WhenToBird

Sialia currucoides · Turdidae

When Do Mountain Bluebirds Arrive in Colorado?

Adult male Mountain Bluebird
Photo: Josiah Londerée, CC BY 4.0 via iNaturalist

Mountain Bluebirds are winter birds in Colorado: the first arrive in late February, they are common by early March, peak in late March (7.7% of checklists), and most are gone by late October.

When to look

First arrivalsFeb 22-28late February
Common byMar 1-7early March
PeakMar 22-31late March
Most gone byOct 22-31late October

Best: late March. First arrivals late February; most are gone by late October. Peak: on about 7.7% of Colorado checklists.

  1. Januncommon
  2. Febuncommon
  3. Marpeak season
  4. Aprpeak season
  5. Maypeak season
  6. Junpeak season
  7. Julpeak season
  8. Augcommon
  9. Seppeak season
  10. Octpeak season
  11. Novuncommon
  12. Decuncommon

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

0%5%10%Jan 1-7: 1.4% of 32254 checklistsJan 8-14: 1.4% of 23278 checklistsJan 15-21: 1.3% of 22933 checklistsJan 22-31: 1.1% of 30856 checklistsFeb 1-7: 1.0% of 21464 checklistsFeb 8-14: 0.9% of 22910 checklistsFeb 15-21: 1.1% of 28739 checklistsFeb 22-28: 2.1% of 21833 checklistsMar 1-7: 3.9% of 23066 checklistsMar 8-14: 6.1% of 23783 checklistsMar 15-21: 8.2% of 24797 checklistsMar 22-31: 7.6% of 38439 checklistsApr 1-7: 7.4% of 31676 checklistsApr 8-14: 6.9% of 35092 checklistsApr 15-21: 7.0% of 36778 checklistsApr 22-30: 5.1% of 50885 checklistsMay 1-7: 4.1% of 44186 checklistsMay 8-14: 4.3% of 49011 checklistsMay 15-21: 5.0% of 40784 checklistsMay 22-31: 5.9% of 53073 checklistsJun 1-7: 6.8% of 32432 checklistsJun 8-14: 7.2% of 29978 checklistsJun 15-21: 7.3% of 29457 checklistsJun 22-30: 7.4% of 36072 checklistsJul 1-7: 7.5% of 28857 checklistsJul 8-14: 6.7% of 27224 checklistsJul 15-21: 6.3% of 27629 checklistsJul 22-31: 5.6% of 37318 checklistsAug 1-7: 5.1% of 25893 checklistsAug 8-14: 5.0% of 24870 checklistsAug 15-21: 4.8% of 24035 checklistsAug 22-31: 4.3% of 35691 checklistsSep 1-7: 4.3% of 27068 checklistsSep 8-14: 4.9% of 26709 checklistsSep 15-21: 4.9% of 26098 checklistsSep 22-30: 5.8% of 31550 checklistsOct 1-7: 7.2% of 24110 checklistsOct 8-14: 7.1% of 23352 checklistsOct 15-21: 5.1% of 21895 checklistsOct 22-31: 3.8% of 28319 checklistsNov 1-7: 2.3% of 21698 checklistsNov 8-14: 1.8% of 21061 checklistsNov 15-21: 1.3% of 19855 checklistsNov 22-30: 1.3% of 25798 checklistsDec 1-7: 1.3% of 18626 checklistsDec 8-14: 1.2% of 19004 checklistsDec 15-21: 1.4% of 23103 checklistsDec 22-31: 1.2% 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. Conejos CountyBest the second week of March · 28 checklists that week, 1,636 in all48%
  2. Baca CountyBest early November · 16 checklists that week, 3,209 in all47%
  3. Dolores CountyBest mid April · 64 checklists that week, 2,000 in all45%
  4. Ouray CountyBest early April · 172 checklists that week, 10,572 in all42%
  5. Park CountyBest early April · 184 checklists that week, 11,432 in all37%
  6. Huerfano CountyBest late November · 42 checklists that week, 3,008 in all37%

Best spots

Share of checklists at the peak
  1. Ridgway State Park (north)Ouray County, best early June · 22 checklists that week, 626 in all86%
  2. Sweitzer Lake State ParkDelta County, best the second week of November · 20 checklists that week, 852 in all76%
  3. Billy Creek State Wildlife AreaOuray County, best the second week of May · 27 checklists that week, 361 in all75%
  4. Ridgway State Park (Deer Creek)Ouray County, best late September · 27 checklists that week, 813 in all75%
  5. Joder ReservoirBoulder County, best early March · 21 checklists that week, 232 in all73%
  6. Wrights ReservoirTeller County, best late April · 25 checklists that week, 431 in all72%

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

Best time of day

In Colorado, the Mountain Bluebird is most often listed on checklists started between 9 and 11 am (5.0% of those checklists).

0%2%4%6%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: 4.8% of 71991 checklists7 am: 4.8% of 159189 checklists8 am: 4.9% of 177206 checklists9 am: 5.0% of 165269 checklists10 am: 5.0% of 141029 checklists11 am: 4.8% of 115283 checklists12 pm: 4.3% of 96068 checklists1 pm: 4.2% of 89512 checklists2 pm: 4.2% of 86319 checklists3 pm: 4.1% of 82496 checklists4 pm: 4.0% of 71648 checklists5 pm: 4.4% of 52445 checklists6 pm: 4.4% 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
January1.4%1.4%1.3%1.1%
February1.0%0.9%1.1%2.1%
March3.9%6.1%8.2%7.6%
April7.4%6.9%7.0%5.1%
May4.1%4.3%5.0%5.9%
June6.8%7.2%7.3%7.4%
July7.5%6.7%6.3%5.6%
August5.1%5.0%4.8%4.3%
September4.3%4.9%4.9%5.8%
October7.2%7.1%5.1%3.8%
November2.3%1.8%1.3%1.3%
December1.3%1.2%1.4%1.2%

Neighboring states

  • Wyoming: arrives late February, in the same week than Colorado
  • New Mexico: arrives the second week of October, 18 weeks earlier than Colorado
  • Utah: arrives late February, in the same week than Colorado
  • Nebraska: arrives late April, 8 weeks later than Colorado

Common questions

When do Mountain Bluebirds arrive in Colorado?
Mountain Bluebirds are winter birds in Colorado: the first arrive in late February, they are common by early March, peak in late March (7.7% of checklists), and most are gone by late October.
When do Mountain Bluebirds leave Colorado?
Most Mountain Bluebirds have left Colorado by late October, when reports fall below half their usual rate. Stragglers are still reported until the second week of November.
When is the best time to see a Mountain Bluebird in Colorado?
The Mountain Bluebird is reported most often in late March, on about 7.7% of Colorado checklists.
Where in Colorado are Mountain Bluebirds seen most often?
By county, Conejos County, Baca County, and Dolores County have the highest peak reporting rates for the Mountain Bluebird (counties with at least 200 checklists).