WhenToBird

Leiothlypis peregrina · Parulidae

When Do Tennessee Warblers Arrive in Pennsylvania?

Adult Tennessee Warbler
Photo: kcthetc1, CC0 1.0 via iNaturalist

Tennessee Warblers arrive in Pennsylvania in late August, peak in mid September (5.9% of checklists), and most are gone by mid October.

When to look

First arrivalsAug 22-31late August
Common byAug 22-31late August
PeakSep 15-21mid September
Most gone byOct 15-21mid October

Best: mid September. First arrivals late August; most are gone by mid October. Peak: on about 5.9% of Pennsylvania checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Apruncommon
  5. Maypeak season
  6. Junrare
  7. Julnot usually seen
  8. Auguncommon
  9. Seppeak season
  10. Octpeak season
  11. Novnot usually seen
  12. Decnot usually seen

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

0%2%4%6%8%Jan 1-7: 0.1% of 47145 checklistsJan 8-14: 0.1% of 35840 checklistsJan 15-21: 0.1% of 35423 checklistsJan 22-31: 0.1% of 49126 checklistsFeb 1-7: 0% of 36366 checklistsFeb 8-14: 0.1% of 42248 checklistsFeb 15-21: 0.1% of 55888 checklistsFeb 22-28: 0% of 42050 checklistsMar 1-7: 0% of 42709 checklistsMar 8-14: 0% of 43985 checklistsMar 15-21: 0% of 44547 checklistsMar 22-31: 0% of 66940 checklistsApr 1-7: 0% of 51147 checklistsApr 8-14: 0% of 54868 checklistsApr 15-21: 0% of 57252 checklistsApr 22-30: 0.2% of 81727 checklistsMay 1-7: 2.6% of 76472 checklistsMay 8-14: 5.5% of 79341 checklistsMay 15-21: 7.5% of 61724 checklistsMay 22-31: 1.3% of 70722 checklistsJun 1-7: 0.1% of 45652 checklistsJun 8-14: 0.1% of 41810 checklistsJun 15-21: 0.1% of 38973 checklistsJun 22-30: 0% of 44255 checklistsJul 1-7: 0% of 34822 checklistsJul 8-14: 0% of 31104 checklistsJul 15-21: 0.1% of 29262 checklistsJul 22-31: 0.1% of 41436 checklistsAug 1-7: 0.1% of 29189 checklistsAug 8-14: 0.1% of 28840 checklistsAug 15-21: 0.3% of 29948 checklistsAug 22-31: 1.6% of 48235 checklistsSep 1-7: 3.7% of 37175 checklistsSep 8-14: 5.7% of 36527 checklistsSep 15-21: 6.1% of 37261 checklistsSep 22-30: 6.0% of 43583 checklistsOct 1-7: 4.4% of 35352 checklistsOct 8-14: 2.7% of 35560 checklistsOct 15-21: 1.1% of 33119 checklistsOct 22-31: 0.3% 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% of 29486 checklistsDec 15-21: 0.1% of 37465 checklistsDec 22-31: 0.1% 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. Allegheny CountyBest the second week of May · 5457 checklists that week, 152,989 in all18%
  2. Crawford CountyBest the second week of May · 1038 checklists that week, 23,552 in all16%
  3. Mercer CountyBest mid May · 466 checklists that week, 17,853 in all14%
  4. Erie CountyBest late May · 1859 checklists that week, 49,012 in all13%
  5. Somerset CountyBest mid September · 226 checklists that week, 11,903 in all12%
  6. Schuylkill CountyBest mid September · 519 checklists that week, 22,261 in all12%

Best spots

Share of checklists at the peak
  1. Frick Park (northeast 2)Allegheny County, best the second week of May · 35 checklists that week, 453 in all59%
  2. Woodcock Creek LakeCrawford County, best mid September · 29 checklists that week, 389 in all57%
  3. Rutledge Tract AcquisitionAllegheny County, best late September · 24 checklists that week, 552 in all54%
  4. Blue Spruce ParkIndiana County, best mid September · 35 checklists that week, 667 in all54%
  5. Locust Lake State ParkSchuylkill County, best mid September · 41 checklists that week, 919 in all53%
  6. Frick Park (Squirrel Hill)Allegheny County, best the second week of May · 171 checklists that week, 2,146 in all47%

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

Best time of day

In Pennsylvania, the Tennessee Warbler is most often listed on checklists started between 6 and 8 am (2.4% 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: 2.7% of 92903 checklists7 am: 2.3% of 241233 checklists8 am: 1.9% of 271994 checklists9 am: 1.4% 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: 0.5% of 126132 checklists4 pm: 0.6% of 115055 checklists5 pm: 0.7% of 90719 checklists6 pm: 0.5% of 67534 checklists7 pm: 0.2% 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%0.1%0.1%0.1%
February0%0.1%0.1%0%
March0%0%0%0%
April0%0%0%0.2%
May2.6%5.5%7.5%1.3%
June0.1%0.1%0.1%0%
July0%0%0.1%0.1%
August0.1%0.1%0.3%1.6%
September3.7%5.7%6.1%6.0%
October4.4%2.7%1.1%0.3%
November0.1%0.1%0.1%0.1%
December0.1%0%0.1%0.1%

Neighboring states

  • Maryland: arrives late July, 4 weeks earlier than Pennsylvania
  • District of Columbia: arrives mid August, 1 week earlier than Pennsylvania
  • Delaware: arrives late August, in the same week than Pennsylvania
  • New Jersey: arrives mid August, 1 week earlier than Pennsylvania

Common questions

When do Tennessee Warblers arrive in Pennsylvania?
Tennessee Warblers arrive in Pennsylvania in late August, peak in mid September (5.9% of checklists), and most are gone by mid October.
When do Tennessee Warblers leave Pennsylvania?
Most Tennessee Warblers have left Pennsylvania by mid October, when reports fall below half their usual rate.
When is the best time to see a Tennessee Warbler in Pennsylvania?
The Tennessee Warbler is reported most often in mid September, on about 5.9% of Pennsylvania checklists.
Where in Pennsylvania are Tennessee Warblers seen most often?
By county, Allegheny County, Crawford County, and Mercer County have the highest peak reporting rates for the Tennessee Warbler (counties with at least 200 checklists).