WhenToBird

Calidris alpina · Scolopacidae

When Do Dunlins Arrive in Pennsylvania?

Adult Dunlin
Photo: Paulo Martins, CC BY-SA 4.0 via iNaturalist

Dunlins mostly pass through Pennsylvania: they arrive in the second week of September, peak in early November (1.1% of checklists), and most are gone by early December.

When to look

First arrivalsSep 8-14the second week of September
Common bySep 8-14the second week of September
PeakNov 1-7early November
Most gone byDec 1-7early December

Best: early November. First arrivals the second week of September; most are gone by early December. Peak: on about 1.1% of Pennsylvania checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marrare
  4. Apruncommon
  5. Maycommon
  6. Jununcommon
  7. Julnot usually seen
  8. Augnot usually seen
  9. Seprare
  10. Octpeak season
  11. Novpeak season
  12. Decrare

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

0%0.5%1%1.5%Jan 1-7: 0.1% of 47145 checklistsJan 8-14: 0% of 35840 checklistsJan 15-21: 0.1% of 35423 checklistsJan 22-31: 0.1% of 49126 checklistsFeb 1-7: 0.1% of 36366 checklistsFeb 8-14: 0.1% of 42248 checklistsFeb 15-21: 0.1% of 55888 checklistsFeb 22-28: 0.1% of 42050 checklistsMar 1-7: 0.1% of 42709 checklistsMar 8-14: 0% of 43985 checklistsMar 15-21: 0% of 44547 checklistsMar 22-31: 0.1% of 66940 checklistsApr 1-7: 0.1% of 51147 checklistsApr 8-14: 0.1% of 54868 checklistsApr 15-21: 0.3% of 57252 checklistsApr 22-30: 0.3% of 81727 checklistsMay 1-7: 0.3% of 76472 checklistsMay 8-14: 0.6% of 79341 checklistsMay 15-21: 0.7% of 61724 checklistsMay 22-31: 0.5% 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: 0.1% of 44255 checklistsJul 1-7: 0% of 34822 checklistsJul 8-14: 0.1% 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: 0.1% of 29948 checklistsAug 22-31: 0.1% of 48235 checklistsSep 1-7: 0.1% of 37175 checklistsSep 8-14: 0.1% of 36527 checklistsSep 15-21: 0.1% of 37261 checklistsSep 22-30: 0.1% of 43583 checklistsOct 1-7: 0.2% of 35352 checklistsOct 8-14: 0.3% of 35560 checklistsOct 15-21: 0.6% of 33119 checklistsOct 22-31: 1.2% of 44654 checklistsNov 1-7: 1.4% of 32965 checklistsNov 8-14: 0.8% of 31305 checklistsNov 15-21: 0.4% 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: 0.1% 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.

Embed this map on your site

Where in Pennsylvania

Best counties

Share of checklists at the peak
  1. Snyder CountyBest early December · 45 checklists that week, 5,676 in all17%
  2. Erie CountyBest early November · 748 checklists that week, 49,012 in all8.4%
  3. Lebanon CountyBest late October · 689 checklists that week, 33,727 in all5.2%
  4. Indiana CountyBest early November · 346 checklists that week, 20,768 in all5.0%
  5. Crawford CountyBest early November · 303 checklists that week, 23,552 in all4.9%
  6. Somerset CountyBest early November · 150 checklists that week, 11,903 in all4.7%

Best spots

Share of checklists at the peak
  1. Woodcock Creek Lake (west)Crawford County, best late October · 23 checklists that week, 317 in all50%
  2. Faylor LakeSnyder County, best late November · 23 checklists that week, 752 in all45%
  3. Codorus State ParkYork County, best the second week of November · 25 checklists that week, 603 in all44%

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

Best time of day

In Pennsylvania, the Dunlin is most often listed on checklists started between 5 and 7 pm (0.2% of those checklists).

0%0.5%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: 0.2% of 92903 checklists7 am: 0.2% of 241233 checklists8 am: 0.2% of 271994 checklists9 am: 0.2% of 236842 checklists10 am: 0.2% of 199508 checklists11 am: 0.2% of 161893 checklists12 pm: 0.2% of 143945 checklists1 pm: 0.2% of 134352 checklists2 pm: 0.2% of 129692 checklists3 pm: 0.2% of 126132 checklists4 pm: 0.2% of 115055 checklists5 pm: 0.3% of 90719 checklists6 pm: 0.2% 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%0.1%0.1%
February0.1%0.1%0.1%0.1%
March0.1%0%0%0.1%
April0.1%0.1%0.3%0.3%
May0.3%0.6%0.7%0.5%
June0.1%0.1%0.1%0.1%
July0%0.1%0.1%0.1%
August0.1%0.1%0.1%0.1%
September0.1%0.1%0.1%0.1%
October0.2%0.3%0.6%1.2%
November1.4%0.8%0.4%0.1%
December0.1%0.1%0.1%0.1%

Neighboring states

  • Maryland: arrives the second week of October, 4 weeks later than Pennsylvania
  • Delaware: arrives mid September, 1 week later than Pennsylvania
  • New Jersey: arrives late September, 2 weeks later than Pennsylvania
  • New York: arrives mid September, 1 week later than Pennsylvania

Common questions

When do Dunlins arrive in Pennsylvania?
Dunlins mostly pass through Pennsylvania: they arrive in the second week of September, peak in early November (1.1% of checklists), and most are gone by early December.
When do Dunlins leave Pennsylvania?
Most Dunlins have left Pennsylvania by early December, when reports fall below half their usual rate.
When is the best time to see a Dunlin in Pennsylvania?
The Dunlin is reported most often in early November, on about 1.1% of Pennsylvania checklists.
Where in Pennsylvania are Dunlins seen most often?
By county, Snyder County, Erie County, and Lebanon County have the highest peak reporting rates for the Dunlin (counties with at least 200 checklists).