WhenToBird

Salpinctes obsoletus · Troglodytidae

When Do Rock Wrens Arrive in Colorado?

Adult Rock Wren
Photo: Chris Acree, CC BY-SA 4.0 via iNaturalist

Rock Wrens reach Colorado in the second week of April, are common by mid April, peak in mid September (3.6% of checklists), and most are gone by the second week of October.

When to look

First arrivalsApr 8-14the second week of April
Common byApr 15-21mid April
PeakSep 15-21mid September
Most gone byOct 8-14the second week of October

Best: mid September. First arrivals the second week of April; most are gone by the second week of October. Peak: on about 3.6% of Colorado checklists.

  1. Janrare
  2. Febrare
  3. Marrare
  4. Aprcommon
  5. Maypeak season
  6. Junpeak season
  7. Julcommon
  8. Augcommon
  9. Seppeak season
  10. Octcommon
  11. Novrare
  12. Decrare

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

0%1%2%3%4%Jan 1-7: 0.2% of 32254 checklistsJan 8-14: 0.2% of 23278 checklistsJan 15-21: 0.2% of 22933 checklistsJan 22-31: 0.2% of 30856 checklistsFeb 1-7: 0.2% of 21464 checklistsFeb 8-14: 0.1% of 22910 checklistsFeb 15-21: 0.1% of 28739 checklistsFeb 22-28: 0.1% of 21833 checklistsMar 1-7: 0.1% of 23066 checklistsMar 8-14: 0.2% of 23783 checklistsMar 15-21: 0.3% of 24797 checklistsMar 22-31: 0.5% of 38439 checklistsApr 1-7: 0.7% of 31676 checklistsApr 8-14: 1.3% of 35092 checklistsApr 15-21: 1.6% of 36778 checklistsApr 22-30: 2.1% of 50885 checklistsMay 1-7: 2.9% of 44186 checklistsMay 8-14: 2.6% of 49011 checklistsMay 15-21: 3.0% of 40784 checklistsMay 22-31: 2.8% of 53073 checklistsJun 1-7: 3.0% of 32432 checklistsJun 8-14: 3.2% of 29978 checklistsJun 15-21: 3.1% of 29457 checklistsJun 22-30: 2.7% of 36072 checklistsJul 1-7: 2.6% of 28857 checklistsJul 8-14: 2.5% of 27224 checklistsJul 15-21: 2.2% of 27629 checklistsJul 22-31: 1.9% of 37318 checklistsAug 1-7: 1.7% of 25893 checklistsAug 8-14: 1.9% of 24870 checklistsAug 15-21: 1.9% of 24035 checklistsAug 22-31: 2.3% of 35691 checklistsSep 1-7: 3.1% of 27068 checklistsSep 8-14: 3.7% of 26709 checklistsSep 15-21: 3.7% of 26098 checklistsSep 22-30: 3.3% of 31550 checklistsOct 1-7: 2.4% of 24110 checklistsOct 8-14: 1.5% of 23352 checklistsOct 15-21: 0.8% of 21895 checklistsOct 22-31: 0.4% of 28319 checklistsNov 1-7: 0.2% of 21698 checklistsNov 8-14: 0.2% of 21061 checklistsNov 15-21: 0.1% of 19855 checklistsNov 22-30: 0.2% of 25798 checklistsDec 1-7: 0.2% of 18626 checklistsDec 8-14: 0.2% of 19004 checklistsDec 15-21: 0.3% of 23103 checklistsDec 22-31: 0.1% 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. Baca CountyBest late May · 165 checklists that week, 3,209 in all32%
  2. Las Animas CountyBest mid May · 230 checklists that week, 3,491 in all22%
  3. Otero CountyBest mid July · 77 checklists that week, 4,404 in all18%
  4. Lincoln CountyBest late September · 69 checklists that week, 2,707 in all17%
  5. Rio Blanco CountyBest early June · 134 checklists that week, 2,806 in all16%
  6. Moffat CountyBest late May · 320 checklists that week, 5,700 in all16%

Best spots

Share of checklists at the peak
  1. Comanche National GrasslandBaca County, best early May · 28 checklists that week, 219 in all90%
  2. Coal GulchMesa County, best late June · 22 checklists that week, 552 in all86%
  3. Heil Valley Ranch (Plumely Canyon)Boulder County, best the second week of July · 22 checklists that week, 313 in all74%
  4. Rabbit MountainBoulder County, best early July · 41 checklists that week, 1,238 in all68%
  5. Heil Valley Ranch (Geer Canyon)Boulder County, best late May · 36 checklists that week, 227 in all65%
  6. Colorado National MonumentMesa County, best late April · 52 checklists that week, 691 in all63%

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

Best time of day

In Colorado, the Rock Wren is most often listed on checklists started between 6 and 8 am (2.2% of those checklists).

0%1%2%3%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: 2.7% of 71991 checklists7 am: 2.0% of 159189 checklists8 am: 2.0% of 177206 checklists9 am: 1.8% of 165269 checklists10 am: 1.6% of 141029 checklists11 am: 1.4% of 115283 checklists12 pm: 1.3% of 96068 checklists1 pm: 1.1% of 89512 checklists2 pm: 1.0% of 86319 checklists3 pm: 0.9% of 82496 checklists4 pm: 1.0% of 71648 checklists5 pm: 1.2% of 52445 checklists6 pm: 1.2% 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
January0.2%0.2%0.2%0.2%
February0.2%0.1%0.1%0.1%
March0.1%0.2%0.3%0.5%
April0.7%1.3%1.6%2.1%
May2.9%2.6%3.0%2.8%
June3.0%3.2%3.1%2.7%
July2.6%2.5%2.2%1.9%
August1.7%1.9%1.9%2.3%
September3.1%3.7%3.7%3.3%
October2.4%1.5%0.8%0.4%
November0.2%0.2%0.1%0.2%
December0.2%0.2%0.3%0.1%

Neighboring states

  • Wyoming: arrives late April, 2 weeks later than Colorado
  • New Mexico: arrives late February, 6 weeks earlier than Colorado
  • Utah: arrives mid January, 11 weeks earlier than Colorado
  • Nebraska: arrives mid May, 5 weeks later than Colorado

Common questions

When do Rock Wrens arrive in Colorado?
Rock Wrens reach Colorado in the second week of April, are common by mid April, peak in mid September (3.6% of checklists), and most are gone by the second week of October.
When do Rock Wrens leave Colorado?
Most Rock Wrens have left Colorado by the second week of October, when reports fall below half their usual rate.
When is the best time to see a Rock Wren in Colorado?
The Rock Wren is reported most often in mid September, on about 3.6% of Colorado checklists.
Where in Colorado are Rock Wrens seen most often?
By county, Baca County, Las Animas County, and Otero County have the highest peak reporting rates for the Rock Wren (counties with at least 200 checklists).