WhenToBird

Loxia curvirostra · Fringillidae

When Do Red Crossbills Arrive in Colorado?

Adult male Red Crossbill
Photo: Leslie Alanís, CC BY 4.0 via iNaturalist

Red Crossbills reach Colorado in the second week of December, are common by late February, peak in late July (4.1% of checklists), and most are gone by late October.

When to look

First arrivalsDec 8-14the second week of December
Common byFeb 22-28late February
PeakJul 22-31late July
Most gone byOct 22-31late October

Best: late July. First arrivals the second week of December; most are gone by late October. Peak: on about 4.1% of Colorado checklists.

  1. Januncommon
  2. Febuncommon
  3. Maruncommon
  4. Apruncommon
  5. Maycommon
  6. Juncommon
  7. Julpeak season
  8. Augpeak season
  9. Sepcommon
  10. Octcommon
  11. Novuncommon
  12. Decuncommon

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

0%2%4%6%Jan 1-7: 0.9% of 32254 checklistsJan 8-14: 0.9% of 23278 checklistsJan 15-21: 1.2% of 22933 checklistsJan 22-31: 1.1% of 30856 checklistsFeb 1-7: 1.1% of 21464 checklistsFeb 8-14: 1.0% of 22910 checklistsFeb 15-21: 1.1% of 28739 checklistsFeb 22-28: 1.2% of 21833 checklistsMar 1-7: 1.3% of 23066 checklistsMar 8-14: 1.4% of 23783 checklistsMar 15-21: 1.2% of 24797 checklistsMar 22-31: 1.5% of 38439 checklistsApr 1-7: 1.4% of 31676 checklistsApr 8-14: 1.6% of 35092 checklistsApr 15-21: 1.1% of 36778 checklistsApr 22-30: 1.2% of 50885 checklistsMay 1-7: 1.2% of 44186 checklistsMay 8-14: 1.3% of 49011 checklistsMay 15-21: 1.6% of 40784 checklistsMay 22-31: 1.9% of 53073 checklistsJun 1-7: 2.4% of 32432 checklistsJun 8-14: 2.8% of 29978 checklistsJun 15-21: 2.4% of 29457 checklistsJun 22-30: 2.8% of 36072 checklistsJul 1-7: 2.7% of 28857 checklistsJul 8-14: 3.4% of 27224 checklistsJul 15-21: 4.0% of 27629 checklistsJul 22-31: 4.3% of 37318 checklistsAug 1-7: 4.1% of 25893 checklistsAug 8-14: 3.8% of 24870 checklistsAug 15-21: 3.4% of 24035 checklistsAug 22-31: 3.1% of 35691 checklistsSep 1-7: 2.6% of 27068 checklistsSep 8-14: 2.4% of 26709 checklistsSep 15-21: 2.2% of 26098 checklistsSep 22-30: 1.9% of 31550 checklistsOct 1-7: 1.8% of 24110 checklistsOct 8-14: 1.5% of 23352 checklistsOct 15-21: 1.4% of 21895 checklistsOct 22-31: 1.2% of 28319 checklistsNov 1-7: 1.2% of 21698 checklistsNov 8-14: 1.0% of 21061 checklistsNov 15-21: 1.0% of 19855 checklistsNov 22-30: 0.8% of 25798 checklistsDec 1-7: 0.9% of 18626 checklistsDec 8-14: 1.1% of 19004 checklistsDec 15-21: 1.1% of 23103 checklistsDec 22-31: 1.0% 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. Grand CountyBest mid March · 97 checklists that week, 11,286 in all19%
  2. Lake CountyBest early April · 10 checklists that week, 2,361 in all19%
  3. Clear Creek CountyBest early September · 209 checklists that week, 8,581 in all16%
  4. Teller CountyBest late August · 413 checklists that week, 11,258 in all16%
  5. Park CountyBest early April · 184 checklists that week, 11,432 in all15%
  6. Summit CountyBest mid April · 381 checklists that week, 14,176 in all15%

Best spots

Share of checklists at the peak
  1. Eagles Nest WildernessSummit County, best late July · 63 checklists that week, 185 in all62%
  2. Manitou Park LakeTeller County, best late August · 60 checklists that week, 1,376 in all57%
  3. Homestead Ranch Regional ParkEl Paso County, best late March · 20 checklists that week, 281 in all48%
  4. Mesa Cortina/Wildemest BufferSummit County, best late April · 65 checklists that week, 596 in all42%
  5. Wrights ReservoirTeller County, best mid May · 23 checklists that week, 431 in all40%
  6. Walker Ranch ParkBoulder County, best mid July · 22 checklists that week, 365 in all40%

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

Best time of day

In Colorado, the Red Crossbill is most often listed on checklists started between 6 and 8 am (2.9% of those checklists).

0%1%2%3%4%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: 3.3% of 71991 checklists7 am: 2.7% of 159189 checklists8 am: 2.2% of 177206 checklists9 am: 2.0% of 165269 checklists10 am: 1.8% of 141029 checklists11 am: 1.6% of 115283 checklists12 pm: 1.4% of 96068 checklists1 pm: 1.5% of 89512 checklists2 pm: 1.3% of 86319 checklists3 pm: 1.3% of 82496 checklists4 pm: 1.2% of 71648 checklists5 pm: 1.2% of 52445 checklists6 pm: 1.0% 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
January0.9%0.9%1.2%1.1%
February1.1%1.0%1.1%1.2%
March1.3%1.4%1.2%1.5%
April1.4%1.6%1.1%1.2%
May1.2%1.3%1.6%1.9%
June2.4%2.8%2.4%2.8%
July2.7%3.4%4.0%4.3%
August4.1%3.8%3.4%3.1%
September2.6%2.4%2.2%1.9%
October1.8%1.5%1.4%1.2%
November1.2%1.0%1.0%0.8%
December0.9%1.1%1.1%1.0%

Neighboring states

  • Wyoming: arrives mid April, 17 weeks later than Colorado
  • New Mexico: arrives mid January, 5 weeks later than Colorado
  • Utah: arrives the second week of June, 24 weeks earlier than Colorado
  • Nebraska: arrives late April, 18 weeks later than Colorado

Common questions

When do Red Crossbills arrive in Colorado?
Red Crossbills reach Colorado in the second week of December, are common by late February, peak in late July (4.1% of checklists), and most are gone by late October.
When do Red Crossbills leave Colorado?
Most Red Crossbills 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 Red Crossbill in Colorado?
The Red Crossbill is reported most often in late July, on about 4.1% of Colorado checklists.
Where in Colorado are Red Crossbills seen most often?
By county, Grand County, Lake County, and Clear Creek County have the highest peak reporting rates for the Red Crossbill (counties with at least 200 checklists).