WhenToBird

Haemorhous cassinii · Fringillidae

When Do Cassin's Finches Arrive in Colorado?

Adult male Cassin's Finch
Photo: Craig Martin, CC0 1.0 via iNaturalist

Cassin's Finches reach Colorado in mid September, are common by the second week of October, peak in the second week of April (3.7% of checklists), and most are gone by the second week of August.

When to look

First arrivalsSep 15-21mid September
Common byOct 8-14the second week of October
PeakApr 8-14the second week of April
Most gone byAug 8-14the second week of August

Best: the second week of April. First arrivals mid September; most are gone by the second week of August. Peak: on about 3.7% of Colorado checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marpeak season
  4. Aprpeak season
  5. Maypeak season
  6. Juncommon
  7. Julcommon
  8. Augcommon
  9. Sepcommon
  10. Octcommon
  11. Novcommon
  12. Decpeak season

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

0%1%2%3%4%Jan 1-7: 3.2% of 32254 checklistsJan 8-14: 3.1% of 23278 checklistsJan 15-21: 3.3% of 22933 checklistsJan 22-31: 3.1% of 30856 checklistsFeb 1-7: 3.0% of 21464 checklistsFeb 8-14: 2.9% of 22910 checklistsFeb 15-21: 3.3% of 28739 checklistsFeb 22-28: 3.1% of 21833 checklistsMar 1-7: 3.1% of 23066 checklistsMar 8-14: 3.0% of 23783 checklistsMar 15-21: 3.2% of 24797 checklistsMar 22-31: 3.3% of 38439 checklistsApr 1-7: 3.3% of 31676 checklistsApr 8-14: 3.9% of 35092 checklistsApr 15-21: 3.8% of 36778 checklistsApr 22-30: 3.1% of 50885 checklistsMay 1-7: 2.8% of 44186 checklistsMay 8-14: 2.6% of 49011 checklistsMay 15-21: 2.4% of 40784 checklistsMay 22-31: 2.6% of 53073 checklistsJun 1-7: 2.8% of 32432 checklistsJun 8-14: 2.4% of 29978 checklistsJun 15-21: 2.3% of 29457 checklistsJun 22-30: 2.6% of 36072 checklistsJul 1-7: 2.7% of 28857 checklistsJul 8-14: 2.8% of 27224 checklistsJul 15-21: 2.5% of 27629 checklistsJul 22-31: 2.6% of 37318 checklistsAug 1-7: 2.2% of 25893 checklistsAug 8-14: 1.9% of 24870 checklistsAug 15-21: 1.6% of 24035 checklistsAug 22-31: 1.2% of 35691 checklistsSep 1-7: 1.1% of 27068 checklistsSep 8-14: 1.0% of 26709 checklistsSep 15-21: 1.4% of 26098 checklistsSep 22-30: 1.5% of 31550 checklistsOct 1-7: 1.9% of 24110 checklistsOct 8-14: 1.9% of 23352 checklistsOct 15-21: 2.1% of 21895 checklistsOct 22-31: 2.1% of 28319 checklistsNov 1-7: 1.6% of 21698 checklistsNov 8-14: 1.8% of 21061 checklistsNov 15-21: 1.9% of 19855 checklistsNov 22-30: 2.3% of 25798 checklistsDec 1-7: 2.2% of 18626 checklistsDec 8-14: 2.7% of 19004 checklistsDec 15-21: 2.5% of 23103 checklistsDec 22-31: 2.9% 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. San Miguel CountyBest early March · 110 checklists that week, 8,094 in all37%
  2. Clear Creek CountyBest late January · 127 checklists that week, 8,581 in all32%
  3. Dolores CountyBest early April · 35 checklists that week, 2,000 in all29%
  4. Rio Blanco CountyBest the second week of May · 89 checklists that week, 2,806 in all24%
  5. Park CountyBest mid April · 99 checklists that week, 11,432 in all24%
  6. San Juan CountyBest the second week of April · 11 checklists that week, 2,012 in all24%

Best spots

Share of checklists at the peak
  1. NorwoodSan Miguel County, best late April · 22 checklists that week, 1,247 in all87%
  2. Box CanyonOuray County, best late August · 33 checklists that week, 833 in all81%
  3. State Forest State ParkJackson County, best late May · 31 checklists that week, 748 in all79%
  4. Lake QuiviraClear Creek County, best late August · 23 checklists that week, 1,149 in all67%

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

Best time of day

In Colorado, the Cassin's Finch is most often listed on checklists started between 6 and 8 am (4.0% 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: 2.7% of 71991 checklists7 am: 4.6% of 159189 checklists8 am: 3.2% of 177206 checklists9 am: 2.7% of 165269 checklists10 am: 2.4% of 141029 checklists11 am: 2.2% of 115283 checklists12 pm: 2.1% of 96068 checklists1 pm: 2.0% of 89512 checklists2 pm: 2.0% of 86319 checklists3 pm: 1.8% of 82496 checklists4 pm: 1.7% of 71648 checklists5 pm: 1.6% of 52445 checklists6 pm: 1.6% 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
January3.2%3.1%3.3%3.1%
February3.0%2.9%3.3%3.1%
March3.1%3.0%3.2%3.3%
April3.3%3.9%3.8%3.1%
May2.8%2.6%2.4%2.6%
June2.8%2.4%2.3%2.6%
July2.7%2.8%2.5%2.6%
August2.2%1.9%1.6%1.2%
September1.1%1.0%1.4%1.5%
October1.9%1.9%2.1%2.1%
November1.6%1.8%1.9%2.3%
December2.2%2.7%2.5%2.9%

Neighboring states

  • Wyoming: arrives the second week of January, 15 weeks later than Colorado
  • New Mexico: arrives mid September, in the same week than Colorado
  • Utah: arrives the second week of January, 15 weeks later than Colorado
  • Arizona: arrives early October, 2 weeks later than Colorado

Common questions

When do Cassin's Finches arrive in Colorado?
Cassin's Finches reach Colorado in mid September, are common by the second week of October, peak in the second week of April (3.7% of checklists), and most are gone by the second week of August.
When do Cassin's Finches leave Colorado?
Most Cassin's Finches have left Colorado by the second week of August, when reports fall below half their usual rate. Stragglers are still reported until late August.
When is the best time to see a Cassin's Finch in Colorado?
The Cassin's Finch is reported most often in the second week of April, on about 3.7% of Colorado checklists.
Where in Colorado are Cassin's Finches seen most often?
By county, San Miguel County, Clear Creek County, and Dolores County have the highest peak reporting rates for the Cassin's Finch (counties with at least 200 checklists).