WhenToBird

Vireo griseus · Vireonidae

When Do White-eyed Vireos Arrive in Pennsylvania?

Adult White-eyed Vireo
Photo: Amber M. King, CC BY 4.0 via iNaturalist

White-eyed Vireos arrive in Pennsylvania in mid April, peak in the second week of May (2.9% of checklists), and most are gone by late September.

When to look

First arrivalsApr 15-21mid April
Common byApr 15-21mid April
PeakMay 8-14the second week of May
Most gone bySep 22-30late September

Best: the second week of May. First arrivals mid April; most are gone by late September. Peak: on about 2.9% of Pennsylvania checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprcommon
  5. Maypeak season
  6. Juncommon
  7. Julcommon
  8. Augcommon
  9. Seppeak season
  10. Octuncommon
  11. Novnot usually seen
  12. Decnot usually seen

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

0%1%2%3%Jan 1-7: 0.1% of 47145 checklistsJan 8-14: 0% of 35840 checklistsJan 15-21: 0% of 35423 checklistsJan 22-31: 0% of 49126 checklistsFeb 1-7: 0% of 36366 checklistsFeb 8-14: 0% of 42248 checklistsFeb 15-21: 0% of 55888 checklistsFeb 22-28: 0% of 42050 checklistsMar 1-7: 0.1% of 42709 checklistsMar 8-14: 0.1% of 43985 checklistsMar 15-21: 0% of 44547 checklistsMar 22-31: 0% of 66940 checklistsApr 1-7: 0.1% of 51147 checklistsApr 8-14: 0.1% of 54868 checklistsApr 15-21: 0.6% of 57252 checklistsApr 22-30: 2.1% of 81727 checklistsMay 1-7: 3.0% of 76472 checklistsMay 8-14: 2.9% of 79341 checklistsMay 15-21: 2.7% of 61724 checklistsMay 22-31: 2.3% of 70722 checklistsJun 1-7: 2.0% of 45652 checklistsJun 8-14: 1.7% of 41810 checklistsJun 15-21: 1.7% of 38973 checklistsJun 22-30: 1.7% of 44255 checklistsJul 1-7: 1.7% of 34822 checklistsJul 8-14: 1.6% of 31104 checklistsJul 15-21: 1.4% of 29262 checklistsJul 22-31: 1.3% of 41436 checklistsAug 1-7: 1.0% of 29189 checklistsAug 8-14: 1.0% of 28840 checklistsAug 15-21: 1.0% of 29948 checklistsAug 22-31: 1.5% of 48235 checklistsSep 1-7: 2.5% of 37175 checklistsSep 8-14: 2.8% of 36527 checklistsSep 15-21: 2.2% of 37261 checklistsSep 22-30: 1.0% of 43583 checklistsOct 1-7: 0.4% of 35352 checklistsOct 8-14: 0.1% of 35560 checklistsOct 15-21: 0.1% of 33119 checklistsOct 22-31: 0.1% of 44654 checklistsNov 1-7: 0.1% of 32965 checklistsNov 8-14: 0.1% of 31305 checklistsNov 15-21: 0.1% of 29471 checklistsNov 22-30: 0.1% of 38642 checklistsDec 1-7: 0.1% of 28779 checklistsDec 8-14: 0.1% of 29486 checklistsDec 15-21: 0.1% of 37465 checklistsDec 22-31: 0% of 50651 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 Pennsylvania 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 Pennsylvania

Best counties

Share of checklists at the peak
  1. Greene CountyBest mid September · 38 checklists that week, 2,997 in all24%
  2. Washington CountyBest the second week of September · 357 checklists that week, 23,823 in all13%
  3. Cumberland CountyBest the second week of September · 917 checklists that week, 50,879 in all9.9%
  4. Armstrong CountyBest the second week of May · 354 checklists that week, 11,221 in all8.8%
  5. York CountyBest the second week of May · 1977 checklists that week, 57,382 in all8.3%
  6. Butler CountyBest the second week of May · 1638 checklists that week, 46,093 in all7.9%

Best spots

Share of checklists at the peak
  1. State Game Land 230Cumberland County, best early September · 54 checklists that week, 1,268 in all76%
  2. Safe Harbor Nature PreserveLancaster County, best late April · 36 checklists that week, 437 in all69%
  3. Ridley Creek State Park (Hunting Hill)Delaware County, best the second week of May · 113 checklists that week, 1,073 in all66%
  4. White Clay Creek PreserveChester County, best early July · 27 checklists that week, 944 in all65%
  5. Spring Valley ParkYork County, best late August · 21 checklists that week, 624 in all65%
  6. Nottingham County ParkChester County, best late May · 21 checklists that week, 356 in all61%

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

Best time of day

In Pennsylvania, the White-eyed Vireo is most often listed on checklists started between 6 and 8 am (1.8% of those checklists).

0%1%2%3%12 am: too few checklists (1558) to judge1 am: too few checklists (1136) to judge2 am: too few checklists (839) to judge3 am: too few checklists (842) to judge4 am: too few checklists (2550) to judge5 am: too few checklists (18294) to judge6 am: 2.2% of 92903 checklists7 am: 1.7% of 241233 checklists8 am: 1.4% of 271994 checklists9 am: 1.1% of 236842 checklists10 am: 0.9% of 199508 checklists11 am: 0.7% of 161893 checklists12 pm: 0.6% of 143945 checklists1 pm: 0.5% of 134352 checklists2 pm: 0.5% of 129692 checklists3 pm: 0.4% of 126132 checklists4 pm: 0.4% of 115055 checklists5 pm: 0.6% of 90719 checklists6 pm: 0.6% of 67534 checklists7 pm: 0.4% of 43004 checklists8 pm: too few checklists (13966) to judge9 pm: too few checklists (3913) to judge10 pm: too few checklists (1989) to judge11 pm: too few checklists (1146) 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
January0.1%0%0%0%
February0%0%0%0%
March0.1%0.1%0%0%
April0.1%0.1%0.6%2.1%
May3.0%2.9%2.7%2.3%
June2.0%1.7%1.7%1.7%
July1.7%1.6%1.4%1.3%
August1.0%1.0%1.0%1.5%
September2.5%2.8%2.2%1.0%
October0.4%0.1%0.1%0.1%
November0.1%0.1%0.1%0.1%
December0.1%0.1%0.1%0%

Neighboring states

  • Maryland: arrives the second week of April, 1 week earlier than Pennsylvania
  • District of Columbia: arrives the second week of April, 1 week earlier than Pennsylvania
  • Delaware: arrives the second week of April, 1 week earlier than Pennsylvania
  • New Jersey: arrives the second week of April, 1 week earlier than Pennsylvania

Common questions

When do White-eyed Vireos arrive in Pennsylvania?
White-eyed Vireos arrive in Pennsylvania in mid April, peak in the second week of May (2.9% of checklists), and most are gone by late September.
When do White-eyed Vireos leave Pennsylvania?
Most White-eyed Vireos have left Pennsylvania by late September, when reports fall below half their usual rate.
When is the best time to see a White-eyed Vireo in Pennsylvania?
The White-eyed Vireo is reported most often in the second week of May, on about 2.9% of Pennsylvania checklists.
Where in Pennsylvania are White-eyed Vireos seen most often?
By county, Greene County, Washington County, and Cumberland County have the highest peak reporting rates for the White-eyed Vireo (counties with at least 200 checklists).