WhenToBird

Haemorhous cassinii · Fringillidae

When Do Cassin's Finches Arrive in Idaho?

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

Cassin's Finches reach Idaho in mid January, are common by the second week of April, peak in the second week of May (12% of checklists), and most are gone by early October.

When to look

First arrivalsJan 15-21mid January
Common byApr 8-14the second week of April
PeakMay 8-14the second week of May
Most gone byOct 1-7early October

Best: the second week of May. First arrivals mid January; most are gone by early October. Peak: on about 12% of Idaho checklists.

  1. Janrare
  2. Febuncommon
  3. Maruncommon
  4. Aprpeak season
  5. Maypeak season
  6. Junpeak season
  7. Julpeak season
  8. Augcommon
  9. Sepcommon
  10. Octuncommon
  11. Novrare
  12. Decrare

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

0%5%10%15%Jan 1-7: 0.7% of 9357 checklistsJan 8-14: 1.1% of 6408 checklistsJan 15-21: 0.9% of 6358 checklistsJan 22-31: 1.1% of 8601 checklistsFeb 1-7: 1.2% of 5611 checklistsFeb 8-14: 2.4% of 6090 checklistsFeb 15-21: 2.0% of 7973 checklistsFeb 22-28: 1.8% of 5866 checklistsMar 1-7: 2.3% of 6144 checklistsMar 8-14: 2.1% of 6456 checklistsMar 15-21: 2.2% of 6786 checklistsMar 22-31: 2.7% of 9539 checklistsApr 1-7: 4.0% of 7202 checklistsApr 8-14: 5.5% of 7608 checklistsApr 15-21: 7.0% of 8069 checklistsApr 22-30: 9.5% of 10973 checklistsMay 1-7: 12% of 9481 checklistsMay 8-14: 12% of 11318 checklistsMay 15-21: 11% of 9141 checklistsMay 22-31: 10% of 13984 checklistsJun 1-7: 10% of 8897 checklistsJun 8-14: 10% of 8504 checklistsJun 15-21: 10% of 8078 checklistsJun 22-30: 10% of 9665 checklistsJul 1-7: 10% of 7144 checklistsJul 8-14: 9.8% of 6557 checklistsJul 15-21: 10% of 6430 checklistsJul 22-31: 9.4% of 8696 checklistsAug 1-7: 7.6% of 5896 checklistsAug 8-14: 7.4% of 5643 checklistsAug 15-21: 6.8% of 6151 checklistsAug 22-31: 5.0% of 7863 checklistsSep 1-7: 4.5% of 5769 checklistsSep 8-14: 4.4% of 5646 checklistsSep 15-21: 4.5% of 5460 checklistsSep 22-30: 5.3% of 6363 checklistsOct 1-7: 4.6% of 4980 checklistsOct 8-14: 2.4% of 5096 checklistsOct 15-21: 2.2% of 4878 checklistsOct 22-31: 1.6% of 6426 checklistsNov 1-7: 1.0% of 4822 checklistsNov 8-14: 1.1% of 4999 checklistsNov 15-21: 0.8% of 4601 checklistsNov 22-30: 0.9% of 6027 checklistsDec 1-7: 0.7% of 4180 checklistsDec 8-14: 0.6% of 4775 checklistsDec 15-21: 0.6% of 6522 checklistsDec 22-31: 0.7% of 7792 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 Idaho 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 Idaho

Best counties

Share of checklists at the peak
  1. Adams CountyBest mid May · 147 checklists that week, 5,826 in all63%
  2. Bear Lake CountyBest early March · 10 checklists that week, 1,581 in all38%
  3. Boise CountyBest late July · 255 checklists that week, 6,761 in all37%
  4. Butte CountyBest the second week of March · 12 checklists that week, 1,276 in all35%
  5. Valley CountyBest mid May · 202 checklists that week, 8,991 in all30%
  6. Blaine CountyBest the second week of May · 402 checklists that week, 12,004 in all30%

Best spots

Share of checklists at the peak
  1. Fall CreekValley County, best late May · 28 checklists that week, 539 in all86%
  2. Aldape SummitAda County, best late May · 30 checklists that week, 210 in all65%
  3. Bogus Basin State ParkBoise County, best early July · 29 checklists that week, 339 in all54%
  4. Lake ClevelandCassia County, best early August · 21 checklists that week, 110 in all52%
  5. Sawtooth National Forest (Little Fork Spring)Cassia County, best early June · 21 checklists that week, 406 in all51%

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

Best time of day

In Idaho, the Cassin's Finch is most often listed on checklists started between 6 and 8 am (10% of those checklists).

0%5%10%15%12 am: too few checklists (180) to judge1 am: too few checklists (176) to judge2 am: too few checklists (169) to judge3 am: too few checklists (164) to judge4 am: too few checklists (450) to judge5 am: too few checklists (2270) to judge6 am: 12% of 9122 checklists7 am: 9.3% of 22204 checklists8 am: 10% of 38672 checklists9 am: 5.7% of 38930 checklists10 am: 4.8% of 37338 checklists11 am: 4.6% of 33508 checklists12 pm: 3.7% of 28544 checklists1 pm: 3.3% of 25774 checklists2 pm: 3.1% of 24296 checklists3 pm: 3.0% of 21784 checklists4 pm: 3.7% of 19051 checklists5 pm: 4.9% of 14150 checklists6 pm: 5.3% of 10014 checklists7 pm: 4.8% of 7495 checklists8 pm: too few checklists (4352) to judge9 pm: too few checklists (1449) to judge10 pm: too few checklists (525) to judge11 pm: too few checklists (208) 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
January0.7%1.1%0.9%1.1%
February1.2%2.4%2.0%1.8%
March2.3%2.1%2.2%2.7%
April4.0%5.5%7.0%9.5%
May12%12%11%10%
June10%10%10%10%
July10%9.8%10%9.4%
August7.6%7.4%6.8%5.0%
September4.5%4.4%4.5%5.3%
October4.6%2.4%2.2%1.6%
November1.0%1.1%0.8%0.9%
December0.7%0.6%0.6%0.7%

Neighboring states

  • Montana: arrives late January, 1 week later than Idaho
  • Utah: arrives the second week of January, 1 week earlier than Idaho
  • Oregon: arrives early April, 10 weeks later than Idaho
  • Washington: arrives the second week of April, 11 weeks later than Idaho

Common questions

When do Cassin's Finches arrive in Idaho?
Cassin's Finches reach Idaho in mid January, are common by the second week of April, peak in the second week of May (12% of checklists), and most are gone by early October.
When do Cassin's Finches leave Idaho?
Most Cassin's Finches have left Idaho by early October, when reports fall below half their usual rate. Stragglers are still reported until early November.
When is the best time to see a Cassin's Finch in Idaho?
The Cassin's Finch is reported most often in the second week of May, on about 12% of Idaho checklists.
Where in Idaho are Cassin's Finches seen most often?
By county, Adams County, Bear Lake County, and Boise County have the highest peak reporting rates for the Cassin's Finch (counties with at least 200 checklists).