WhenToBird

Coccyzus erythropthalmus · Cuculidae

When Do Black-billed Cuckoos Arrive in Connecticut?

Adult Black-billed Cuckoo
Photo: Bill Keim, CC BY 4.0 via iNaturalist

Black-billed Cuckoos mostly pass through Connecticut: they arrive in the second week of May, peak in late May (2.0% of checklists), and most are gone by the second week of July.

When to look

First arrivalsMay 8-14the second week of May
Common byMay 8-14the second week of May
PeakMay 22-31late May
Most gone byJul 8-14the second week of July

Best: late May. First arrivals the second week of May; most are gone by the second week of July. Peak: on about 2.0% of Connecticut checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprrare
  5. Maypeak season
  6. Junpeak season
  7. Julcommon
  8. Augrare
  9. Seprare
  10. Octrare
  11. Novnot usually seen
  12. Decnot usually seen

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

0%1%2%3%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: 0.3% of 22494 checklistsMay 8-14: 0.9% of 23363 checklistsMay 15-21: 2.1% of 20219 checklistsMay 22-31: 2.3% of 20778 checklistsJun 1-7: 1.4% of 12234 checklistsJun 8-14: 1.0% of 12491 checklistsJun 15-21: 1.0% of 10856 checklistsJun 22-30: 0.8% of 11964 checklistsJul 1-7: 1.0% of 9437 checklistsJul 8-14: 0.7% of 8599 checklistsJul 15-21: 0.4% of 8252 checklistsJul 22-31: 0.3% of 11329 checklistsAug 1-7: 0.2% of 8116 checklistsAug 8-14: 0.1% of 8051 checklistsAug 15-21: 0.1% of 8502 checklistsAug 22-31: 0.1% of 13673 checklistsSep 1-7: 0.2% of 9873 checklistsSep 8-14: 0.1% of 9735 checklistsSep 15-21: 0.1% of 10120 checklistsSep 22-30: 0.2% of 12543 checklistsOct 1-7: 0.1% of 10735 checklistsOct 8-14: 0.1% of 10869 checklistsOct 15-21: 0.1% of 10436 checklistsOct 22-31: 0.1% of 13808 checklistsNov 1-7: 0.1% 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.

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Where in Connecticut

Best counties

Share of checklists at the peak
  1. Windham CountyBest early June · 391 checklists that week, 19,034 in all5.8%
  2. Litchfield CountyBest late May · 2808 checklists that week, 69,766 in all3.8%
  3. Tolland CountyBest early June · 856 checklists that week, 39,004 in all2.7%
  4. Middlesex CountyBest late May · 1452 checklists that week, 39,919 in all2.6%
  5. New London CountyBest late May · 1936 checklists that week, 65,205 in all1.8%
  6. Hartford CountyBest late May · 3441 checklists that week, 105,735 in all1.8%

Best spots

Share of checklists at the peak
  1. Nathan Hale State ForestTolland County, best late May · 26 checklists that week, 297 in all23%
  2. Dooley PondMiddlesex County, best late May · 34 checklists that week, 344 in all21%
  3. Lake ChamberlainNew Haven County, best late May · 28 checklists that week, 463 in all19%

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

Best time of day

In Connecticut, the Black-billed Cuckoo is most often listed on checklists started between 6 and 8 am (0.7% of those checklists).

0%0.5%1%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: 0.8% of 33657 checklists7 am: 0.6% of 62964 checklists8 am: 0.5% of 70645 checklists9 am: 0.3% of 64870 checklists10 am: 0.2% of 58827 checklists11 am: 0.2% of 51689 checklists12 pm: 0.2% of 45288 checklists1 pm: 0.2% of 44765 checklists2 pm: 0.2% of 44173 checklists3 pm: 0.2% of 41979 checklists4 pm: 0.2% of 33219 checklists5 pm: 0.2% 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
January0%0%0%0%
February0%0%0%0%
March0%0%0%0%
April0%0%0%0.1%
May0.3%0.9%2.1%2.3%
June1.4%1.0%1.0%0.8%
July1.0%0.7%0.4%0.3%
August0.2%0.1%0.1%0.1%
September0.2%0.1%0.1%0.2%
October0.1%0.1%0.1%0.1%
November0.1%0%0%0%
December0%0%0%0%

Neighboring states

  • Rhode Island: arrives the second week of May, in the same week than Connecticut
  • Massachusetts: arrives the second week of May, in the same week than Connecticut
  • New Jersey: arrives late April, 2 weeks earlier than Connecticut
  • New York: arrives the second week of May, in the same week than Connecticut

Common questions

When do Black-billed Cuckoos arrive in Connecticut?
Black-billed Cuckoos mostly pass through Connecticut: they arrive in the second week of May, peak in late May (2.0% of checklists), and most are gone by the second week of July.
When do Black-billed Cuckoos leave Connecticut?
Most Black-billed Cuckoos have left Connecticut by the second week of July, when reports fall below half their usual rate.
When is the best time to see a Black-billed Cuckoo in Connecticut?
The Black-billed Cuckoo is reported most often in late May, on about 2.0% of Connecticut checklists.
Where in Connecticut are Black-billed Cuckoos seen most often?
By county, Windham County, Litchfield County, and Tolland County have the highest peak reporting rates for the Black-billed Cuckoo (counties with at least 200 checklists).