WhenToBird

Stercorarius parasiticus · Stercorariidae

When Do Parasitic Jaegers Arrive in Alaska?

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

Parasitic Jaegers arrive in Alaska in mid May, peak in the second week of June (4.3% of checklists), and most are gone by late August.

When to look

First arrivalsMay 15-21mid May
Common byMay 15-21mid May
PeakJun 8-14the second week of June
Most gone byAug 22-31late August

Best: the second week of June. First arrivals mid May; most are gone by late August. Peak: on about 4.3% of Alaska checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprnot usually seen
  5. Maycommon
  6. Junpeak season
  7. Julpeak season
  8. Augcommon
  9. Sepuncommon
  10. Octrare
  11. Novnot usually seen
  12. Decnot usually seen

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

0%2%4%6%Jan 1-7: 0% of 3788 checklistsJan 8-14: 0% of 2852 checklistsJan 15-21: 0% of 2810 checklistsJan 22-31: 0% of 3629 checklistsFeb 1-7: 0% of 2519 checklistsFeb 8-14: 0% of 2927 checklistsFeb 15-21: 0% of 3743 checklistsFeb 22-28: 0% of 2846 checklistsMar 1-7: 0% of 2904 checklistsMar 8-14: 0% of 3073 checklistsMar 15-21: 0% of 3359 checklistsMar 22-31: 0% of 5855 checklistsApr 1-7: 0% of 4329 checklistsApr 8-14: 0% of 4949 checklistsApr 15-21: 0.1% of 7114 checklistsApr 22-30: 0.1% of 10916 checklistsMay 1-7: 0.2% of 11827 checklistsMay 8-14: 0.5% of 14115 checklistsMay 15-21: 1.2% of 12152 checklistsMay 22-31: 1.9% of 19919 checklistsJun 1-7: 3.8% of 15816 checklistsJun 8-14: 4.6% of 17194 checklistsJun 15-21: 4.5% of 15943 checklistsJun 22-30: 3.8% of 16192 checklistsJul 1-7: 3.2% of 9815 checklistsJul 8-14: 3.8% of 8263 checklistsJul 15-21: 3.2% of 7081 checklistsJul 22-31: 2.4% of 9434 checklistsAug 1-7: 1.9% of 6380 checklistsAug 8-14: 1.6% of 6258 checklistsAug 15-21: 1.2% of 6114 checklistsAug 22-31: 1.5% of 8189 checklistsSep 1-7: 1.3% of 5848 checklistsSep 8-14: 0.6% of 4853 checklistsSep 15-21: 0.6% of 4415 checklistsSep 22-30: 0.5% of 5086 checklistsOct 1-7: 0.3% of 3576 checklistsOct 8-14: 0.2% of 4212 checklistsOct 15-21: 0.1% of 3339 checklistsOct 22-31: 0% of 4169 checklistsNov 1-7: 0% of 2844 checklistsNov 8-14: 0% of 2753 checklistsNov 15-21: 0% of 2291 checklistsNov 22-30: 0% of 3066 checklistsDec 1-7: 0% of 2199 checklistsDec 8-14: 0% of 2472 checklistsDec 15-21: 0% of 3071 checklistsDec 22-31: 0% of 3442 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 Alaska 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 Alaska

Best counties

Share of checklists at the peak
  1. Kusilvak Census AreaBest late May · 50 checklists that week, 573 in all34%
  2. North Slope BoroughBest the second week of July · 543 checklists that week, 10,891 in all34%
  3. Yakutat City and BoroughBest the second week of August · 18 checklists that week, 545 in all29%
  4. Bristol Bay BoroughBest late July · 57 checklists that week, 980 in all25%
  5. Aleutians West Census AreaBest early August · 100 checklists that week, 6,087 in all17%
  6. Lake and Peninsula BoroughBest late July · 85 checklists that week, 1,172 in all16%

Best spots

Share of checklists at the peak
  1. Arctic National Wildlife RefugeNorth Slope Borough, best mid July · 41 checklists that week, 522 in all64%
  2. Nerravak LagoonNorth Slope Borough, best mid June · 75 checklists that week, 267 in all59%

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

Best time of day

In Alaska, the Parasitic Jaeger is most often listed on checklists started between 7 and 9 pm (2.3% of those checklists).

0%1%2%3%12 am: too few checklists (549) to judge1 am: too few checklists (365) to judge2 am: too few checklists (291) to judge3 am: too few checklists (624) to judge4 am: too few checklists (1241) to judge5 am: too few checklists (3532) to judge6 am: 1.4% of 9751 checklists7 am: 1.2% of 17236 checklists8 am: 1.3% of 24936 checklists9 am: 1.4% of 30139 checklists10 am: 1.5% of 30866 checklists11 am: 1.5% of 28207 checklists12 pm: 1.3% of 25650 checklists1 pm: 1.6% of 24144 checklists2 pm: 1.5% of 23323 checklists3 pm: 1.6% of 20763 checklists4 pm: 1.9% of 18245 checklists5 pm: 1.8% of 14895 checklists6 pm: 1.9% of 11707 checklists7 pm: 1.9% of 9365 checklists8 pm: 2.9% of 6934 checklists9 pm: too few checklists (4176) to judge10 pm: too few checklists (2050) to judge11 pm: too few checklists (952) 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%0.1%0.1%
May0.2%0.5%1.2%1.9%
June3.8%4.6%4.5%3.8%
July3.2%3.8%3.2%2.4%
August1.9%1.6%1.2%1.5%
September1.3%0.6%0.6%0.5%
October0.3%0.2%0.1%0%
November0%0%0%0%
December0%0%0%0%

Neighboring states

  • Washington: arrives mid August, 12 weeks later than Alaska
  • New Jersey: arrives mid September, 16 weeks later than Alaska

Common questions

When do Parasitic Jaegers arrive in Alaska?
Parasitic Jaegers arrive in Alaska in mid May, peak in the second week of June (4.3% of checklists), and most are gone by late August.
When do Parasitic Jaegers leave Alaska?
Most Parasitic Jaegers have left Alaska by late August, when reports fall below half their usual rate. Stragglers are still reported until early September.
When is the best time to see a Parasitic Jaeger in Alaska?
The Parasitic Jaeger is reported most often in the second week of June, on about 4.3% of Alaska checklists.
Where in Alaska are Parasitic Jaegers seen most often?
By county, Kusilvak Census Area, North Slope Borough, and Yakutat City and Borough have the highest peak reporting rates for the Parasitic Jaeger (counties with at least 200 checklists).