WhenToBird

Nannopterum auritum · Phalacrocoracidae

When Do Double-crested Cormorants Arrive in Montana?

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

Double-crested Cormorants reach Montana in mid March, are common by the second week of April, peak in late August (11% of checklists), and most are gone by mid October.

When to look

First arrivalsMar 15-21mid March
Common byApr 8-14the second week of April
PeakAug 22-31late August
Most gone byOct 15-21mid October

Best: late August. First arrivals mid March; most are gone by mid October. Peak: on about 11% of Montana checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Maruncommon
  4. Aprcommon
  5. Maycommon
  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%15%Jan 1-7: 0.2% of 7987 checklistsJan 8-14: 0.1% of 5561 checklistsJan 15-21: 0.1% of 5613 checklistsJan 22-31: 0.1% of 7881 checklistsFeb 1-7: 0.1% of 5018 checklistsFeb 8-14: 0.1% of 5598 checklistsFeb 15-21: 0.1% of 7247 checklistsFeb 22-28: 0.1% of 5531 checklistsMar 1-7: 0.2% of 6110 checklistsMar 8-14: 0.3% of 6623 checklistsMar 15-21: 0.4% of 7687 checklistsMar 22-31: 2.0% of 11095 checklistsApr 1-7: 3.3% of 7774 checklistsApr 8-14: 4.5% of 8785 checklistsApr 15-21: 6.2% of 9684 checklistsApr 22-30: 7.2% of 13805 checklistsMay 1-7: 6.6% of 11847 checklistsMay 8-14: 7.2% of 13547 checklistsMay 15-21: 6.3% of 13019 checklistsMay 22-31: 6.5% of 20456 checklistsJun 1-7: 5.8% of 12993 checklistsJun 8-14: 5.8% of 11594 checklistsJun 15-21: 6.0% of 11159 checklistsJun 22-30: 5.8% of 13786 checklistsJul 1-7: 5.3% of 9584 checklistsJul 8-14: 5.6% of 9078 checklistsJul 15-21: 6.1% of 7905 checklistsJul 22-31: 7.7% of 10906 checklistsAug 1-7: 9.0% of 7335 checklistsAug 8-14: 10% of 6868 checklistsAug 15-21: 11% of 6866 checklistsAug 22-31: 11% of 10076 checklistsSep 1-7: 11% of 7670 checklistsSep 8-14: 10% of 7490 checklistsSep 15-21: 11% of 6804 checklistsSep 22-30: 9.2% of 8016 checklistsOct 1-7: 7.5% of 5996 checklistsOct 8-14: 5.5% of 6156 checklistsOct 15-21: 4.1% of 5742 checklistsOct 22-31: 2.3% of 7790 checklistsNov 1-7: 2.4% of 5353 checklistsNov 8-14: 1.6% of 5475 checklistsNov 15-21: 1.2% of 4603 checklistsNov 22-30: 1.1% of 6067 checklistsDec 1-7: 0.7% of 4362 checklistsDec 8-14: 0.4% of 4467 checklistsDec 15-21: 0.3% of 5328 checklistsDec 22-31: 0.2% of 6672 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 Montana 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 Montana

Best counties

Share of checklists at the peak
  1. Deer Lodge CountyBest the second week of August · 158 checklists that week, 8,732 in all49%
  2. Broadwater CountyBest mid August · 84 checklists that week, 2,470 in all44%
  3. Teton CountyBest late April · 81 checklists that week, 2,579 in all41%
  4. Cascade CountyBest the second week of September · 344 checklists that week, 16,190 in all40%
  5. Sheridan CountyBest early August · 19 checklists that week, 2,316 in all38%
  6. McCone CountyBest late August · 15 checklists that week, 537 in all36%

Best spots

Share of checklists at the peak
  1. Kicking Horse ReservoirLake County, best late August · 21 checklists that week, 661 in all90%
  2. Giant Springs State ParkCascade County, best late August · 26 checklists that week, 1,249 in all88%
  3. Canyon Ferry Wildlife Management AreaBroadwater County, best early September · 30 checklists that week, 301 in all87%
  4. Cottonwood ReservoirPark County, best mid August · 24 checklists that week, 638 in all85%
  5. Helena Valley Reservoir Fishing Access SiteLewis and Clark County, best mid August · 24 checklists that week, 1,628 in all85%
  6. Warm Springs Wildlife Management AreaDeer Lodge County, best mid April · 30 checklists that week, 838 in all85%

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

Best time of day

In Montana, the Double-crested Cormorant is most often listed on checklists started between 6 and 8 am (6.6% of those checklists).

0%5%10%12 am: too few checklists (183) to judge1 am: too few checklists (169) to judge2 am: too few checklists (163) to judge3 am: too few checklists (212) to judge4 am: too few checklists (503) to judge5 am: too few checklists (4022) to judge6 am: 8.4% of 12719 checklists7 am: 5.9% of 31202 checklists8 am: 4.8% of 47646 checklists9 am: 4.8% of 44624 checklists10 am: 4.8% of 40704 checklists11 am: 4.5% of 33825 checklists12 pm: 4.4% of 29407 checklists1 pm: 4.5% of 27959 checklists2 pm: 4.0% of 26928 checklists3 pm: 4.1% of 25313 checklists4 pm: 4.4% of 22151 checklists5 pm: 5.2% of 16884 checklists6 pm: 8.2% of 13780 checklists7 pm: 4.4% of 9926 checklists8 pm: too few checklists (5765) to judge9 pm: too few checklists (2099) to judge10 pm: too few checklists (595) to judge11 pm: too few checklists (230) 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
January0.2%0.1%0.1%0.1%
February0.1%0.1%0.1%0.1%
March0.2%0.3%0.4%2.0%
April3.3%4.5%6.2%7.2%
May6.6%7.2%6.3%6.5%
June5.8%5.8%6.0%5.8%
July5.3%5.6%6.1%7.7%
August9.0%10%11%11%
September11%10%11%9.2%
October7.5%5.5%4.1%2.3%
November2.4%1.6%1.2%1.1%
December0.7%0.4%0.3%0.2%

Neighboring states

  • Idaho: arrives the second week of July, 15 weeks later than Montana
  • Wyoming: arrives late March, 1 week later than Montana
  • Utah: arrives early January, 10 weeks earlier than Montana
  • Washington: arrives early September, 22 weeks later than Montana

Common questions

When do Double-crested Cormorants arrive in Montana?
Double-crested Cormorants reach Montana in mid March, are common by the second week of April, peak in late August (11% of checklists), and most are gone by mid October.
When do Double-crested Cormorants leave Montana?
Most Double-crested Cormorants have left Montana 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 Montana?
The Double-crested Cormorant is reported most often in late August, on about 11% of Montana checklists.
Where in Montana are Double-crested Cormorants seen most often?
By county, Deer Lodge County, Broadwater County, and Teton County have the highest peak reporting rates for the Double-crested Cormorant (counties with at least 200 checklists).