22-30: 17% of 21753 checklistsMay 1-7: 15% of 22494 checklistsMay 8-14: 14% of 23363 checklistsMay 15-21: 14% of 20219 checklistsMay 22-31: 16% of 20778 checklistsJun 1-7: 16% of 12234 checklistsJun 8-14: 15% of 12491 checklistsJun 15-21: 14% of 10856 checklistsJun 22-30: 16% of 11964 checklistsJul 1-7: 17% of 9437 checklistsJul 8-14: 19% of 8599 checklistsJul 15-21: 21% of 8252 checklistsJul 22-31: 23% of 11329 checklistsAug 1-7: 25% of 8116 checklistsAug 8-14: 25% of 8051 checklistsAug 15-21: 25% of 8502 checklistsAug 22-31: 25% of 13673 checklistsSep 1-7: 26% of 9873 checklistsSep 8-14: 23% of 9735 checklistsSep 15-21: 23% of 10120 checklistsSep 22-30: 23% of 12543 checklistsOct 1-7: 22% of 10735 checklistsOct 8-14: 20% of 10869 checklistsOct 15-21: 20% of 10436 checklistsOct 22-31: 20% of 13808 checklistsNov 1-7: 18% of 10507 checklistsNov 8-14: 14% of 9827 checklistsNov 15-21: 9.4% of 9904 checklistsNov 22-30: 6.2% of 13396 checklistsDec 1-7: 4.4% of 8974 checklistsDec 8-14: 2.7% of 9468 checklistsDec 15-21: 1.9% 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 Haven CountyBest late August · 3384 checklists that week, 139,721 in all45%
  2. New London CountyBest the second week of August · 869 checklists that week, 65,205 in all40%
  3. Fairfield CountyBest early August · 1666 checklists that week, 139,848 in all32%
  4. Middlesex CountyBest late August · 834 checklists that week, 39,919 in all20%
  5. Windham CountyBest late August · 396 checklists that week, 19,034 in all14%
  6. Litchfield CountyBest mid October · 1062 checklists that week, 69,766 in all12%

Best spots

Share of checklists at the peak
  1. Stonington PointNew London County, best late August · 23 checklists that week, 1,092 in all100%
  2. Leetes IslandNew Haven County, best the second week of August · 20 checklists that week, 1,057 in all98%
  3. Town BeachNew London County, best early October · 21 checklists that week, 222 in all98%
  4. Compo CoveFairfield County, best late September · 35 checklists that week, 368 in all98%
  5. Harkness Memorial State ParkNew London County, best the second week of September · 58 checklists that week, 2,880 in all98%
  6. Cedar PointFairfield County, best late July · 29 checklists that week, 1,206 in all97%

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

Best time of day

In Connecticut, the Double-crested Cormorant is most often listed on checklists started between 8 and 10 am (13% of those checklists).

0%5%10%15%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: 15% of 33657 checklists7 am: 12% of 62964 checklists8 am: 14% of 70645 checklists9 am: 13% of 64870 checklists10 am: 13% of 58827 checklists11 am: 12% of 51689 checklists12 pm: 11% of 45288 checklists1 pm: 11% of 44765 checklists2 pm: 11% of 44173 checklists3 pm: 12% of 41979 checklists4 pm: 12% of 33219 checklists5 pm: 13% of 24828 checklists6 pm: 12% 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
January1.9%0.8%0.6%0.7%
February0.4%0.3%0.3%0.3%
March0.5%0.8%2.4%6.7%
April12%16%18%17%
May15%14%14%16%
June16%15%14%16%
July17%19%21%23%
August25%25%25%25%
September26%23%23%23%
October22%20%20%20%
November18%14%9.4%6.2%
December4.4%2.7%1.9%2.1%

Neighboring states

  • Rhode Island: arrives the second week of March, 1 week earlier than Connecticut
  • Massachusetts: arrives mid March, in the same week than Connecticut
  • New Jersey: arrives mid July, 16 weeks later than Connecticut
  • New York: arrives the second week of July, 15 weeks later than Connecticut

Common questions

When do Double-crested Cormorants arrive in Connecticut?
Double-crested Cormorants reach Connecticut in mid March, are common by early April, peak in late August (25% of checklists), and most are gone by mid November.
When do Double-crested Cormorants leave Connecticut?
Most Double-crested Cormorants have left Connecticut by mid November, when reports fall below half their usual rate. Stragglers are still reported until late December.
When is the best time to see a Double-crested Cormorant in Connecticut?
The Double-crested Cormorant is reported most often in late August, on about 25% of Connecticut checklists.
Where in Connecticut are Double-crested Cormorants seen most often?
By county, New Haven County, New London County, and Fairfield County have the highest peak reporting rates for the Double-crested Cormorant (counties with at least 200 checklists).