WhenToBird

Junco hyemalis · Passerellidae

When Do Dark-eyed Juncos Arrive in Colorado?

Adult male Dark-eyed Junco
Photo: Jimmy Dee, CC BY-SA 4.0 via iNaturalist

Dark-eyed Juncos are in Colorado all year, but most are here in winter: numbers build from the second week of October, peak in the second week of December (38% of checklists), and fall back by early April. In the quietest week (the second week of May) they are still on about 6.4% of checklists.

When to look

Numbers buildOct 8-14the second week of October
PeakDec 8-14the second week of December
Fall back byApr 1-7early April
FewestMay 8-14the second week of May

Best: the second week of December. Here all year; numbers build from the second week of October and fall back by early April. Peak: on about 38% of Colorado checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marpeak season
  4. Aprcommon
  5. Mayuncommon
  6. Jununcommon
  7. Juluncommon
  8. Auguncommon
  9. Sepuncommon
  10. Octpeak season
  11. Novpeak season
  12. Decpeak season

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

0%10%20%30%40%Jan 1-7: 36% of 32254 checklistsJan 8-14: 35% of 23278 checklistsJan 15-21: 35% of 22933 checklistsJan 22-31: 34% of 30856 checklistsFeb 1-7: 33% of 21464 checklistsFeb 8-14: 36% of 22910 checklistsFeb 15-21: 39% of 28739 checklistsFeb 22-28: 35% of 21833 checklistsMar 1-7: 37% of 23066 checklistsMar 8-14: 37% of 23783 checklistsMar 15-21: 35% of 24797 checklistsMar 22-31: 30% of 38439 checklistsApr 1-7: 24% of 31676 checklistsApr 8-14: 17% of 35092 checklistsApr 15-21: 14% of 36778 checklistsApr 22-30: 9.5% of 50885 checklistsMay 1-7: 6.3% of 44186 checklistsMay 8-14: 6.1% of 49011 checklistsMay 15-21: 6.7% of 40784 checklistsMay 22-31: 7.7% of 53073 checklistsJun 1-7: 8.5% of 32432 checklistsJun 8-14: 10% of 29978 checklistsJun 15-21: 11% of 29457 checklistsJun 22-30: 12% of 36072 checklistsJul 1-7: 13% of 28857 checklistsJul 8-14: 15% of 27224 checklistsJul 15-21: 13% of 27629 checklistsJul 22-31: 11% of 37318 checklistsAug 1-7: 10% of 25893 checklistsAug 8-14: 9.2% of 24870 checklistsAug 15-21: 8.6% of 24035 checklistsAug 22-31: 8.0% of 35691 checklistsSep 1-7: 7.8% of 27068 checklistsSep 8-14: 7.9% of 26709 checklistsSep 15-21: 9.5% of 26098 checklistsSep 22-30: 13% of 31550 checklistsOct 1-7: 18% of 24110 checklistsOct 8-14: 24% of 23352 checklistsOct 15-21: 30% of 21895 checklistsOct 22-31: 35% of 28319 checklistsNov 1-7: 35% of 21698 checklistsNov 8-14: 35% of 21061 checklistsNov 15-21: 37% of 19855 checklistsNov 22-30: 38% of 25798 checklistsDec 1-7: 36% of 18626 checklistsDec 8-14: 39% of 19004 checklistsDec 15-21: 38% of 23103 checklistsDec 22-31: 36% 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. Dolores CountyBest early February · 20 checklists that week, 2,000 in all85%
  2. San Juan CountyBest mid March · 13 checklists that week, 2,012 in all78%
  3. Prowers CountyBest the second week of December · 91 checklists that week, 11,307 in all77%
  4. La Plata CountyBest early November · 292 checklists that week, 21,744 in all71%
  5. Teller CountyBest the second week of December · 101 checklists that week, 11,258 in all67%
  6. El Paso CountyBest early December · 1480 checklists that week, 104,376 in all66%

Best spots

Share of checklists at the peak
  1. NorwoodSan Miguel County, best late November · 29 checklists that week, 1,247 in all100%
  2. Lake QuiviraClear Creek County, best late March · 37 checklists that week, 1,149 in all98%
  3. Valley Reservoir Number One (Pigs Eye)El Paso County, best mid November · 48 checklists that week, 1,702 in all97%
  4. Pike National ForestEl Paso County, best late June · 25 checklists that week, 434 in all95%
  5. Sheldon Lake (east)Larimer County, best the second week of March · 27 checklists that week, 1,413 in all94%

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

Best time of day

In Colorado, the Dark-eyed Junco is most often listed on checklists started between 7 and 9 am (27% of those checklists).

0%10%20%30%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: 19% of 71991 checklists7 am: 28% of 159189 checklists8 am: 25% of 177206 checklists9 am: 23% of 165269 checklists10 am: 21% of 141029 checklists11 am: 20% of 115283 checklists12 pm: 19% of 96068 checklists1 pm: 19% of 89512 checklists2 pm: 19% of 86319 checklists3 pm: 19% of 82496 checklists4 pm: 16% of 71648 checklists5 pm: 12% of 52445 checklists6 pm: 7.9% 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
January36%35%35%34%
February33%36%39%35%
March37%37%35%30%
April24%17%14%9.5%
May6.3%6.1%6.7%7.7%
June8.5%10%11%12%
July13%15%13%11%
August10%9.2%8.6%8.0%
September7.8%7.9%9.5%13%
October18%24%30%35%
November35%35%37%38%
December36%39%38%36%

Neighboring states

  • Wyoming: arrives the second week of February, 16 weeks later than Colorado
  • New Mexico: arrives the second week of October, in the same week than Colorado
  • Utah: arrives the second week of October, in the same week than Colorado
  • Nebraska: arrives early October, 1 week earlier than Colorado

Common questions

When do Dark-eyed Juncos arrive in Colorado?
Dark-eyed Juncos are in Colorado all year, but most are here in winter: numbers build from the second week of October, peak in the second week of December (38% of checklists), and fall back by early April. In the quietest week (the second week of May) they are still on about 6.4% of checklists.
When do Dark-eyed Juncos leave Colorado?
Dark-eyed Juncos never fully leave Colorado: numbers fall back below half their usual rate by early April, but some are still reported in every week, about 6.4% of checklists at the low.
When is the best time to see a Dark-eyed Junco in Colorado?
The Dark-eyed Junco is reported most often in the second week of December, on about 38% of Colorado checklists.
Where in Colorado are Dark-eyed Juncos seen most often?
By county, Dolores County, San Juan County, and Prowers County have the highest peak reporting rates for the Dark-eyed Junco (counties with at least 200 checklists).