WhenToBird

Aythya marila · Anatidae

When Do Greater Scaups Arrive in Colorado?

Adult Greater Scaup
Photo: Se Lena, CC BY 4.0 via iNaturalist

Greater Scaups are winter birds in Colorado: they arrive in the second week of November, peak in mid March (1.1% of checklists), and most are gone by mid April.

When to look

First arrivalsNov 8-14the second week of November
Common byNov 8-14the second week of November
PeakMar 15-21mid March
Most gone byApr 15-21mid April

Best: mid March. First arrivals the second week of November; most are gone by mid April. Peak: on about 1.1% of Colorado checklists.

  1. Janpeak season
  2. Febcommon
  3. Marpeak season
  4. Aprpeak season
  5. Mayrare
  6. Junnot usually seen
  7. Julnot usually seen
  8. Augnot usually seen
  9. Sepnot usually seen
  10. Octuncommon
  11. Novcommon
  12. Decpeak season

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

0%0.5%1%1.5%Jan 1-7: 1.3% of 32254 checklistsJan 8-14: 1.1% of 23278 checklistsJan 15-21: 0.8% of 22933 checklistsJan 22-31: 0.7% of 30856 checklistsFeb 1-7: 0.6% of 21464 checklistsFeb 8-14: 0.6% of 22910 checklistsFeb 15-21: 0.6% of 28739 checklistsFeb 22-28: 0.7% of 21833 checklistsMar 1-7: 1.0% of 23066 checklistsMar 8-14: 1.0% of 23783 checklistsMar 15-21: 1.2% of 24797 checklistsMar 22-31: 1.2% of 38439 checklistsApr 1-7: 1.0% of 31676 checklistsApr 8-14: 0.8% of 35092 checklistsApr 15-21: 0.6% of 36778 checklistsApr 22-30: 0.2% of 50885 checklistsMay 1-7: 0.1% of 44186 checklistsMay 8-14: 0.1% of 49011 checklistsMay 15-21: 0.1% of 40784 checklistsMay 22-31: 0.1% of 53073 checklistsJun 1-7: 0.1% of 32432 checklistsJun 8-14: 0.1% of 29978 checklistsJun 15-21: 0% of 29457 checklistsJun 22-30: 0% of 36072 checklistsJul 1-7: 0.1% of 28857 checklistsJul 8-14: 0% of 27224 checklistsJul 15-21: 0.1% of 27629 checklistsJul 22-31: 0% of 37318 checklistsAug 1-7: 0% of 25893 checklistsAug 8-14: 0% of 24870 checklistsAug 15-21: 0% of 24035 checklistsAug 22-31: 0% of 35691 checklistsSep 1-7: 0% of 27068 checklistsSep 8-14: 0% of 26709 checklistsSep 15-21: 0% of 26098 checklistsSep 22-30: 0.1% of 31550 checklistsOct 1-7: 0.1% of 24110 checklistsOct 8-14: 0.1% of 23352 checklistsOct 15-21: 0.1% of 21895 checklistsOct 22-31: 0.2% of 28319 checklistsNov 1-7: 0.3% of 21698 checklistsNov 8-14: 0.4% of 21061 checklistsNov 15-21: 0.5% of 19855 checklistsNov 22-30: 0.7% of 25798 checklistsDec 1-7: 0.7% of 18626 checklistsDec 8-14: 0.7% of 19004 checklistsDec 15-21: 0.9% of 23103 checklistsDec 22-31: 0.8% of 30802 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 Colorado 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 Colorado

Best counties

Share of checklists at the peak
  1. Crowley CountyBest early January · 15 checklists that week, 1,883 in all7.9%
  2. Jackson CountyBest early November · 56 checklists that week, 7,472 in all6.1%
  3. Otero CountyBest mid January · 50 checklists that week, 4,404 in all6.0%
  4. Arapahoe CountyBest the second week of January · 2150 checklists that week, 98,030 in all5.5%
  5. Sedgwick CountyBest mid April · 12 checklists that week, 1,168 in all5.5%
  6. Bent CountyBest mid November · 23 checklists that week, 5,275 in all5.3%

Best spots

Share of checklists at the peak
  1. South Platte Pk\ Carson Nature Area (Blackrock Lake)Arapahoe County, best mid January · 25 checklists that week, 395 in all46%
  2. The Ridge Recreation CenterJefferson County, best the second week of March · 37 checklists that week, 1,899 in all46%
  3. South Platte Park/Carson Nature AreaArapahoe County, best mid February · 38 checklists that week, 663 in all40%
  4. Reynolds LandingArapahoe County, best mid February · 24 checklists that week, 350 in all38%
  5. South Platte Pk\ Carson Nature AreaArapahoe County, best mid December · 51 checklists that week, 2,247 in all34%

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

Best time of day

In Colorado, the Greater Scaup is most often listed on checklists started between 1 and 3 pm (0.5% of those checklists).

0%0.5%1%12 am: too few checklists (512) to judge1 am: too few checklists (468) to judge2 am: too few checklists (513) to judge3 am: too few checklists (656) to judge4 am: too few checklists (1918) to judge5 am: too few checklists (16045) to judge6 am: 0.1% of 71991 checklists7 am: 0.2% of 159189 checklists8 am: 0.3% of 177206 checklists9 am: 0.4% of 165269 checklists10 am: 0.4% of 141029 checklists11 am: 0.5% of 115283 checklists12 pm: 0.5% of 96068 checklists1 pm: 0.5% of 89512 checklists2 pm: 0.6% of 86319 checklists3 pm: 0.5% of 82496 checklists4 pm: 0.3% of 71648 checklists5 pm: 0.3% of 52445 checklists6 pm: 0.1% of 40199 checklists7 pm: too few checklists (24246) to judge8 pm: too few checklists (7986) to judge9 pm: too few checklists (2004) to judge10 pm: too few checklists (888) to judge11 pm: too few checklists (450) 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
January1.3%1.1%0.8%0.7%
February0.6%0.6%0.6%0.7%
March1.0%1.0%1.2%1.2%
April1.0%0.8%0.6%0.2%
May0.1%0.1%0.1%0.1%
June0.1%0.1%0%0%
July0.1%0%0.1%0%
August0%0%0%0%
September0%0%0%0.1%
October0.1%0.1%0.1%0.2%
November0.3%0.4%0.5%0.7%
December0.7%0.7%0.9%0.8%

Neighboring states

  • Nebraska: arrives late February, 14 weeks later than Colorado
  • South Dakota: arrives early November, 1 week earlier than Colorado
  • Kansas: arrives early November, 1 week earlier than Colorado
  • Oklahoma: arrives early November, 1 week earlier than Colorado

Common questions

When do Greater Scaups arrive in Colorado?
Greater Scaups are winter birds in Colorado: they arrive in the second week of November, peak in mid March (1.1% of checklists), and most are gone by mid April.
When do Greater Scaups leave Colorado?
Most Greater Scaups have left Colorado by mid April, when reports fall below half their usual rate.
When is the best time to see a Greater Scaup in Colorado?
The Greater Scaup is reported most often in mid March, on about 1.1% of Colorado checklists.
Where in Colorado are Greater Scaups seen most often?
By county, Crowley County, Jackson County, and Otero County have the highest peak reporting rates for the Greater Scaup (counties with at least 200 checklists).