WhenToBird

Podilymbus podiceps · Podicipedidae

When Do Pied-billed Grebes Arrive in Colorado?

Adult Pied-billed Grebe
Photo: Rodrigo Paiva Lázaro, CC BY 4.0 via iNaturalist

Pied-billed Grebes are in Colorado all year, but most are here in fall: numbers build from late September, peak in late October (15% of checklists), and fall back by late November. In the quietest week (mid June) they are still on about 2.0% of checklists.

When to look

Numbers buildSep 22-30late September
PeakOct 22-31late October
Fall back byNov 22-30late November
FewestJun 15-21mid June

Best: late October. Here all year; numbers build from late September and fall back by late November. Peak: on about 15% of Colorado checklists.

  1. Januncommon
  2. Febuncommon
  3. Maruncommon
  4. Aprcommon
  5. Mayuncommon
  6. Jununcommon
  7. Juluncommon
  8. Auguncommon
  9. Sepcommon
  10. Octpeak season
  11. Novpeak season
  12. Deccommon

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

0%5%10%15%20%Jan 1-7: 5.9% of 32254 checklistsJan 8-14: 5.1% of 23278 checklistsJan 15-21: 5.0% of 22933 checklistsJan 22-31: 4.0% of 30856 checklistsFeb 1-7: 3.1% of 21464 checklistsFeb 8-14: 2.8% of 22910 checklistsFeb 15-21: 2.5% of 28739 checklistsFeb 22-28: 2.8% of 21833 checklistsMar 1-7: 2.8% of 23066 checklistsMar 8-14: 2.8% of 23783 checklistsMar 15-21: 3.2% of 24797 checklistsMar 22-31: 3.9% of 38439 checklistsApr 1-7: 5.1% of 31676 checklistsApr 8-14: 5.8% of 35092 checklistsApr 15-21: 7.3% of 36778 checklistsApr 22-30: 6.9% of 50885 checklistsMay 1-7: 5.6% of 44186 checklistsMay 8-14: 4.1% of 49011 checklistsMay 15-21: 3.6% of 40784 checklistsMay 22-31: 2.8% of 53073 checklistsJun 1-7: 2.4% of 32432 checklistsJun 8-14: 2.1% of 29978 checklistsJun 15-21: 2.1% of 29457 checklistsJun 22-30: 2.0% of 36072 checklistsJul 1-7: 2.2% of 28857 checklistsJul 8-14: 2.1% of 27224 checklistsJul 15-21: 2.6% of 27629 checklistsJul 22-31: 2.7% of 37318 checklistsAug 1-7: 3.4% of 25893 checklistsAug 8-14: 4.3% of 24870 checklistsAug 15-21: 4.6% of 24035 checklistsAug 22-31: 5.1% of 35691 checklistsSep 1-7: 6.3% of 27068 checklistsSep 8-14: 7.0% of 26709 checklistsSep 15-21: 7.8% of 26098 checklistsSep 22-30: 9.9% of 31550 checklistsOct 1-7: 10% of 24110 checklistsOct 8-14: 12% of 23352 checklistsOct 15-21: 14% of 21895 checklistsOct 22-31: 15% of 28319 checklistsNov 1-7: 15% of 21698 checklistsNov 8-14: 14% of 21061 checklistsNov 15-21: 11% of 19855 checklistsNov 22-30: 9.0% of 25798 checklistsDec 1-7: 7.3% of 18626 checklistsDec 8-14: 5.4% of 19004 checklistsDec 15-21: 5.1% of 23103 checklistsDec 22-31: 4.7% 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. Huerfano CountyBest early November · 37 checklists that week, 3,008 in all39%
  2. Delta CountyBest early November · 62 checklists that week, 6,509 in all39%
  3. Broomfield CountyBest early October · 287 checklists that week, 16,139 in all38%
  4. Pueblo CountyBest the second week of November · 458 checklists that week, 26,547 in all35%
  5. Rio Blanco CountyBest the second week of November · 51 checklists that week, 2,806 in all33%
  6. Costilla CountyBest mid October · 20 checklists that week, 1,323 in all31%

Best spots

Share of checklists at the peak
  1. Pastorius Reservoir State Wildlife AreaLa Plata County, best early October · 65 checklists that week, 3,014 in all98%
  2. Third CreekAdams County, best late October · 32 checklists that week, 298 in all93%
  3. Rueter-Hess ReservoirDouglas County, best early January · 22 checklists that week, 742 in all90%
  4. Plaster ReservoirBroomfield County, best the second week of October · 78 checklists that week, 2,987 in all89%
  5. Denny Lake ParkMontezuma County, best the second week of November · 20 checklists that week, 834 in all87%
  6. James M. Robb - Colorado River State Park - Connected LakesMesa County, best the second week of November · 23 checklists that week, 1,425 in all86%

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

Best time of day

In Colorado, the Pied-billed Grebe is most often listed on checklists started between 9 and 11 am (6.1% of those checklists).

0%2%4%6%8%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: 4.4% of 71991 checklists7 am: 4.9% of 159189 checklists8 am: 6.1% of 177206 checklists9 am: 6.2% of 165269 checklists10 am: 6.1% of 141029 checklists11 am: 6.1% of 115283 checklists12 pm: 5.9% of 96068 checklists1 pm: 6.1% of 89512 checklists2 pm: 5.7% of 86319 checklists3 pm: 5.5% of 82496 checklists4 pm: 5.3% of 71648 checklists5 pm: 4.7% of 52445 checklists6 pm: 3.6% 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
January5.9%5.1%5.0%4.0%
February3.1%2.8%2.5%2.8%
March2.8%2.8%3.2%3.9%
April5.1%5.8%7.3%6.9%
May5.6%4.1%3.6%2.8%
June2.4%2.1%2.1%2.0%
July2.2%2.1%2.6%2.7%
August3.4%4.3%4.6%5.1%
September6.3%7.0%7.8%9.9%
October10%12%14%15%
November15%14%11%9.0%
December7.3%5.4%5.1%4.7%

Neighboring states

  • Wyoming: arrives early April, 23 weeks earlier than Colorado
  • New Mexico: arrives mid July, 9 weeks earlier than Colorado
  • Utah: arrives the second week of October, 2 weeks later than Colorado
  • Nebraska: arrives the second week of March, 22 weeks later than Colorado

Common questions

When do Pied-billed Grebes arrive in Colorado?
Pied-billed Grebes are in Colorado all year, but most are here in fall: numbers build from late September, peak in late October (15% of checklists), and fall back by late November. In the quietest week (mid June) they are still on about 2.0% of checklists.
When do Pied-billed Grebes leave Colorado?
Pied-billed Grebes never fully leave Colorado: numbers fall back below half their usual rate by late November, but some are still reported in every week, about 2.0% of checklists at the low.
When is the best time to see a Pied-billed Grebe in Colorado?
The Pied-billed Grebe is reported most often in late October, on about 15% of Colorado checklists.
Where in Colorado are Pied-billed Grebes seen most often?
By county, Huerfano County, Delta County, and Broomfield County have the highest peak reporting rates for the Pied-billed Grebe (counties with at least 200 checklists).