WhenToBird

Vireo philadelphicus · Vireonidae

When Do Philadelphia Vireos Arrive in Connecticut?

Adult Philadelphia Vireo
Photo: Sue Carnahan, CC BY 4.0 via iNaturalist

Philadelphia Vireos mostly pass through Connecticut: they arrive in early September, peak in mid September (1.4% of checklists), and most are gone by early October.

When to look

First arrivalsSep 1-7early September
Common bySep 1-7early September
PeakSep 15-21mid September
Most gone byOct 1-7early October

Best: mid September. First arrivals early September; most are gone by early October. Peak: on about 1.4% of Connecticut checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprnot usually seen
  5. Mayrare
  6. Junnot usually seen
  7. Julnot usually seen
  8. Auguncommon
  9. Seppeak season
  10. Octuncommon
  11. Novnot usually seen
  12. Decnot usually seen

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

0%0.5%1%1.5%2%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% of 21753 checklistsMay 1-7: 0% 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% of 12491 checklistsJun 15-21: 0% of 10856 checklistsJun 22-30: 0% of 11964 checklistsJul 1-7: 0% of 9437 checklistsJul 8-14: 0% of 8599 checklistsJul 15-21: 0% of 8252 checklistsJul 22-31: 0% of 11329 checklistsAug 1-7: 0% of 8116 checklistsAug 8-14: 0.1% of 8051 checklistsAug 15-21: 0.1% of 8502 checklistsAug 22-31: 0.3% of 13673 checklistsSep 1-7: 0.6% of 9873 checklistsSep 8-14: 1.6% of 9735 checklistsSep 15-21: 1.6% of 10120 checklistsSep 22-30: 1.0% of 12543 checklistsOct 1-7: 0.3% of 10735 checklistsOct 8-14: 0.2% of 10869 checklistsOct 15-21: 0.1% of 10436 checklistsOct 22-31: 0% of 13808 checklistsNov 1-7: 0% 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. New London CountyBest mid September · 1000 checklists that week, 65,205 in all3.0%
  2. Litchfield CountyBest mid September · 1052 checklists that week, 69,766 in all1.6%
  3. Fairfield CountyBest the second week of September · 2180 checklists that week, 139,848 in all1.5%
  4. Tolland CountyBest mid September · 637 checklists that week, 39,004 in all1.2%
  5. Middlesex CountyBest the second week of September · 621 checklists that week, 39,919 in all1.1%
  6. Windham CountyBest the second week of September · 235 checklists that week, 19,034 in all1.0%

Best spots

Share of checklists at the peak
  1. Bluff PointNew London County, best late September · 113 checklists that week, 770 in all23%
  2. Bluff Point State ParkNew London County, best mid September · 27 checklists that week, 767 in all15%
  3. Fitzgerald PropertyNew Haven County, best the second week of September · 38 checklists that week, 724 in all10%
  4. Veterans ParkFairfield County, best late May · 26 checklists that week, 589 in all9.8%

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

Best time of day

In Connecticut, the Philadelphia Vireo is most often listed on checklists started between 6 and 8 am (0.3% of those checklists).

0%0.5%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: 0.5% of 33657 checklists7 am: 0.3% of 62964 checklists8 am: 0.1% of 70645 checklists9 am: 0.1% of 64870 checklists10 am: 0.1% of 58827 checklists11 am: 0.1% of 51689 checklists12 pm: 0.1% of 45288 checklists1 pm: 0.1% of 44765 checklists2 pm: 0.1% of 44173 checklists3 pm: 0.1% of 41979 checklists4 pm: 0.1% of 33219 checklists5 pm: 0.1% 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
January0%0%0%0%
February0%0%0%0%
March0%0%0%0%
April0%0%0%0%
May0%0.1%0.1%0.1%
June0.1%0%0%0%
July0%0%0%0%
August0%0.1%0.1%0.3%
September0.6%1.6%1.6%1.0%
October0.3%0.2%0.1%0%
November0%0%0%0%
December0%0%0%0%

Neighboring states

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

Common questions

When do Philadelphia Vireos arrive in Connecticut?
Philadelphia Vireos mostly pass through Connecticut: they arrive in early September, peak in mid September (1.4% of checklists), and most are gone by early October.
When do Philadelphia Vireos leave Connecticut?
Most Philadelphia Vireos have left Connecticut by early October, when reports fall below half their usual rate.
When is the best time to see a Philadelphia Vireo in Connecticut?
The Philadelphia Vireo is reported most often in mid September, on about 1.4% of Connecticut checklists.
Where in Connecticut are Philadelphia Vireos seen most often?
By county, New London County, Litchfield County, and Fairfield County have the highest peak reporting rates for the Philadelphia Vireo (counties with at least 200 checklists).