WhenToBird

Stercorarius parasiticus · Stercorariidae

When Do Parasitic Jaegers Arrive in Washington?

Adult Parasitic Jaeger
Photo: Christopher Stephens, CC BY-SA 4.0 via iNaturalist

Parasitic Jaegers mostly pass through Washington: they arrive in mid August, peak in the second week of September (1.2% of checklists), and most are gone by late October.

When to look

First arrivalsAug 15-21mid August
Common byAug 15-21mid August
PeakSep 8-14the second week of September
Most gone byOct 22-31late October

Best: the second week of September. First arrivals mid August; most are gone by late October. Peak: on about 1.2% of Washington checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprnot usually seen
  5. Mayrare
  6. Junrare
  7. Julrare
  8. Augcommon
  9. Seppeak season
  10. Octcommon
  11. Novuncommon
  12. Decnot usually seen

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

0%0.5%1%1.5%Jan 1-7: 0% of 41928 checklistsJan 8-14: 0% of 31152 checklistsJan 15-21: 0% of 31753 checklistsJan 22-31: 0% of 42530 checklistsFeb 1-7: 0% of 29739 checklistsFeb 8-14: 0% of 32746 checklistsFeb 15-21: 0% of 40328 checklistsFeb 22-28: 0% of 28432 checklistsMar 1-7: 0% of 30758 checklistsMar 8-14: 0% of 29368 checklistsMar 15-21: 0% of 32580 checklistsMar 22-31: 0% of 45614 checklistsApr 1-7: 0% of 33997 checklistsApr 8-14: 0% of 34729 checklistsApr 15-21: 0% of 38474 checklistsApr 22-30: 0.1% of 52185 checklistsMay 1-7: 0.1% of 44236 checklistsMay 8-14: 0.1% of 48708 checklistsMay 15-21: 0.2% of 41742 checklistsMay 22-31: 0.2% of 57082 checklistsJun 1-7: 0.1% of 39193 checklistsJun 8-14: 0.1% of 36042 checklistsJun 15-21: 0.1% of 34003 checklistsJun 22-30: 0.1% of 39711 checklistsJul 1-7: 0.1% of 31949 checklistsJul 8-14: 0.1% of 29086 checklistsJul 15-21: 0.1% of 28045 checklistsJul 22-31: 0.1% of 38275 checklistsAug 1-7: 0.1% of 28846 checklistsAug 8-14: 0.2% of 28036 checklistsAug 15-21: 0.3% of 27614 checklistsAug 22-31: 0.5% of 40356 checklistsSep 1-7: 1.0% of 31214 checklistsSep 8-14: 1.5% of 27795 checklistsSep 15-21: 1.3% of 29677 checklistsSep 22-30: 0.9% of 35241 checklistsOct 1-7: 0.6% of 28605 checklistsOct 8-14: 0.6% of 28655 checklistsOct 15-21: 0.8% of 24643 checklistsOct 22-31: 0.4% of 34874 checklistsNov 1-7: 0.1% of 25658 checklistsNov 8-14: 0.1% of 25700 checklistsNov 15-21: 0% of 24331 checklistsNov 22-30: 0.1% of 32784 checklistsDec 1-7: 0% of 24099 checklistsDec 8-14: 0% of 23339 checklistsDec 15-21: 0% of 27666 checklistsDec 22-31: 0% of 42130 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 Washington 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 Washington

Best counties

Share of checklists at the peak
  1. Pierce CountyBest the second week of September · 1525 checklists that week, 92,224 in all6.8%
  2. Kitsap CountyBest mid September · 1236 checklists that week, 74,545 in all6.4%
  3. Asotin CountyBest mid September · 38 checklists that week, 4,316 in all3.4%
  4. Grays Harbor CountyBest the second week of September · 953 checklists that week, 28,443 in all1.6%
  5. Whatcom CountyBest mid September · 1201 checklists that week, 64,687 in all1.5%
  6. Island CountyBest mid September · 847 checklists that week, 46,092 in all1.3%

Best spots

Share of checklists at the peak
  1. Dune Peninsula at Point Defiance ParkPierce County, best early September · 155 checklists that week, 4,257 in all56%
  2. Point No PointKitsap County, best late September · 146 checklists that week, 4,564 in all44%
  3. Alki PointKing County, best late May · 33 checklists that week, 1,446 in all44%
  4. Point Defiance Park (northwest)Pierce County, best late September · 20 checklists that week, 446 in all43%
  5. Norwegian Point ParkKitsap County, best mid September · 29 checklists that week, 723 in all35%
  6. Vancouver Lake ParkClark County, best early October · 21 checklists that week, 443 in all28%

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

Best time of day

In Washington, the Parasitic Jaeger 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 (796) to judge1 am: too few checklists (776) to judge2 am: too few checklists (709) to judge3 am: too few checklists (901) to judge4 am: too few checklists (3221) to judge5 am: too few checklists (16576) to judge6 am: 0.4% of 56744 checklists7 am: 0.3% of 133294 checklists8 am: 0.2% of 184196 checklists9 am: 0.2% of 186303 checklists10 am: 0.2% of 177063 checklists11 am: 0.2% of 154936 checklists12 pm: 0.1% of 138061 checklists1 pm: 0.1% of 127449 checklists2 pm: 0.1% of 121511 checklists3 pm: 0.1% of 107793 checklists4 pm: 0.1% of 82862 checklists5 pm: 0.1% of 57183 checklists6 pm: 0.1% of 39886 checklists7 pm: too few checklists (26969) to judge8 pm: too few checklists (12427) to judge9 pm: too few checklists (3658) to judge10 pm: too few checklists (1500) to judge11 pm: too few checklists (834) 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%
May0.1%0.1%0.2%0.2%
June0.1%0.1%0.1%0.1%
July0.1%0.1%0.1%0.1%
August0.1%0.2%0.3%0.5%
September1.0%1.5%1.3%0.9%
October0.6%0.6%0.8%0.4%
November0.1%0.1%0%0.1%
December0%0%0%0%

Neighboring states

  • Alaska: arrives mid May, 12 weeks earlier than Washington
  • New Jersey: arrives mid September, 4 weeks later than Washington

Common questions

When do Parasitic Jaegers arrive in Washington?
Parasitic Jaegers mostly pass through Washington: they arrive in mid August, peak in the second week of September (1.2% of checklists), and most are gone by late October.
When do Parasitic Jaegers leave Washington?
Most Parasitic Jaegers have left Washington by late October, when reports fall below half their usual rate.
When is the best time to see a Parasitic Jaeger in Washington?
The Parasitic Jaeger is reported most often in the second week of September, on about 1.2% of Washington checklists.
Where in Washington are Parasitic Jaegers seen most often?
By county, Pierce County, Kitsap County, and Asotin County have the highest peak reporting rates for the Parasitic Jaeger (counties with at least 200 checklists).