WhenToBird

Larus smithsonianus · Laridae

When Do American Herring Gulls Arrive in Wyoming?

Adult American Herring Gull
Photo: Priya Sandhu, CC BY 4.0 via iNaturalist

American Herring Gulls are winter birds in Wyoming: they arrive in mid September, peak in the second week of November (2.7% of checklists), and most are gone by mid December.

When to look

First arrivalsSep 15-21mid September
Common bySep 15-21mid September
PeakNov 8-14the second week of November
Most gone byDec 15-21mid December

Best: the second week of November. First arrivals mid September; most are gone by mid December. Peak: on about 2.7% of Wyoming checklists.

  1. Jannot usually seen
  2. Febrare
  3. Marcommon
  4. Aprcommon
  5. Mayrare
  6. Junnot usually seen
  7. Julnot usually seen
  8. Augnot usually seen
  9. Seprare
  10. Octcommon
  11. Novpeak season
  12. Deccommon

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

0%1%2%3%4%Jan 1-7: 0% of 2543 checklistsJan 8-14: 0.1% of 2114 checklistsJan 15-21: 0% of 1984 checklistsJan 22-31: 0% of 2605 checklistsFeb 1-7: 0% of 1940 checklistsFeb 8-14: 0% of 1954 checklistsFeb 15-21: 0% of 2575 checklistsFeb 22-28: 0.1% of 1932 checklistsMar 1-7: 0.4% of 2486 checklistsMar 8-14: 1.2% of 2535 checklistsMar 15-21: 1.4% of 2726 checklistsMar 22-31: 2.0% of 4349 checklistsApr 1-7: 1.9% of 3300 checklistsApr 8-14: 1.2% of 3500 checklistsApr 15-21: 1.3% of 3701 checklistsApr 22-30: 0.4% of 5887 checklistsMay 1-7: 0.2% of 5341 checklistsMay 8-14: 0.1% of 6910 checklistsMay 15-21: 0.1% of 6884 checklistsMay 22-31: 0.1% of 10652 checklistsJun 1-7: 0% of 6807 checklistsJun 8-14: 0.1% of 6714 checklistsJun 15-21: 0.1% of 6708 checklistsJun 22-30: 0% of 8160 checklistsJul 1-7: 0% of 5755 checklistsJul 8-14: 0% of 5379 checklistsJul 15-21: 0% of 5299 checklistsJul 22-31: 0% of 6830 checklistsAug 1-7: 0.1% of 4581 checklistsAug 8-14: 0.1% of 4625 checklistsAug 15-21: 0.1% of 4466 checklistsAug 22-31: 0.1% of 6562 checklistsSep 1-7: 0.1% of 4543 checklistsSep 8-14: 0.2% of 4652 checklistsSep 15-21: 0.4% of 4186 checklistsSep 22-30: 0.2% of 5301 checklistsOct 1-7: 0.5% of 3248 checklistsOct 8-14: 1.1% of 3010 checklistsOct 15-21: 1.1% of 2624 checklistsOct 22-31: 1.5% of 3170 checklistsNov 1-7: 2.1% of 2110 checklistsNov 8-14: 3.0% of 2153 checklistsNov 15-21: 2.9% of 1971 checklistsNov 22-30: 1.8% of 2136 checklistsDec 1-7: 1.0% of 1646 checklistsDec 8-14: 0.9% of 1609 checklistsDec 15-21: 0.3% of 1954 checklistsDec 22-31: 0.1% of 2392 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 Wyoming 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 Wyoming

Best counties

Share of checklists at the peak
  1. Natrona CountyBest mid November · 53 checklists that week, 5,810 in all14%
  2. Albany CountyBest mid March · 333 checklists that week, 21,857 in all9.0%
  3. Platte CountyBest mid March · 14 checklists that week, 1,645 in all8.2%
  4. Carbon CountyBest early December · 16 checklists that week, 6,429 in all6.7%
  5. Johnson CountyBest the second week of November · 104 checklists that week, 5,977 in all3.9%
  6. Sweetwater CountyBest early November · 23 checklists that week, 5,064 in all3.9%

Best spots

Share of checklists at the peak
  1. Lake Hattie ReservoirAlbany County, best late November · 23 checklists that week, 476 in all73%
  2. Gelatt LakeAlbany County, best late March · 21 checklists that week, 180 in all37%
  3. Meeboer LakeAlbany County, best late March · 33 checklists that week, 300 in all33%
  4. Twin Buttes LakeAlbany County, best late March · 23 checklists that week, 405 in all31%
  5. Osterman LakeAlbany County, best late March · 59 checklists that week, 543 in all25%

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

Best time of day

In Wyoming, the American Herring Gull is most often listed on checklists started between 10 am and 12 pm (0.5% of those checklists).

0%0.5%1%12 am: too few checklists (59) to judge1 am: too few checklists (76) to judge2 am: too few checklists (86) to judge3 am: too few checklists (79) to judge4 am: too few checklists (326) to judge5 am: too few checklists (2271) to judge6 am: 0.1% of 8808 checklists7 am: 0.4% of 18458 checklists8 am: 0.5% of 22143 checklists9 am: 0.4% of 21499 checklists10 am: 0.5% of 19425 checklists11 am: 0.5% of 16017 checklists12 pm: 0.5% of 13868 checklists1 pm: 0.5% of 12984 checklists2 pm: 0.5% of 12605 checklists3 pm: 0.5% of 11821 checklists4 pm: 0.4% of 10571 checklists5 pm: 0.3% of 8746 checklists6 pm: 0.1% of 6707 checklists7 pm: 0.1% of 4890 checklists8 pm: too few checklists (2323) to judge9 pm: too few checklists (554) to judge10 pm: too few checklists (134) to judge11 pm: too few checklists (59) 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%0.1%0%0%
February0%0%0%0.1%
March0.4%1.2%1.4%2.0%
April1.9%1.2%1.3%0.4%
May0.2%0.1%0.1%0.1%
June0%0.1%0.1%0%
July0%0%0%0%
August0.1%0.1%0.1%0.1%
September0.1%0.2%0.4%0.2%
October0.5%1.1%1.1%1.5%
November2.1%3.0%2.9%1.8%
December1.0%0.9%0.3%0.1%

Neighboring states

  • Colorado: arrives early October, 2 weeks later than Wyoming
  • Utah: arrives mid October, 4 weeks later than Wyoming
  • Montana: arrives mid September, in the same week than Wyoming
  • Idaho: arrives late September, 1 week later than Wyoming

Common questions

When do American Herring Gulls arrive in Wyoming?
American Herring Gulls are winter birds in Wyoming: they arrive in mid September, peak in the second week of November (2.7% of checklists), and most are gone by mid December.
When do American Herring Gulls leave Wyoming?
Most American Herring Gulls have left Wyoming by mid December, when reports fall below half their usual rate.
When is the best time to see a American Herring Gull in Wyoming?
The American Herring Gull is reported most often in the second week of November, on about 2.7% of Wyoming checklists.
Where in Wyoming are American Herring Gulls seen most often?
By county, Natrona County, Albany County, and Platte County have the highest peak reporting rates for the American Herring Gull (counties with at least 200 checklists).