WhenToBird

Nannopterum auritum · Phalacrocoracidae

When Do Double-crested Cormorants Arrive in Wyoming?

Adult Double-crested Cormorant
Photo: jubileej, CC0 1.0 via iNaturalist

Double-crested Cormorants reach Wyoming in late March, are common by early April, peak in late April (8.2% of checklists), and most are gone by mid October.

When to look

First arrivalsMar 22-31late March
Common byApr 1-7early April
PeakApr 22-30late April
Most gone byOct 15-21mid October

Best: late April. First arrivals late March; most are gone by mid October. Peak: on about 8.2% of Wyoming checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Maruncommon
  4. Aprpeak season
  5. Maypeak season
  6. Juncommon
  7. Julcommon
  8. Augpeak season
  9. Seppeak season
  10. Octcommon
  11. Novuncommon
  12. Decrare

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

0%5%10%Jan 1-7: 0.1% of 2543 checklistsJan 8-14: 0.1% of 2114 checklistsJan 15-21: 0.2% 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% of 1932 checklistsMar 1-7: 0.1% of 2486 checklistsMar 8-14: 0.1% of 2535 checklistsMar 15-21: 0.3% of 2726 checklistsMar 22-31: 1.1% of 4349 checklistsApr 1-7: 4.2% of 3300 checklistsApr 8-14: 7.3% of 3500 checklistsApr 15-21: 8.5% of 3701 checklistsApr 22-30: 8.5% of 5887 checklistsMay 1-7: 7.8% of 5341 checklistsMay 8-14: 7.3% of 6910 checklistsMay 15-21: 6.4% of 6884 checklistsMay 22-31: 5.2% of 10652 checklistsJun 1-7: 3.9% of 6807 checklistsJun 8-14: 3.0% of 6714 checklistsJun 15-21: 3.4% of 6708 checklistsJun 22-30: 3.7% of 8160 checklistsJul 1-7: 3.8% of 5755 checklistsJul 8-14: 4.1% of 5379 checklistsJul 15-21: 4.7% of 5299 checklistsJul 22-31: 5.8% of 6830 checklistsAug 1-7: 5.9% of 4581 checklistsAug 8-14: 5.5% of 4625 checklistsAug 15-21: 7.0% of 4466 checklistsAug 22-31: 7.3% of 6562 checklistsSep 1-7: 6.9% of 4543 checklistsSep 8-14: 8.1% of 4652 checklistsSep 15-21: 6.4% of 4186 checklistsSep 22-30: 6.6% of 5301 checklistsOct 1-7: 5.2% of 3248 checklistsOct 8-14: 4.6% of 3010 checklistsOct 15-21: 3.3% of 2624 checklistsOct 22-31: 2.3% of 3170 checklistsNov 1-7: 1.7% of 2110 checklistsNov 8-14: 1.5% of 2153 checklistsNov 15-21: 1.6% of 1971 checklistsNov 22-30: 0.8% of 2136 checklistsDec 1-7: 0.7% of 1646 checklistsDec 8-14: 0.5% of 1609 checklistsDec 15-21: 0.4% of 1954 checklistsDec 22-31: 0.4% 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. Hot Springs CountyBest the second week of July · 35 checklists that week, 1,345 in all24%
  2. Natrona CountyBest late April · 257 checklists that week, 5,810 in all23%
  3. Platte CountyBest early October · 36 checklists that week, 1,645 in all21%
  4. Goshen CountyBest the second week of September · 27 checklists that week, 1,920 in all20%
  5. Laramie CountyBest mid July · 279 checklists that week, 15,593 in all20%
  6. Uinta CountyBest late August · 58 checklists that week, 1,881 in all16%

Best spots

Share of checklists at the peak
  1. Wyoming Hereford Ranch Reservoir Number OneLaramie County, best mid July · 40 checklists that week, 1,242 in all89%
  2. Grand Teton National ParkTeton County, best early October · 41 checklists that week, 988 in all89%
  3. Twin Buttes LakeAlbany County, best the second week of April · 20 checklists that week, 405 in all76%
  4. State Lands 1111116182Natrona County, best late April · 44 checklists that week, 483 in all67%
  5. Lake Hattie ReservoirAlbany County, best mid September · 22 checklists that week, 476 in all63%
  6. Lions ParkLaramie County, best late April · 68 checklists that week, 1,309 in all63%

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

Best time of day

In Wyoming, the Double-crested Cormorant is most often listed on checklists started between 10 am and 12 pm (4.9% of those checklists).

0%2%4%6%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: 4.5% of 8808 checklists7 am: 4.0% of 18458 checklists8 am: 4.4% of 22143 checklists9 am: 4.6% of 21499 checklists10 am: 4.9% of 19425 checklists11 am: 4.8% of 16017 checklists12 pm: 4.5% of 13868 checklists1 pm: 4.7% of 12984 checklists2 pm: 4.8% of 12605 checklists3 pm: 4.3% of 11821 checklists4 pm: 4.3% of 10571 checklists5 pm: 4.5% of 8746 checklists6 pm: 3.7% of 6707 checklists7 pm: 2.6% 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
January0.1%0.1%0.2%0%
February0%0%0%0%
March0.1%0.1%0.3%1.1%
April4.2%7.3%8.5%8.5%
May7.8%7.3%6.4%5.2%
June3.9%3.0%3.4%3.7%
July3.8%4.1%4.7%5.8%
August5.9%5.5%7.0%7.3%
September6.9%8.1%6.4%6.6%
October5.2%4.6%3.3%2.3%
November1.7%1.5%1.6%0.8%
December0.7%0.5%0.4%0.4%

Neighboring states

  • Colorado: arrives late February, 4 weeks earlier than Wyoming
  • Utah: arrives early January, 11 weeks earlier than Wyoming
  • Montana: arrives mid March, 1 week earlier than Wyoming
  • Idaho: arrives the second week of July, 14 weeks later than Wyoming

Common questions

When do Double-crested Cormorants arrive in Wyoming?
Double-crested Cormorants reach Wyoming in late March, are common by early April, peak in late April (8.2% of checklists), and most are gone by mid October.
When do Double-crested Cormorants leave Wyoming?
Most Double-crested Cormorants have left Wyoming by mid October, when reports fall below half their usual rate. Stragglers are still reported until late November.
When is the best time to see a Double-crested Cormorant in Wyoming?
The Double-crested Cormorant is reported most often in late April, on about 8.2% of Wyoming checklists.
Where in Wyoming are Double-crested Cormorants seen most often?
By county, Hot Springs County, Natrona County, and Platte County have the highest peak reporting rates for the Double-crested Cormorant (counties with at least 200 checklists).